Resguardo inicial

linux-7.2.3/fs/pstore/Kconfig

@@ -0,0 +1,191 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config PSTORE
+	tristate "Persistent store support"
+	default n
+	help
+	   This option enables generic access to platform level
+	   persistent storage via "pstore" filesystem that can
+	   be mounted as /dev/pstore.  Only useful if you have
+	   a platform level driver that registers with pstore to
+	   provide the data, so you probably should just go say "Y"
+	   (or "M") to a platform specific persistent store driver
+	   (e.g. ACPI_APEI on X86) which will select this for you.
+	   If you don't have a platform persistent store driver,
+	   say N.
+
+config PSTORE_DEFAULT_KMSG_BYTES
+	int "Default kernel log storage space" if EXPERT
+	depends on PSTORE
+	default "10240"
+	help
+	  Defines default size of pstore kernel log storage.
+	  Can be enlarged if needed, not recommended to shrink it.
+
+config PSTORE_COMPRESS
+	bool "Pstore compression (deflate)"
+	depends on PSTORE
+	select ZLIB_INFLATE
+	select ZLIB_DEFLATE
+	default y
+	help
+	  Whether pstore records should be compressed before being written to
+	  the backing store. This is implemented using the zlib 'deflate'
+	  algorithm, using the library implementation instead of using the full
+	  blown crypto API. This reduces the risk of secondary oopses or other
+	  problems while pstore is recording panic metadata.
+
+config PSTORE_CONSOLE
+	bool "Log kernel console messages"
+	depends on PSTORE
+	help
+	  When the option is enabled, pstore will log all kernel
+	  messages, even if no oops or panic happened.
+
+config PSTORE_PMSG
+	bool "Log user space messages"
+	depends on PSTORE
+	select RT_MUTEXES
+	help
+	  When the option is enabled, pstore will export a character
+	  interface /dev/pmsg0 to log user space messages. On reboot
+	  data can be retrieved from /sys/fs/pstore/pmsg-ramoops-[ID].
+
+	  If unsure, say N.
+
+config PSTORE_FTRACE
+	bool "Persistent function tracer"
+	depends on PSTORE
+	depends on FUNCTION_TRACER
+	depends on DEBUG_FS
+	help
+	  With this option kernel traces function calls into a persistent
+	  ram buffer that can be decoded and dumped after reboot through
+	  pstore filesystem. It can be used to determine what function
+	  was last called before a reset or panic.
+
+	  If unsure, say N.
+
+config PSTORE_RAM
+	tristate "Log panic/oops to a RAM buffer"
+	depends on PSTORE
+	depends on HAS_IOMEM
+	select REED_SOLOMON
+	select REED_SOLOMON_ENC8
+	select REED_SOLOMON_DEC8
+	help
+	  This enables panic and oops messages to be logged to a circular
+	  buffer in RAM where it can be read back at some later point.
+
+	  Note that for historical reasons, the module will be named
+	  "ramoops.ko".
+
+	  For more information, see Documentation/admin-guide/ramoops.rst.
+
+config PSTORE_ZONE
+	tristate
+	depends on PSTORE
+	help
+	  The common layer for pstore/blk (and pstore/ram in the future)
+	  to manage storage in zones.
+
+config PSTORE_BLK
+	tristate "Log panic/oops to a block device"
+	depends on PSTORE
+	depends on BLOCK
+	select PSTORE_ZONE
+	default n
+	help
+	  This enables panic and oops message to be logged to a block dev
+	  where it can be read back at some later point.
+
+	  For more information, see Documentation/admin-guide/pstore-blk.rst
+
+	  If unsure, say N.
+
+config PSTORE_BLK_BLKDEV
+	string "block device identifier"
+	depends on PSTORE_BLK
+	default ""
+	help
+	  Which block device should be used for pstore/blk.
+
+	  It accepts the following variants:
+	  1) <hex_major><hex_minor> device number in hexadecimal representation,
+	     with no leading 0x, for example b302.
+	  2) /dev/<disk_name> represents the device name of disk
+	  3) /dev/<disk_name><decimal> represents the device name and number
+	     of partition - device number of disk plus the partition number
+	  4) /dev/<disk_name>p<decimal> - same as the above, this form is
+	     used when disk name of partitioned disk ends with a digit.
+	  5) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
+	     unique id of a partition if the partition table provides it.
+	     The UUID may be either an EFI/GPT UUID, or refer to an MSDOS
+	     partition using the format SSSSSSSS-PP, where SSSSSSSS is a zero-
+	     filled hex representation of the 32-bit "NT disk signature", and PP
+	     is a zero-filled hex representation of the 1-based partition number.
+	  6) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation
+	     to a partition with a known unique id.
+	  7) <major>:<minor> major and minor number of the device separated by
+	     a colon.
+
+	  NOTE that, both Kconfig and module parameters can configure
+	  pstore/blk, but module parameters have priority over Kconfig.
+
+config PSTORE_BLK_KMSG_SIZE
+	int "Size in Kbytes of kmsg dump log to store"
+	depends on PSTORE_BLK
+	default 64
+	help
+	  This just sets size of kmsg dump (oops, panic, etc) log for
+	  pstore/blk. The size is in KB and must be a multiple of 4.
+
+	  NOTE that, both Kconfig and module parameters can configure
+	  pstore/blk, but module parameters have priority over Kconfig.
+
+config PSTORE_BLK_MAX_REASON
+	int "Maximum kmsg dump reason to store"
+	depends on PSTORE_BLK
+	default 2
+	help
+	  The maximum reason for kmsg dumps to store. The default is
+	  2 (KMSG_DUMP_OOPS), see include/linux/kmsg_dump.h's
+	  enum kmsg_dump_reason for more details.
+
+	  NOTE that, both Kconfig and module parameters can configure
+	  pstore/blk, but module parameters have priority over Kconfig.
+
+config PSTORE_BLK_PMSG_SIZE
+	int "Size in Kbytes of pmsg to store"
+	depends on PSTORE_BLK
+	depends on PSTORE_PMSG
+	default 64
+	help
+	  This just sets size of pmsg (pmsg_size) for pstore/blk. The size is
+	  in KB and must be a multiple of 4.
+
+	  NOTE that, both Kconfig and module parameters can configure
+	  pstore/blk, but module parameters have priority over Kconfig.
+
+config PSTORE_BLK_CONSOLE_SIZE
+	int "Size in Kbytes of console log to store"
+	depends on PSTORE_BLK
+	depends on PSTORE_CONSOLE
+	default 64
+	help
+	  This just sets size of console log (console_size) to store via
+	  pstore/blk. The size is in KB and must be a multiple of 4.
+
+	  NOTE that, both Kconfig and module parameters can configure
+	  pstore/blk, but module parameters have priority over Kconfig.
+
+config PSTORE_BLK_FTRACE_SIZE
+	int "Size in Kbytes of ftrace log to store"
+	depends on PSTORE_BLK
+	depends on PSTORE_FTRACE
+	default 64
+	help
+	  This just sets size of ftrace log (ftrace_size) for pstore/blk. The
+	  size is in KB and must be a multiple of 4.
+
+	  NOTE that, both Kconfig and module parameters can configure
+	  pstore/blk, but module parameters have priority over Kconfig.

linux-7.2.3/fs/pstore/Makefile

@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the linux pstorefs routines.
+#
+
+obj-$(CONFIG_PSTORE) += pstore.o
+
+pstore-objs += inode.o platform.o
+pstore-$(CONFIG_PSTORE_FTRACE)	+= ftrace.o
+
+pstore-$(CONFIG_PSTORE_PMSG)	+= pmsg.o
+
+ramoops-objs += ram.o ram_core.o
+obj-$(CONFIG_PSTORE_RAM)	+= ramoops.o
+
+pstore_zone-objs += zone.o
+obj-$(CONFIG_PSTORE_ZONE)	+= pstore_zone.o
+
+pstore_blk-objs += blk.o
+obj-$(CONFIG_PSTORE_BLK)	+= pstore_blk.o

linux-7.2.3/fs/pstore/blk.c

@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Implements pstore backend driver that write to block (or non-block) storage
+ * devices, using the pstore/zone API.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/blkdev.h>
+#include <linux/string.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pstore_blk.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/init_syscalls.h>
+#include <linux/mount.h>
+
+static long kmsg_size = CONFIG_PSTORE_BLK_KMSG_SIZE;
+module_param(kmsg_size, long, 0400);
+MODULE_PARM_DESC(kmsg_size, "kmsg dump record size in kbytes");
+
+static int max_reason = CONFIG_PSTORE_BLK_MAX_REASON;
+module_param(max_reason, int, 0400);
+MODULE_PARM_DESC(max_reason,
+		 "maximum reason for kmsg dump (default 2: Oops and Panic)");
+
+#if IS_ENABLED(CONFIG_PSTORE_PMSG)
+static long pmsg_size = CONFIG_PSTORE_BLK_PMSG_SIZE;
+#else
+static long pmsg_size = -1;
+#endif
+module_param(pmsg_size, long, 0400);
+MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
+
+#if IS_ENABLED(CONFIG_PSTORE_CONSOLE)
+static long console_size = CONFIG_PSTORE_BLK_CONSOLE_SIZE;
+#else
+static long console_size = -1;
+#endif
+module_param(console_size, long, 0400);
+MODULE_PARM_DESC(console_size, "console size in kbytes");
+
+#if IS_ENABLED(CONFIG_PSTORE_FTRACE)
+static long ftrace_size = CONFIG_PSTORE_BLK_FTRACE_SIZE;
+#else
+static long ftrace_size = -1;
+#endif
+module_param(ftrace_size, long, 0400);
+MODULE_PARM_DESC(ftrace_size, "ftrace size in kbytes");
+
+static bool best_effort;
+module_param(best_effort, bool, 0400);
+MODULE_PARM_DESC(best_effort, "use best effort to write (i.e. do not require storage driver pstore support, default: off)");
+
+/*
+ * blkdev - the block device to use for pstore storage
+ * See Documentation/admin-guide/pstore-blk.rst for details.
+ */
+static char blkdev[80] = CONFIG_PSTORE_BLK_BLKDEV;
+module_param_string(blkdev, blkdev, 80, 0400);
+MODULE_PARM_DESC(blkdev, "block device for pstore storage");
+
+/*
+ * All globals must only be accessed under the pstore_blk_lock
+ * during the register/unregister functions.
+ */
+static DEFINE_MUTEX(pstore_blk_lock);
+static struct file *psblk_file;
+static struct pstore_device_info *pstore_device_info;
+
+#define check_size(name, alignsize) ({				\
+	long _##name_ = (name);					\
+	_##name_ = _##name_ <= 0 ? 0 : (_##name_ * 1024);	\
+	if (_##name_ & ((alignsize) - 1)) {			\
+		pr_info(#name " must align to %d\n",		\
+				(alignsize));			\
+		_##name_ = ALIGN(name, (alignsize));		\
+	}							\
+	_##name_;						\
+})
+
+#define verify_size(name, alignsize, enabled) {			\
+	long _##name_;						\
+	if (enabled)						\
+		_##name_ = check_size(name, alignsize);		\
+	else							\
+		_##name_ = 0;					\
+	/* Synchronize module parameters with results. */	\
+	name = _##name_ / 1024;					\
+	dev->zone.name = _##name_;				\
+}
+
+static int __register_pstore_device(struct pstore_device_info *dev)
+{
+	int ret;
+
+	lockdep_assert_held(&pstore_blk_lock);
+
+	if (!dev) {
+		pr_err("NULL device info\n");
+		return -EINVAL;
+	}
+	if (!dev->zone.total_size) {
+		pr_err("zero sized device\n");
+		return -EINVAL;
+	}
+	if (!dev->zone.read) {
+		pr_err("no read handler for device\n");
+		return -EINVAL;
+	}
+	if (!dev->zone.write) {
+		pr_err("no write handler for device\n");
+		return -EINVAL;
+	}
+
+	/* someone already registered before */
+	if (pstore_device_info)
+		return -EBUSY;
+
+	/* zero means no limit on which backends attempt to store. */
+	if (!dev->flags)
+		dev->flags = UINT_MAX;
+
+	/* Copy in module parameters. */
+	verify_size(kmsg_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
+	verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG);
+	verify_size(console_size, 4096, dev->flags & PSTORE_FLAGS_CONSOLE);
+	verify_size(ftrace_size, 4096, dev->flags & PSTORE_FLAGS_FTRACE);
+	dev->zone.max_reason = max_reason;
+
+	/* Initialize required zone ownership details. */
+	dev->zone.name = KBUILD_MODNAME;
+	dev->zone.owner = THIS_MODULE;
+
+	ret = register_pstore_zone(&dev->zone);
+	if (ret == 0)
+		pstore_device_info = dev;
+
+	return ret;
+}
+/**
+ * register_pstore_device() - register non-block device to pstore/blk
+ *
+ * @dev: non-block device information
+ *
+ * Return:
+ * * 0		- OK
+ * * Others	- something error.
+ */
+int register_pstore_device(struct pstore_device_info *dev)
+{
+	int ret;
+
+	mutex_lock(&pstore_blk_lock);
+	ret = __register_pstore_device(dev);
+	mutex_unlock(&pstore_blk_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_pstore_device);
+
+static void __unregister_pstore_device(struct pstore_device_info *dev)
+{
+	lockdep_assert_held(&pstore_blk_lock);
+	if (pstore_device_info && pstore_device_info == dev) {
+		unregister_pstore_zone(&dev->zone);
+		pstore_device_info = NULL;
+	}
+}
+
+/**
+ * unregister_pstore_device() - unregister non-block device from pstore/blk
+ *
+ * @dev: non-block device information
+ */
+void unregister_pstore_device(struct pstore_device_info *dev)
+{
+	mutex_lock(&pstore_blk_lock);
+	__unregister_pstore_device(dev);
+	mutex_unlock(&pstore_blk_lock);
+}
+EXPORT_SYMBOL_GPL(unregister_pstore_device);
+
+static ssize_t psblk_generic_blk_read(char *buf, size_t bytes, loff_t pos)
+{
+	return kernel_read(psblk_file, buf, bytes, &pos);
+}
+
+static ssize_t psblk_generic_blk_write(const char *buf, size_t bytes,
+		loff_t pos)
+{
+	/* Console/Ftrace backend may handle buffer until flush dirty zones */
+	if (in_interrupt() || irqs_disabled())
+		return -EBUSY;
+	return kernel_write(psblk_file, buf, bytes, &pos);
+}
+
+/*
+ * This takes its configuration only from the module parameters now.
+ */
+static int __register_pstore_blk(struct pstore_device_info *dev,
+				 const char *devpath)
+{
+	int ret = -ENODEV;
+
+	lockdep_assert_held(&pstore_blk_lock);
+
+	psblk_file = filp_open(devpath, O_RDWR | O_DSYNC | O_NOATIME | O_EXCL, 0);
+	if (IS_ERR(psblk_file)) {
+		ret = PTR_ERR(psblk_file);
+		pr_err("failed to open '%s': %d!\n", devpath, ret);
+		goto err;
+	}
+
+	if (!S_ISBLK(file_inode(psblk_file)->i_mode)) {
+		pr_err("'%s' is not block device!\n", devpath);
+		goto err_fput;
+	}
+
+	dev->zone.total_size =
+		bdev_nr_bytes(I_BDEV(psblk_file->f_mapping->host));
+
+	ret = __register_pstore_device(dev);
+	if (ret)
+		goto err_fput;
+
+	return 0;
+
+err_fput:
+	fput(psblk_file);
+err:
+	psblk_file = NULL;
+
+	return ret;
+}
+
+/* get information of pstore/blk */
+int pstore_blk_get_config(struct pstore_blk_config *info)
+{
+	strscpy(info->device, blkdev);
+	info->max_reason = max_reason;
+	info->kmsg_size = check_size(kmsg_size, 4096);
+	info->pmsg_size = check_size(pmsg_size, 4096);
+	info->ftrace_size = check_size(ftrace_size, 4096);
+	info->console_size = check_size(console_size, 4096);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pstore_blk_get_config);
+
+
+#ifndef MODULE
+static const char devname[] = "/dev/pstore-blk";
+static __init const char *early_boot_devpath(const char *initial_devname)
+{
+	/*
+	 * During early boot the real root file system hasn't been
+	 * mounted yet, and no device nodes are present yet. Use the
+	 * same scheme to find the device that we use for mounting
+	 * the root file system.
+	 */
+	dev_t dev;
+
+	if (early_lookup_bdev(initial_devname, &dev)) {
+		pr_err("failed to resolve '%s'!\n", initial_devname);
+		return initial_devname;
+	}
+
+	init_unlink(devname);
+	init_mknod(devname, S_IFBLK | 0600, new_encode_dev(dev));
+
+	return devname;
+}
+#else
+static inline const char *early_boot_devpath(const char *initial_devname)
+{
+	return initial_devname;
+}
+#endif
+
+static int __init __best_effort_init(void)
+{
+	struct pstore_device_info *best_effort_dev;
+	int ret;
+
+	/* No best-effort mode requested. */
+	if (!best_effort)
+		return 0;
+
+	/* Reject an empty blkdev. */
+	if (!blkdev[0]) {
+		pr_err("blkdev empty with best_effort=Y\n");
+		return -EINVAL;
+	}
+
+	best_effort_dev = kzalloc_obj(*best_effort_dev);
+	if (!best_effort_dev)
+		return -ENOMEM;
+
+	best_effort_dev->zone.read = psblk_generic_blk_read;
+	best_effort_dev->zone.write = psblk_generic_blk_write;
+
+	ret = __register_pstore_blk(best_effort_dev,
+				    early_boot_devpath(blkdev));
+	if (ret)
+		kfree(best_effort_dev);
+	else
+		pr_info("attached %s (%lu) (no dedicated panic_write!)\n",
+			blkdev, best_effort_dev->zone.total_size);
+
+	return ret;
+}
+
+static void __exit __best_effort_exit(void)
+{
+	/*
+	 * Currently, the only user of psblk_file is best_effort, so
+	 * we can assume that pstore_device_info is associated with it.
+	 * Once there are "real" blk devices, there will need to be a
+	 * dedicated pstore_blk_info, etc.
+	 */
+	if (psblk_file) {
+		struct pstore_device_info *dev = pstore_device_info;
+
+		__unregister_pstore_device(dev);
+		kfree(dev);
+		fput(psblk_file);
+		psblk_file = NULL;
+	}
+}
+
+static int __init pstore_blk_init(void)
+{
+	int ret;
+
+	mutex_lock(&pstore_blk_lock);
+	ret = __best_effort_init();
+	mutex_unlock(&pstore_blk_lock);
+
+	return ret;
+}
+late_initcall(pstore_blk_init);
+
+static void __exit pstore_blk_exit(void)
+{
+	mutex_lock(&pstore_blk_lock);
+	__best_effort_exit();
+	/* If we've been asked to unload, unregister any remaining device. */
+	__unregister_pstore_device(pstore_device_info);
+	mutex_unlock(&pstore_blk_lock);
+}
+module_exit(pstore_blk_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>");
+MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
+MODULE_DESCRIPTION("pstore backend for block devices");

