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linux-7.2.3/arch/arm64/include/asm/stacktrace/common.h

@@ -0,0 +1,171 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Common arm64 stack unwinder code.
+ *
+ * See: arch/arm64/kernel/stacktrace.c for the reference implementation.
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ */
+#ifndef __ASM_STACKTRACE_COMMON_H
+#define __ASM_STACKTRACE_COMMON_H
+
+#include <linux/types.h>
+
+struct stack_info {
+	unsigned long low;
+	unsigned long high;
+};
+
+/**
+ * struct unwind_state - state used for robust unwinding.
+ *
+ * @fp:          The fp value in the frame record (or the real fp)
+ * @pc:          The lr value in the frame record (or the real lr)
+ *
+ * @stack:       The stack currently being unwound.
+ * @stacks:      An array of stacks which can be unwound.
+ * @nr_stacks:   The number of stacks in @stacks.
+ */
+struct unwind_state {
+	unsigned long fp;
+	unsigned long pc;
+
+	struct stack_info stack;
+	struct stack_info *stacks;
+	int nr_stacks;
+};
+
+static inline struct stack_info stackinfo_get_unknown(void)
+{
+	return (struct stack_info) {
+		.low = 0,
+		.high = 0,
+	};
+}
+
+static inline bool stackinfo_on_stack(const struct stack_info *info,
+				      unsigned long sp, unsigned long size)
+{
+	if (!info->low)
+		return false;
+
+	if (sp < info->low || sp + size < sp || sp + size > info->high)
+		return false;
+
+	return true;
+}
+
+static inline void unwind_init_common(struct unwind_state *state)
+{
+	state->stack = stackinfo_get_unknown();
+}
+
+/**
+ * unwind_find_stack() - Find the accessible stack which entirely contains an
+ * object.
+ *
+ * @state: the current unwind state.
+ * @sp:    the base address of the object.
+ * @size:  the size of the object.
+ *
+ * Return: a pointer to the relevant stack_info if found; NULL otherwise.
+ */
+static struct stack_info *unwind_find_stack(struct unwind_state *state,
+					    unsigned long sp,
+					    unsigned long size)
+{
+	struct stack_info *info = &state->stack;
+
+	if (stackinfo_on_stack(info, sp, size))
+		return info;
+
+	for (int i = 0; i < state->nr_stacks; i++) {
+		info = &state->stacks[i];
+		if (stackinfo_on_stack(info, sp, size))
+			return info;
+	}
+
+	return NULL;
+}
+
+/**
+ * unwind_consume_stack() - Update stack boundaries so that future unwind steps
+ * cannot consume this object again.
+ *
+ * @state: the current unwind state.
+ * @info:  the stack_info of the stack containing the object.
+ * @sp:    the base address of the object.
+ * @size:  the size of the object.
+ *
+ * Return: 0 upon success, an error code otherwise.
+ */
+static inline void unwind_consume_stack(struct unwind_state *state,
+					struct stack_info *info,
+					unsigned long sp,
+					unsigned long size)
+{
+	struct stack_info tmp;
+
+	/*
+	 * Stack transitions are strictly one-way, and once we've
+	 * transitioned from one stack to another, it's never valid to
+	 * unwind back to the old stack.
+	 *
+	 * Destroy the old stack info so that it cannot be found upon a
+	 * subsequent transition. If the stack has not changed, we'll
+	 * immediately restore the current stack info.
+	 *
+	 * Note that stacks can nest in several valid orders, e.g.
+	 *
+	 *   TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL
+	 *   TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW
+	 *   HYP -> OVERFLOW
+	 *
+	 * ... so we do not check the specific order of stack
+	 * transitions.
+	 */
+	tmp = *info;
+	*info = stackinfo_get_unknown();
+	state->stack = tmp;
+
+	/*
+	 * Future unwind steps can only consume stack above this frame record.
+	 * Update the current stack to start immediately above it.
+	 */
+	state->stack.low = sp + size;
+}
+
+/**
+ * unwind_next_frame_record() - Unwind to the next frame record.
+ *
+ * @state:        the current unwind state.
+ *
+ * Return: 0 upon success, an error code otherwise.
+ */
+static inline int
+unwind_next_frame_record(struct unwind_state *state)
+{
+	struct stack_info *info;
+	struct frame_record *record;
+	unsigned long fp = state->fp;
+
+	if (fp & 0x7)
+		return -EINVAL;
+
+	info = unwind_find_stack(state, fp, sizeof(*record));
+	if (!info)
+		return -EINVAL;
+
+	unwind_consume_stack(state, info, fp, sizeof(*record));
+
+	/*
+	 * Record this frame record's values.
+	 */
+	record = (struct frame_record *)fp;
+	state->fp = READ_ONCE(record->fp);
+	state->pc = READ_ONCE(record->lr);
+
+	return 0;
+}
+
+#endif	/* __ASM_STACKTRACE_COMMON_H */

