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linux-7.2.3/tools/testing/selftests/powerpc/mm/.gitignore

@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+bad_accesses
+exec_prot
+hugetlb_vs_thp_test
+large_vm_fork_separation
+large_vm_gpr_corruption
+pkey_exec_prot
+pkey_siginfo
+prot_sao
+segv_errors
+stack_expansion_ldst
+stack_expansion_signal
+subpage_prot
+tempfile
+tlbie_test
+wild_bctr

linux-7.2.3/tools/testing/selftests/powerpc/mm/Makefile

@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0
+noarg:
+	$(MAKE) -C ../
+
+TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot prot_sao segv_errors wild_bctr \
+		  large_vm_fork_separation bad_accesses exec_prot pkey_exec_prot \
+		  pkey_siginfo stack_expansion_signal stack_expansion_ldst \
+		  large_vm_gpr_corruption
+TEST_PROGS := stress_code_patching.sh
+
+TEST_GEN_PROGS_EXTENDED := tlbie_test
+TEST_GEN_FILES := tempfile
+
+top_srcdir = ../../../../..
+include ../../lib.mk
+include ../flags.mk
+
+$(TEST_GEN_PROGS): ../harness.c ../utils.c
+
+$(OUTPUT)/prot_sao: ../utils.c
+
+$(OUTPUT)/wild_bctr: CFLAGS += -m64
+$(OUTPUT)/large_vm_fork_separation: CFLAGS += -m64
+$(OUTPUT)/large_vm_gpr_corruption: CFLAGS += -m64
+$(OUTPUT)/bad_accesses: CFLAGS += -m64
+$(OUTPUT)/exec_prot: CFLAGS += -m64
+$(OUTPUT)/pkey_exec_prot: CFLAGS += -m64
+$(OUTPUT)/pkey_siginfo: CFLAGS += -m64
+
+$(OUTPUT)/stack_expansion_signal: ../utils.c ../pmu/lib.c
+
+$(OUTPUT)/stack_expansion_ldst: CFLAGS += -fno-stack-protector
+$(OUTPUT)/stack_expansion_ldst: ../utils.c
+
+$(OUTPUT)/tempfile:
+	dd if=/dev/zero of=$@ bs=64k count=1 status=none
+
+$(OUTPUT)/tlbie_test: LDLIBS += -lpthread
+$(OUTPUT)/pkey_siginfo: LDLIBS += -lpthread

linux-7.2.3/tools/testing/selftests/powerpc/mm/bad_accesses.c

@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright 2019, Michael Ellerman, IBM Corp.
+//
+// Test that out-of-bounds reads/writes behave as expected.
+
+#include <setjmp.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+// Old distros (Ubuntu 16.04 at least) don't define this
+#ifndef SEGV_BNDERR
+#define SEGV_BNDERR	3
+#endif
+
+// 64-bit kernel is always here
+#define PAGE_OFFSET	(0xcul << 60)
+
+static unsigned long kernel_virt_end;
+
+static volatile int fault_code;
+static volatile unsigned long fault_addr;
+static jmp_buf setjmp_env;
+
+static void segv_handler(int n, siginfo_t *info, void *ctxt_v)
+{
+	fault_code = info->si_code;
+	fault_addr = (unsigned long)info->si_addr;
+	siglongjmp(setjmp_env, 1);
+}
+
+int bad_access(char *p, bool write)
+{
+	char x = 0;
+
+	fault_code = 0;
+	fault_addr = 0;
+
+	if (sigsetjmp(setjmp_env, 1) == 0) {
+		if (write)
+			*p = 1;
+		else
+			x = *p;
+
+		printf("Bad - no SEGV! (%c)\n", x);
+		return 1;
+	}
+
+	// If we see MAPERR that means we took a page fault rather than an SLB
+	// miss. We only expect to take page faults for addresses within the
+	// valid kernel range.
+	FAIL_IF(fault_code == SEGV_MAPERR && \
+		(fault_addr < PAGE_OFFSET || fault_addr >= kernel_virt_end));
+
+	FAIL_IF(fault_code != SEGV_MAPERR && fault_code != SEGV_BNDERR);
+
+	return 0;
+}
+
+static int test(void)
+{
+	unsigned long i, j, addr, region_shift, page_shift, page_size;
+	struct sigaction sig;
+	bool hash_mmu;
+
+	sig = (struct sigaction) {
+		.sa_sigaction = segv_handler,
+		.sa_flags = SA_SIGINFO,
+	};
+
+	FAIL_IF(sigaction(SIGSEGV, &sig, NULL) != 0);
+
+	FAIL_IF(using_hash_mmu(&hash_mmu));
+
+	page_size = sysconf(_SC_PAGESIZE);
+	if (page_size == (64 * 1024))
+		page_shift = 16;
+	else
+		page_shift = 12;
+
+	if (page_size == (64 * 1024) || !hash_mmu) {
+		region_shift = 52;
+
+		// We have 7 512T regions (4 kernel linear, vmalloc, io, vmemmap)
+		kernel_virt_end = PAGE_OFFSET + (7 * (512ul << 40));
+	} else if (page_size == (4 * 1024) && hash_mmu) {
+		region_shift = 46;
+
+		// We have 7 64T regions (4 kernel linear, vmalloc, io, vmemmap)
+		kernel_virt_end = PAGE_OFFSET + (7 * (64ul << 40));
+	} else
+		FAIL_IF(true);
+
+	printf("Using %s MMU, PAGE_SIZE = %dKB start address 0x%016lx\n",
+	       hash_mmu ? "hash" : "radix",
+	       (1 << page_shift) >> 10,
+	       1ul << region_shift);
+
+	// This generates access patterns like:
+	//   0x0010000000000000
+	//   0x0010000000010000
+	//   0x0010000000020000
+	//   ...
+	//   0x0014000000000000
+	//   0x0018000000000000
+	//   0x0020000000000000
+	//   0x0020000000010000
+	//   0x0020000000020000
+	//   ...
+	//   0xf400000000000000
+	//   0xf800000000000000
+
+	for (i = 1; i <= ((0xful << 60) >> region_shift); i++) {
+		for (j = page_shift - 1; j < 60; j++) {
+			unsigned long base, delta;
+
+			base  = i << region_shift;
+			delta = 1ul << j;
+
+			if (delta >= base)
+				break;
+
+			addr = (base | delta) & ~((1 << page_shift) - 1);
+
+			FAIL_IF(bad_access((char *)addr, false));
+			FAIL_IF(bad_access((char *)addr, true));
+		}
+	}
+
+	return 0;
+}
+
+int main(void)
+{
+	test_harness_set_timeout(300);
+	return test_harness(test, "bad_accesses");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/exec_prot.c

@@ -0,0 +1,231 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2022, Nicholas Miehlbradt, IBM Corporation
+ * based on pkey_exec_prot.c
+ *
+ * Test if applying execute protection on pages works as expected.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+
+#include <unistd.h>
+#include <sys/mman.h>
+
+#include "pkeys.h"
+
+
+#define PPC_INST_NOP	0x60000000
+#define PPC_INST_TRAP	0x7fe00008
+#define PPC_INST_BLR	0x4e800020
+
+static volatile sig_atomic_t fault_code;
+static volatile sig_atomic_t remaining_faults;
+static volatile unsigned int *fault_addr;
+static unsigned long pgsize, numinsns;
+static unsigned int *insns;
+static bool pkeys_supported;
+
+static bool is_fault_expected(int fault_code)
+{
+	if (fault_code == SEGV_ACCERR)
+		return true;
+
+	/* Assume any pkey error is fine since pkey_exec_prot test covers them */
+	if (fault_code == SEGV_PKUERR && pkeys_supported)
+		return true;
+
+	return false;
+}
+
+static void trap_handler(int signum, siginfo_t *sinfo, void *ctx)
+{
+	/* Check if this fault originated from the expected address */
+	if (sinfo->si_addr != (void *)fault_addr)
+		sigsafe_err("got a fault for an unexpected address\n");
+
+	_exit(1);
+}
+
+static void segv_handler(int signum, siginfo_t *sinfo, void *ctx)
+{
+	fault_code = sinfo->si_code;
+
+	/* Check if this fault originated from the expected address */
+	if (sinfo->si_addr != (void *)fault_addr) {
+		sigsafe_err("got a fault for an unexpected address\n");
+		_exit(1);
+	}
+
+	/* Check if too many faults have occurred for a single test case */
+	if (!remaining_faults) {
+		sigsafe_err("got too many faults for the same address\n");
+		_exit(1);
+	}
+
+
+	/* Restore permissions in order to continue */
+	if (is_fault_expected(fault_code)) {
+		if (mprotect(insns, pgsize, PROT_READ | PROT_WRITE | PROT_EXEC)) {
+			sigsafe_err("failed to set access permissions\n");
+			_exit(1);
+		}
+	} else {
+		sigsafe_err("got a fault with an unexpected code\n");
+		_exit(1);
+	}
+
+	remaining_faults--;
+}
+
+static int check_exec_fault(int rights)
+{
+	/*
+	 * Jump to the executable region.
+	 *
+	 * The first iteration also checks if the overwrite of the
+	 * first instruction word from a trap to a no-op succeeded.
+	 */
+	fault_code = -1;
+	remaining_faults = 0;
+	if (!(rights & PROT_EXEC))
+		remaining_faults = 1;
+
+	FAIL_IF(mprotect(insns, pgsize, rights) != 0);
+	asm volatile("mtctr	%0; bctrl" : : "r"(insns));
+
+	FAIL_IF(remaining_faults != 0);
+	if (!(rights & PROT_EXEC))
+		FAIL_IF(!is_fault_expected(fault_code));
+
+	return 0;
+}
+
+static int test(void)
+{
+	struct sigaction segv_act, trap_act;
+	int i;
+
+	/* Skip the test if the CPU doesn't support Radix */
+	SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_3_00));
+
+	/* Check if pkeys are supported */
+	pkeys_supported = pkeys_unsupported() == 0;
+
+	/* Setup SIGSEGV handler */
+	segv_act.sa_handler = 0;
+	segv_act.sa_sigaction = segv_handler;
+	FAIL_IF(sigprocmask(SIG_SETMASK, 0, &segv_act.sa_mask) != 0);
+	segv_act.sa_flags = SA_SIGINFO;
+	segv_act.sa_restorer = 0;
+	FAIL_IF(sigaction(SIGSEGV, &segv_act, NULL) != 0);
+
+	/* Setup SIGTRAP handler */
+	trap_act.sa_handler = 0;
+	trap_act.sa_sigaction = trap_handler;
+	FAIL_IF(sigprocmask(SIG_SETMASK, 0, &trap_act.sa_mask) != 0);
+	trap_act.sa_flags = SA_SIGINFO;
+	trap_act.sa_restorer = 0;
+	FAIL_IF(sigaction(SIGTRAP, &trap_act, NULL) != 0);
+
+	/* Setup executable region */
+	pgsize = getpagesize();
+	numinsns = pgsize / sizeof(unsigned int);
+	insns = (unsigned int *)mmap(NULL, pgsize, PROT_READ | PROT_WRITE,
+				      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	FAIL_IF(insns == MAP_FAILED);
+
+	/* Write the instruction words */
+	for (i = 1; i < numinsns - 1; i++)
+		insns[i] = PPC_INST_NOP;
+
+	/*
+	 * Set the first instruction as an unconditional trap. If
+	 * the last write to this address succeeds, this should
+	 * get overwritten by a no-op.
+	 */
+	insns[0] = PPC_INST_TRAP;
+
+	/*
+	 * Later, to jump to the executable region, we use a branch
+	 * and link instruction (bctrl) which sets the return address
+	 * automatically in LR. Use that to return back.
+	 */
+	insns[numinsns - 1] = PPC_INST_BLR;
+
+	/*
+	 * Pick the first instruction's address from the executable
+	 * region.
+	 */
+	fault_addr = insns;
+
+	/*
+	 * Read an instruction word from the address when the page
+	 * is execute only. This should generate an access fault.
+	 */
+	fault_code = -1;
+	remaining_faults = 1;
+	printf("Testing read on --x, should fault...");
+	FAIL_IF(mprotect(insns, pgsize, PROT_EXEC) != 0);
+	i = *fault_addr;
+	FAIL_IF(remaining_faults != 0 || !is_fault_expected(fault_code));
+	printf("ok!\n");
+
+	/*
+	 * Write an instruction word to the address when the page
+	 * execute only. This should also generate an access fault.
+	 */
+	fault_code = -1;
+	remaining_faults = 1;
+	printf("Testing write on --x, should fault...");
+	FAIL_IF(mprotect(insns, pgsize, PROT_EXEC) != 0);
+	*fault_addr = PPC_INST_NOP;
+	FAIL_IF(remaining_faults != 0 || !is_fault_expected(fault_code));
+	printf("ok!\n");
+
+	printf("Testing exec on ---, should fault...");
+	FAIL_IF(check_exec_fault(PROT_NONE));
+	printf("ok!\n");
+
+	printf("Testing exec on r--, should fault...");
+	FAIL_IF(check_exec_fault(PROT_READ));
+	printf("ok!\n");
+
+	printf("Testing exec on -w-, should fault...");
+	FAIL_IF(check_exec_fault(PROT_WRITE));
+	printf("ok!\n");
+
+	printf("Testing exec on rw-, should fault...");
+	FAIL_IF(check_exec_fault(PROT_READ | PROT_WRITE));
+	printf("ok!\n");
+
+	printf("Testing exec on --x, should succeed...");
+	FAIL_IF(check_exec_fault(PROT_EXEC));
+	printf("ok!\n");
+
+	printf("Testing exec on r-x, should succeed...");
+	FAIL_IF(check_exec_fault(PROT_READ | PROT_EXEC));
+	printf("ok!\n");
+
+	printf("Testing exec on -wx, should succeed...");
+	FAIL_IF(check_exec_fault(PROT_WRITE | PROT_EXEC));
+	printf("ok!\n");
+
+	printf("Testing exec on rwx, should succeed...");
+	FAIL_IF(check_exec_fault(PROT_READ | PROT_WRITE | PROT_EXEC));
+	printf("ok!\n");
+
+	/* Cleanup */
+	FAIL_IF(munmap((void *)insns, pgsize));
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test, "exec_prot");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c