linux-7.2.3/fs/pstore/ftrace.c

@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2012  Google, Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/compiler.h>
+#include <linux/irqflags.h>
+#include <linux/percpu.h>
+#include <linux/smp.h>
+#include <linux/atomic.h>
+#include <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/ftrace.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/err.h>
+#include <linux/cache.h>
+#include <linux/slab.h>
+#include <asm/barrier.h>
+#include <asm/setup.h>
+#include "internal.h"
+
+/* This doesn't need to be atomic: speed is chosen over correctness here. */
+static u64 pstore_ftrace_stamp;
+
+static inline unsigned long adjust_ip(unsigned long ip)
+{
+#if defined(CONFIG_RANDOMIZE_BASE) && !defined(PSTORE_CPU_IN_IP) && IS_BUILTIN(CONFIG_PSTORE)
+	if (core_kernel_text(ip))
+		return ip - kaslr_offset();
+
+	__clear_bit(BITS_PER_LONG - 1, &ip);
+#endif
+	return ip;
+}
+
+inline unsigned long decode_ip(unsigned long ip)
+{
+#if defined(CONFIG_RANDOMIZE_BASE) && !defined(PSTORE_CPU_IN_IP) && IS_BUILTIN(CONFIG_PSTORE)
+	if (test_bit(BITS_PER_LONG - 1, &ip))
+		return ip + kaslr_offset();
+
+	__set_bit(BITS_PER_LONG - 1, &ip);
+
+#endif
+	return ip;
+}
+
+static void notrace pstore_ftrace_call(unsigned long ip,
+				       unsigned long parent_ip,
+				       struct ftrace_ops *op,
+				       struct ftrace_regs *fregs)
+{
+	int bit;
+	unsigned long flags;
+	struct pstore_ftrace_record rec = {};
+	struct pstore_record record = {
+		.type = PSTORE_TYPE_FTRACE,
+		.buf = (char *)&rec,
+		.size = sizeof(rec),
+		.psi = psinfo,
+	};
+
+	if (unlikely(oops_in_progress))
+		return;
+
+	bit = ftrace_test_recursion_trylock(ip, parent_ip);
+	if (bit < 0)
+		return;
+
+	local_irq_save(flags);
+
+	rec.ip = adjust_ip(ip);
+	rec.parent_ip = adjust_ip(parent_ip);
+	pstore_ftrace_write_timestamp(&rec, pstore_ftrace_stamp++);
+	pstore_ftrace_encode_cpu(&rec, raw_smp_processor_id());
+	psinfo->write(&record);
+
+	local_irq_restore(flags);
+	ftrace_test_recursion_unlock(bit);
+}
+
+static struct ftrace_ops pstore_ftrace_ops __read_mostly = {
+	.func	= pstore_ftrace_call,
+};
+
+static DEFINE_MUTEX(pstore_ftrace_lock);
+static bool record_ftrace;
+module_param(record_ftrace, bool, 0400);
+MODULE_PARM_DESC(record_ftrace,
+		 "enable ftrace recording immediately (default: off)");
+
+static int pstore_set_ftrace_enabled(bool on)
+{
+	ssize_t ret;
+
+	if (on == record_ftrace)
+		return 0;
+
+	if (on) {
+		ftrace_ops_set_global_filter(&pstore_ftrace_ops);
+		ret = register_ftrace_function(&pstore_ftrace_ops);
+	} else {
+		ret = unregister_ftrace_function(&pstore_ftrace_ops);
+	}
+
+	if (ret) {
+		pr_err("%s: unable to %sregister ftrace ops: %zd\n",
+		       __func__, on ? "" : "un", ret);
+	} else {
+		record_ftrace = on;
+	}
+
+	return ret;
+}
+
+static ssize_t pstore_ftrace_knob_write(struct file *f, const char __user *buf,
+					size_t count, loff_t *ppos)
+{
+	u8 on;
+	ssize_t ret;
+
+	ret = kstrtou8_from_user(buf, count, 2, &on);
+	if (ret)
+		return ret;
+
+	mutex_lock(&pstore_ftrace_lock);
+	ret = pstore_set_ftrace_enabled(on);
+	mutex_unlock(&pstore_ftrace_lock);
+
+	if (ret == 0)
+		ret = count;
+
+	return ret;
+}
+
+static ssize_t pstore_ftrace_knob_read(struct file *f, char __user *buf,
+				       size_t count, loff_t *ppos)
+{
+	char val[] = { '0' + record_ftrace, '\n' };
+
+	return simple_read_from_buffer(buf, count, ppos, val, sizeof(val));
+}
+
+static const struct file_operations pstore_knob_fops = {
+	.open	= simple_open,
+	.read	= pstore_ftrace_knob_read,
+	.write	= pstore_ftrace_knob_write,
+};
+
+static struct dentry *pstore_ftrace_dir;
+
+void pstore_register_ftrace(void)
+{
+	if (!psinfo->write)
+		return;
+
+	pstore_ftrace_dir = debugfs_create_dir("pstore", NULL);
+
+	pstore_set_ftrace_enabled(record_ftrace);
+
+	debugfs_create_file("record_ftrace", 0600, pstore_ftrace_dir, NULL,
+			    &pstore_knob_fops);
+}
+
+void pstore_unregister_ftrace(void)
+{
+	mutex_lock(&pstore_ftrace_lock);
+	if (record_ftrace) {
+		unregister_ftrace_function(&pstore_ftrace_ops);
+		record_ftrace = false;
+	}
+	mutex_unlock(&pstore_ftrace_lock);
+
+	debugfs_remove_recursive(pstore_ftrace_dir);
+}
+
+ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size,
+				  const char *src_log, size_t src_log_size)
+{
+	size_t dest_size, src_size, total, dest_off, src_off;
+	size_t dest_idx = 0, src_idx = 0, merged_idx = 0;
+	void *merged_buf;
+	struct pstore_ftrace_record *drec, *srec, *mrec;
+	size_t record_size = sizeof(struct pstore_ftrace_record);
+
+	dest_off = *dest_log_size % record_size;
+	dest_size = *dest_log_size - dest_off;
+
+	src_off = src_log_size % record_size;
+	src_size = src_log_size - src_off;
+
+	total = dest_size + src_size;
+	merged_buf = kmalloc(total, GFP_KERNEL);
+	if (!merged_buf)
+		return -ENOMEM;
+
+	drec = (struct pstore_ftrace_record *)(*dest_log + dest_off);
+	srec = (struct pstore_ftrace_record *)(src_log + src_off);
+	mrec = (struct pstore_ftrace_record *)(merged_buf);
+
+	while (dest_size > 0 && src_size > 0) {
+		if (pstore_ftrace_read_timestamp(&drec[dest_idx]) <
+		    pstore_ftrace_read_timestamp(&srec[src_idx])) {
+			mrec[merged_idx++] = drec[dest_idx++];
+			dest_size -= record_size;
+		} else {
+			mrec[merged_idx++] = srec[src_idx++];
+			src_size -= record_size;
+		}
+	}
+
+	while (dest_size > 0) {
+		mrec[merged_idx++] = drec[dest_idx++];
+		dest_size -= record_size;
+	}
+
+	while (src_size > 0) {
+		mrec[merged_idx++] = srec[src_idx++];
+		src_size -= record_size;
+	}
+
+	kfree(*dest_log);
+	*dest_log = merged_buf;
+	*dest_log_size = total;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pstore_ftrace_combine_log);