linux-7.2.3/arch/arm64/include/asm/stacktrace/frame.h

@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_STACKTRACE_FRAME_H
+#define __ASM_STACKTRACE_FRAME_H
+
+/*
+ * - FRAME_META_TYPE_NONE
+ *
+ *   This value is reserved.
+ *
+ * - FRAME_META_TYPE_FINAL
+ *
+ *   The record is the last entry on the stack.
+ *   Unwinding should terminate successfully.
+ *
+ * - FRAME_META_TYPE_PT_REGS
+ *
+ *   The record is embedded within a struct pt_regs, recording the registers at
+ *   an arbitrary point in time.
+ *   Unwinding should consume pt_regs::pc, followed by pt_regs::lr.
+ *
+ * Note: all other values are reserved and should result in unwinding
+ * terminating with an error.
+ */
+#define FRAME_META_TYPE_NONE		0
+#define FRAME_META_TYPE_FINAL		1
+#define FRAME_META_TYPE_PT_REGS		2
+
+#ifndef __ASSEMBLER__
+/* 
+ * A standard AAPCS64 frame record.
+ */
+struct frame_record {
+	u64 fp;
+	u64 lr;
+};
+
+/*
+ * A metadata frame record indicating a special unwind.
+ * The record::{fp,lr} fields must be zero to indicate the presence of
+ * metadata.
+ */
+struct frame_record_meta {
+	struct frame_record record;
+	u64 type;
+};
+#endif /* __ASSEMBLER__ */
+
+#endif /* __ASM_STACKTRACE_FRAME_H */

linux-7.2.3/arch/arm64/include/asm/stacktrace/nvhe.h

@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * KVM nVHE hypervisor stack tracing support.
+ *
+ * The unwinder implementation depends on the nVHE mode:
+ *
+ *   1) Non-protected nVHE mode - the host can directly access the
+ *      HYP stack pages and unwind the HYP stack in EL1. This saves having
+ *      to allocate shared buffers for the host to read the unwinded
+ *      stacktrace.
+ *
+ *   2) pKVM (protected nVHE) mode - the host cannot directly access
+ *      the HYP memory. The stack is unwinded in EL2 and dumped to a shared
+ *      buffer where the host can read and print the stacktrace.
+ *
+ * Copyright (C) 2022 Google LLC
+ */
+#ifndef __ASM_STACKTRACE_NVHE_H
+#define __ASM_STACKTRACE_NVHE_H
+
+#include <asm/stacktrace/common.h>
+
+/**
+ * kvm_nvhe_unwind_init() - Start an unwind from the given nVHE HYP fp and pc
+ *
+ * @state : unwind_state to initialize
+ * @fp    : frame pointer at which to start the unwinding.
+ * @pc    : program counter at which to start the unwinding.
+ */
+static inline void kvm_nvhe_unwind_init(struct unwind_state *state,
+					unsigned long fp,
+					unsigned long pc)
+{
+	unwind_init_common(state);
+
+	state->fp = fp;
+	state->pc = pc;
+}
+
+#ifndef __KVM_NVHE_HYPERVISOR__
+/*
+ * Conventional (non-protected) nVHE HYP stack unwinder
+ *
+ * In non-protected mode, the unwinding is done from kernel proper context
+ * (by the host in EL1).
+ */
+
+DECLARE_KVM_NVHE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
+DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info);
+DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stack_base);
+
+void kvm_nvhe_dump_backtrace(unsigned long hyp_offset);
+
+#endif	/* __KVM_NVHE_HYPERVISOR__ */
+#endif	/* __ASM_STACKTRACE_NVHE_H */