@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+/* This must match the huge page & THP size */
+#define SIZE	(16 * 1024 * 1024)
+
+static int test_body(void)
+{
+	void *addr;
+	char *p;
+
+	addr = (void *)0xa0000000;
+
+	p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
+		 MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (p != MAP_FAILED) {
+		/*
+		 * Typically the mmap will fail because no huge pages are
+		 * allocated on the system. But if there are huge pages
+		 * allocated the mmap will succeed. That's fine too, we just
+		 * munmap here before continuing.  munmap() length of
+		 * MAP_HUGETLB memory must be hugepage aligned.
+		 */
+		if (munmap(addr, SIZE)) {
+			perror("munmap");
+			return 1;
+		}
+	}
+
+	p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,
+		 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (p == MAP_FAILED) {
+		printf("Mapping failed @ %p\n", addr);
+		perror("mmap");
+		return 1;
+	}
+
+	/*
+	 * Either a user or kernel access is sufficient to trigger the bug.
+	 * A kernel access is easier to spot & debug, as it will trigger the
+	 * softlockup or RCU stall detectors, and when the system is kicked
+	 * into xmon we get a backtrace in the kernel.
+	 *
+	 * A good option is:
+	 *  getcwd(p, SIZE);
+	 *
+	 * For the purposes of this testcase it's preferable to spin in
+	 * userspace, so the harness can kill us if we get stuck. That way we
+	 * see a test failure rather than a dead system.
+	 */
+	*p = 0xf;
+
+	munmap(addr, SIZE);
+
+	return 0;
+}
+
+static int test_main(void)
+{
+	int i;
+
+	/* 10,000 because it's a "bunch", and completes reasonably quickly */
+	for (i = 0; i < 10000; i++)
+		if (test_body())
+			return 1;
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test_main, "hugetlb_vs_thp");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/large_vm_fork_separation.c

@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright 2019, Michael Ellerman, IBM Corp.
+//
+// Test that allocating memory beyond the memory limit and then forking is
+// handled correctly, ie. the child is able to access the mappings beyond the
+// memory limit and the child's writes are not visible to the parent.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+
+#ifndef MAP_FIXED_NOREPLACE
+#define MAP_FIXED_NOREPLACE	MAP_FIXED	// "Should be safe" above 512TB
+#endif
+
+
+static int test(void)
+{
+	int p2c[2], c2p[2], rc, status, c, *p;
+	unsigned long page_size;
+	pid_t pid;
+
+	page_size = sysconf(_SC_PAGESIZE);
+	SKIP_IF(page_size != 65536);
+
+	// Create a mapping at 512TB to allocate an extended_id
+	p = mmap((void *)(512ul << 40), page_size, PROT_READ | PROT_WRITE,
+		MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE, -1, 0);
+	if (p == MAP_FAILED) {
+		perror("mmap");
+		printf("Error: couldn't mmap(), confirm kernel has 4TB support?\n");
+		return 1;
+	}
+
+	printf("parent writing %p = 1\n", p);
+	*p = 1;
+
+	FAIL_IF(pipe(p2c) == -1 || pipe(c2p) == -1);
+
+	pid = fork();
+	if (pid == 0) {
+		FAIL_IF(read(p2c[0], &c, 1) != 1);
+
+		pid = getpid();
+		printf("child writing  %p = %d\n", p, pid);
+		*p = pid;
+
+		FAIL_IF(write(c2p[1], &c, 1) != 1);
+		FAIL_IF(read(p2c[0], &c, 1) != 1);
+		exit(0);
+	}
+
+	c = 0;
+	FAIL_IF(write(p2c[1], &c, 1) != 1);
+	FAIL_IF(read(c2p[0], &c, 1) != 1);
+
+	// Prevent compiler optimisation
+	barrier();
+
+	rc = 0;
+	printf("parent reading %p = %d\n", p, *p);
+	if (*p != 1) {
+		printf("Error: BUG! parent saw child's write! *p = %d\n", *p);
+		rc = 1;
+	}
+
+	FAIL_IF(write(p2c[1], &c, 1) != 1);
+	FAIL_IF(waitpid(pid, &status, 0) == -1);
+	FAIL_IF(!WIFEXITED(status) || WEXITSTATUS(status));
+
+	if (rc == 0)
+		printf("success: test completed OK\n");
+
+	return rc;
+}
+
+int main(void)
+{
+	return test_harness(test, "large_vm_fork_separation");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/large_vm_gpr_corruption.c

@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright 2022, Michael Ellerman, IBM Corp.
+//
+// Test that the 4PB address space SLB handling doesn't corrupt userspace registers
+// (r9-r13) due to a SLB fault while saving the PPR.
+//
+// The bug was introduced in f384796c4 ("powerpc/mm: Add support for handling > 512TB
+// address in SLB miss") and fixed in 4c2de74cc869 ("powerpc/64: Interrupts save PPR on
+// stack rather than thread_struct").
+//
+// To hit the bug requires the task struct and kernel stack to be in different segments.
+// Usually that requires more than 1TB of RAM, or if that's not practical, boot the kernel
+// with "disable_1tb_segments".
+//
+// The test works by creating mappings above 512TB, to trigger the large address space
+// support. It creates 64 mappings, double the size of the SLB, to cause SLB faults on
+// each access (assuming naive replacement). It then loops over those mappings touching
+// each, and checks that r9-r13 aren't corrupted.
+//
+// It then forks another child and tries again, because a new child process will get a new
+// kernel stack and thread struct allocated, which may be more optimally placed to trigger
+// the bug. It would probably be better to leave the previous child processes hanging
+// around, so that kernel stack & thread struct allocations are not reused, but that would
+// amount to a 30 second fork bomb. The current design reliably triggers the bug on
+// unpatched kernels.
+
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+#ifndef MAP_FIXED_NOREPLACE
+#define MAP_FIXED_NOREPLACE MAP_FIXED // "Should be safe" above 512TB
+#endif
+
+#define BASE_ADDRESS (1ul << 50) // 1PB
+#define STRIDE	     (2ul << 40) // 2TB
+#define SLB_SIZE     32
+#define NR_MAPPINGS  (SLB_SIZE * 2)
+
+static volatile sig_atomic_t signaled;
+
+static void signal_handler(int sig)
+{
+	signaled = 1;
+}
+
+#define CHECK_REG(_reg)                                                                \
+	if (_reg != _reg##_orig) {                                                     \
+		printf(str(_reg) " corrupted! Expected 0x%lx != 0x%lx\n", _reg##_orig, \
+		       _reg);                                                          \
+		_exit(1);                                                              \
+	}
+
+static int touch_mappings(void)
+{
+	unsigned long r9_orig, r10_orig, r11_orig, r12_orig, r13_orig;
+	unsigned long r9, r10, r11, r12, r13;
+	unsigned long addr, *p;
+	int i;
+
+	for (i = 0; i < NR_MAPPINGS; i++) {
+		addr = BASE_ADDRESS + (i * STRIDE);
+		p = (unsigned long *)addr;
+
+		asm volatile("mr   %0, %%r9	;" // Read original GPR values
+			     "mr   %1, %%r10	;"
+			     "mr   %2, %%r11	;"
+			     "mr   %3, %%r12	;"
+			     "mr   %4, %%r13	;"
+			     "std %10, 0(%11)   ;" // Trigger SLB fault
+			     "mr   %5, %%r9	;" // Save possibly corrupted values
+			     "mr   %6, %%r10	;"
+			     "mr   %7, %%r11	;"
+			     "mr   %8, %%r12	;"
+			     "mr   %9, %%r13	;"
+			     "mr   %%r9,  %0	;" // Restore original values
+			     "mr   %%r10, %1	;"
+			     "mr   %%r11, %2	;"
+			     "mr   %%r12, %3	;"
+			     "mr   %%r13, %4	;"
+			     : "=&b"(r9_orig), "=&b"(r10_orig), "=&b"(r11_orig),
+			       "=&b"(r12_orig), "=&b"(r13_orig), "=&b"(r9), "=&b"(r10),
+			       "=&b"(r11), "=&b"(r12), "=&b"(r13)
+			     : "b"(i), "b"(p)
+			     : "r9", "r10", "r11", "r12", "r13");
+
+		CHECK_REG(r9);
+		CHECK_REG(r10);
+		CHECK_REG(r11);
+		CHECK_REG(r12);
+		CHECK_REG(r13);
+	}
+
+	return 0;
+}
+
+static int test(void)
+{
+	unsigned long page_size, addr, *p;
+	struct sigaction action;
+	bool hash_mmu;
+	int i, status;
+	pid_t pid;
+
+	// This tests a hash MMU specific bug.
+	FAIL_IF(using_hash_mmu(&hash_mmu));
+	SKIP_IF(!hash_mmu);
+	// 4K kernels don't support 4PB address space
+	SKIP_IF(sysconf(_SC_PAGESIZE) < 65536);
+
+	page_size = sysconf(_SC_PAGESIZE);
+
+	for (i = 0; i < NR_MAPPINGS; i++) {
+		addr = BASE_ADDRESS + (i * STRIDE);
+
+		p = mmap((void *)addr, page_size, PROT_READ | PROT_WRITE,
+			 MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE, -1, 0);
+		if (p == MAP_FAILED) {
+			perror("mmap");
+			printf("Error: couldn't mmap(), confirm kernel has 4PB support?\n");
+			return 1;
+		}
+	}
+
+	action.sa_handler = signal_handler;
+	action.sa_flags = SA_RESTART;
+	FAIL_IF(sigaction(SIGALRM, &action, NULL) < 0);
+
+	// Seen to always crash in under ~10s on affected kernels.
+	alarm(30);
+
+	while (!signaled) {
+		// Fork new processes, to increase the chance that we hit the case where
+		// the kernel stack and task struct are in different segments.
+		pid = fork();
+		if (pid == 0)
+			exit(touch_mappings());
+
+		FAIL_IF(waitpid(-1, &status, 0) == -1);
+		FAIL_IF(WIFSIGNALED(status));
+		FAIL_IF(!WIFEXITED(status));
+		FAIL_IF(WEXITSTATUS(status));
+	}
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test, "large_vm_gpr_corruption");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/pkey_exec_prot.c