linux-7.2.3/fs/pstore/inode.c

@@ -0,0 +1,528 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Persistent Storage - ramfs parts.
+ *
+ * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/fsnotify.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/string.h>
+#include <linux/seq_file.h>
+#include <linux/ramfs.h>
+#include <linux/fs_parser.h>
+#include <linux/fs_context.h>
+#include <linux/sched.h>
+#include <linux/magic.h>
+#include <linux/pstore.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/cleanup.h>
+
+#include "internal.h"
+
+#define	PSTORE_NAMELEN	64
+
+static DEFINE_MUTEX(records_list_lock);
+static LIST_HEAD(records_list);
+
+static DEFINE_MUTEX(pstore_sb_lock);
+static struct super_block *pstore_sb;
+
+DEFINE_FREE(pstore_iput, struct inode *, if (_T) iput(_T))
+
+struct pstore_private {
+	struct list_head list;
+	struct dentry *dentry;
+	struct pstore_record *record;
+	size_t total_size;
+};
+
+struct pstore_ftrace_seq_data {
+	const void *ptr;
+	size_t off;
+	size_t size;
+};
+
+#define REC_SIZE sizeof(struct pstore_ftrace_record)
+
+static void free_pstore_private(struct pstore_private *private)
+{
+	if (!private)
+		return;
+	if (private->record) {
+		kvfree(private->record->buf);
+		kfree(private->record->priv);
+		kfree(private->record);
+	}
+	kfree(private);
+}
+DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T));
+
+static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data __free(kfree) = NULL;
+
+	data = kzalloc_obj(*data);
+	if (!data)
+		return NULL;
+
+	data->off = ps->record->size % REC_SIZE;
+	data->off += *pos * REC_SIZE;
+	if (data->off + REC_SIZE > ps->record->size)
+		return NULL;
+
+	return_ptr(data);
+}
+
+static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
+{
+	kfree(v);
+}
+
+static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+
+	(*pos)++;
+	data->off += REC_SIZE;
+	if (data->off + REC_SIZE > ps->record->size)
+		return NULL;
+
+	return data;
+}
+
+static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
+{
+	struct pstore_private *ps = s->private;
+	struct pstore_ftrace_seq_data *data = v;
+	struct pstore_ftrace_record *rec;
+	unsigned long ip, parent_ip;
+
+	if (!data)
+		return 0;
+
+	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
+
+	ip = decode_ip(rec->ip);
+	parent_ip = decode_ip(rec->parent_ip);
+	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
+		   pstore_ftrace_decode_cpu(rec),
+		   pstore_ftrace_read_timestamp(rec),
+		   ip, parent_ip, (void *)ip, (void *)parent_ip);
+
+	return 0;
+}
+
+static const struct seq_operations pstore_ftrace_seq_ops = {
+	.start	= pstore_ftrace_seq_start,
+	.next	= pstore_ftrace_seq_next,
+	.stop	= pstore_ftrace_seq_stop,
+	.show	= pstore_ftrace_seq_show,
+};
+
+static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
+						size_t count, loff_t *ppos)
+{
+	struct seq_file *sf = file->private_data;
+	struct pstore_private *ps = sf->private;
+
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
+		return seq_read(file, userbuf, count, ppos);
+	return simple_read_from_buffer(userbuf, count, ppos,
+				       ps->record->buf, ps->total_size);
+}
+
+static int pstore_file_open(struct inode *inode, struct file *file)
+{
+	struct pstore_private *ps = inode->i_private;
+	struct seq_file *sf;
+	int err;
+	const struct seq_operations *sops = NULL;
+
+	if (ps->record->type == PSTORE_TYPE_FTRACE)
+		sops = &pstore_ftrace_seq_ops;
+
+	err = seq_open(file, sops);
+	if (err < 0)
+		return err;
+
+	sf = file->private_data;
+	sf->private = ps;
+
+	return 0;
+}
+
+static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
+{
+	struct seq_file *sf = file->private_data;
+
+	if (sf->op)
+		return seq_lseek(file, off, whence);
+	return default_llseek(file, off, whence);
+}
+
+static const struct file_operations pstore_file_operations = {
+	.open		= pstore_file_open,
+	.read		= pstore_file_read,
+	.llseek		= pstore_file_llseek,
+	.release	= seq_release,
+};
+
+/*
+ * When a file is unlinked from our file system we call the
+ * platform driver to erase the record from persistent store.
+ */
+static int pstore_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct pstore_private *p = d_inode(dentry)->i_private;
+	struct pstore_record *record = p->record;
+
+	if (!record->psi->erase)
+		return -EPERM;
+
+	/* Make sure we can't race while removing this file. */
+	scoped_guard(mutex, &records_list_lock) {
+		if (!list_empty(&p->list))
+			list_del_init(&p->list);
+		else
+			return -ENOENT;
+		p->dentry = NULL;
+	}
+
+	scoped_guard(mutex, &record->psi->read_mutex)
+		record->psi->erase(record);
+
+	return simple_unlink(dir, dentry);
+}
+
+static void pstore_evict_inode(struct inode *inode)
+{
+	struct pstore_private	*p = inode->i_private;
+
+	clear_inode(inode);
+	free_pstore_private(p);
+}
+
+static const struct inode_operations pstore_dir_inode_operations = {
+	.lookup		= simple_lookup,
+	.unlink		= pstore_unlink,
+};
+
+static struct inode *pstore_get_inode(struct super_block *sb)
+{
+	struct inode *inode = new_inode(sb);
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		simple_inode_init_ts(inode);
+	}
+	return inode;
+}
+
+enum {
+	Opt_kmsg_bytes
+};
+
+static const struct fs_parameter_spec pstore_param_spec[] = {
+	fsparam_u32	("kmsg_bytes",	Opt_kmsg_bytes),
+	{}
+};
+
+struct pstore_context {
+	unsigned int kmsg_bytes;
+};
+
+static int pstore_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct pstore_context *ctx = fc->fs_private;
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, pstore_param_spec, param, &result);
+	/* pstore has historically ignored invalid kmsg_bytes param */
+	if (opt < 0)
+		return 0;
+
+	switch (opt) {
+	case Opt_kmsg_bytes:
+		ctx->kmsg_bytes = result.uint_32;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int pstore_show_options(struct seq_file *m, struct dentry *root)
+{
+	if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
+		seq_printf(m, ",kmsg_bytes=%u", kmsg_bytes);
+	return 0;
+}
+
+static int pstore_reconfigure(struct fs_context *fc)
+{
+	struct pstore_context *ctx = fc->fs_private;
+
+	sync_filesystem(fc->root->d_sb);
+	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
+
+	return 0;
+}
+
+static const struct super_operations pstore_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= inode_just_drop,
+	.evict_inode	= pstore_evict_inode,
+	.show_options	= pstore_show_options,
+};
+
+static struct dentry *psinfo_lock_root(void)
+{
+	struct dentry *root;
+
+	guard(mutex)(&pstore_sb_lock);
+	/*
+	 * Having no backend is fine -- no records appear.
+	 * Not being mounted is fine -- nothing to do.
+	 */
+	if (!psinfo || !pstore_sb)
+		return NULL;
+
+	root = pstore_sb->s_root;
+	inode_lock_nested(d_inode(root), I_MUTEX_PARENT);
+
+	return root;
+}
+
+int pstore_put_backend_records(struct pstore_info *psi)
+{
+	struct pstore_private *pos, *tmp;
+	struct dentry *root;
+
+	root = psinfo_lock_root();
+	if (!root)
+		return 0;
+
+	scoped_guard(mutex, &records_list_lock) {
+		list_for_each_entry_safe(pos, tmp, &records_list, list) {
+			if (pos->record->psi == psi) {
+				list_del_init(&pos->list);
+				locked_recursive_removal(pos->dentry, NULL);
+				pos->dentry = NULL;
+			}
+		}
+	}
+
+	inode_unlock(d_inode(root));
+
+	return 0;
+}
+
+/*
+ * Make a regular file in the root directory of our file system.
+ * Load it up with "size" bytes of data from "buf".
+ * Set the mtime & ctime to the date that this record was originally stored.
+ */
+int pstore_mkfile(struct dentry *root, struct pstore_record *record)
+{
+	struct dentry		*dentry;
+	struct inode		*inode __free(pstore_iput) = NULL;
+	char			name[PSTORE_NAMELEN];
+	struct pstore_private	*private __free(pstore_private) = NULL, *pos;
+	size_t			size = record->size + record->ecc_notice_size;
+
+	if (WARN_ON(!inode_is_locked(d_inode(root))))
+		return -EINVAL;
+
+	guard(mutex)(&records_list_lock);
+
+	/* Skip records that are already present in the filesystem. */
+	list_for_each_entry(pos, &records_list, list) {
+		if (pos->record->type == record->type &&
+		    pos->record->id == record->id &&
+		    pos->record->psi == record->psi)
+			return -EEXIST;
+	}
+
+	inode = pstore_get_inode(root->d_sb);
+	if (!inode)
+		return -ENOMEM;
+	inode->i_mode = S_IFREG | 0444;
+	inode->i_fop = &pstore_file_operations;
+	scnprintf(name, sizeof(name), "%s-%s-%llu%s",
+			pstore_type_to_name(record->type),
+			record->psi->name, record->id,
+			record->compressed ? ".enc.z" : "");
+
+	private = kzalloc_obj(*private);
+	if (!private)
+		return -ENOMEM;
+
+	dentry = d_alloc_name(root, name);
+	if (!dentry)
+		return -ENOMEM;
+
+	private->dentry = dentry; // borrowed
+	private->record = record;
+	inode->i_size = private->total_size = size;
+	inode->i_private = private;
+
+	if (record->time.tv_sec)
+		inode_set_mtime_to_ts(inode,
+				      inode_set_ctime_to_ts(inode, record->time));
+
+	d_make_persistent(dentry, no_free_ptr(inode));
+	dput(dentry);
+
+	list_add(&(no_free_ptr(private))->list, &records_list);
+
+	return 0;
+}
+
+/*
+ * Read all the records from the persistent store. Create
+ * files in our filesystem.  Don't warn about -EEXIST errors
+ * when we are re-scanning the backing store looking to add new
+ * error records.
+ */
+void pstore_get_records(int quiet)
+{
+	struct dentry *root;
+
+	root = psinfo_lock_root();
+	if (!root)
+		return;
+
+	pstore_get_backend_records(psinfo, root, quiet);
+	inode_unlock(d_inode(root));
+}
+
+static int pstore_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct pstore_context *ctx = fc->fs_private;
+	struct inode *inode;
+
+	sb->s_maxbytes		= MAX_LFS_FILESIZE;
+	sb->s_blocksize		= PAGE_SIZE;
+	sb->s_blocksize_bits	= PAGE_SHIFT;
+	sb->s_magic		= PSTOREFS_MAGIC;
+	sb->s_op		= &pstore_ops;
+	sb->s_time_gran		= 1;
+
+	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
+
+	inode = pstore_get_inode(sb);
+	if (inode) {
+		inode->i_mode = S_IFDIR | 0750;
+		inode->i_op = &pstore_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
+		inc_nlink(inode);
+	}
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		return -ENOMEM;
+
+	scoped_guard(mutex, &pstore_sb_lock)
+		pstore_sb = sb;
+
+	pstore_get_records(0);
+
+	return 0;
+}
+
+static int pstore_get_tree(struct fs_context *fc)
+{
+	if (fc->root)
+		return pstore_reconfigure(fc);
+
+	return get_tree_single(fc, pstore_fill_super);
+}
+
+static void pstore_free_fc(struct fs_context *fc)
+{
+	kfree(fc->fs_private);
+}
+
+static const struct fs_context_operations pstore_context_ops = {
+	.parse_param	= pstore_parse_param,
+	.get_tree	= pstore_get_tree,
+	.reconfigure	= pstore_reconfigure,
+	.free		= pstore_free_fc,
+};
+
+static void pstore_kill_sb(struct super_block *sb)
+{
+	guard(mutex)(&pstore_sb_lock);
+	WARN_ON(pstore_sb && pstore_sb != sb);
+
+	kill_anon_super(sb);
+	pstore_sb = NULL;
+
+	guard(mutex)(&records_list_lock);
+	INIT_LIST_HEAD(&records_list);
+}
+
+static int pstore_init_fs_context(struct fs_context *fc)
+{
+	struct pstore_context *ctx;
+
+	ctx = kzalloc_obj(struct pstore_context);
+	if (!ctx)
+		return -ENOMEM;
+
+	/*
+	 * Global kmsg_bytes is initialized to default, and updated
+	 * every time we (re)mount the single-sb filesystem with the
+	 * option specified.
+	 */
+	ctx->kmsg_bytes = kmsg_bytes;
+
+	fc->fs_private = ctx;
+	fc->ops = &pstore_context_ops;
+
+	return 0;
+}
+
+static struct file_system_type pstore_fs_type = {
+	.owner          = THIS_MODULE,
+	.name		= "pstore",
+	.kill_sb	= pstore_kill_sb,
+	.init_fs_context = pstore_init_fs_context,
+	.parameters	= pstore_param_spec,
+};
+
+int __init pstore_init_fs(void)
+{
+	int err;
+
+	/* Create a convenient mount point for people to access pstore */
+	err = sysfs_create_mount_point(fs_kobj, "pstore");
+	if (err)
+		goto out;
+
+	err = register_filesystem(&pstore_fs_type);
+	if (err < 0)
+		sysfs_remove_mount_point(fs_kobj, "pstore");
+
+out:
+	return err;
+}
+
+void __exit pstore_exit_fs(void)
+{
+	unregister_filesystem(&pstore_fs_type);
+	sysfs_remove_mount_point(fs_kobj, "pstore");
+}

linux-7.2.3/fs/pstore/internal.h

@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __PSTORE_INTERNAL_H__
+#define __PSTORE_INTERNAL_H__
+
+#include <linux/types.h>
+#include <linux/time.h>
+#include <linux/pstore.h>
+
+extern unsigned int kmsg_bytes;
+
+#ifdef CONFIG_PSTORE_FTRACE
+extern unsigned long decode_ip(unsigned long ip);
+extern void pstore_register_ftrace(void);
+extern void pstore_unregister_ftrace(void);
+ssize_t pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size,
+				  const char *src_log, size_t src_log_size);
+#else
+static inline void pstore_register_ftrace(void) {}
+static inline void pstore_unregister_ftrace(void) {}
+static inline unsigned long decode_ip(unsigned long ip) { return ip; }
+static inline ssize_t
+pstore_ftrace_combine_log(char **dest_log, size_t *dest_log_size,
+			  const char *src_log, size_t src_log_size)
+{
+	*dest_log_size = 0;
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_PSTORE_PMSG
+extern void pstore_register_pmsg(void);
+extern void pstore_unregister_pmsg(void);
+#else
+static inline void pstore_register_pmsg(void) {}
+static inline void pstore_unregister_pmsg(void) {}
+#endif
+
+extern struct pstore_info *psinfo;
+
+extern void	pstore_set_kmsg_bytes(unsigned int bytes);
+extern void	pstore_get_records(int);
+extern void	pstore_get_backend_records(struct pstore_info *psi,
+					   struct dentry *root, int quiet);
+extern int	pstore_put_backend_records(struct pstore_info *psi);
+extern int	pstore_mkfile(struct dentry *root,
+			      struct pstore_record *record);
+extern void	pstore_record_init(struct pstore_record *record,
+				   struct pstore_info *psi);
+
+/* Called during pstore init/exit. */
+int __init	pstore_init_fs(void);
+void __exit	pstore_exit_fs(void);
+
+#endif

