Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

5 files changed, 927 insertions, 0 deletions

diff --git a/tools/testing/selftests/breakpoints/.gitignore b/tools/testing/selftests/breakpoints/.gitignore
new file mode 100644
index 000000000..def2e97da
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/.gitignore
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+breakpoint_test
+step_after_suspend_test
diff --git a/tools/testing/selftests/breakpoints/Makefile b/tools/testing/selftests/breakpoints/Makefile
new file mode 100644
index 000000000..0b8f5acf7
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/Makefile
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0
+# Taken from perf makefile
+ARCH ?= $(shell uname -m 2>/dev/null || echo not)
+override ARCH := $(shell echo $(ARCH) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
+
+TEST_GEN_PROGS := step_after_suspend_test
+
+ifeq ($(ARCH),x86)
+TEST_GEN_PROGS += breakpoint_test
+endif
+ifneq (,$(filter $(ARCH),aarch64 arm64))
+TEST_GEN_PROGS += breakpoint_test_arm64
+endif
+
+include ../lib.mk
+
diff --git a/tools/testing/selftests/breakpoints/breakpoint_test.c b/tools/testing/selftests/breakpoints/breakpoint_test.c
new file mode 100644
index 000000000..1159d8189
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/breakpoint_test.c
@@ -0,0 +1,409 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
+ *
+ * Selftests for breakpoints (and more generally the do_debug() path) in x86.
+ */
+
+
+#include <sys/ptrace.h>
+#include <unistd.h>
+#include <stddef.h>
+#include <sys/user.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <errno.h>
+#include <string.h>
+
+#include "kselftest.h"
+
+#define COUNT_ISN_BPS	4
+#define COUNT_WPS	4
+
+/* Breakpoint access modes */
+enum {
+	BP_X = 1,
+	BP_RW = 2,
+	BP_W = 4,
+};
+
+static pid_t child_pid;
+
+/*
+ * Ensures the child and parent are always "talking" about
+ * the same test sequence. (ie: that we haven't forgotten
+ * to call check_trapped() somewhere).
+ */
+static int nr_tests;
+
+static void set_breakpoint_addr(void *addr, int n)
+{
+	int ret;
+
+	ret = ptrace(PTRACE_POKEUSER, child_pid,
+		     offsetof(struct user, u_debugreg[n]), addr);
+	if (ret)
+		ksft_exit_fail_msg("Can't set breakpoint addr: %s\n",
+			strerror(errno));
+}
+
+static void toggle_breakpoint(int n, int type, int len,
+			      int local, int global, int set)
+{
+	int ret;
+
+	int xtype, xlen;
+	unsigned long vdr7, dr7;
+
+	switch (type) {
+	case BP_X:
+		xtype = 0;
+		break;
+	case BP_W:
+		xtype = 1;
+		break;
+	case BP_RW:
+		xtype = 3;
+		break;
+	}
+
+	switch (len) {
+	case 1:
+		xlen = 0;
+		break;
+	case 2:
+		xlen = 4;
+		break;
+	case 4:
+		xlen = 0xc;
+		break;
+	case 8:
+		xlen = 8;
+		break;
+	}
+
+	dr7 = ptrace(PTRACE_PEEKUSER, child_pid,
+		     offsetof(struct user, u_debugreg[7]), 0);
+
+	vdr7 = (xlen | xtype) << 16;
+	vdr7 <<= 4 * n;
+
+	if (local) {
+		vdr7 |= 1 << (2 * n);
+		vdr7 |= 1 << 8;
+	}
+	if (global) {
+		vdr7 |= 2 << (2 * n);
+		vdr7 |= 1 << 9;
+	}
+
+	if (set)
+		dr7 |= vdr7;
+	else
+		dr7 &= ~vdr7;
+
+	ret = ptrace(PTRACE_POKEUSER, child_pid,
+		     offsetof(struct user, u_debugreg[7]), dr7);
+	if (ret) {
+		ksft_print_msg("Can't set dr7: %s\n", strerror(errno));
+		exit(-1);
+	}
+}
+
+/* Dummy variables to test read/write accesses */
+static unsigned long long dummy_var[4];
+
+/* Dummy functions to test execution accesses */
+static void dummy_func(void) { }
+static void dummy_func1(void) { }
+static void dummy_func2(void) { }
+static void dummy_func3(void) { }
+
+static void (*dummy_funcs[])(void) = {
+	dummy_func,
+	dummy_func1,
+	dummy_func2,
+	dummy_func3,
+};
+
+static int trapped;
+
+static void check_trapped(void)
+{
+	/*
+	 * If we haven't trapped, wake up the parent
+	 * so that it notices the failure.
+	 */
+	if (!trapped)
+		kill(getpid(), SIGUSR1);
+	trapped = 0;
+
+	nr_tests++;
+}
+
+static void write_var(int len)
+{
+	char *pcval; short *psval; int *pival; long long *plval;
+	int i;
+
+	for (i = 0; i < 4; i++) {
+		switch (len) {
+		case 1:
+			pcval = (char *)&dummy_var[i];
+			*pcval = 0xff;
+			break;
+		case 2:
+			psval = (short *)&dummy_var[i];
+			*psval = 0xffff;
+			break;
+		case 4:
+			pival = (int *)&dummy_var[i];
+			*pival = 0xffffffff;
+			break;
+		case 8:
+			plval = (long long *)&dummy_var[i];
+			*plval = 0xffffffffffffffffLL;
+			break;
+		}
+		check_trapped();
+	}
+}
+
+static void read_var(int len)
+{
+	char cval; short sval; int ival; long long lval;
+	int i;
+
+	for (i = 0; i < 4; i++) {
+		switch (len) {
+		case 1:
+			cval = *(char *)&dummy_var[i];
+			break;
+		case 2:
+			sval = *(short *)&dummy_var[i];
+			break;
+		case 4:
+			ival = *(int *)&dummy_var[i];
+			break;
+		case 8:
+			lval = *(long long *)&dummy_var[i];
+			break;
+		}
+		check_trapped();
+	}
+}
+
+/*
+ * Do the r/w/x accesses to trigger the breakpoints. And run
+ * the usual traps.