@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Copyright 2020, Sandipan Das, IBM Corp.
+ *
+ * Test if applying execute protection on pages using memory
+ * protection keys works as expected.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+
+#include <unistd.h>
+
+#include "pkeys.h"
+
+#define PPC_INST_NOP	0x60000000
+#define PPC_INST_TRAP	0x7fe00008
+#define PPC_INST_BLR	0x4e800020
+
+static volatile sig_atomic_t fault_pkey, fault_code, fault_type;
+static volatile sig_atomic_t remaining_faults;
+static volatile unsigned int *fault_addr;
+static unsigned long pgsize, numinsns;
+static unsigned int *insns;
+
+static void trap_handler(int signum, siginfo_t *sinfo, void *ctx)
+{
+	/* Check if this fault originated from the expected address */
+	if (sinfo->si_addr != (void *) fault_addr)
+		sigsafe_err("got a fault for an unexpected address\n");
+
+	_exit(1);
+}
+
+static void segv_handler(int signum, siginfo_t *sinfo, void *ctx)
+{
+	int signal_pkey;
+
+	signal_pkey = siginfo_pkey(sinfo);
+	fault_code = sinfo->si_code;
+
+	/* Check if this fault originated from the expected address */
+	if (sinfo->si_addr != (void *) fault_addr) {
+		sigsafe_err("got a fault for an unexpected address\n");
+		_exit(1);
+	}
+
+	/* Check if too many faults have occurred for a single test case */
+	if (!remaining_faults) {
+		sigsafe_err("got too many faults for the same address\n");
+		_exit(1);
+	}
+
+
+	/* Restore permissions in order to continue */
+	switch (fault_code) {
+	case SEGV_ACCERR:
+		if (mprotect(insns, pgsize, PROT_READ | PROT_WRITE)) {
+			sigsafe_err("failed to set access permissions\n");
+			_exit(1);
+		}
+		break;
+	case SEGV_PKUERR:
+		if (signal_pkey != fault_pkey) {
+			sigsafe_err("got a fault for an unexpected pkey\n");
+			_exit(1);
+		}
+
+		switch (fault_type) {
+		case PKEY_DISABLE_ACCESS:
+			pkey_set_rights(fault_pkey, PKEY_UNRESTRICTED);
+			break;
+		case PKEY_DISABLE_EXECUTE:
+			/*
+			 * Reassociate the exec-only pkey with the region
+			 * to be able to continue. Unlike AMR, we cannot
+			 * set IAMR directly from userspace to restore the
+			 * permissions.
+			 */
+			if (mprotect(insns, pgsize, PROT_EXEC)) {
+				sigsafe_err("failed to set execute permissions\n");
+				_exit(1);
+			}
+			break;
+		default:
+			sigsafe_err("got a fault with an unexpected type\n");
+			_exit(1);
+		}
+		break;
+	default:
+		sigsafe_err("got a fault with an unexpected code\n");
+		_exit(1);
+	}
+
+	remaining_faults--;
+}
+
+static int test(void)
+{
+	struct sigaction segv_act, trap_act;
+	unsigned long rights;
+	int pkey, ret, i;
+
+	ret = pkeys_unsupported();
+	if (ret)
+		return ret;
+
+	/* Setup SIGSEGV handler */
+	segv_act.sa_handler = 0;
+	segv_act.sa_sigaction = segv_handler;
+	FAIL_IF(sigprocmask(SIG_SETMASK, 0, &segv_act.sa_mask) != 0);
+	segv_act.sa_flags = SA_SIGINFO;
+	segv_act.sa_restorer = 0;
+	FAIL_IF(sigaction(SIGSEGV, &segv_act, NULL) != 0);
+
+	/* Setup SIGTRAP handler */
+	trap_act.sa_handler = 0;
+	trap_act.sa_sigaction = trap_handler;
+	FAIL_IF(sigprocmask(SIG_SETMASK, 0, &trap_act.sa_mask) != 0);
+	trap_act.sa_flags = SA_SIGINFO;
+	trap_act.sa_restorer = 0;
+	FAIL_IF(sigaction(SIGTRAP, &trap_act, NULL) != 0);
+
+	/* Setup executable region */
+	pgsize = getpagesize();
+	numinsns = pgsize / sizeof(unsigned int);
+	insns = (unsigned int *) mmap(NULL, pgsize, PROT_READ | PROT_WRITE,
+				      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	FAIL_IF(insns == MAP_FAILED);
+
+	/* Write the instruction words */
+	for (i = 1; i < numinsns - 1; i++)
+		insns[i] = PPC_INST_NOP;
+
+	/*
+	 * Set the first instruction as an unconditional trap. If
+	 * the last write to this address succeeds, this should
+	 * get overwritten by a no-op.
+	 */
+	insns[0] = PPC_INST_TRAP;
+
+	/*
+	 * Later, to jump to the executable region, we use a branch
+	 * and link instruction (bctrl) which sets the return address
+	 * automatically in LR. Use that to return back.
+	 */
+	insns[numinsns - 1] = PPC_INST_BLR;
+
+	/* Allocate a pkey that restricts execution */
+	rights = PKEY_DISABLE_EXECUTE;
+	pkey = sys_pkey_alloc(0, rights);
+	FAIL_IF(pkey < 0);
+
+	/*
+	 * Pick the first instruction's address from the executable
+	 * region.
+	 */
+	fault_addr = insns;
+
+	/* The following two cases will avoid SEGV_PKUERR */
+	fault_type = -1;
+	fault_pkey = -1;
+
+	/*
+	 * Read an instruction word from the address when AMR bits
+	 * are not set i.e. the pkey permits both read and write
+	 * access.
+	 *
+	 * This should not generate a fault as having PROT_EXEC
+	 * implies PROT_READ on GNU systems. The pkey currently
+	 * restricts execution only based on the IAMR bits. The
+	 * AMR bits are cleared.
+	 */
+	remaining_faults = 0;
+	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
+	printf("read from %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
+	i = *fault_addr;
+	FAIL_IF(remaining_faults != 0);
+
+	/*
+	 * Write an instruction word to the address when AMR bits
+	 * are not set i.e. the pkey permits both read and write
+	 * access.
+	 *
+	 * This should generate an access fault as having just
+	 * PROT_EXEC also restricts writes. The pkey currently
+	 * restricts execution only based on the IAMR bits. The
+	 * AMR bits are cleared.
+	 */
+	remaining_faults = 1;
+	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
+	printf("write to %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
+	*fault_addr = PPC_INST_TRAP;
+	FAIL_IF(remaining_faults != 0 || fault_code != SEGV_ACCERR);
+
+	/* The following three cases will generate SEGV_PKUERR */
+	rights |= PKEY_DISABLE_ACCESS;
+	fault_type = PKEY_DISABLE_ACCESS;
+	fault_pkey = pkey;
+
+	/*
+	 * Read an instruction word from the address when AMR bits
+	 * are set i.e. the pkey permits neither read nor write
+	 * access.
+	 *
+	 * This should generate a pkey fault based on AMR bits only
+	 * as having PROT_EXEC implicitly allows reads.
+	 */
+	remaining_faults = 1;
+	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
+	pkey_set_rights(pkey, rights);
+	printf("read from %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
+	i = *fault_addr;
+	FAIL_IF(remaining_faults != 0 || fault_code != SEGV_PKUERR);
+
+	/*
+	 * Write an instruction word to the address when AMR bits
+	 * are set i.e. the pkey permits neither read nor write
+	 * access.
+	 *
+	 * This should generate two faults. First, a pkey fault
+	 * based on AMR bits and then an access fault since
+	 * PROT_EXEC does not allow writes.
+	 */
+	remaining_faults = 2;
+	FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
+	pkey_set_rights(pkey, rights);
+	printf("write to %p, pkey permissions are %s\n", fault_addr,
+	       pkey_rights(rights));
+	*fault_addr = PPC_INST_NOP;
+	FAIL_IF(remaining_faults != 0 || fault_code != SEGV_ACCERR);
+
+	/* Free the current pkey */
+	sys_pkey_free(pkey);
+
+	rights = 0;
+	do {
+		/*
+		 * Allocate pkeys with all valid combinations of read,
+		 * write and execute restrictions.
+		 */
+		pkey = sys_pkey_alloc(0, rights);
+		FAIL_IF(pkey < 0);
+
+		/*
+		 * Jump to the executable region. AMR bits may or may not
+		 * be set but they should not affect execution.
+		 *
+		 * This should generate pkey faults based on IAMR bits which
+		 * may be set to restrict execution.
+		 *
+		 * The first iteration also checks if the overwrite of the
+		 * first instruction word from a trap to a no-op succeeded.
+		 */
+		fault_pkey = pkey;
+		fault_type = -1;
+		remaining_faults = 0;
+		if (rights & PKEY_DISABLE_EXECUTE) {
+			fault_type = PKEY_DISABLE_EXECUTE;
+			remaining_faults = 1;
+		}
+
+		FAIL_IF(sys_pkey_mprotect(insns, pgsize, PROT_EXEC, pkey) != 0);
+		printf("execute at %p, pkey permissions are %s\n", fault_addr,
+		       pkey_rights(rights));
+		asm volatile("mtctr	%0; bctrl" : : "r"(insns));
+		FAIL_IF(remaining_faults != 0);
+		if (rights & PKEY_DISABLE_EXECUTE)
+			FAIL_IF(fault_code != SEGV_PKUERR);
+
+		/* Free the current pkey */
+		sys_pkey_free(pkey);
+
+		/* Find next valid combination of pkey rights */
+		rights = next_pkey_rights(rights);
+	} while (rights);
+
+	/* Cleanup */
+	munmap((void *) insns, pgsize);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test, "pkey_exec_prot");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/pkey_siginfo.c