linux-7.2.3/fs/pstore/platform.c

@@ -0,0 +1,766 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Persistent Storage - platform driver interface parts.
+ *
+ * Copyright (C) 2007-2008 Google, Inc.
+ * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
+ */
+
+#define pr_fmt(fmt) "pstore: " fmt
+
+#include <linux/atomic.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kmsg_dump.h>
+#include <linux/console.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/pstore.h>
+#include <linux/string.h>
+#include <linux/timer.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/jiffies.h>
+#include <linux/vmalloc.h>
+#include <linux/workqueue.h>
+#include <linux/zlib.h>
+
+#include "internal.h"
+
+/*
+ * We defer making "oops" entries appear in pstore - see
+ * whether the system is actually still running well enough
+ * to let someone see the entry
+ */
+static int pstore_update_ms = -1;
+module_param_named(update_ms, pstore_update_ms, int, 0600);
+MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
+		 "(default is -1, which means runtime updates are disabled; "
+		 "enabling this option may not be safe; it may lead to further "
+		 "corruption on Oopses)");
+
+/* Names should be in the same order as the enum pstore_type_id */
+static const char * const pstore_type_names[] = {
+	"dmesg",
+	"mce",
+	"console",
+	"ftrace",
+	"rtas",
+	"powerpc-ofw",
+	"powerpc-common",
+	"pmsg",
+	"powerpc-opal",
+};
+
+static int pstore_new_entry;
+
+static void pstore_timefunc(struct timer_list *);
+static DEFINE_TIMER(pstore_timer, pstore_timefunc);
+
+static void pstore_dowork(struct work_struct *);
+static DECLARE_WORK(pstore_work, pstore_dowork);
+
+/*
+ * psinfo_lock protects "psinfo" during calls to
+ * pstore_register(), pstore_unregister(), and
+ * the filesystem mount/unmount routines.
+ */
+static DEFINE_MUTEX(psinfo_lock);
+struct pstore_info *psinfo;
+
+static char *backend;
+module_param(backend, charp, 0444);
+MODULE_PARM_DESC(backend, "specific backend to use");
+
+/*
+ * pstore no longer implements compression via the crypto API, and only
+ * supports zlib deflate compression implemented using the zlib library
+ * interface. This removes additional complexity which is hard to justify for a
+ * diagnostic facility that has to operate in conditions where the system may
+ * have become unstable. Zlib deflate is comparatively small in terms of code
+ * size, and compresses ASCII text comparatively well. In terms of compression
+ * speed, deflate is not the best performer but for recording the log output on
+ * a kernel panic, this is not considered critical.
+ *
+ * The only remaining arguments supported by the compress= module parameter are
+ * 'deflate' and 'none'. To retain compatibility with existing installations,
+ * all other values are logged and replaced with 'deflate'.
+ */
+static char *compress = "deflate";
+module_param(compress, charp, 0444);
+MODULE_PARM_DESC(compress, "compression to use");
+
+/* How much of the kernel log to snapshot */
+unsigned int kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
+module_param(kmsg_bytes, uint, 0444);
+MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
+
+static void *compress_workspace;
+
+/*
+ * Compression is only used for dmesg output, which consists of low-entropy
+ * ASCII text, and so we can assume worst-case 60%.
+ */
+#define DMESG_COMP_PERCENT	60
+
+static char *big_oops_buf;
+static size_t max_compressed_size;
+
+void pstore_set_kmsg_bytes(unsigned int bytes)
+{
+	WRITE_ONCE(kmsg_bytes, bytes);
+}
+
+/* Tag each group of saved records with a sequence number */
+static int	oopscount;
+
+const char *pstore_type_to_name(enum pstore_type_id type)
+{
+	BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
+
+	if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
+		return "unknown";
+
+	return pstore_type_names[type];
+}
+EXPORT_SYMBOL_GPL(pstore_type_to_name);
+
+enum pstore_type_id pstore_name_to_type(const char *name)
+{
+	int i;
+
+	for (i = 0; i < PSTORE_TYPE_MAX; i++) {
+		if (!strcmp(pstore_type_names[i], name))
+			return i;
+	}
+
+	return PSTORE_TYPE_MAX;
+}
+EXPORT_SYMBOL_GPL(pstore_name_to_type);
+
+static void pstore_timer_kick(void)
+{
+	if (pstore_update_ms < 0)
+		return;
+
+	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
+}
+
+static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
+{
+	/*
+	 * In case of NMI path, pstore shouldn't be blocked
+	 * regardless of reason.
+	 */
+	if (in_nmi())
+		return true;
+
+	switch (reason) {
+	/* In panic case, other cpus are stopped by smp_send_stop(). */
+	case KMSG_DUMP_PANIC:
+	/*
+	 * Emergency restart shouldn't be blocked by spinning on
+	 * pstore_info::buf_lock.
+	 */
+	case KMSG_DUMP_EMERG:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static int pstore_compress(const void *in, void *out,
+			   unsigned int inlen, unsigned int outlen)
+{
+	struct z_stream_s zstream = {
+		.next_in	= in,
+		.avail_in	= inlen,
+		.next_out	= out,
+		.avail_out	= outlen,
+		.workspace	= compress_workspace,
+	};
+	int ret;
+
+	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
+		return -EINVAL;
+
+	ret = zlib_deflateInit2(&zstream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
+				-MAX_WBITS, DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY);
+	if (ret != Z_OK)
+		return -EINVAL;
+
+	ret = zlib_deflate(&zstream, Z_FINISH);
+	if (ret != Z_STREAM_END)
+		return -EINVAL;
+
+	ret = zlib_deflateEnd(&zstream);
+	if (ret != Z_OK)
+		pr_warn_once("zlib_deflateEnd() failed: %d\n", ret);
+
+	return zstream.total_out;
+}
+
+static void allocate_buf_for_compression(void)
+{
+	size_t compressed_size;
+	char *buf;
+
+	/* Skip if not built-in or compression disabled. */
+	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !compress ||
+	    !strcmp(compress, "none")) {
+		compress = NULL;
+		return;
+	}
+
+	if (strcmp(compress, "deflate")) {
+		pr_err("Unsupported compression '%s', falling back to deflate\n",
+		       compress);
+		compress = "deflate";
+	}
+
+	/*
+	 * The compression buffer only needs to be as large as the maximum
+	 * uncompressed record size, since any record that would be expanded by
+	 * compression is just stored uncompressed.
+	 */
+	compressed_size = (psinfo->bufsize * 100) / DMESG_COMP_PERCENT;
+	buf = kvzalloc(compressed_size, GFP_KERNEL);
+	if (!buf) {
+		pr_err("Failed %zu byte compression buffer allocation for: %s\n",
+		       psinfo->bufsize, compress);
+		return;
+	}
+
+	compress_workspace =
+		vmalloc(zlib_deflate_workspacesize(MAX_WBITS, DEF_MEM_LEVEL));
+	if (!compress_workspace) {
+		pr_err("Failed to allocate zlib deflate workspace\n");
+		kvfree(buf);
+		return;
+	}
+
+	/* A non-NULL big_oops_buf indicates compression is available. */
+	big_oops_buf = buf;
+	max_compressed_size = compressed_size;
+
+	pr_info("Using crash dump compression: %s\n", compress);
+}
+
+static void free_buf_for_compression(void)
+{
+	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress_workspace) {
+		vfree(compress_workspace);
+		compress_workspace = NULL;
+	}
+
+	kvfree(big_oops_buf);
+	big_oops_buf = NULL;
+	max_compressed_size = 0;
+}
+
+void pstore_record_init(struct pstore_record *record,
+			struct pstore_info *psinfo)
+{
+	memset(record, 0, sizeof(*record));
+
+	record->psi = psinfo;
+
+	/* Report zeroed timestamp if called before timekeeping has resumed. */
+	record->time = ns_to_timespec64(ktime_get_real_fast_ns());
+}
+
+/*
+ * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
+ * end of the buffer.
+ */
+static void pstore_dump(struct kmsg_dumper *dumper,
+			struct kmsg_dump_detail *detail)
+{
+	struct kmsg_dump_iter iter;
+	unsigned int	remaining = READ_ONCE(kmsg_bytes);
+	unsigned long	total = 0;
+	const char	*why;
+	unsigned int	part = 1;
+	unsigned long	flags = 0;
+	int		saved_ret = 0;
+	int		ret;
+
+	why = kmsg_dump_reason_str(detail->reason);
+
+	if (pstore_cannot_block_path(detail->reason)) {
+		if (!raw_spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
+			pr_err("dump skipped in %s path because of concurrent dump\n",
+					in_nmi() ? "NMI" : why);
+			return;
+		}
+	} else {
+		raw_spin_lock_irqsave(&psinfo->buf_lock, flags);
+	}
+
+	kmsg_dump_rewind(&iter);
+
+	oopscount++;
+	while (total < remaining) {
+		char *dst;
+		size_t dst_size;
+		int header_size;
+		int zipped_len = -1;
+		size_t dump_size;
+		struct pstore_record record;
+
+		pstore_record_init(&record, psinfo);
+		record.type = PSTORE_TYPE_DMESG;
+		record.count = oopscount;
+		record.reason = detail->reason;
+		record.part = part;
+		record.buf = psinfo->buf;
+
+		dst = big_oops_buf ?: psinfo->buf;
+		dst_size = max_compressed_size ?: psinfo->bufsize;
+
+		/* Write dump header. */
+		header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
+				 oopscount, part);
+		dst_size -= header_size;
+
+		/* Write dump contents. */
+		if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
+					  dst_size, &dump_size))
+			break;
+
+		if (big_oops_buf) {
+			zipped_len = pstore_compress(dst, psinfo->buf,
+						header_size + dump_size,
+						psinfo->bufsize);
+
+			if (zipped_len > 0) {
+				record.compressed = true;
+				record.size = zipped_len;
+			} else {
+				/*
+				 * Compression failed, so the buffer is most
+				 * likely filled with binary data that does not
+				 * compress as well as ASCII text. Copy as much
+				 * of the uncompressed data as possible into
+				 * the pstore record, and discard the rest.
+				 */
+				record.size = psinfo->bufsize;
+				memcpy(psinfo->buf, dst, psinfo->bufsize);
+			}
+		} else {
+			record.size = header_size + dump_size;
+		}
+
+		ret = psinfo->write(&record);
+		if (ret == 0 && detail->reason == KMSG_DUMP_OOPS) {
+			pstore_new_entry = 1;
+			pstore_timer_kick();
+		} else {
+			/* Preserve only the first non-zero returned value. */
+			if (!saved_ret)
+				saved_ret = ret;
+		}
+
+		total += record.size;
+		part++;
+	}
+	raw_spin_unlock_irqrestore(&psinfo->buf_lock, flags);
+
+	if (saved_ret) {
+		pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
+			    saved_ret);
+	}
+}
+
+static struct kmsg_dumper pstore_dumper = {
+	.dump = pstore_dump,
+};
+
+/*
+ * Register with kmsg_dump to save last part of console log on panic.
+ */
+static void pstore_register_kmsg(void)
+{
+	kmsg_dump_register(&pstore_dumper);
+}
+
+static void pstore_unregister_kmsg(void)
+{
+	kmsg_dump_unregister(&pstore_dumper);
+}
+
+#ifdef CONFIG_PSTORE_CONSOLE
+static void pstore_console_write(struct console *con, const char *s, unsigned c)
+{
+	struct pstore_record record;
+
+	if (!c)
+		return;
+
+	pstore_record_init(&record, psinfo);
+	record.type = PSTORE_TYPE_CONSOLE;
+
+	record.buf = (char *)s;
+	record.size = c;
+	psinfo->write(&record);
+}
+
+static struct console pstore_console = {
+	.write	= pstore_console_write,
+	.index	= -1,
+};
+
+static void pstore_register_console(void)
+{
+	/* Show which backend is going to get console writes. */
+	strscpy(pstore_console.name, psinfo->name,
+		sizeof(pstore_console.name));
+	/*
+	 * Always initialize flags here since prior unregister_console()
+	 * calls may have changed settings (specifically CON_ENABLED).
+	 */
+	pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
+	register_console(&pstore_console);
+}
+
+static void pstore_unregister_console(void)
+{
+	unregister_console(&pstore_console);
+}
+#else
+static void pstore_register_console(void) {}
+static void pstore_unregister_console(void) {}
+#endif
+
+static int pstore_write_user_compat(struct pstore_record *record,
+				    const char __user *buf)
+{
+	int ret = 0;
+
+	if (record->buf)
+		return -EINVAL;
+
+	record->buf = vmemdup_user(buf, record->size);
+	if (IS_ERR(record->buf)) {
+		ret = PTR_ERR(record->buf);
+		goto out;
+	}
+
+	ret = record->psi->write(record);
+
+	kvfree(record->buf);
+out:
+	record->buf = NULL;
+
+	return unlikely(ret < 0) ? ret : record->size;
+}
+
+/*
+ * platform specific persistent storage driver registers with
+ * us here. If pstore is already mounted, call the platform
+ * read function right away to populate the file system. If not
+ * then the pstore mount code will call us later to fill out
+ * the file system.
+ */
+int pstore_register(struct pstore_info *psi)
+{
+	char *new_backend;
+
+	if (backend && strcmp(backend, psi->name)) {
+		pr_warn("backend '%s' already in use: ignoring '%s'\n",
+			backend, psi->name);
+		return -EBUSY;
+	}
+
+	/* Sanity check flags. */
+	if (!psi->flags) {
+		pr_warn("backend '%s' must support at least one frontend\n",
+			psi->name);
+		return -EINVAL;
+	}
+
+	/* Check for required functions. */
+	if (!psi->read || !psi->write) {
+		pr_warn("backend '%s' must implement read() and write()\n",
+			psi->name);
+		return -EINVAL;
+	}
+
+	new_backend = kstrdup(psi->name, GFP_KERNEL);
+	if (!new_backend)
+		return -ENOMEM;
+
+	mutex_lock(&psinfo_lock);
+	if (psinfo) {
+		pr_warn("backend '%s' already loaded: ignoring '%s'\n",
+			psinfo->name, psi->name);
+		mutex_unlock(&psinfo_lock);
+		kfree(new_backend);
+		return -EBUSY;
+	}
+
+	if (!psi->write_user)
+		psi->write_user = pstore_write_user_compat;
+	psinfo = psi;
+	mutex_init(&psinfo->read_mutex);
+	raw_spin_lock_init(&psinfo->buf_lock);
+
+	if (psi->flags & PSTORE_FLAGS_DMESG)
+		allocate_buf_for_compression();
+
+	pstore_get_records(0);
+
+	if (psi->flags & PSTORE_FLAGS_DMESG) {
+		pstore_dumper.max_reason = psinfo->max_reason;
+		pstore_register_kmsg();
+	}
+	if (psi->flags & PSTORE_FLAGS_CONSOLE)
+		pstore_register_console();
+	if (psi->flags & PSTORE_FLAGS_FTRACE)
+		pstore_register_ftrace();
+	if (psi->flags & PSTORE_FLAGS_PMSG)
+		pstore_register_pmsg();
+
+	/* Start watching for new records, if desired. */
+	pstore_timer_kick();
+
+	/*
+	 * Update the module parameter backend, so it is visible
+	 * through /sys/module/pstore/parameters/backend
+	 */
+	backend = new_backend;
+
+	pr_info("Registered %s as persistent store backend\n", psi->name);
+
+	mutex_unlock(&psinfo_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pstore_register);
+
+void pstore_unregister(struct pstore_info *psi)
+{
+	/* It's okay to unregister nothing. */
+	if (!psi)
+		return;
+
+	mutex_lock(&psinfo_lock);
+
+	/* Only one backend can be registered at a time. */
+	if (WARN_ON(psi != psinfo)) {
+		mutex_unlock(&psinfo_lock);
+		return;
+	}
+
+	/* Unregister all callbacks. */
+	if (psi->flags & PSTORE_FLAGS_PMSG)
+		pstore_unregister_pmsg();
+	if (psi->flags & PSTORE_FLAGS_FTRACE)
+		pstore_unregister_ftrace();
+	if (psi->flags & PSTORE_FLAGS_CONSOLE)
+		pstore_unregister_console();
+	if (psi->flags & PSTORE_FLAGS_DMESG)
+		pstore_unregister_kmsg();
+
+	/* Stop timer and make sure all work has finished. */
+	timer_delete_sync(&pstore_timer);
+	flush_work(&pstore_work);
+
+	/* Remove all backend records from filesystem tree. */
+	pstore_put_backend_records(psi);
+
+	free_buf_for_compression();
+
+	psinfo = NULL;
+	kfree(backend);
+	backend = NULL;
+
+	pr_info("Unregistered %s as persistent store backend\n", psi->name);
+	mutex_unlock(&psinfo_lock);
+}
+EXPORT_SYMBOL_GPL(pstore_unregister);
+
+static void decompress_record(struct pstore_record *record,
+			      struct z_stream_s *zstream)
+{
+	int ret;
+	int unzipped_len;
+	char *unzipped, *workspace;
+	size_t max_uncompressed_size;
+
+	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
+		return;
+
+	/* Only PSTORE_TYPE_DMESG support compression. */
+	if (record->type != PSTORE_TYPE_DMESG) {
+		pr_warn("ignored compressed record type %d\n", record->type);
+		return;
+	}
+
+	/* Missing compression buffer means compression was not initialized. */
+	if (!zstream->workspace) {
+		pr_warn("no decompression method initialized!\n");
+		return;
+	}
+
+	ret = zlib_inflateReset(zstream);
+	if (ret != Z_OK) {
+		pr_err("zlib_inflateReset() failed, ret = %d!\n", ret);
+		return;
+	}
+
+	/* Allocate enough space to hold max decompression and ECC. */
+	max_uncompressed_size = 3 * psinfo->bufsize;
+	workspace = kvzalloc(max_uncompressed_size + record->ecc_notice_size,
+			     GFP_KERNEL);
+	if (!workspace)
+		return;
+
+	zstream->next_in	= record->buf;
+	zstream->avail_in	= record->size;
+	zstream->next_out	= workspace;
+	zstream->avail_out	= max_uncompressed_size;
+
+	ret = zlib_inflate(zstream, Z_FINISH);
+	if (ret != Z_STREAM_END) {
+		pr_err_ratelimited("zlib_inflate() failed, ret = %d!\n", ret);
+		kvfree(workspace);
+		return;
+	}
+
+	unzipped_len = zstream->total_out;
+
+	/* Append ECC notice to decompressed buffer. */
+	memcpy(workspace + unzipped_len, record->buf + record->size,
+	       record->ecc_notice_size);
+
+	/* Copy decompressed contents into an minimum-sized allocation. */
+	unzipped = kvmemdup(workspace, unzipped_len + record->ecc_notice_size,
+			    GFP_KERNEL);
+	kvfree(workspace);
+	if (!unzipped)
+		return;
+
+	/* Swap out compressed contents with decompressed contents. */
+	kvfree(record->buf);
+	record->buf = unzipped;
+	record->size = unzipped_len;
+	record->compressed = false;
+}
+
+/*
+ * Read all the records from one persistent store backend. Create
+ * files in our filesystem.  Don't warn about -EEXIST errors
+ * when we are re-scanning the backing store looking to add new
+ * error records.
+ */
+void pstore_get_backend_records(struct pstore_info *psi,
+				struct dentry *root, int quiet)
+{
+	int failed = 0;
+	unsigned int stop_loop = 65536;
+	struct z_stream_s zstream = {};
+
+	if (!psi || !root)
+		return;
+
+	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress) {
+		zstream.workspace = kvmalloc(zlib_inflate_workspacesize(),
+					     GFP_KERNEL);
+		zlib_inflateInit2(&zstream, -DEF_WBITS);
+	}
+
+	mutex_lock(&psi->read_mutex);
+	if (psi->open && psi->open(psi))
+		goto out;
+
+	/*
+	 * Backend callback read() allocates record.buf. decompress_record()
+	 * may reallocate record.buf. On success, pstore_mkfile() will keep
+	 * the record.buf, so free it only on failure.
+	 */
+	for (; stop_loop; stop_loop--) {
+		struct pstore_record *record;
+		int rc;
+
+		record = kzalloc_obj(*record);
+		if (!record) {
+			pr_err("out of memory creating record\n");
+			break;
+		}
+		pstore_record_init(record, psi);
+
+		record->size = psi->read(record);
+
+		/* No more records left in backend? */
+		if (record->size <= 0) {
+			kfree(record);
+			break;
+		}
+
+		decompress_record(record, &zstream);
+		rc = pstore_mkfile(root, record);
+		if (rc) {
+			/* pstore_mkfile() did not take record, so free it. */
+			kvfree(record->buf);
+			kfree(record->priv);
+			kfree(record);
+			if (rc != -EEXIST || !quiet)
+				failed++;
+		}
+	}
+	if (psi->close)
+		psi->close(psi);
+out:
+	mutex_unlock(&psi->read_mutex);
+
+	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && compress) {
+		if (zlib_inflateEnd(&zstream) != Z_OK)
+			pr_warn("zlib_inflateEnd() failed\n");
+		kvfree(zstream.workspace);
+	}
+
+	if (failed)
+		pr_warn("failed to create %d record(s) from '%s'\n",
+			failed, psi->name);
+	if (!stop_loop)
+		pr_err("looping? Too many records seen from '%s'\n",
+			psi->name);
+}
+
+static void pstore_dowork(struct work_struct *work)
+{
+	pstore_get_records(1);
+}
+
+static void pstore_timefunc(struct timer_list *unused)
+{
+	if (pstore_new_entry) {
+		pstore_new_entry = 0;
+		schedule_work(&pstore_work);
+	}
+
+	pstore_timer_kick();
+}
+
+static int __init pstore_init(void)
+{
+	int ret;
+
+	ret = pstore_init_fs();
+	if (ret)
+		free_buf_for_compression();
+
+	return ret;
+}
+late_initcall(pstore_init);
+
+static void __exit pstore_exit(void)
+{
+	pstore_exit_fs();
+}
+module_exit(pstore_exit)
+
+MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
+MODULE_DESCRIPTION("Persistent Storage - platform driver interface");
+MODULE_LICENSE("GPL");