@@ -0,0 +1,333 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2020, Sandipan Das, IBM Corp.
+ *
+ * Test if the signal information reports the correct memory protection
+ * key upon getting a key access violation fault for a page that was
+ * attempted to be protected by two different keys from two competing
+ * threads at the same time.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+
+#include <unistd.h>
+#include <pthread.h>
+#include <sys/mman.h>
+
+#include "pkeys.h"
+
+#define PPC_INST_NOP	0x60000000
+#define PPC_INST_BLR	0x4e800020
+#define PROT_RWX	(PROT_READ | PROT_WRITE | PROT_EXEC)
+
+#define NUM_ITERATIONS	1000000
+
+static volatile sig_atomic_t perm_pkey, rest_pkey;
+static volatile sig_atomic_t rights, fault_count;
+static volatile unsigned int *volatile fault_addr;
+static pthread_barrier_t iteration_barrier;
+
+static void segv_handler(int signum, siginfo_t *sinfo, void *ctx)
+{
+	void *pgstart;
+	size_t pgsize;
+	int pkey;
+
+	pkey = siginfo_pkey(sinfo);
+
+	/* Check if this fault originated from a pkey access violation */
+	if (sinfo->si_code != SEGV_PKUERR) {
+		sigsafe_err("got a fault for an unexpected reason\n");
+		_exit(1);
+	}
+
+	/* Check if this fault originated from the expected address */
+	if (sinfo->si_addr != (void *) fault_addr) {
+		sigsafe_err("got a fault for an unexpected address\n");
+		_exit(1);
+	}
+
+	/* Check if this fault originated from the restrictive pkey */
+	if (pkey != rest_pkey) {
+		sigsafe_err("got a fault for an unexpected pkey\n");
+		_exit(1);
+	}
+
+	/* Check if too many faults have occurred for the same iteration */
+	if (fault_count > 0) {
+		sigsafe_err("got too many faults for the same address\n");
+		_exit(1);
+	}
+
+	pgsize = getpagesize();
+	pgstart = (void *) ((unsigned long) fault_addr & ~(pgsize - 1));
+
+	/*
+	 * If the current fault occurred due to lack of execute rights,
+	 * reassociate the page with the exec-only pkey since execute
+	 * rights cannot be changed directly for the faulting pkey as
+	 * IAMR is inaccessible from userspace.
+	 *
+	 * Otherwise, if the current fault occurred due to lack of
+	 * read-write rights, change the AMR permission bits for the
+	 * pkey.
+	 *
+	 * This will let the test continue.
+	 */
+	if (rights == PKEY_DISABLE_EXECUTE &&
+	    mprotect(pgstart, pgsize, PROT_EXEC))
+		_exit(1);
+	else
+		pkey_set_rights(pkey, PKEY_UNRESTRICTED);
+
+	fault_count++;
+}
+
+struct region {
+	unsigned long rights;
+	unsigned int *base;
+	size_t size;
+};
+
+static void *protect(void *p)
+{
+	unsigned long rights;
+	unsigned int *base;
+	size_t size;
+	int tid, i;
+
+	tid = gettid();
+	base = ((struct region *) p)->base;
+	size = ((struct region *) p)->size;
+	FAIL_IF_EXIT(!base);
+
+	/* No read, write and execute restrictions */
+	rights = 0;
+
+	printf("tid %d, pkey permissions are %s\n", tid, pkey_rights(rights));
+
+	/* Allocate the permissive pkey */
+	perm_pkey = sys_pkey_alloc(0, rights);
+	FAIL_IF_EXIT(perm_pkey < 0);
+
+	/*
+	 * Repeatedly try to protect the common region with a permissive
+	 * pkey
+	 */
+	for (i = 0; i < NUM_ITERATIONS; i++) {
+		/*
+		 * Wait until the other thread has finished allocating the
+		 * restrictive pkey or until the next iteration has begun
+		 */
+		pthread_barrier_wait(&iteration_barrier);
+
+		/* Try to associate the permissive pkey with the region */
+		FAIL_IF_EXIT(sys_pkey_mprotect(base, size, PROT_RWX,
+					       perm_pkey));
+	}
+
+	/* Free the permissive pkey */
+	sys_pkey_free(perm_pkey);
+
+	return NULL;
+}
+
+static void *protect_access(void *p)
+{
+	size_t size, numinsns;
+	unsigned int *base;
+	int tid, i;
+
+	tid = gettid();
+	base = ((struct region *) p)->base;
+	size = ((struct region *) p)->size;
+	rights = ((struct region *) p)->rights;
+	numinsns = size / sizeof(base[0]);
+	FAIL_IF_EXIT(!base);
+
+	/* Allocate the restrictive pkey */
+	rest_pkey = sys_pkey_alloc(0, rights);
+	FAIL_IF_EXIT(rest_pkey < 0);
+
+	printf("tid %d, pkey permissions are %s\n", tid, pkey_rights(rights));
+	printf("tid %d, %s randomly in range [%p, %p]\n", tid,
+	       (rights == PKEY_DISABLE_EXECUTE) ? "execute" :
+	       (rights == PKEY_DISABLE_WRITE)  ? "write" : "read",
+	       base, base + numinsns);
+
+	/*
+	 * Repeatedly try to protect the common region with a restrictive
+	 * pkey and read, write or execute from it
+	 */
+	for (i = 0; i < NUM_ITERATIONS; i++) {
+		/*
+		 * Wait until the other thread has finished allocating the
+		 * permissive pkey or until the next iteration has begun
+		 */
+		pthread_barrier_wait(&iteration_barrier);
+
+		/* Try to associate the restrictive pkey with the region */
+		FAIL_IF_EXIT(sys_pkey_mprotect(base, size, PROT_RWX,
+					       rest_pkey));
+
+		/* Choose a random instruction word address from the region */
+		fault_addr = base + (rand() % numinsns);
+		fault_count = 0;
+
+		switch (rights) {
+		/* Read protection test */
+		case PKEY_DISABLE_ACCESS:
+			/*
+			 * Read an instruction word from the region and
+			 * verify if it has not been overwritten to
+			 * something unexpected
+			 */
+			FAIL_IF_EXIT(*fault_addr != PPC_INST_NOP &&
+				     *fault_addr != PPC_INST_BLR);
+			break;
+
+		/* Write protection test */
+		case PKEY_DISABLE_WRITE:
+			/*
+			 * Write an instruction word to the region and
+			 * verify if the overwrite has succeeded
+			 */
+			*fault_addr = PPC_INST_BLR;
+			FAIL_IF_EXIT(*fault_addr != PPC_INST_BLR);
+			break;
+
+		/* Execute protection test */
+		case PKEY_DISABLE_EXECUTE:
+			/* Jump to the region and execute instructions */
+			asm volatile(
+				"mtctr	%0; bctrl"
+				: : "r"(fault_addr) : "ctr", "lr");
+			break;
+		}
+
+		/*
+		 * Restore the restrictions originally imposed by the
+		 * restrictive pkey as the signal handler would have
+		 * cleared out the corresponding AMR bits
+		 */
+		pkey_set_rights(rest_pkey, rights);
+	}
+
+	/* Free restrictive pkey */
+	sys_pkey_free(rest_pkey);
+
+	return NULL;
+}
+
+static void reset_pkeys(unsigned long rights)
+{
+	int pkeys[NR_PKEYS], i;
+
+	/* Exhaustively allocate all available pkeys */
+	for (i = 0; i < NR_PKEYS; i++)
+		pkeys[i] = sys_pkey_alloc(0, rights);
+
+	/* Free all allocated pkeys */
+	for (i = 0; i < NR_PKEYS; i++)
+		sys_pkey_free(pkeys[i]);
+}
+
+static int test(void)
+{
+	pthread_t prot_thread, pacc_thread;
+	struct sigaction act;
+	pthread_attr_t attr;
+	size_t numinsns;
+	struct region r;
+	int ret, i;
+
+	srand(time(NULL));
+	ret = pkeys_unsupported();
+	if (ret)
+		return ret;
+
+	/* Allocate the region */
+	r.size = getpagesize();
+	r.base = mmap(NULL, r.size, PROT_RWX,
+		      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	FAIL_IF(r.base == MAP_FAILED);
+
+	/*
+	 * Fill the region with no-ops with a branch at the end
+	 * for returning to the caller
+	 */
+	numinsns = r.size / sizeof(r.base[0]);
+	for (i = 0; i < numinsns - 1; i++)
+		r.base[i] = PPC_INST_NOP;
+	r.base[i] = PPC_INST_BLR;
+
+	/* Setup SIGSEGV handler */
+	act.sa_handler = 0;
+	act.sa_sigaction = segv_handler;
+	FAIL_IF(sigprocmask(SIG_SETMASK, 0, &act.sa_mask) != 0);
+	act.sa_flags = SA_SIGINFO;
+	act.sa_restorer = 0;
+	FAIL_IF(sigaction(SIGSEGV, &act, NULL) != 0);
+
+	/*
+	 * For these tests, the parent process should clear all bits of
+	 * AMR and IAMR, i.e. impose no restrictions, for all available
+	 * pkeys. This will be the base for the initial AMR and IAMR
+	 * values for all the test thread pairs.
+	 *
+	 * If the AMR and IAMR bits of all available pkeys are cleared
+	 * before running the tests and a fault is generated when
+	 * attempting to read, write or execute instructions from a
+	 * pkey protected region, the pkey responsible for this must be
+	 * the one from the protect-and-access thread since the other
+	 * one is fully permissive. Despite that, if the pkey reported
+	 * by siginfo is not the restrictive pkey, then there must be a
+	 * kernel bug.
+	 */
+	reset_pkeys(0);
+
+	/* Setup barrier for protect and protect-and-access threads */
+	FAIL_IF(pthread_attr_init(&attr) != 0);
+	FAIL_IF(pthread_barrier_init(&iteration_barrier, NULL, 2) != 0);
+
+	/* Setup and start protect and protect-and-read threads */
+	puts("starting thread pair (protect, protect-and-read)");
+	r.rights = PKEY_DISABLE_ACCESS;
+	FAIL_IF(pthread_create(&prot_thread, &attr, &protect, &r) != 0);
+	FAIL_IF(pthread_create(&pacc_thread, &attr, &protect_access, &r) != 0);
+	FAIL_IF(pthread_join(prot_thread, NULL) != 0);
+	FAIL_IF(pthread_join(pacc_thread, NULL) != 0);
+
+	/* Setup and start protect and protect-and-write threads */
+	puts("starting thread pair (protect, protect-and-write)");
+	r.rights = PKEY_DISABLE_WRITE;
+	FAIL_IF(pthread_create(&prot_thread, &attr, &protect, &r) != 0);
+	FAIL_IF(pthread_create(&pacc_thread, &attr, &protect_access, &r) != 0);
+	FAIL_IF(pthread_join(prot_thread, NULL) != 0);
+	FAIL_IF(pthread_join(pacc_thread, NULL) != 0);
+
+	/* Setup and start protect and protect-and-execute threads */
+	puts("starting thread pair (protect, protect-and-execute)");
+	r.rights = PKEY_DISABLE_EXECUTE;
+	FAIL_IF(pthread_create(&prot_thread, &attr, &protect, &r) != 0);
+	FAIL_IF(pthread_create(&pacc_thread, &attr, &protect_access, &r) != 0);
+	FAIL_IF(pthread_join(prot_thread, NULL) != 0);
+	FAIL_IF(pthread_join(pacc_thread, NULL) != 0);
+
+	/* Cleanup */
+	FAIL_IF(pthread_attr_destroy(&attr) != 0);
+	FAIL_IF(pthread_barrier_destroy(&iteration_barrier) != 0);
+	munmap(r.base, r.size);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test, "pkey_siginfo");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/prot_sao.c

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2016, Michael Ellerman, IBM Corp.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include <asm/cputable.h>
+
+#include "utils.h"
+
+#define SIZE (64 * 1024)
+
+int test_prot_sao(void)
+{
+	char *p;
+
+	/*
+	 * SAO was introduced in 2.06 and removed in 3.1. It's disabled in
+	 * guests/LPARs by default, so also skip if we are running in a guest.
+	 */
+	SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06) ||
+		have_hwcap2(PPC_FEATURE2_ARCH_3_1) ||
+		access("/proc/device-tree/rtas/ibm,hypertas-functions", F_OK) == 0);
+
+	/*
+	 * Ensure we can ask for PROT_SAO.
+	 * We can't really verify that it does the right thing, but at least we
+	 * confirm the kernel will accept it.
+	 */
+	p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE | PROT_SAO,
+		 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	FAIL_IF(p == MAP_FAILED);
+
+	/* Write to the mapping, to at least cause a fault */
+	memset(p, 0xaa, SIZE);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test_prot_sao, "prot-sao");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/segv_errors.c