linux-7.2.3/fs/pstore/pmsg.c

@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2014  Google, Inc.
+ */
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include "internal.h"
+
+static DEFINE_MUTEX(pmsg_lock);
+
+static ssize_t write_pmsg(struct file *file, const char __user *buf,
+			  size_t count, loff_t *ppos)
+{
+	struct pstore_record record;
+	int ret;
+
+	if (!count)
+		return 0;
+
+	pstore_record_init(&record, psinfo);
+	record.type = PSTORE_TYPE_PMSG;
+	record.size = count;
+
+	/* check outside lock, page in any data. write_user also checks */
+	if (!access_ok(buf, count))
+		return -EFAULT;
+
+	mutex_lock(&pmsg_lock);
+	ret = psinfo->write_user(&record, buf);
+	mutex_unlock(&pmsg_lock);
+	return ret ? ret : count;
+}
+
+static const struct file_operations pmsg_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= noop_llseek,
+	.write		= write_pmsg,
+};
+
+static struct class *pmsg_class;
+static int pmsg_major;
+#define PMSG_NAME "pmsg"
+#undef pr_fmt
+#define pr_fmt(fmt) PMSG_NAME ": " fmt
+
+static char *pmsg_devnode(const struct device *dev, umode_t *mode)
+{
+	if (mode)
+		*mode = 0220;
+	return NULL;
+}
+
+void pstore_register_pmsg(void)
+{
+	struct device *pmsg_device;
+
+	pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops);
+	if (pmsg_major < 0) {
+		pr_err("register_chrdev failed\n");
+		goto err;
+	}
+
+	pmsg_class = class_create(PMSG_NAME);
+	if (IS_ERR(pmsg_class)) {
+		pr_err("device class file already in use\n");
+		goto err_class;
+	}
+	pmsg_class->devnode = pmsg_devnode;
+
+	pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0),
+					NULL, "%s%d", PMSG_NAME, 0);
+	if (IS_ERR(pmsg_device)) {
+		pr_err("failed to create device\n");
+		goto err_device;
+	}
+	return;
+
+err_device:
+	class_destroy(pmsg_class);
+err_class:
+	unregister_chrdev(pmsg_major, PMSG_NAME);
+err:
+	return;
+}
+
+void pstore_unregister_pmsg(void)
+{
+	device_destroy(pmsg_class, MKDEV(pmsg_major, 0));
+	class_destroy(pmsg_class);
+	unregister_chrdev(pmsg_major, PMSG_NAME);
+}

linux-7.2.3/fs/pstore/ram.c

@@ -0,0 +1,999 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * RAM Oops/Panic logger
+ *
+ * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
+ * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/pstore.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/compiler.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/mm.h>
+
+#include "internal.h"
+#include "ram_internal.h"
+
+#define RAMOOPS_KERNMSG_HDR "===="
+#define MIN_MEM_SIZE 4096UL
+
+static ulong record_size = MIN_MEM_SIZE;
+module_param(record_size, ulong, 0400);
+MODULE_PARM_DESC(record_size,
+		"size of each dump done on oops/panic");
+
+static ulong ramoops_console_size = MIN_MEM_SIZE;
+module_param_named(console_size, ramoops_console_size, ulong, 0400);
+MODULE_PARM_DESC(console_size, "size of kernel console log");
+
+static ulong ramoops_ftrace_size = MIN_MEM_SIZE;
+module_param_named(ftrace_size, ramoops_ftrace_size, ulong, 0400);
+MODULE_PARM_DESC(ftrace_size, "size of ftrace log");
+
+static ulong ramoops_pmsg_size = MIN_MEM_SIZE;
+module_param_named(pmsg_size, ramoops_pmsg_size, ulong, 0400);
+MODULE_PARM_DESC(pmsg_size, "size of user space message log");
+
+static unsigned long long mem_address;
+module_param_hw(mem_address, ullong, other, 0400);
+MODULE_PARM_DESC(mem_address,
+		"start of reserved RAM used to store oops/panic logs");
+
+static char *mem_name;
+module_param_named(mem_name, mem_name, charp, 0400);
+MODULE_PARM_DESC(mem_name, "name of kernel param that holds addr");
+
+static ulong mem_size;
+module_param(mem_size, ulong, 0400);
+MODULE_PARM_DESC(mem_size,
+		"size of reserved RAM used to store oops/panic logs");
+
+static unsigned int mem_type;
+module_param(mem_type, uint, 0400);
+MODULE_PARM_DESC(mem_type,
+		"memory type: 0=write-combined (default), 1=unbuffered, 2=cached");
+
+static int ramoops_max_reason = -1;
+module_param_named(max_reason, ramoops_max_reason, int, 0400);
+MODULE_PARM_DESC(max_reason,
+		 "maximum reason for kmsg dump (default 2: Oops and Panic) ");
+
+static int ramoops_ecc;
+module_param_named(ecc, ramoops_ecc, int, 0400);
+MODULE_PARM_DESC(ecc,
+		"if non-zero, the option enables ECC support and specifies "
+		"ECC buffer size in bytes (1 is a special value, means 16 "
+		"bytes ECC)");
+
+static int ramoops_dump_oops = -1;
+module_param_named(dump_oops, ramoops_dump_oops, int, 0400);
+MODULE_PARM_DESC(dump_oops,
+		 "(deprecated: use max_reason instead) set to 1 to dump oopses & panics, 0 to only dump panics");
+
+struct ramoops_context {
+	struct persistent_ram_zone **dprzs;	/* Oops dump zones */
+	struct persistent_ram_zone *cprz;	/* Console zone */
+	struct persistent_ram_zone **fprzs;	/* Ftrace zones */
+	struct persistent_ram_zone *mprz;	/* PMSG zone */
+	phys_addr_t phys_addr;
+	unsigned long size;
+	unsigned int memtype;
+	size_t record_size;
+	size_t console_size;
+	size_t ftrace_size;
+	size_t pmsg_size;
+	u32 flags;
+	struct persistent_ram_ecc_info ecc_info;
+	unsigned int max_dump_cnt;
+	unsigned int dump_write_cnt;
+	/* _read_cnt need clear on ramoops_pstore_open */
+	unsigned int dump_read_cnt;
+	unsigned int console_read_cnt;
+	unsigned int max_ftrace_cnt;
+	unsigned int ftrace_read_cnt;
+	unsigned int pmsg_read_cnt;
+	struct pstore_info pstore;
+};
+
+static struct platform_device *dummy;
+
+static int ramoops_pstore_open(struct pstore_info *psi)
+{
+	struct ramoops_context *cxt = psi->data;
+
+	cxt->dump_read_cnt = 0;
+	cxt->console_read_cnt = 0;
+	cxt->ftrace_read_cnt = 0;
+	cxt->pmsg_read_cnt = 0;
+	return 0;
+}
+
+static struct persistent_ram_zone *
+ramoops_get_next_prz(struct persistent_ram_zone *przs[], int id,
+		     struct pstore_record *record)
+{
+	struct persistent_ram_zone *prz;
+
+	/* Give up if we never existed or have hit the end. */
+	if (!przs)
+		return NULL;
+
+	prz = przs[id];
+	if (!prz)
+		return NULL;
+
+	/* Update old/shadowed buffer. */
+	if (prz->type == PSTORE_TYPE_DMESG)
+		persistent_ram_save_old(prz);
+
+	if (!persistent_ram_old_size(prz))
+		return NULL;
+
+	record->type = prz->type;
+	record->id = id;
+
+	return prz;
+}
+
+static int ramoops_read_kmsg_hdr(char *buffer, struct timespec64 *time,
+				  bool *compressed)
+{
+	char data_type;
+	int header_length = 0;
+
+	if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu-%c\n%n",
+		   (time64_t *)&time->tv_sec, &time->tv_nsec, &data_type,
+		   &header_length) == 3) {
+		time->tv_nsec *= 1000;
+		if (data_type == 'C')
+			*compressed = true;
+		else
+			*compressed = false;
+	} else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu\n%n",
+			  (time64_t *)&time->tv_sec, &time->tv_nsec,
+			  &header_length) == 2) {
+		time->tv_nsec *= 1000;
+		*compressed = false;
+	} else {
+		time->tv_sec = 0;
+		time->tv_nsec = 0;
+		*compressed = false;
+	}
+	return header_length;
+}
+
+static bool prz_ok(struct persistent_ram_zone *prz)
+{
+	return !!prz && !!(persistent_ram_old_size(prz) +
+			   persistent_ram_ecc_string(prz, NULL, 0));
+}
+
+static ssize_t ramoops_pstore_read(struct pstore_record *record)
+{
+	ssize_t size = 0;
+	struct ramoops_context *cxt = record->psi->data;
+	struct persistent_ram_zone *prz = NULL;
+	int header_length = 0;
+	bool free_prz = false;
+
+	/*
+	 * Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but
+	 * PSTORE_TYPE_CONSOLE and PSTORE_TYPE_FTRACE don't currently have
+	 * valid time stamps, so it is initialized to zero.
+	 */
+	record->time.tv_sec = 0;
+	record->time.tv_nsec = 0;
+	record->compressed = false;
+
+	/* Find the next valid persistent_ram_zone for DMESG */
+	while (cxt->dump_read_cnt < cxt->max_dump_cnt && !prz) {
+		prz = ramoops_get_next_prz(cxt->dprzs, cxt->dump_read_cnt++,
+					   record);
+		if (!prz_ok(prz))
+			continue;
+		header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz),
+						      &record->time,
+						      &record->compressed);
+		/* Clear and skip this DMESG record if it has no valid header */
+		if (!header_length) {
+			persistent_ram_free_old(prz);
+			persistent_ram_zap(prz);
+			prz = NULL;
+		}
+	}
+
+	if (!prz_ok(prz) && !cxt->console_read_cnt++)
+		prz = ramoops_get_next_prz(&cxt->cprz, 0 /* single */, record);
+
+	if (!prz_ok(prz) && !cxt->pmsg_read_cnt++)
+		prz = ramoops_get_next_prz(&cxt->mprz, 0 /* single */, record);
+
+	/* ftrace is last since it may want to dynamically allocate memory. */
+	if (!prz_ok(prz)) {
+		if (!(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU) &&
+		    !cxt->ftrace_read_cnt++) {
+			prz = ramoops_get_next_prz(cxt->fprzs, 0 /* single */,
+						   record);
+		} else {
+			/*
+			 * Build a new dummy record which combines all the
+			 * per-cpu records including metadata and ecc info.
+			 */
+			struct persistent_ram_zone *tmp_prz, *prz_next;
+
+			tmp_prz = kzalloc_obj(struct persistent_ram_zone);
+			if (!tmp_prz)
+				return -ENOMEM;
+			prz = tmp_prz;
+			free_prz = true;
+
+			while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt) {
+				prz_next = ramoops_get_next_prz(cxt->fprzs,
+						cxt->ftrace_read_cnt++, record);
+
+				if (!prz_ok(prz_next))
+					continue;
+
+				tmp_prz->ecc_info = prz_next->ecc_info;
+				tmp_prz->corrected_bytes +=
+						prz_next->corrected_bytes;
+				tmp_prz->bad_blocks += prz_next->bad_blocks;
+
+				size = pstore_ftrace_combine_log(
+						&tmp_prz->old_log,
+						&tmp_prz->old_log_size,
+						prz_next->old_log,
+						prz_next->old_log_size);
+				if (size)
+					goto out;
+			}
+			record->id = 0;
+		}
+	}
+
+	if (!prz_ok(prz)) {
+		size = 0;
+		goto out;
+	}
+
+	size = persistent_ram_old_size(prz) - header_length;
+
+	/* ECC correction notice */
+	record->ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
+
+	record->buf = kvzalloc(size + record->ecc_notice_size + 1, GFP_KERNEL);
+	if (record->buf == NULL) {
+		size = -ENOMEM;
+		goto out;
+	}
+
+	memcpy(record->buf, (char *)persistent_ram_old(prz) + header_length,
+	       size);
+
+	persistent_ram_ecc_string(prz, record->buf + size,
+				  record->ecc_notice_size + 1);
+
+out:
+	if (free_prz) {
+		kvfree(prz->old_log);
+		kfree(prz);
+	}
+
+	return size;
+}
+
+static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
+				     struct pstore_record *record)
+{
+	char hdr[36]; /* "===="(4), %lld(20), "."(1), %06lu(6), "-%c\n"(3) */
+	size_t len;
+
+	len = scnprintf(hdr, sizeof(hdr),
+		RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
+		(time64_t)record->time.tv_sec,
+		record->time.tv_nsec / 1000,
+		record->compressed ? 'C' : 'D');
+	persistent_ram_write(prz, hdr, len);
+
+	return len;
+}
+
+static int notrace ramoops_pstore_write(struct pstore_record *record)
+{
+	struct ramoops_context *cxt = record->psi->data;
+	struct persistent_ram_zone *prz;
+	size_t size, hlen;
+
+	if (record->type == PSTORE_TYPE_CONSOLE) {
+		if (!cxt->cprz)
+			return -ENOMEM;
+		persistent_ram_write(cxt->cprz, record->buf, record->size);
+		return 0;
+	} else if (record->type == PSTORE_TYPE_FTRACE) {
+		int zonenum;
+
+		if (!cxt->fprzs)
+			return -ENOMEM;
+		/*
+		 * Choose zone by if we're using per-cpu buffers.
+		 */
+		if (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
+			zonenum = smp_processor_id();
+		else
+			zonenum = 0;
+
+		persistent_ram_write(cxt->fprzs[zonenum], record->buf,
+				     record->size);
+		return 0;
+	} else if (record->type == PSTORE_TYPE_PMSG) {
+		pr_warn_ratelimited("PMSG shouldn't call %s\n", __func__);
+		return -EINVAL;
+	}
+
+	if (record->type != PSTORE_TYPE_DMESG)
+		return -EINVAL;
+
+	/*
+	 * We could filter on record->reason here if we wanted to (which
+	 * would duplicate what happened before the "max_reason" setting
+	 * was added), but that would defeat the purpose of a system
+	 * changing printk.always_kmsg_dump, so instead log everything that
+	 * the kmsg dumper sends us, since it should be doing the filtering
+	 * based on the combination of printk.always_kmsg_dump and our
+	 * requested "max_reason".
+	 */
+
+	/*
+	 * Explicitly only take the first part of any new crash.
+	 * If our buffer is larger than kmsg_bytes, this can never happen,
+	 * and if our buffer is smaller than kmsg_bytes, we don't want the
+	 * report split across multiple records.
+	 */
+	if (record->part != 1)
+		return -ENOSPC;
+
+	if (!cxt->dprzs)
+		return -ENOSPC;
+
+	prz = cxt->dprzs[cxt->dump_write_cnt];
+
+	/*
+	 * Since this is a new crash dump, we need to reset the buffer in
+	 * case it still has an old dump present. Without this, the new dump
+	 * will get appended, which would seriously confuse anything trying
+	 * to check dump file contents. Specifically, ramoops_read_kmsg_hdr()
+	 * expects to find a dump header in the beginning of buffer data, so
+	 * we must to reset the buffer values, in order to ensure that the
+	 * header will be written to the beginning of the buffer.
+	 */
+	persistent_ram_zap(prz);
+
+	/* Build header and append record contents. */
+	hlen = ramoops_write_kmsg_hdr(prz, record);
+	if (!hlen)
+		return -ENOMEM;
+
+	size = record->size;
+	if (size + hlen > prz->buffer_size)
+		size = prz->buffer_size - hlen;
+	persistent_ram_write(prz, record->buf, size);
+
+	cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;
+
+	return 0;
+}
+
+static int notrace ramoops_pstore_write_user(struct pstore_record *record,
+					     const char __user *buf)
+{
+	if (record->type == PSTORE_TYPE_PMSG) {
+		struct ramoops_context *cxt = record->psi->data;
+
+		if (!cxt->mprz)
+			return -ENOMEM;
+		return persistent_ram_write_user(cxt->mprz, buf, record->size);
+	}
+
+	return -EINVAL;
+}
+
+static int ramoops_pstore_erase(struct pstore_record *record)
+{
+	struct ramoops_context *cxt = record->psi->data;
+	struct persistent_ram_zone *prz;
+
+	switch (record->type) {
+	case PSTORE_TYPE_DMESG:
+		if (record->id >= cxt->max_dump_cnt)
+			return -EINVAL;
+		prz = cxt->dprzs[record->id];
+		break;
+	case PSTORE_TYPE_CONSOLE:
+		prz = cxt->cprz;
+		break;
+	case PSTORE_TYPE_FTRACE:
+		if (record->id >= cxt->max_ftrace_cnt)
+			return -EINVAL;
+		prz = cxt->fprzs[record->id];
+		break;
+	case PSTORE_TYPE_PMSG:
+		prz = cxt->mprz;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	persistent_ram_free_old(prz);
+	persistent_ram_zap(prz);
+
+	return 0;
+}
+
+static struct ramoops_context oops_cxt = {
+	.pstore = {
+		.owner	= THIS_MODULE,
+		.name	= "ramoops",
+		.open	= ramoops_pstore_open,
+		.read	= ramoops_pstore_read,
+		.write	= ramoops_pstore_write,
+		.write_user	= ramoops_pstore_write_user,
+		.erase	= ramoops_pstore_erase,
+	},
+};
+
+static void ramoops_free_przs(struct ramoops_context *cxt)
+{
+	int i;
+
+	/* Free pmsg PRZ */
+	persistent_ram_free(&cxt->mprz);
+
+	/* Free console PRZ */
+	persistent_ram_free(&cxt->cprz);
+
+	/* Free dump PRZs */
+	if (cxt->dprzs) {
+		for (i = 0; i < cxt->max_dump_cnt; i++)
+			persistent_ram_free(&cxt->dprzs[i]);
+
+		kfree(cxt->dprzs);
+		cxt->dprzs = NULL;
+		cxt->max_dump_cnt = 0;
+	}
+
+	/* Free ftrace PRZs */
+	if (cxt->fprzs) {
+		for (i = 0; i < cxt->max_ftrace_cnt; i++)
+			persistent_ram_free(&cxt->fprzs[i]);
+		kfree(cxt->fprzs);
+		cxt->fprzs = NULL;
+		cxt->max_ftrace_cnt = 0;
+	}
+}
+
+static int ramoops_init_przs(const char *name,
+			     struct device *dev, struct ramoops_context *cxt,
+			     struct persistent_ram_zone ***przs,
+			     phys_addr_t *paddr, size_t mem_sz,
+			     ssize_t record_size,
+			     unsigned int *cnt, u32 sig, u32 flags)
+{
+	int err = -ENOMEM;
+	int i;
+	size_t zone_sz;
+	struct persistent_ram_zone **prz_ar;
+
+	/* Allocate nothing for 0 mem_sz or 0 record_size. */
+	if (mem_sz == 0 || record_size == 0) {
+		*cnt = 0;
+		return 0;
+	}
+
+	/*
+	 * If we have a negative record size, calculate it based on