@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2017 John Sperbeck
+ *
+ * Test that an access to a mapped but inaccessible area causes a SEGV and
+ * reports si_code == SEGV_ACCERR.
+ */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <assert.h>
+#include <ucontext.h>
+
+#include "utils.h"
+
+static bool faulted;
+static int si_code;
+
+static void segv_handler(int n, siginfo_t *info, void *ctxt_v)
+{
+	ucontext_t *ctxt = (ucontext_t *)ctxt_v;
+	struct pt_regs *regs = ctxt->uc_mcontext.regs;
+
+	faulted = true;
+	si_code = info->si_code;
+	regs->nip += 4;
+}
+
+int test_segv_errors(void)
+{
+	struct sigaction act = {
+		.sa_sigaction = segv_handler,
+		.sa_flags = SA_SIGINFO,
+	};
+	char c, *p = NULL;
+
+	p = mmap(NULL, getpagesize(), 0, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+	FAIL_IF(p == MAP_FAILED);
+
+	FAIL_IF(sigaction(SIGSEGV, &act, NULL) != 0);
+
+	faulted = false;
+	si_code = 0;
+
+	/*
+	 * We just need a compiler barrier, but mb() works and has the nice
+	 * property of being easy to spot in the disassembly.
+	 */
+	mb();
+	c = *p;
+	mb();
+
+	FAIL_IF(!faulted);
+	FAIL_IF(si_code != SEGV_ACCERR);
+
+	faulted = false;
+	si_code = 0;
+
+	mb();
+	*p = c;
+	mb();
+
+	FAIL_IF(!faulted);
+	FAIL_IF(si_code != SEGV_ACCERR);
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test_segv_errors, "segv_errors");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/settings

@@ -0,0 +1 @@
+timeout=130

linux-7.2.3/tools/testing/selftests/powerpc/mm/stack_expansion_ldst.c

@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test that loads/stores expand the stack segment, or trigger a SEGV, in
+ * various conditions.
+ *
+ * Based on test code by Tom Lane.
+ */
+
+#undef NDEBUG
+#include <assert.h>
+
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define _KB (1024)
+#define _MB (1024 * 1024)
+
+volatile char *stack_top_ptr;
+volatile unsigned long stack_top_sp;
+volatile char c;
+
+enum access_type {
+	LOAD,
+	STORE,
+};
+
+/*
+ * Consume stack until the stack pointer is below @target_sp, then do an access
+ * (load or store) at offset @delta from either the base of the stack or the
+ * current stack pointer.
+ */
+__attribute__ ((noinline))
+int consume_stack(unsigned long target_sp, unsigned long stack_high, int delta, enum access_type type)
+{
+	unsigned long target;
+	char stack_cur;
+
+	if ((unsigned long)&stack_cur > target_sp)
+		return consume_stack(target_sp, stack_high, delta, type);
+	else {
+		// We don't really need this, but without it GCC might not
+		// generate a recursive call above.
+		stack_top_ptr = &stack_cur;
+
+#ifdef __powerpc__
+		asm volatile ("mr %[sp], %%r1" : [sp] "=r" (stack_top_sp));
+#else
+		asm volatile ("mov %%rsp, %[sp]" : [sp] "=r" (stack_top_sp));
+#endif
+		target = stack_high - delta + 1;
+		volatile char *p = (char *)target;
+
+		if (type == STORE)
+			*p = c;
+		else
+			c = *p;
+
+		// Do something to prevent the stack frame being popped prior to
+		// our access above.
+		getpid();
+	}
+
+	return 0;
+}
+
+static int search_proc_maps(char *needle, unsigned long *low, unsigned long *high)
+{
+	unsigned long start, end;
+	static char buf[4096];
+	char name[128];
+	FILE *f;
+	int rc;
+
+	f = fopen("/proc/self/maps", "r");
+	if (!f) {
+		perror("fopen");
+		return -1;
+	}
+
+	while (fgets(buf, sizeof(buf), f)) {
+		rc = sscanf(buf, "%lx-%lx %*c%*c%*c%*c %*x %*d:%*d %*d %127s\n",
+			    &start, &end, name);
+		if (rc == 2)
+			continue;
+
+		if (rc != 3) {
+			printf("sscanf errored\n");
+			rc = -1;
+			break;
+		}
+
+		if (strstr(name, needle)) {
+			*low = start;
+			*high = end - 1;
+			rc = 0;
+			break;
+		}
+	}
+
+	fclose(f);
+
+	return rc;
+}
+
+int child(unsigned int stack_used, int delta, enum access_type type)
+{
+	unsigned long low, stack_high;
+
+	assert(search_proc_maps("[stack]", &low, &stack_high) == 0);
+
+	assert(consume_stack(stack_high - stack_used, stack_high, delta, type) == 0);
+
+	printf("Access OK: %s delta %-7d used size 0x%06x stack high 0x%lx top_ptr %p top sp 0x%lx actual used 0x%lx\n",
+	       type == LOAD ? "load" : "store", delta, stack_used, stack_high,
+	       stack_top_ptr, stack_top_sp, stack_high - stack_top_sp + 1);
+
+	return 0;
+}
+
+static int test_one(unsigned int stack_used, int delta, enum access_type type)
+{
+	pid_t pid;
+	int rc;
+
+	pid = fork();
+	if (pid == 0)
+		exit(child(stack_used, delta, type));
+
+	assert(waitpid(pid, &rc, 0) != -1);
+
+	if (WIFEXITED(rc) && WEXITSTATUS(rc) == 0)
+		return 0;
+
+	// We don't expect a non-zero exit that's not a signal
+	assert(!WIFEXITED(rc));
+
+	printf("Faulted:   %s delta %-7d used size 0x%06x signal %d\n",
+	       type == LOAD ? "load" : "store", delta, stack_used,
+	       WTERMSIG(rc));
+
+	return 1;
+}
+
+// This is fairly arbitrary but is well below any of the targets below,
+// so that the delta between the stack pointer and the target is large.
+#define DEFAULT_SIZE	(32 * _KB)
+
+static void test_one_type(enum access_type type, unsigned long page_size, unsigned long rlim_cur)
+{
+	unsigned long delta;
+
+	// We should be able to access anywhere within the rlimit
+	for (delta = page_size; delta <= rlim_cur; delta += page_size)
+		assert(test_one(DEFAULT_SIZE, delta, type) == 0);
+
+	assert(test_one(DEFAULT_SIZE, rlim_cur, type) == 0);
+
+	// But if we go past the rlimit it should fail
+	assert(test_one(DEFAULT_SIZE, rlim_cur + 1, type) != 0);
+}
+
+static int test(void)
+{
+	unsigned long page_size;
+	struct rlimit rlimit;
+
+	page_size = getpagesize();
+	getrlimit(RLIMIT_STACK, &rlimit);
+	printf("Stack rlimit is 0x%llx\n", (unsigned long long)rlimit.rlim_cur);
+
+	printf("Testing loads ...\n");
+	test_one_type(LOAD, page_size, rlimit.rlim_cur);
+	printf("Testing stores ...\n");
+	test_one_type(STORE, page_size, rlimit.rlim_cur);
+
+	printf("All OK\n");
+
+	return 0;
+}
+
+#ifdef __powerpc__
+#include "utils.h"
+
+int main(void)
+{
+	return test_harness(test, "stack_expansion_ldst");
+}
+#else
+int main(void)
+{
+	return test();
+}
+#endif

linux-7.2.3/tools/testing/selftests/powerpc/mm/stack_expansion_signal.c

@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test that signal delivery is able to expand the stack segment without
+ * triggering a SEGV.
+ *
+ * Based on test code by Tom Lane.
+ */
+
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "../pmu/lib.h"
+#include "utils.h"
+
+#define _KB (1024)
+#define _MB (1024 * 1024)
+
+static char *stack_base_ptr;
+static char *stack_top_ptr;
+
+static volatile sig_atomic_t sig_occurred = 0;
+
+static void sigusr1_handler(int signal_arg)
+{
+	sig_occurred = 1;
+}
+
+static int consume_stack(unsigned int stack_size, union pipe write_pipe)
+{
+	char stack_cur;
+
+	if ((stack_base_ptr - &stack_cur) < stack_size)
+		return consume_stack(stack_size, write_pipe);
+	else {
+		stack_top_ptr = &stack_cur;
+
+		FAIL_IF(notify_parent(write_pipe));
+
+		while (!sig_occurred)
+			barrier();
+	}
+
+	return 0;
+}
+
+static int child(unsigned int stack_size, union pipe write_pipe)
+{
+	struct sigaction act;
+	char stack_base;
+
+	act.sa_handler = sigusr1_handler;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	if (sigaction(SIGUSR1, &act, NULL) < 0)
+		err(1, "sigaction");
+
+	stack_base_ptr = (char *) (((size_t) &stack_base + 65535) & ~65535UL);
+
+	FAIL_IF(consume_stack(stack_size, write_pipe));
+
+	printf("size 0x%06x: OK, stack base %p top %p (%zx used)\n",
+		stack_size, stack_base_ptr, stack_top_ptr,
+		stack_base_ptr - stack_top_ptr);
+
+	return 0;
+}
+
+static int test_one_size(unsigned int stack_size)
+{
+	union pipe read_pipe, write_pipe;
+	pid_t pid;
+
+	FAIL_IF(pipe(read_pipe.fds) == -1);
+	FAIL_IF(pipe(write_pipe.fds) == -1);
+
+	pid = fork();
+	if (pid == 0) {
+		close(read_pipe.read_fd);
+		close(write_pipe.write_fd);
+		exit(child(stack_size, read_pipe));
+	}
+
+	close(read_pipe.write_fd);
+	close(write_pipe.read_fd);
+	FAIL_IF(sync_with_child(read_pipe, write_pipe));
+
+	kill(pid, SIGUSR1);
+
+	FAIL_IF(wait_for_child(pid));
+
+	close(read_pipe.read_fd);
+	close(write_pipe.write_fd);
+
+	return 0;
+}
+
+int test(void)
+{
+	unsigned int i, size;
+
+	// Test with used stack from 1MB - 64K to 1MB + 64K
+	// Increment by 64 to get more coverage of odd sizes
+	for (i = 0; i < (128 * _KB); i += 64) {
+		size = i + (1 * _MB) - (64 * _KB);
+		FAIL_IF(test_one_size(size));
+	}
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test, "stack_expansion_signal");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/stress_code_patching.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+TIMEOUT=30
+
+DEBUFS_DIR=`cat /proc/mounts | grep debugfs | awk '{print $2}'`
+if [ ! -e "$DEBUFS_DIR" ]
+then
+	echo "debugfs not found, skipping" 1>&2
+	exit 4
+fi
+
+if [ ! -e "$DEBUFS_DIR/tracing/current_tracer" ]
+then
+	echo "Tracing files not found, skipping" 1>&2
+	exit 4
+fi
+
+
+echo "Testing for spurious faults when mapping kernel memory..."
+
+if grep -q "FUNCTION TRACING IS CORRUPTED" "$DEBUFS_DIR/tracing/trace"
+then
+	echo "FAILED: Ftrace already dead. Probably due to a spurious fault" 1>&2
+	exit 1
+fi
+
+dmesg -C
+START_TIME=`date +%s`
+END_TIME=`expr $START_TIME + $TIMEOUT`
+while [ `date +%s` -lt $END_TIME ]
+do
+	echo function > $DEBUFS_DIR/tracing/current_tracer
+	echo nop > $DEBUFS_DIR/tracing/current_tracer
+	if dmesg | grep -q 'ftrace bug'
+	then
+		break
+	fi
+done
+
+echo nop > $DEBUFS_DIR/tracing/current_tracer
+if dmesg | grep -q 'ftrace bug'
+then
+	echo "FAILED: Mapping kernel memory causes spurious faults" 1>&2
+	exit 1
+else
+	echo "OK: Mapping kernel memory does not cause spurious faults"
+	exit 0
+fi

linux-7.2.3/tools/testing/selftests/powerpc/mm/subpage_prot.c

@@ -0,0 +1,236 @@
+/*
+ * Copyright IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/ptrace.h>
+#include <sys/syscall.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+char *file_name;
+
+int in_test;
+volatile int faulted;
+volatile void *dar;
+int errors;
+
+static void segv(int signum, siginfo_t *info, void *ctxt_v)
+{
+	ucontext_t *ctxt = (ucontext_t *)ctxt_v;
+	struct pt_regs *regs = ctxt->uc_mcontext.regs;
+
+	if (!in_test) {
+		fprintf(stderr, "Segfault outside of test !\n");
+		exit(1);
+	}
+
+	faulted = 1;
+	dar = (void *)regs->dar;
+	regs->nip += 4;
+}
+
+static inline void do_read(const volatile void *addr)
+{
+	int ret;
+
+	asm volatile("lwz %0,0(%1); twi 0,%0,0; isync;\n"
+		     : "=r" (ret) : "r" (addr) : "memory");
+}
+
+static inline void do_write(const volatile void *addr)
+{
+	int val = 0x1234567;
+
+	asm volatile("stw %0,0(%1); sync; \n"
+		     : : "r" (val), "r" (addr) : "memory");
+}
+
+static inline void check_faulted(void *addr, long page, long subpage, int write)
+{
+	int want_fault = (subpage == ((page + 3) % 16));
+
+	if (write)
+		want_fault |= (subpage == ((page + 1) % 16));
+
+	if (faulted != want_fault) {
+		printf("Failed at %p (p=%ld,sp=%ld,w=%d), want=%s, got=%s !\n",
+		       addr, page, subpage, write,
+		       want_fault ? "fault" : "pass",
+		       faulted ? "fault" : "pass");
+		++errors;
+	}
+
+	if (faulted) {
+		if (dar != addr) {
+			printf("Fault expected at %p and happened at %p !\n",
+			       addr, dar);
+		}
+		faulted = 0;
+		asm volatile("sync" : : : "memory");
+	}
+}
+
+static int run_test(void *addr, unsigned long size)
+{
+	unsigned int *map;
+	long i, j, pages, err;
+
+	pages = size / 0x10000;
+	map = malloc(pages * 4);
+	assert(map);
+
+	/*
+	 * for each page, mark subpage i % 16 read only and subpage
+	 * (i + 3) % 16 inaccessible
+	 */
+	for (i = 0; i < pages; i++) {
+		map[i] = (0x40000000 >> (((i + 1) * 2) % 32)) |
+			(0xc0000000 >> (((i + 3) * 2) % 32));
+	}
+
+	err = syscall(__NR_subpage_prot, addr, size, map);
+	if (err) {
+		perror("subpage_perm");
+		return 1;
+	}
+	free(map);
+
+	in_test = 1;
+	errors = 0;
+	for (i = 0; i < pages; i++) {
+		for (j = 0; j < 16; j++, addr += 0x1000) {
+			do_read(addr);
+			check_faulted(addr, i, j, 0);
+			do_write(addr);
+			check_faulted(addr, i, j, 1);
+		}
+	}
+
+	in_test = 0;
+	if (errors) {
+		printf("%d errors detected\n", errors);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int syscall_available(void)
+{
+	int rc;
+
+	errno = 0;
+	rc = syscall(__NR_subpage_prot, 0, 0, 0);
+
+	return rc == 0 || (errno != ENOENT && errno != ENOSYS);
+}
+
+int test_anon(void)
+{
+	unsigned long align;
+	struct sigaction act = {
+		.sa_sigaction = segv,
+		.sa_flags = SA_SIGINFO
+	};
+	void *mallocblock;
+	unsigned long mallocsize;
+
+	SKIP_IF(!syscall_available());
+
+	if (getpagesize() != 0x10000) {
+		fprintf(stderr, "Kernel page size must be 64K!\n");
+		return 1;
+	}
+
+	sigaction(SIGSEGV, &act, NULL);
+
+	mallocsize = 4 * 16 * 1024 * 1024;
+
+	FAIL_IF(posix_memalign(&mallocblock, 64 * 1024, mallocsize));
+
+	align = (unsigned long)mallocblock;
+	if (align & 0xffff)
+		align = (align | 0xffff) + 1;
+
+	mallocblock = (void *)align;
+
+	printf("allocated malloc block of 0x%lx bytes at %p\n",
+	       mallocsize, mallocblock);
+
+	printf("testing malloc block...\n");
+
+	return run_test(mallocblock, mallocsize);
+}
+
+int test_file(void)
+{
+	struct sigaction act = {
+		.sa_sigaction = segv,
+		.sa_flags = SA_SIGINFO
+	};
+	void *fileblock;
+	off_t filesize;
+	int fd;
+
+	SKIP_IF(!syscall_available());
+
+	fd = open(file_name, O_RDWR);
+	if (fd == -1) {
+		perror("failed to open file");
+		return 1;
+	}
+	sigaction(SIGSEGV, &act, NULL);
+
+	filesize = lseek(fd, 0, SEEK_END);
+	if (filesize & 0xffff)
+		filesize &= ~0xfffful;
+
+	fileblock = mmap(NULL, filesize, PROT_READ | PROT_WRITE,
+			 MAP_SHARED, fd, 0);
+	if (fileblock == MAP_FAILED) {
+		perror("failed to map file");
+		return 1;
+	}
+	printf("allocated %s for 0x%llx bytes at %p\n",
+	       file_name, (long long)filesize, fileblock);
+
+	printf("testing file map...\n");
+
+	return run_test(fileblock, filesize);
+}
+
+int main(int argc, char *argv[])
+{
+	int rc;
+
+	rc = test_harness(test_anon, "subpage_prot_anon");
+	if (rc)
+		return rc;
+
+	if (argc > 1)
+		file_name = argv[1];
+	else
+		file_name = "tempfile";
+
+	return test_harness(test_file, "subpage_prot_file");
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/tlbie_test.c