+	 * mem_sz / *cnt. If we have a positive record size, calculate
+	 * cnt from mem_sz / record_size.
+	 */
+	if (record_size < 0) {
+		if (*cnt == 0)
+			return 0;
+		record_size = mem_sz / *cnt;
+		if (record_size == 0) {
+			dev_err(dev, "%s record size == 0 (%zu / %u)\n",
+				name, mem_sz, *cnt);
+			goto fail;
+		}
+	} else {
+		*cnt = mem_sz / record_size;
+		if (*cnt == 0) {
+			dev_err(dev, "%s record count == 0 (%zu / %zu)\n",
+				name, mem_sz, record_size);
+			goto fail;
+		}
+	}
+
+	if (*paddr + mem_sz - cxt->phys_addr > cxt->size) {
+		dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
+			name,
+			mem_sz, (unsigned long long)*paddr,
+			cxt->size, (unsigned long long)cxt->phys_addr);
+		goto fail;
+	}
+
+	zone_sz = mem_sz / *cnt;
+	zone_sz = ALIGN_DOWN(zone_sz, 2);
+	if (!zone_sz) {
+		dev_err(dev, "%s zone size == 0\n", name);
+		goto fail;
+	}
+
+	prz_ar = kzalloc_objs(**przs, *cnt);
+	if (!prz_ar)
+		goto fail;
+
+	for (i = 0; i < *cnt; i++) {
+		char *label;
+
+		if (*cnt == 1)
+			label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
+		else
+			label = kasprintf(GFP_KERNEL, "ramoops:%s(%d/%d)",
+					  name, i, *cnt - 1);
+		prz_ar[i] = persistent_ram_new(*paddr, zone_sz, sig,
+					       &cxt->ecc_info,
+					       cxt->memtype, flags, label);
+		kfree(label);
+		if (IS_ERR(prz_ar[i])) {
+			err = PTR_ERR(prz_ar[i]);
+			dev_err(dev, "failed to request %s mem region (0x%zx@0x%llx): %d\n",
+				name, record_size,
+				(unsigned long long)*paddr, err);
+
+			while (i > 0) {
+				i--;
+				persistent_ram_free(&prz_ar[i]);
+			}
+			kfree(prz_ar);
+			prz_ar = NULL;
+			goto fail;
+		}
+		*paddr += zone_sz;
+		prz_ar[i]->type = pstore_name_to_type(name);
+	}
+
+	*przs = prz_ar;
+	return 0;
+
+fail:
+	*cnt = 0;
+	return err;
+}
+
+static int ramoops_init_prz(const char *name,
+			    struct device *dev, struct ramoops_context *cxt,
+			    struct persistent_ram_zone **prz,
+			    phys_addr_t *paddr, size_t sz, u32 sig)
+{
+	char *label;
+
+	if (!sz)
+		return 0;
+
+	if (*paddr + sz - cxt->phys_addr > cxt->size) {
+		dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
+			name, sz, (unsigned long long)*paddr,
+			cxt->size, (unsigned long long)cxt->phys_addr);
+		return -ENOMEM;
+	}
+
+	label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
+	*prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info,
+				  cxt->memtype, PRZ_FLAG_ZAP_OLD, label);
+	kfree(label);
+	if (IS_ERR(*prz)) {
+		int err = PTR_ERR(*prz);
+
+		dev_err(dev, "failed to request %s mem region (0x%zx@0x%llx): %d\n",
+			name, sz, (unsigned long long)*paddr, err);
+		return err;
+	}
+
+	*paddr += sz;
+	(*prz)->type = pstore_name_to_type(name);
+
+	return 0;
+}
+
+/* Read a u32 from a dt property and make sure it's safe for an int. */
+static int ramoops_parse_dt_u32(struct platform_device *pdev,
+				const char *propname,
+				u32 default_value, u32 *value)
+{
+	u32 val32 = 0;
+	int ret;
+
+	ret = of_property_read_u32(pdev->dev.of_node, propname, &val32);
+	if (ret == -EINVAL) {
+		/* field is missing, use default value. */
+		val32 = default_value;
+	} else if (ret < 0) {
+		dev_err(&pdev->dev, "failed to parse property %s: %d\n",
+			propname, ret);
+		return ret;
+	}
+
+	/* Sanity check our results. */
+	if (val32 > INT_MAX) {
+		dev_err(&pdev->dev, "%s %u > INT_MAX\n", propname, val32);
+		return -EOVERFLOW;
+	}
+
+	*value = val32;
+	return 0;
+}
+
+static int ramoops_parse_dt(struct platform_device *pdev,
+			    struct ramoops_platform_data *pdata)
+{
+	struct device_node *of_node = pdev->dev.of_node;
+	struct device_node *parent_node;
+	struct resource *res;
+	u32 value;
+	int ret;
+
+	dev_dbg(&pdev->dev, "using Device Tree\n");
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev,
+			"failed to locate DT /reserved-memory resource\n");
+		return -EINVAL;
+	}
+
+	pdata->mem_size = resource_size(res);
+	pdata->mem_address = res->start;
+	/*
+	 * Setting "unbuffered" is deprecated and will be ignored if
+	 * "mem_type" is also specified.
+	 */
+	pdata->mem_type = of_property_read_bool(of_node, "unbuffered");
+	/*
+	 * Setting "no-dump-oops" is deprecated and will be ignored if
+	 * "max_reason" is also specified.
+	 */
+	if (of_property_read_bool(of_node, "no-dump-oops"))
+		pdata->max_reason = KMSG_DUMP_PANIC;
+	else
+		pdata->max_reason = KMSG_DUMP_OOPS;
+
+#define parse_u32(name, field, default_value) {				\
+		ret = ramoops_parse_dt_u32(pdev, name, default_value,	\
+					    &value);			\
+		if (ret < 0)						\
+			return ret;					\
+		field = value;						\
+	}
+
+	parse_u32("mem-type", pdata->mem_type, pdata->mem_type);
+	parse_u32("record-size", pdata->record_size, 0);
+	parse_u32("console-size", pdata->console_size, 0);
+	parse_u32("ftrace-size", pdata->ftrace_size, 0);
+	parse_u32("pmsg-size", pdata->pmsg_size, 0);
+	parse_u32("ecc-size", pdata->ecc_info.ecc_size, 0);
+	parse_u32("flags", pdata->flags, 0);
+	parse_u32("max-reason", pdata->max_reason, pdata->max_reason);
+
+#undef parse_u32
+
+	/*
+	 * Some old Chromebooks relied on the kernel setting the
+	 * console_size and pmsg_size to the record size since that's
+	 * what the downstream kernel did.  These same Chromebooks had
+	 * "ramoops" straight under the root node which isn't
+	 * according to the current upstream bindings (though it was
+	 * arguably acceptable under a prior version of the bindings).
+	 * Let's make those old Chromebooks work by detecting that
+	 * we're not a child of "reserved-memory" and mimicking the
+	 * expected behavior.
+	 */
+	parent_node = of_get_parent(of_node);
+	if (!of_node_name_eq(parent_node, "reserved-memory") &&
+	    !pdata->console_size && !pdata->ftrace_size &&
+	    !pdata->pmsg_size && !pdata->ecc_info.ecc_size) {
+		pdata->console_size = pdata->record_size;
+		pdata->pmsg_size = pdata->record_size;
+	}
+	of_node_put(parent_node);
+
+	return 0;
+}
+
+static int ramoops_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct ramoops_platform_data *pdata = dev->platform_data;
+	struct ramoops_platform_data pdata_local;
+	struct ramoops_context *cxt = &oops_cxt;
+	size_t dump_mem_sz;
+	phys_addr_t paddr;
+	int err = -EINVAL;
+
+	/*
+	 * Only a single ramoops area allowed at a time, so fail extra
+	 * probes.
+	 */
+	if (cxt->max_dump_cnt) {
+		pr_err("already initialized\n");
+		goto fail_out;
+	}
+
+	if (dev_of_node(dev) && !pdata) {
+		pdata = &pdata_local;
+		memset(pdata, 0, sizeof(*pdata));
+
+		err = ramoops_parse_dt(pdev, pdata);
+		if (err < 0)
+			goto fail_out;
+	}
+
+	/* Make sure we didn't get bogus platform data pointer. */
+	if (!pdata) {
+		pr_err("NULL platform data\n");
+		err = -EINVAL;
+		goto fail_out;
+	}
+
+	if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size &&
+			!pdata->ftrace_size && !pdata->pmsg_size)) {
+		pr_err("The memory size and the record/console size must be "
+			"non-zero\n");
+		err = -EINVAL;
+		goto fail_out;
+	}
+
+	if (pdata->record_size && !is_power_of_2(pdata->record_size))
+		pdata->record_size = rounddown_pow_of_two(pdata->record_size);
+	if (pdata->console_size && !is_power_of_2(pdata->console_size))
+		pdata->console_size = rounddown_pow_of_two(pdata->console_size);
+	if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
+		pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
+	if (pdata->pmsg_size && !is_power_of_2(pdata->pmsg_size))
+		pdata->pmsg_size = rounddown_pow_of_two(pdata->pmsg_size);
+
+	cxt->size = pdata->mem_size;
+	cxt->phys_addr = pdata->mem_address;
+	cxt->memtype = pdata->mem_type;
+	cxt->record_size = pdata->record_size;
+	cxt->console_size = pdata->console_size;
+	cxt->ftrace_size = pdata->ftrace_size;
+	cxt->pmsg_size = pdata->pmsg_size;
+	cxt->flags = pdata->flags;
+	cxt->ecc_info = pdata->ecc_info;
+
+	paddr = cxt->phys_addr;
+
+	dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
+			- cxt->pmsg_size;
+	err = ramoops_init_przs("dmesg", dev, cxt, &cxt->dprzs, &paddr,
+				dump_mem_sz, cxt->record_size,
+				&cxt->max_dump_cnt, 0, 0);
+	if (err)
+		goto fail_init;
+
+	err = ramoops_init_prz("console", dev, cxt, &cxt->cprz, &paddr,
+			       cxt->console_size, 0);
+	if (err)
+		goto fail_init;
+
+	err = ramoops_init_prz("pmsg", dev, cxt, &cxt->mprz, &paddr,
+				cxt->pmsg_size, 0);
+	if (err)
+		goto fail_init;
+
+	cxt->max_ftrace_cnt = (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
+				? nr_cpu_ids
+				: 1;
+	err = ramoops_init_przs("ftrace", dev, cxt, &cxt->fprzs, &paddr,
+				cxt->ftrace_size, -1,
+				&cxt->max_ftrace_cnt, LINUX_VERSION_CODE,
+				(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
+					? PRZ_FLAG_NO_LOCK : 0);
+	if (err)
+		goto fail_init;
+
+	cxt->pstore.data = cxt;
+	/*
+	 * Prepare frontend flags based on which areas are initialized.
+	 * For ramoops_init_przs() cases, the "max count" variable tells
+	 * if there are regions present. For ramoops_init_prz() cases,
+	 * the single region size is how to check.
+	 */
+	cxt->pstore.flags = 0;
+	if (cxt->max_dump_cnt) {
+		cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
+		cxt->pstore.max_reason = pdata->max_reason;
+	}
+	if (cxt->console_size)
+		cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
+	if (cxt->max_ftrace_cnt)
+		cxt->pstore.flags |= PSTORE_FLAGS_FTRACE;
+	if (cxt->pmsg_size)
+		cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
+
+	/*
+	 * Since bufsize is only used for dmesg crash dumps, it
+	 * must match the size of the dprz record (after PRZ header
+	 * and ECC bytes have been accounted for).
+	 */
+	if (cxt->pstore.flags & PSTORE_FLAGS_DMESG) {
+		cxt->pstore.bufsize = cxt->dprzs[0]->buffer_size;
+		cxt->pstore.buf = kvzalloc(cxt->pstore.bufsize, GFP_KERNEL);
+		if (!cxt->pstore.buf) {
+			pr_err("cannot allocate pstore crash dump buffer\n");
+			err = -ENOMEM;
+			goto fail_clear;
+		}
+	}
+
+	err = pstore_register(&cxt->pstore);
+	if (err) {
+		pr_err("registering with pstore failed\n");
+		goto fail_buf;
+	}
+
+	/*
+	 * Update the module parameter variables as well so they are visible
+	 * through /sys/module/ramoops/parameters/
+	 */
+	mem_size = pdata->mem_size;
+	mem_address = pdata->mem_address;
+	record_size = pdata->record_size;
+	ramoops_max_reason = pdata->max_reason;
+	ramoops_console_size = pdata->console_size;
+	ramoops_pmsg_size = pdata->pmsg_size;
+	ramoops_ftrace_size = pdata->ftrace_size;
+	mem_type = pdata->mem_type;
+	ramoops_ecc = pdata->ecc_info.ecc_size;
+
+	pr_info("using 0x%lx@0x%llx, ecc: %d\n",
+		cxt->size, (unsigned long long)cxt->phys_addr,
+		cxt->ecc_info.ecc_size);
+
+	return 0;
+
+fail_buf:
+	kvfree(cxt->pstore.buf);
+fail_clear:
+	cxt->pstore.bufsize = 0;
+fail_init:
+	ramoops_free_przs(cxt);
+fail_out:
+	return err;
+}
+
+static void ramoops_remove(struct platform_device *pdev)
+{
+	struct ramoops_context *cxt = &oops_cxt;
+
+	pstore_unregister(&cxt->pstore);
+
+	kvfree(cxt->pstore.buf);
+	cxt->pstore.bufsize = 0;
+
+	ramoops_free_przs(cxt);
+}
+
+static const struct of_device_id dt_match[] = {
+	{ .compatible = "ramoops" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, dt_match);
+
+static struct platform_driver ramoops_driver = {
+	.probe		= ramoops_probe,
+	.remove		= ramoops_remove,
+	.driver		= {
+		.name		= "ramoops",
+		.of_match_table	= dt_match,
+	},
+};
+
+static inline void ramoops_unregister_dummy(void)
+{
+	platform_device_unregister(dummy);
+	dummy = NULL;
+}
+
+static void __init ramoops_register_dummy(void)
+{
+	struct ramoops_platform_data pdata;
+
+	if (mem_name) {
+		phys_addr_t start;
+		phys_addr_t size;
+
+		if (reserve_mem_find_by_name(mem_name, &start, &size)) {
+			mem_address = start;
+			mem_size = size;
+		}
+	}
+
+	/*
+	 * Prepare a dummy platform data structure to carry the module
+	 * parameters. If mem_size isn't set, then there are no module
+	 * parameters, and we can skip this.
+	 */
+	if (!mem_size)
+		return;
+
+	pr_info("using module parameters\n");
+
+	memset(&pdata, 0, sizeof(pdata));
+	pdata.mem_size = mem_size;
+	pdata.mem_address = mem_address;
+	pdata.mem_type = mem_type;
+	pdata.record_size = record_size;
+	pdata.console_size = ramoops_console_size;
+	pdata.ftrace_size = ramoops_ftrace_size;
+	pdata.pmsg_size = ramoops_pmsg_size;
+	/* If "max_reason" is set, its value has priority over "dump_oops". */
+	if (ramoops_max_reason >= 0)
+		pdata.max_reason = ramoops_max_reason;
+	/* Otherwise, if "dump_oops" is set, parse it into "max_reason". */
+	else if (ramoops_dump_oops != -1)
+		pdata.max_reason = ramoops_dump_oops ? KMSG_DUMP_OOPS
+						     : KMSG_DUMP_PANIC;
+	/* And if neither are explicitly set, use the default. */
+	else
+		pdata.max_reason = KMSG_DUMP_OOPS;
+	pdata.flags = RAMOOPS_FLAG_FTRACE_PER_CPU;
+
+	/*
+	 * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
+	 * (using 1 byte for ECC isn't much of use anyway).
+	 */
+	pdata.ecc_info.ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;
+
+	dummy = platform_device_register_data(NULL, "ramoops", -1,
+			&pdata, sizeof(pdata));
+	if (IS_ERR(dummy)) {
+		pr_info("could not create platform device: %ld\n",
+			PTR_ERR(dummy));
+		dummy = NULL;
+	}
+}
+
+static int __init ramoops_init(void)
+{
+	int ret;
+
+	ramoops_register_dummy();
+	ret = platform_driver_register(&ramoops_driver);
+	if (ret != 0)
+		ramoops_unregister_dummy();
+
+	return ret;
+}
+postcore_initcall(ramoops_init);
+
+static void __exit ramoops_exit(void)
+{
+	platform_driver_unregister(&ramoops_driver);
+	ramoops_unregister_dummy();
+}
+module_exit(ramoops_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marco Stornelli <marco.stornelli@gmail.com>");
+MODULE_DESCRIPTION("RAM Oops/Panic logger/driver");