@@ -0,0 +1,733 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2019, Nick Piggin, Gautham R. Shenoy, Aneesh Kumar K.V, IBM Corp.
+ */
+
+/*
+ *
+ * Test tlbie/mtpidr race. We have 4 threads doing flush/load/compare/store
+ * sequence in a loop. The same threads also rung a context switch task
+ * that does sched_yield() in loop.
+ *
+ * The snapshot thread mark the mmap area PROT_READ in between, make a copy
+ * and copy it back to the original area. This helps us to detect if any
+ * store continued to happen after we marked the memory PROT_READ.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/ipc.h>
+#include <sys/shm.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <linux/futex.h>
+#include <unistd.h>
+#include <asm/unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <time.h>
+#include <stdarg.h>
+#include <pthread.h>
+#include <signal.h>
+#include <sys/prctl.h>
+
+static inline void dcbf(volatile unsigned int *addr)
+{
+	__asm__ __volatile__ ("dcbf %y0; sync" : : "Z"(*(unsigned char *)addr) : "memory");
+}
+
+static void err_msg(char *msg)
+{
+
+	time_t now;
+	time(&now);
+	printf("=================================\n");
+	printf("    Error: %s\n", msg);
+	printf("    %s", ctime(&now));
+	printf("=================================\n");
+	exit(1);
+}
+
+static char *map1;
+static char *map2;
+static pid_t rim_process_pid;
+
+/*
+ * A "rim-sequence" is defined to be the sequence of the following
+ * operations performed on a memory word:
+ *	1) FLUSH the contents of that word.
+ *	2) LOAD the contents of that word.
+ *	3) COMPARE the contents of that word with the content that was
+ *	           previously stored at that word
+ *	4) STORE new content into that word.
+ *
+ * The threads in this test that perform the rim-sequence are termed
+ * as rim_threads.
+ */
+
+/*
+ * A "corruption" is defined to be the failed COMPARE operation in a
+ * rim-sequence.
+ *
+ * A rim_thread that detects a corruption informs about it to all the
+ * other rim_threads, and the mem_snapshot thread.
+ */
+static volatile unsigned int corruption_found;
+
+/*
+ * This defines the maximum number of rim_threads in this test.
+ *
+ * The THREAD_ID_BITS denote the number of bits required
+ * to represent the thread_ids [0..MAX_THREADS - 1].
+ * We are being a bit paranoid here and set it to 8 bits,
+ * though 6 bits suffice.
+ *
+ */
+#define MAX_THREADS 		64
+#define THREAD_ID_BITS		8
+#define THREAD_ID_MASK		((1 << THREAD_ID_BITS) - 1)
+static unsigned int rim_thread_ids[MAX_THREADS];
+static pthread_t rim_threads[MAX_THREADS];
+
+
+/*
+ * Each rim_thread works on an exclusive "chunk" of size
+ * RIM_CHUNK_SIZE.
+ *
+ * The ith rim_thread works on the ith chunk.
+ *
+ * The ith chunk begins at
+ * map1 + (i * RIM_CHUNK_SIZE)
+ */
+#define RIM_CHUNK_SIZE  	1024
+#define BITS_PER_BYTE 		8
+#define WORD_SIZE     		(sizeof(unsigned int))
+#define WORD_BITS		(WORD_SIZE * BITS_PER_BYTE)
+#define WORDS_PER_CHUNK		(RIM_CHUNK_SIZE/WORD_SIZE)
+
+static inline char *compute_chunk_start_addr(unsigned int thread_id)
+{
+	char *chunk_start;
+
+	chunk_start = (char *)((unsigned long)map1 +
+			       (thread_id * RIM_CHUNK_SIZE));
+
+	return chunk_start;
+}
+
+/*
+ * The "word-offset" of a word-aligned address inside a chunk, is
+ * defined to be the number of words that precede the address in that
+ * chunk.
+ *
+ * WORD_OFFSET_BITS denote the number of bits required to represent
+ * the word-offsets of all the word-aligned addresses of a chunk.
+ */
+#define WORD_OFFSET_BITS	(__builtin_ctz(WORDS_PER_CHUNK))
+#define WORD_OFFSET_MASK	((1 << WORD_OFFSET_BITS) - 1)
+
+static inline unsigned int compute_word_offset(char *start, unsigned int *addr)
+{
+	unsigned int delta_bytes, ret;
+	delta_bytes = (unsigned long)addr - (unsigned long)start;
+
+	ret = delta_bytes/WORD_SIZE;
+
+	return ret;
+}
+
+/*
+ * A "sweep" is defined to be the sequential execution of the
+ * rim-sequence by a rim_thread on its chunk one word at a time,
+ * starting from the first word of its chunk and ending with the last
+ * word of its chunk.
+ *
+ * Each sweep of a rim_thread is uniquely identified by a sweep_id.
+ * SWEEP_ID_BITS denote the number of bits required to represent
+ * the sweep_ids of rim_threads.
+ *
+ * As to why SWEEP_ID_BITS are computed as a function of THREAD_ID_BITS,
+ * WORD_OFFSET_BITS, and WORD_BITS, see the "store-pattern" below.
+ */
+#define SWEEP_ID_BITS		(WORD_BITS - (THREAD_ID_BITS + WORD_OFFSET_BITS))
+#define SWEEP_ID_MASK		((1 << SWEEP_ID_BITS) - 1)
+
+/*
+ * A "store-pattern" is the word-pattern that is stored into a word
+ * location in the 4)STORE step of the rim-sequence.
+ *
+ * In the store-pattern, we shall encode:
+ *
+ *      - The thread-id of the rim_thread performing the store
+ *        (The most significant THREAD_ID_BITS)
+ *
+ *      - The word-offset of the address into which the store is being
+ *        performed (The next WORD_OFFSET_BITS)
+ *
+ *      - The sweep_id of the current sweep in which the store is
+ *        being performed. (The lower SWEEP_ID_BITS)
+ *
+ * Store Pattern: 32 bits
+ * |------------------|--------------------|---------------------------------|
+ * |    Thread id     |  Word offset       |         sweep_id                |
+ * |------------------|--------------------|---------------------------------|
+ *    THREAD_ID_BITS     WORD_OFFSET_BITS          SWEEP_ID_BITS
+ *
+ * In the store pattern, the (Thread-id + Word-offset) uniquely identify the
+ * address to which the store is being performed i.e,
+ *    address == map1 +
+ *              (Thread-id * RIM_CHUNK_SIZE) + (Word-offset * WORD_SIZE)
+ *
+ * And the sweep_id in the store pattern identifies the time when the
+ * store was performed by the rim_thread.
+ *
+ * We shall use this property in the 3)COMPARE step of the
+ * rim-sequence.
+ */
+#define SWEEP_ID_SHIFT	0
+#define WORD_OFFSET_SHIFT	(SWEEP_ID_BITS)
+#define THREAD_ID_SHIFT		(WORD_OFFSET_BITS + SWEEP_ID_BITS)
+
+/*
+ * Compute the store pattern for a given thread with id @tid, at
+ * location @addr in the sweep identified by @sweep_id
+ */
+static inline unsigned int compute_store_pattern(unsigned int tid,
+						 unsigned int *addr,
+						 unsigned int sweep_id)
+{
+	unsigned int ret = 0;
+	char *start = compute_chunk_start_addr(tid);
+	unsigned int word_offset = compute_word_offset(start, addr);
+
+	ret += (tid & THREAD_ID_MASK) << THREAD_ID_SHIFT;
+	ret += (word_offset & WORD_OFFSET_MASK) << WORD_OFFSET_SHIFT;
+	ret += (sweep_id & SWEEP_ID_MASK) << SWEEP_ID_SHIFT;
+	return ret;
+}
+
+/* Extract the thread-id from the given store-pattern */
+static inline unsigned int extract_tid(unsigned int pattern)
+{
+	unsigned int ret;
+
+	ret = (pattern >> THREAD_ID_SHIFT) & THREAD_ID_MASK;
+	return ret;
+}
+
+/* Extract the word-offset from the given store-pattern */
+static inline unsigned int extract_word_offset(unsigned int pattern)
+{
+	unsigned int ret;
+
+	ret = (pattern >> WORD_OFFSET_SHIFT) & WORD_OFFSET_MASK;
+
+	return ret;
+}
+
+/* Extract the sweep-id from the given store-pattern */
+static inline unsigned int extract_sweep_id(unsigned int pattern)
+
+{
+	unsigned int ret;
+
+	ret = (pattern >> SWEEP_ID_SHIFT) & SWEEP_ID_MASK;
+
+	return ret;
+}
+
+/************************************************************
+ *                                                          *
+ *          Logging the output of the verification          *
+ *                                                          *
+ ************************************************************/
+#define LOGDIR_NAME_SIZE 100
+static char logdir[LOGDIR_NAME_SIZE];
+
+static FILE *fp[MAX_THREADS];
+static const char logfilename[] ="Thread-%02d-Chunk";
+
+static inline void start_verification_log(unsigned int tid,
+					  unsigned int *addr,
+					  unsigned int cur_sweep_id,
+					  unsigned int prev_sweep_id)
+{
+	FILE *f;
+	char logfile[30];
+	char path[LOGDIR_NAME_SIZE + 30];
+	char separator[2] = "/";
+	char *chunk_start = compute_chunk_start_addr(tid);
+	unsigned int size = RIM_CHUNK_SIZE;
+
+	sprintf(logfile, logfilename, tid);
+	strcpy(path, logdir);
+	strcat(path, separator);
+	strcat(path, logfile);
+	f = fopen(path, "w");
+
+	if (!f) {
+		err_msg("Unable to create logfile\n");
+	}
+
+	fp[tid] = f;
+
+	fprintf(f, "----------------------------------------------------------\n");
+	fprintf(f, "PID                = %d\n", rim_process_pid);
+	fprintf(f, "Thread id          = %02d\n", tid);
+	fprintf(f, "Chunk Start Addr   = 0x%016lx\n", (unsigned long)chunk_start);
+	fprintf(f, "Chunk Size         = %d\n", size);
+	fprintf(f, "Next Store Addr    = 0x%016lx\n", (unsigned long)addr);
+	fprintf(f, "Current sweep-id   = 0x%08x\n", cur_sweep_id);
+	fprintf(f, "Previous sweep-id  = 0x%08x\n", prev_sweep_id);
+	fprintf(f, "----------------------------------------------------------\n");
+}
+
+static inline void log_anamoly(unsigned int tid, unsigned int *addr,
+			       unsigned int expected, unsigned int observed)
+{
+	FILE *f = fp[tid];
+
+	fprintf(f, "Thread %02d: Addr 0x%lx: Expected 0x%x, Observed 0x%x\n",
+	        tid, (unsigned long)addr, expected, observed);
+	fprintf(f, "Thread %02d: Expected Thread id   = %02d\n", tid, extract_tid(expected));
+	fprintf(f, "Thread %02d: Observed Thread id   = %02d\n", tid, extract_tid(observed));
+	fprintf(f, "Thread %02d: Expected Word offset = %03d\n", tid, extract_word_offset(expected));
+	fprintf(f, "Thread %02d: Observed Word offset = %03d\n", tid, extract_word_offset(observed));
+	fprintf(f, "Thread %02d: Expected sweep-id    = 0x%x\n", tid, extract_sweep_id(expected));
+	fprintf(f, "Thread %02d: Observed sweep-id    = 0x%x\n", tid, extract_sweep_id(observed));
+	fprintf(f, "----------------------------------------------------------\n");
+}
+
+static inline void end_verification_log(unsigned int tid, unsigned nr_anamolies)
+{
+	FILE *f = fp[tid];
+	char logfile[30];
+	char path[LOGDIR_NAME_SIZE + 30];
+	char separator[] = "/";
+
+	fclose(f);
+
+	sprintf(logfile, logfilename, tid);
+	strcpy(path, logdir);
+	strcat(path, separator);
+	strcat(path, logfile);
+
+	if (nr_anamolies == 0) {
+		remove(path);
+		return;
+	}
+
+	printf("Thread %02d chunk has %d corrupted words. For details check %s\n",
+		tid, nr_anamolies, path);
+}
+
+/*
+ * When a COMPARE step of a rim-sequence fails, the rim_thread informs
+ * everyone else via the shared_memory pointed to by
+ * corruption_found variable. On seeing this, every thread verifies the
+ * content of its chunk as follows.
+ *
+ * Suppose a thread identified with @tid was about to store (but not
+ * yet stored) to @next_store_addr in its current sweep identified
+ * @cur_sweep_id. Let @prev_sweep_id indicate the previous sweep_id.
+ *
+ * This implies that for all the addresses @addr < @next_store_addr,
+ * Thread @tid has already performed a store as part of its current
+ * sweep. Hence we expect the content of such @addr to be:
+ *    |-------------------------------------------------|
+ *    | tid   | word_offset(addr) |    cur_sweep_id     |
+ *    |-------------------------------------------------|
+ *
+ * Since Thread @tid is yet to perform stores on address
+ * @next_store_addr and above, we expect the content of such an
+ * address @addr to be:
+ *    |-------------------------------------------------|
+ *    | tid   | word_offset(addr) |    prev_sweep_id    |
+ *    |-------------------------------------------------|
+ *
+ * The verifier function @verify_chunk does this verification and logs
+ * any anamolies that it finds.
+ */
+static void verify_chunk(unsigned int tid, unsigned int *next_store_addr,
+		  unsigned int cur_sweep_id,
+		  unsigned int prev_sweep_id)
+{
+	unsigned int *iter_ptr;
+	unsigned int size = RIM_CHUNK_SIZE;
+	unsigned int expected;
+	unsigned int observed;
+	char *chunk_start = compute_chunk_start_addr(tid);
+
+	int nr_anamolies = 0;
+
+	start_verification_log(tid, next_store_addr,
+			       cur_sweep_id, prev_sweep_id);
+
+	for (iter_ptr = (unsigned int *)chunk_start;
+	     (unsigned long)iter_ptr < (unsigned long)chunk_start + size;
+	     iter_ptr++) {
+		unsigned int expected_sweep_id;
+
+		if (iter_ptr < next_store_addr) {
+			expected_sweep_id = cur_sweep_id;
+		} else {
+			expected_sweep_id = prev_sweep_id;
+		}
+
+		expected = compute_store_pattern(tid, iter_ptr, expected_sweep_id);
+
+		dcbf((volatile unsigned int*)iter_ptr); //Flush before reading
+		observed = *iter_ptr;
+
+	        if (observed != expected) {
+			nr_anamolies++;
+			log_anamoly(tid, iter_ptr, expected, observed);
+		}
+	}
+
+	end_verification_log(tid, nr_anamolies);
+}
+
+static void set_pthread_cpu(pthread_t th, int cpu)
+{
+	cpu_set_t run_cpu_mask;
+	struct sched_param param;
+
+	CPU_ZERO(&run_cpu_mask);
+	CPU_SET(cpu, &run_cpu_mask);
+	pthread_setaffinity_np(th, sizeof(cpu_set_t), &run_cpu_mask);
+
+	param.sched_priority = 1;
+	if (0 && sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
+		/* haven't reproduced with this setting, it kills random preemption which may be a factor */
+		fprintf(stderr, "could not set SCHED_FIFO, run as root?\n");
+	}
+}
+
+static void set_mycpu(int cpu)
+{
+	cpu_set_t run_cpu_mask;
+	struct sched_param param;
+
+	CPU_ZERO(&run_cpu_mask);
+	CPU_SET(cpu, &run_cpu_mask);
+	sched_setaffinity(0, sizeof(cpu_set_t), &run_cpu_mask);
+
+	param.sched_priority = 1;
+	if (0 && sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
+		fprintf(stderr, "could not set SCHED_FIFO, run as root?\n");
+	}
+}
+
+static volatile int segv_wait;
+
+static void segv_handler(int signo, siginfo_t *info, void *extra)
+{
+	while (segv_wait) {
+		sched_yield();
+	}
+
+}
+
+static void set_segv_handler(void)
+{
+	struct sigaction sa;
+
+	sa.sa_flags = SA_SIGINFO;
+	sa.sa_sigaction = segv_handler;
+
+	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
+		perror("sigaction");
+		exit(EXIT_FAILURE);
+	}
+}
+
+int timeout = 0;
+/*
+ * This function is executed by every rim_thread.
+ *
+ * This function performs sweeps over the exclusive chunks of the
+ * rim_threads executing the rim-sequence one word at a time.
+ */
+static void *rim_fn(void *arg)
+{
+	unsigned int tid = *((unsigned int *)arg);
+
+	int size = RIM_CHUNK_SIZE;
+	char *chunk_start = compute_chunk_start_addr(tid);
+
+	unsigned int prev_sweep_id;
+	unsigned int cur_sweep_id = 0;
+
+	/* word access */
+	unsigned int pattern = cur_sweep_id;
+	unsigned int *pattern_ptr = &pattern;
+	unsigned int *w_ptr, read_data;
+
+	set_segv_handler();
+
+	/*
+	 * Let us initialize the chunk:
+	 *
+	 * Each word-aligned address addr in the chunk,
+	 * is initialized to :
+	 *    |-------------------------------------------------|
+	 *    | tid   | word_offset(addr) |         0           |
+	 *    |-------------------------------------------------|
+	 */
+	for (w_ptr = (unsigned int *)chunk_start;
+	     (unsigned long)w_ptr < (unsigned long)(chunk_start) + size;
+	     w_ptr++) {
+
+		*pattern_ptr = compute_store_pattern(tid, w_ptr, cur_sweep_id);
+		*w_ptr = *pattern_ptr;
+	}
+
+	while (!corruption_found && !timeout) {
+		prev_sweep_id = cur_sweep_id;
+		cur_sweep_id = cur_sweep_id + 1;
+
+		for (w_ptr = (unsigned int *)chunk_start;
+		     (unsigned long)w_ptr < (unsigned long)(chunk_start) + size;
+		     w_ptr++)  {
+			unsigned int old_pattern;
+
+			/*
+			 * Compute the pattern that we would have
+			 * stored at this location in the previous
+			 * sweep.
+			 */
+			old_pattern = compute_store_pattern(tid, w_ptr, prev_sweep_id);
+
+			/*
+			 * FLUSH:Ensure that we flush the contents of
+			 *       the cache before loading
+			 */
+			dcbf((volatile unsigned int*)w_ptr); //Flush
+
+			/* LOAD: Read the value */
+			read_data = *w_ptr; //Load
+
+			/*
+			 * COMPARE: Is it the same as what we had stored
+			 *          in the previous sweep ? It better be!
+			 */
+			if (read_data != old_pattern) {
+				/* No it isn't! Tell everyone */
+				corruption_found = 1;
+			}
+
+			/*
+			 * Before performing a store, let us check if
+			 * any rim_thread has found a corruption.
+			 */
+			if (corruption_found || timeout) {
+				/*
+				 * Yes. Someone (including us!) has found
+				 * a corruption :(
+				 *
+				 * Let us verify that our chunk is
+				 * correct.
+				 */
+				/* But first, let us allow the dust to settle down! */
+				verify_chunk(tid, w_ptr, cur_sweep_id, prev_sweep_id);
+
+				return 0;
+			}
+
+			/*
+			 * Compute the new pattern that we are going
+			 * to write to this location
+			 */
+			*pattern_ptr = compute_store_pattern(tid, w_ptr, cur_sweep_id);
+
+			/*
+			 * STORE: Now let us write this pattern into
+			 *        the location
+			 */
+			*w_ptr = *pattern_ptr;
+		}
+	}
+
+	return NULL;
+}
+
+
+static unsigned long start_cpu = 0;
+static unsigned long nrthreads = 4;
+
+static pthread_t mem_snapshot_thread;
+
+static void *mem_snapshot_fn(void *arg)
+{
+	int page_size = getpagesize();
+	size_t size = page_size;
+	void *tmp = malloc(size);
+
+	while (!corruption_found && !timeout) {
+		/* Stop memory migration once corruption is found */
+		segv_wait = 1;
+
+		mprotect(map1, size, PROT_READ);
+
+		/*
+		 * Load from the working alias (map1). Loading from map2
+		 * also fails.
+		 */
+		memcpy(tmp, map1, size);
+
+		/*
+		 * Stores must go via map2 which has write permissions, but
+		 * the corrupted data tends to be seen in the snapshot buffer,
+		 * so corruption does not appear to be introduced at the
+		 * copy-back via map2 alias here.
+		 */
+		memcpy(map2, tmp, size);
+		/*
+		 * Before releasing other threads, must ensure the copy
+		 * back to
+		 */
+		asm volatile("sync" ::: "memory");
+		mprotect(map1, size, PROT_READ|PROT_WRITE);
+		asm volatile("sync" ::: "memory");
+		segv_wait = 0;
+
+		usleep(1); /* This value makes a big difference */
+	}
+
+	return 0;
+}
+
+void alrm_sighandler(int sig)
+{
+	timeout = 1;
+}
+
+int main(int argc, char *argv[])
+{
+	int c;
+	int page_size = getpagesize();
+	time_t now;
+	int i, dir_error;
+	pthread_attr_t attr;
+	key_t shm_key = (key_t) getpid();
+	int shmid, run_time = 20 * 60;
+	struct sigaction sa_alrm;
+
+	snprintf(logdir, LOGDIR_NAME_SIZE,
+		 "/tmp/logdir-%u", (unsigned int)getpid());
+	while ((c = getopt(argc, argv, "r:hn:l:t:")) != -1) {
+		switch(c) {
+		case 'r':
+			start_cpu = strtoul(optarg, NULL, 10);
+			break;
+		case 'h':
+			printf("%s [-r <start_cpu>] [-n <nrthreads>] [-l <logdir>] [-t <timeout>]\n", argv[0]);
+			exit(0);
+			break;
+		case 'n':
+			nrthreads = strtoul(optarg, NULL, 10);
+			break;
+		case 'l':
+			strncpy(logdir, optarg, LOGDIR_NAME_SIZE - 1);
+			break;
+		case 't':
+			run_time = strtoul(optarg, NULL, 10);
+			break;
+		default:
+			printf("invalid option\n");
+			exit(0);
+			break;
+		}
+	}
+
+	if (nrthreads > MAX_THREADS)
+		nrthreads = MAX_THREADS;
+
+	shmid = shmget(shm_key, page_size, IPC_CREAT|0666);
+	if (shmid < 0) {
+		err_msg("Failed shmget\n");
+	}
+
+	map1 = shmat(shmid, NULL, 0);
+	if (map1 == (void *) -1) {
+		err_msg("Failed shmat");
+	}
+
+	map2 = shmat(shmid, NULL, 0);
+	if (map2 == (void *) -1) {
+		err_msg("Failed shmat");
+	}
+
+	dir_error = mkdir(logdir, 0755);
+
+	if (dir_error) {
+		err_msg("Failed mkdir");
+	}
+
+	printf("start_cpu list:%lu\n", start_cpu);
+	printf("number of worker threads:%lu + 1 snapshot thread\n", nrthreads);
+	printf("Allocated address:0x%016lx + secondary map:0x%016lx\n", (unsigned long)map1, (unsigned long)map2);
+	printf("logdir at : %s\n", logdir);
+	printf("Timeout: %d seconds\n", run_time);
+
+	time(&now);
+	printf("=================================\n");
+	printf("     Starting Test\n");
+	printf("     %s", ctime(&now));
+	printf("=================================\n");
+
+	for (i = 0; i < nrthreads; i++) {
+		if (1 && !fork()) {
+			prctl(PR_SET_PDEATHSIG, SIGKILL);
+			set_mycpu(start_cpu + i);
+			for (;;)
+				sched_yield();
+			exit(0);
+		}
+	}
+
+
+	sa_alrm.sa_handler = &alrm_sighandler;
+	sigemptyset(&sa_alrm.sa_mask);
+	sa_alrm.sa_flags = 0;
+
+	if (sigaction(SIGALRM, &sa_alrm, 0) == -1) {
+		err_msg("Failed signal handler registration\n");
+	}
+
+	alarm(run_time);
+
+	pthread_attr_init(&attr);
+	for (i = 0; i < nrthreads; i++) {
+		rim_thread_ids[i] = i;
+		pthread_create(&rim_threads[i], &attr, rim_fn, &rim_thread_ids[i]);
+		set_pthread_cpu(rim_threads[i], start_cpu + i);
+	}
+
+	pthread_create(&mem_snapshot_thread, &attr, mem_snapshot_fn, map1);
+	set_pthread_cpu(mem_snapshot_thread, start_cpu + i);
+
+
+	pthread_join(mem_snapshot_thread, NULL);
+	for (i = 0; i < nrthreads; i++) {
+		pthread_join(rim_threads[i], NULL);
+	}
+
+	if (!timeout) {
+		time(&now);
+		printf("=================================\n");
+		printf("      Data Corruption Detected\n");
+		printf("      %s", ctime(&now));
+		printf("      See logfiles in %s\n", logdir);
+		printf("=================================\n");
+		return 1;
+	}
+	return 0;
+}