linux-7.2.3/fs/pstore/ram_core.c

@@ -0,0 +1,642 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Google, Inc.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/rslib.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
+#include <asm/page.h>
+
+#include "ram_internal.h"
+
+/**
+ * struct persistent_ram_buffer - persistent circular RAM buffer
+ *
+ * @sig: Signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
+ * @start: First valid byte in the buffer.
+ * @size: Number of valid bytes in the buffer.
+ * @data: The contents of the buffer.
+ */
+struct persistent_ram_buffer {
+	uint32_t    sig;
+	atomic_t    start;
+	atomic_t    size;
+	uint8_t     data[];
+};
+
+#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
+
+static inline size_t buffer_size(struct persistent_ram_zone *prz)
+{
+	return atomic_read(&prz->buffer->size);
+}
+
+static inline size_t buffer_start(struct persistent_ram_zone *prz)
+{
+	return atomic_read(&prz->buffer->start);
+}
+
+/* increase and wrap the start pointer, returning the old value */
+static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
+{
+	int old;
+	int new;
+	unsigned long flags = 0;
+
+	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
+		raw_spin_lock_irqsave(&prz->buffer_lock, flags);
+
+	old = atomic_read(&prz->buffer->start);
+	new = old + a;
+	while (unlikely(new >= prz->buffer_size))
+		new -= prz->buffer_size;
+	atomic_set(&prz->buffer->start, new);
+
+	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
+		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
+
+	return old;
+}
+
+/* increase the size counter until it hits the max size */
+static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
+{
+	size_t old;
+	size_t new;
+	unsigned long flags = 0;
+
+	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
+		raw_spin_lock_irqsave(&prz->buffer_lock, flags);
+
+	old = atomic_read(&prz->buffer->size);
+	if (old == prz->buffer_size)
+		goto exit;
+
+	new = old + a;
+	if (new > prz->buffer_size)
+		new = prz->buffer_size;
+	atomic_set(&prz->buffer->size, new);
+
+exit:
+	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
+		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
+}
+
+static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
+	uint8_t *data, size_t len, uint8_t *ecc)
+{
+	int i;
+
+	/* Initialize the parity buffer */
+	memset(prz->ecc_info.par, 0,
+	       prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
+	encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
+	for (i = 0; i < prz->ecc_info.ecc_size; i++)
+		ecc[i] = prz->ecc_info.par[i];
+}
+
+static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
+	void *data, size_t len, uint8_t *ecc)
+{
+	int i;
+
+	for (i = 0; i < prz->ecc_info.ecc_size; i++)
+		prz->ecc_info.par[i] = ecc[i];
+	return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
+				NULL, 0, NULL, 0, NULL);
+}
+
+static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
+	unsigned int start, unsigned int count)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	uint8_t *buffer_end = buffer->data + prz->buffer_size;
+	uint8_t *block;
+	uint8_t *par;
+	int ecc_block_size = prz->ecc_info.block_size;
+	int ecc_size = prz->ecc_info.ecc_size;
+	int size = ecc_block_size;
+
+	if (!ecc_size)
+		return;
+
+	block = buffer->data + (start & ~(ecc_block_size - 1));
+	par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
+
+	do {
+		if (block + ecc_block_size > buffer_end)
+			size = buffer_end - block;
+		persistent_ram_encode_rs8(prz, block, size, par);
+		block += ecc_block_size;
+		par += ecc_size;
+	} while (block < buffer->data + start + count);
+}
+
+static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+
+	if (!prz->ecc_info.ecc_size)
+		return;
+
+	persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
+				  prz->par_header);
+}
+
+static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	uint8_t *block;
+	uint8_t *par;
+
+	if (!prz->ecc_info.ecc_size)
+		return;
+
+	block = buffer->data;
+	par = prz->par_buffer;
+	while (block < buffer->data + buffer_size(prz)) {
+		int numerr;
+		int size = prz->ecc_info.block_size;
+		if (block + size > buffer->data + prz->buffer_size)
+			size = buffer->data + prz->buffer_size - block;
+		numerr = persistent_ram_decode_rs8(prz, block, size, par);
+		if (numerr > 0) {
+			pr_devel("error in block %p, %d\n", block, numerr);
+			prz->corrected_bytes += numerr;
+		} else if (numerr < 0) {
+			pr_devel("uncorrectable error in block %p\n", block);
+			prz->bad_blocks++;
+		}
+		block += prz->ecc_info.block_size;
+		par += prz->ecc_info.ecc_size;
+	}
+}
+
+static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
+				   struct persistent_ram_ecc_info *ecc_info)
+{
+	int numerr;
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	size_t ecc_blocks;
+	size_t ecc_total;
+
+	if (!ecc_info || !ecc_info->ecc_size)
+		return 0;
+
+	prz->ecc_info.block_size = ecc_info->block_size ?: 128;
+	prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
+	prz->ecc_info.symsize = ecc_info->symsize ?: 8;
+	prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
+
+	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
+				  prz->ecc_info.block_size +
+				  prz->ecc_info.ecc_size);
+	ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
+	if (ecc_total >= prz->buffer_size) {
+		pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
+		       __func__, prz->ecc_info.ecc_size,
+		       ecc_total, prz->buffer_size);
+		return -EINVAL;
+	}
+
+	prz->buffer_size -= ecc_total;
+	prz->par_buffer = buffer->data + prz->buffer_size;
+	prz->par_header = prz->par_buffer +
+			  ecc_blocks * prz->ecc_info.ecc_size;
+
+	/*
+	 * first consecutive root is 0
+	 * primitive element to generate roots = 1
+	 */
+	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
+				  0, 1, prz->ecc_info.ecc_size);
+	if (prz->rs_decoder == NULL) {
+		pr_info("init_rs failed\n");
+		return -EINVAL;
+	}
+
+	/* allocate workspace instead of using stack VLA */
+	prz->ecc_info.par = kmalloc_objs(*prz->ecc_info.par,
+					 prz->ecc_info.ecc_size);
+	if (!prz->ecc_info.par) {
+		pr_err("cannot allocate ECC parity workspace\n");
+		return -ENOMEM;
+	}
+
+	prz->corrected_bytes = 0;
+	prz->bad_blocks = 0;
+
+	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
+					   prz->par_header);
+	if (numerr > 0) {
+		pr_info("error in header, %d\n", numerr);
+		prz->corrected_bytes += numerr;
+	} else if (numerr < 0) {
+		pr_info_ratelimited("uncorrectable error in header\n");
+		prz->bad_blocks++;
+	}
+
+	return 0;
+}
+
+ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
+	char *str, size_t len)
+{
+	ssize_t ret;
+
+	if (!prz->ecc_info.ecc_size)
+		return 0;
+
+	if (prz->corrected_bytes || prz->bad_blocks)
+		ret = snprintf(str, len, ""
+			"\nECC: %d Corrected bytes, %d unrecoverable blocks\n",
+			prz->corrected_bytes, prz->bad_blocks);
+	else
+		ret = snprintf(str, len, "\nECC: No errors detected\n");
+
+	return ret;
+}
+
+static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
+	const void *s, unsigned int start, unsigned int count)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	memcpy_toio(buffer->data + start, s, count);
+	persistent_ram_update_ecc(prz, start, count);
+}
+
+static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
+	const void __user *s, unsigned int start, unsigned int count)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
+		-EFAULT : 0;
+	persistent_ram_update_ecc(prz, start, count);
+	return ret;
+}
+
+void persistent_ram_save_old(struct persistent_ram_zone *prz)
+{
+	struct persistent_ram_buffer *buffer = prz->buffer;
+	size_t size = buffer_size(prz);
+	size_t start = buffer_start(prz);
+
+	if (!size)
+		return;
+
+	/*
+	 * If the existing buffer is differently sized, free it so a new
+	 * one is allocated. This can happen when persistent_ram_save_old()
+	 * is called early in boot and later for a timer-triggered
+	 * survivable crash when the crash dumps don't match in size
+	 * (which would be extremely unlikely given kmsg buffers usually
+	 * exceed prz buffer sizes).
+	 */
+	if (prz->old_log && prz->old_log_size != size)
+		persistent_ram_free_old(prz);
+
+	if (!prz->old_log) {
+		persistent_ram_ecc_old(prz);
+		prz->old_log = kvzalloc(size, GFP_KERNEL);
+	}
+	if (!prz->old_log) {
+		pr_err("failed to allocate buffer\n");
+		return;
+	}
+
+	prz->old_log_size = size;
+	memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
+	memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
+}
+
+int notrace persistent_ram_write(struct persistent_ram_zone *prz,
+	const void *s, unsigned int count)
+{
+	int rem;
+	int c = count;
+	size_t start;
+
+	if (unlikely(c > prz->buffer_size)) {
+		s += c - prz->buffer_size;
+		c = prz->buffer_size;
+	}
+
+	buffer_size_add(prz, c);
+
+	start = buffer_start_add(prz, c);
+
+	rem = prz->buffer_size - start;
+	if (unlikely(rem < c)) {
+		persistent_ram_update(prz, s, start, rem);
+		s += rem;
+		c -= rem;
+		start = 0;
+	}
+	persistent_ram_update(prz, s, start, c);
+
+	persistent_ram_update_header_ecc(prz);
+
+	return count;
+}
+
+int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
+	const void __user *s, unsigned int count)
+{
+	int rem, ret = 0, c = count;
+	size_t start;
+
+	if (unlikely(c > prz->buffer_size)) {
+		s += c - prz->buffer_size;
+		c = prz->buffer_size;
+	}
+
+	buffer_size_add(prz, c);
+
+	start = buffer_start_add(prz, c);
+
+	rem = prz->buffer_size - start;
+	if (unlikely(rem < c)) {
+		ret = persistent_ram_update_user(prz, s, start, rem);
+		s += rem;
+		c -= rem;
+		start = 0;
+	}
+	if (likely(!ret))
+		ret = persistent_ram_update_user(prz, s, start, c);
+
+	persistent_ram_update_header_ecc(prz);
+
+	return unlikely(ret) ? ret : count;
+}
+
+size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
+{
+	return prz->old_log_size;
+}
+
+void *persistent_ram_old(struct persistent_ram_zone *prz)
+{
+	return prz->old_log;
+}
+
+void persistent_ram_free_old(struct persistent_ram_zone *prz)
+{
+	kvfree(prz->old_log);
+	prz->old_log = NULL;
+	prz->old_log_size = 0;
+}
+
+void persistent_ram_zap(struct persistent_ram_zone *prz)
+{
+	atomic_set(&prz->buffer->start, 0);
+	atomic_set(&prz->buffer->size, 0);
+	persistent_ram_update_header_ecc(prz);
+}
+
+#define MEM_TYPE_WCOMBINE	0
+#define MEM_TYPE_NONCACHED	1
+#define MEM_TYPE_NORMAL		2
+
+static void *persistent_ram_vmap(phys_addr_t start, size_t size,
+		unsigned int memtype)
+{
+	struct page **pages;
+	phys_addr_t page_start;
+	unsigned int page_count;
+	pgprot_t prot;
+	unsigned int i;
+	void *vaddr;
+
+	page_start = start - offset_in_page(start);
+	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
+
+	switch (memtype) {
+	case MEM_TYPE_NORMAL:
+		prot = PAGE_KERNEL;
+		break;
+	case MEM_TYPE_NONCACHED:
+		prot = pgprot_noncached(PAGE_KERNEL);
+		break;
+	case MEM_TYPE_WCOMBINE:
+		prot = pgprot_writecombine(PAGE_KERNEL);
+		break;
+	default:
+		pr_err("invalid mem_type=%d\n", memtype);
+		return NULL;
+	}
+
+	pages = kmalloc_objs(struct page *, page_count);
+	if (!pages) {
+		pr_err("%s: Failed to allocate array for %u pages\n",
+		       __func__, page_count);
+		return NULL;
+	}
+
+	for (i = 0; i < page_count; i++) {
+		phys_addr_t addr = page_start + i * PAGE_SIZE;
+		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
+	}
+	/*
+	 * VM_IOREMAP used here to bypass this region during vread_iter()
+	 * and kmap_atomic() (i.e. kcore) to avoid __va() failures.
+	 */
+	vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
+	kfree(pages);
+
+	/*
+	 * vmap() may fail and return NULL. Do not add the offset in this
+	 * case, otherwise a NULL mapping would appear successful.
+	 */
+	if (!vaddr)
+		return NULL;
+
+	/*
+	 * Since vmap() uses page granularity, we must add the offset
+	 * into the page here, to get the byte granularity address
+	 * into the mapping to represent the actual "start" location.
+	 */
+	return vaddr + offset_in_page(start);
+}
+
+static void *persistent_ram_iomap(phys_addr_t start, size_t size,
+		unsigned int memtype, char *label)
+{
+	void *va;
+
+	if (!request_mem_region(start, size, label ?: "ramoops")) {
+		pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
+			label ?: "ramoops",
+			(unsigned long long)size, (unsigned long long)start);
+		return NULL;
+	}
+
+	if (memtype)
+		va = ioremap(start, size);
+	else
+		va = ioremap_wc(start, size);
+
+	/* We must release the mem region if ioremap fails. */
+	if (!va)
+		release_mem_region(start, size);
+
+	/*
+	 * Since request_mem_region() and ioremap() are byte-granularity
+	 * there is no need handle anything special like we do when the
+	 * vmap() case in persistent_ram_vmap() above.
+	 */
+	return va;
+}
+
+static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
+		struct persistent_ram_zone *prz, int memtype)
+{
+	prz->paddr = start;
+	prz->size = size;
+
+	if (pfn_valid(start >> PAGE_SHIFT))
+		prz->vaddr = persistent_ram_vmap(start, size, memtype);
+	else
+		prz->vaddr = persistent_ram_iomap(start, size, memtype,
+						  prz->label);
+
+	if (!prz->vaddr) {
+		pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
+			(unsigned long long)size, (unsigned long long)start);
+		return -ENOMEM;
+	}
+
+	prz->buffer = prz->vaddr;
+	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
+
+	return 0;
+}
+
+static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
+				    struct persistent_ram_ecc_info *ecc_info)
+{
+	int ret;
+	bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
+
+	ret = persistent_ram_init_ecc(prz, ecc_info);
+	if (ret) {
+		pr_warn("ECC failed %s\n", prz->label);
+		return ret;
+	}
+
+	sig ^= PERSISTENT_RAM_SIG;
+
+	if (prz->buffer->sig == sig) {
+		if (buffer_size(prz) == 0 && buffer_start(prz) == 0) {
+			pr_debug("found existing empty buffer\n");
+			return 0;
+		}
+
+		if (buffer_size(prz) > prz->buffer_size ||
+		    buffer_start(prz) > buffer_size(prz)) {
+			pr_info("found existing invalid buffer, size %zu, start %zu\n",
+				buffer_size(prz), buffer_start(prz));
+			zap = true;
+		} else {
+			pr_debug("found existing buffer, size %zu, start %zu\n",
+				 buffer_size(prz), buffer_start(prz));
+			persistent_ram_save_old(prz);
+		}
+	} else {
+		pr_debug("no valid data in buffer (sig = 0x%08x)\n",
+			 prz->buffer->sig);
+		prz->buffer->sig = sig;
+		zap = true;
+	}
+
+	/* Reset missing, invalid, or single-use memory area. */
+	if (zap)
+		persistent_ram_zap(prz);
+
+	return 0;
+}
+
+void persistent_ram_free(struct persistent_ram_zone **_prz)
+{
+	struct persistent_ram_zone *prz;
+
+	if (!_prz)
+		return;
+
+	prz = *_prz;
+	if (!prz)
+		return;
+
+	if (prz->vaddr) {
+		if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
+			/* We must vunmap() at page-granularity. */
+			vunmap(prz->vaddr - offset_in_page(prz->paddr));
+		} else {
+			iounmap(prz->vaddr);
+			release_mem_region(prz->paddr, prz->size);
+		}
+		prz->vaddr = NULL;
+	}
+	if (prz->rs_decoder) {
+		free_rs(prz->rs_decoder);
+		prz->rs_decoder = NULL;
+	}
+	kfree(prz->ecc_info.par);
+	prz->ecc_info.par = NULL;
+
+	persistent_ram_free_old(prz);
+	kfree(prz->label);
+	kfree(prz);
+	*_prz = NULL;
+}
+
+struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
+			u32 sig, struct persistent_ram_ecc_info *ecc_info,
+			unsigned int memtype, u32 flags, char *label)
+{
+	struct persistent_ram_zone *prz;
+	int ret = -ENOMEM;
+
+	prz = kzalloc_obj(struct persistent_ram_zone);
+	if (!prz) {
+		pr_err("failed to allocate persistent ram zone\n");
+		goto err;
+	}
+
+	/* Initialize general buffer state. */
+	raw_spin_lock_init(&prz->buffer_lock);
+	prz->flags = flags;
+	prz->label = kstrdup(label, GFP_KERNEL);
+	if (!prz->label)
+		goto err;
+
+	ret = persistent_ram_buffer_map(start, size, prz, memtype);
+	if (ret)
+		goto err;
+
+	ret = persistent_ram_post_init(prz, sig, ecc_info);
+	if (ret)
+		goto err;
+
+	pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
+		prz->label, prz->size, (unsigned long long)prz->paddr,
+		sizeof(*prz->buffer), prz->buffer_size,
+		prz->size - sizeof(*prz->buffer) - prz->buffer_size,
+		prz->ecc_info.ecc_size, prz->ecc_info.block_size);
+
+	return prz;
+err:
+	persistent_ram_free(&prz);
+	return ERR_PTR(ret);
+}

linux-7.2.3/fs/pstore/ram_internal.h

@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
+ * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
+ * Copyright (C) 2011 Google, Inc.
+ */
+
+#include <linux/pstore_ram.h>
+
+/*
+ * Choose whether access to the RAM zone requires locking or not.  If a zone
+ * can be written to from different CPUs like with ftrace for example, then
+ * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required.
+ */
+#define PRZ_FLAG_NO_LOCK	BIT(0)
+/*
+ * If a PRZ should only have a single-boot lifetime, this marks it as
+ * getting wiped after its contents get copied out after boot.
+ */
+#define PRZ_FLAG_ZAP_OLD	BIT(1)
+
+/**
+ * struct persistent_ram_zone - Details of a persistent RAM zone (PRZ)
+ *                              used as a pstore backend
+ *
+ * @paddr:	physical address of the mapped RAM area
+ * @size:	size of mapping
+ * @label:	unique name of this PRZ
+ * @type:	frontend type for this PRZ
+ * @flags:	holds PRZ_FLAGS_* bits
+ *
+ * @buffer_lock:
+ *	locks access to @buffer "size" bytes and "start" offset
+ * @buffer:
+ *	pointer to actual RAM area managed by this PRZ
+ * @buffer_size:
+ *	bytes in @buffer->data (not including any trailing ECC bytes)
+ *
+ * @par_buffer:
+ *	pointer into @buffer->data containing ECC bytes for @buffer->data
+ * @par_header:
+ *	pointer into @buffer->data containing ECC bytes for @buffer header
+ *	(i.e. all fields up to @data)
+ * @rs_decoder:
+ *	RSLIB instance for doing ECC calculations
+ * @corrected_bytes:
+ *	ECC corrected bytes accounting since boot
+ * @bad_blocks:
+ *	ECC uncorrectable bytes accounting since boot
+ * @ecc_info:
+ *	ECC configuration details
+ *
+ * @old_log:
+ *	saved copy of @buffer->data prior to most recent wipe
+ * @old_log_size:
+ *	bytes contained in @old_log
+ *
+ */
+struct persistent_ram_zone {
+	phys_addr_t paddr;
+	size_t size;
+	void *vaddr;
+	char *label;
+	enum pstore_type_id type;
+	u32 flags;
+
+	raw_spinlock_t buffer_lock;
+	struct persistent_ram_buffer *buffer;
+	size_t buffer_size;
+
+	char *par_buffer;
+	char *par_header;
+	struct rs_control *rs_decoder;
+	int corrected_bytes;
+	int bad_blocks;
+	struct persistent_ram_ecc_info ecc_info;
+
+	char *old_log;
+	size_t old_log_size;
+};
+
+struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
+			u32 sig, struct persistent_ram_ecc_info *ecc_info,
+			unsigned int memtype, u32 flags, char *label);
+void persistent_ram_free(struct persistent_ram_zone **_prz);
+void persistent_ram_zap(struct persistent_ram_zone *prz);
+
+int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
+			 unsigned int count);
+int persistent_ram_write_user(struct persistent_ram_zone *prz,
+			      const void __user *s, unsigned int count);
+
+void persistent_ram_save_old(struct persistent_ram_zone *prz);
+size_t persistent_ram_old_size(struct persistent_ram_zone *prz);
+void *persistent_ram_old(struct persistent_ram_zone *prz);
+void persistent_ram_free_old(struct persistent_ram_zone *prz);
+ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
+	char *str, size_t len);