linux-7.2.3/tools/testing/selftests/powerpc/mm/wild_bctr.c

@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018, Michael Ellerman, IBM Corp.
+ *
+ * Test that an out-of-bounds branch to counter behaves as expected.
+ */
+
+#include <setjmp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+#include "utils.h"
+
+
+#define BAD_NIP	0x788c545a18000000ull
+
+static struct pt_regs signal_regs;
+static jmp_buf setjmp_env;
+
+static void save_regs(ucontext_t *ctxt)
+{
+	struct pt_regs *regs = ctxt->uc_mcontext.regs;
+
+	memcpy(&signal_regs, regs, sizeof(signal_regs));
+}
+
+static void segv_handler(int signum, siginfo_t *info, void *ctxt_v)
+{
+	save_regs(ctxt_v);
+	longjmp(setjmp_env, 1);
+}
+
+static void usr2_handler(int signum, siginfo_t *info, void *ctxt_v)
+{
+	save_regs(ctxt_v);
+}
+
+static int ok(void)
+{
+	printf("Everything is OK in here.\n");
+	return 0;
+}
+
+#define REG_POISON	0x5a5a
+#define POISONED_REG(n)	((((unsigned long)REG_POISON) << 48) | ((n) << 32) | \
+			 (((unsigned long)REG_POISON) << 16) | (n))
+
+static inline void poison_regs(void)
+{
+	#define POISON_REG(n)	\
+	  "lis  " __stringify(n) "," __stringify(REG_POISON) ";" \
+	  "addi " __stringify(n) "," __stringify(n) "," __stringify(n) ";" \
+	  "sldi " __stringify(n) "," __stringify(n) ", 32 ;" \
+	  "oris " __stringify(n) "," __stringify(n) "," __stringify(REG_POISON) ";" \
+	  "addi " __stringify(n) "," __stringify(n) "," __stringify(n) ";"
+
+	asm (POISON_REG(15)
+	     POISON_REG(16)
+	     POISON_REG(17)
+	     POISON_REG(18)
+	     POISON_REG(19)
+	     POISON_REG(20)
+	     POISON_REG(21)
+	     POISON_REG(22)
+	     POISON_REG(23)
+	     POISON_REG(24)
+	     POISON_REG(25)
+	     POISON_REG(26)
+	     POISON_REG(27)
+	     POISON_REG(28)
+	     POISON_REG(29)
+	     : // inputs
+	     : // outputs
+	     : "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25",
+	       "26", "27", "28", "29"
+	);
+	#undef POISON_REG
+}
+
+static int check_regs(void)
+{
+	unsigned long i;
+
+	for (i = 15; i <= 29; i++)
+		FAIL_IF(signal_regs.gpr[i] != POISONED_REG(i));
+
+	printf("Regs OK\n");
+	return 0;
+}
+
+static void dump_regs(void)
+{
+	for (int i = 0; i < 32; i += 4) {
+		printf("r%02d 0x%016lx  r%02d 0x%016lx  " \
+		       "r%02d 0x%016lx  r%02d 0x%016lx\n",
+		       i, signal_regs.gpr[i],
+		       i+1, signal_regs.gpr[i+1],
+		       i+2, signal_regs.gpr[i+2],
+		       i+3, signal_regs.gpr[i+3]);
+	}
+}
+
+#ifdef _CALL_AIXDESC
+struct opd {
+	unsigned long ip;
+	unsigned long toc;
+	unsigned long env;
+};
+static struct opd bad_opd = {
+	.ip = BAD_NIP,
+};
+#define BAD_FUNC (&bad_opd)
+#else
+#define BAD_FUNC BAD_NIP
+#endif
+
+int test_wild_bctr(void)
+{
+	int (*func_ptr)(void);
+	struct sigaction segv = {
+		.sa_sigaction = segv_handler,
+		.sa_flags = SA_SIGINFO
+	};
+	struct sigaction usr2 = {
+		.sa_sigaction = usr2_handler,
+		.sa_flags = SA_SIGINFO
+	};
+
+	FAIL_IF(sigaction(SIGSEGV, &segv, NULL));
+	FAIL_IF(sigaction(SIGUSR2, &usr2, NULL));
+
+	bzero(&signal_regs, sizeof(signal_regs));
+
+	if (setjmp(setjmp_env) == 0) {
+		func_ptr = ok;
+		func_ptr();
+
+		kill(getpid(), SIGUSR2);
+		printf("Regs before:\n");
+		dump_regs();
+		bzero(&signal_regs, sizeof(signal_regs));
+
+		poison_regs();
+
+		func_ptr = (int (*)(void))BAD_FUNC;
+		func_ptr();
+
+		FAIL_IF(1); /* we didn't segv? */
+	}
+
+	FAIL_IF(signal_regs.nip != BAD_NIP);
+
+	printf("All good - took SEGV as expected branching to 0x%llx\n", BAD_NIP);
+
+	dump_regs();
+	FAIL_IF(check_regs());
+
+	return 0;
+}
+
+int main(void)
+{
+	return test_harness(test_wild_bctr, "wild_bctr");
+}