+ */
+static void trigger_tests(void)
+{
+	int len, local, global, i;
+	char val;
+	int ret;
+
+	ret = ptrace(PTRACE_TRACEME, 0, NULL, 0);
+	if (ret) {
+		ksft_print_msg("Can't be traced? %s\n", strerror(errno));
+		return;
+	}
+
+	/* Wake up father so that it sets up the first test */
+	kill(getpid(), SIGUSR1);
+
+	/* Test instruction breakpoints */
+	for (local = 0; local < 2; local++) {
+		for (global = 0; global < 2; global++) {
+			if (!local && !global)
+				continue;
+
+			for (i = 0; i < COUNT_ISN_BPS; i++) {
+				dummy_funcs[i]();
+				check_trapped();
+			}
+		}
+	}
+
+	/* Test write watchpoints */
+	for (len = 1; len <= sizeof(long); len <<= 1) {
+		for (local = 0; local < 2; local++) {
+			for (global = 0; global < 2; global++) {
+				if (!local && !global)
+					continue;
+				write_var(len);
+			}
+		}
+	}
+
+	/* Test read/write watchpoints (on read accesses) */
+	for (len = 1; len <= sizeof(long); len <<= 1) {
+		for (local = 0; local < 2; local++) {
+			for (global = 0; global < 2; global++) {
+				if (!local && !global)
+					continue;
+				read_var(len);
+			}
+		}
+	}
+
+	/* Icebp trap */
+	asm(".byte 0xf1\n");
+	check_trapped();
+
+	/* Int 3 trap */
+	asm("int $3\n");
+	check_trapped();
+
+	kill(getpid(), SIGUSR1);
+}
+
+static void check_success(const char *msg)
+{
+	int child_nr_tests;
+	int status;
+	int ret;
+
+	/* Wait for the child to SIGTRAP */
+	wait(&status);
+
+	ret = 0;
+
+	if (WSTOPSIG(status) == SIGTRAP) {
+		child_nr_tests = ptrace(PTRACE_PEEKDATA, child_pid,
+					&nr_tests, 0);
+		if (child_nr_tests == nr_tests)
+			ret = 1;
+		if (ptrace(PTRACE_POKEDATA, child_pid, &trapped, 1))
+			ksft_exit_fail_msg("Can't poke: %s\n", strerror(errno));
+	}
+
+	nr_tests++;
+
+	if (ret)
+		ksft_test_result_pass("%s", msg);
+	else
+		ksft_test_result_fail("%s", msg);
+}
+
+static void launch_instruction_breakpoints(char *buf, int local, int global)
+{
+	int i;
+
+	for (i = 0; i < COUNT_ISN_BPS; i++) {
+		set_breakpoint_addr(dummy_funcs[i], i);
+		toggle_breakpoint(i, BP_X, 1, local, global, 1);
+		ptrace(PTRACE_CONT, child_pid, NULL, 0);
+		sprintf(buf, "Test breakpoint %d with local: %d global: %d\n",
+			i, local, global);
+		check_success(buf);
+		toggle_breakpoint(i, BP_X, 1, local, global, 0);
+	}
+}
+
+static void launch_watchpoints(char *buf, int mode, int len,
+			       int local, int global)
+{
+	const char *mode_str;
+	int i;
+
+	if (mode == BP_W)
+		mode_str = "write";
+	else
+		mode_str = "read";
+
+	for (i = 0; i < COUNT_WPS; i++) {
+		set_breakpoint_addr(&dummy_var[i], i);
+		toggle_breakpoint(i, mode, len, local, global, 1);
+		ptrace(PTRACE_CONT, child_pid, NULL, 0);
+		sprintf(buf,
+			"Test %s watchpoint %d with len: %d local: %d global: %d\n",
+			mode_str, i, len, local, global);
+		check_success(buf);
+		toggle_breakpoint(i, mode, len, local, global, 0);
+	}
+}
+
+/* Set the breakpoints and check the child successfully trigger them */
+static void launch_tests(void)
+{
+	char buf[1024];
+	unsigned int tests = 0;
+	int len, local, global, i;
+
+	tests += 3 * COUNT_ISN_BPS;
+	tests += sizeof(long) / 2 * 3 * COUNT_WPS;
+	tests += sizeof(long) / 2 * 3 * COUNT_WPS;
+	tests += 2;
+	ksft_set_plan(tests);
+
+	/* Instruction breakpoints */
+	for (local = 0; local < 2; local++) {
+		for (global = 0; global < 2; global++) {
+			if (!local && !global)
+				continue;
+			launch_instruction_breakpoints(buf, local, global);
+		}
+	}
+
+	/* Write watchpoint */
+	for (len = 1; len <= sizeof(long); len <<= 1) {
+		for (local = 0; local < 2; local++) {
+			for (global = 0; global < 2; global++) {
+				if (!local && !global)
+					continue;
+				launch_watchpoints(buf, BP_W, len,
+						   local, global);
+			}
+		}
+	}
+
+	/* Read-Write watchpoint */
+	for (len = 1; len <= sizeof(long); len <<= 1) {
+		for (local = 0; local < 2; local++) {
+			for (global = 0; global < 2; global++) {
+				if (!local && !global)
+					continue;
+				launch_watchpoints(buf, BP_RW, len,
+						   local, global);
+			}
+		}
+	}
+
+	/* Icebp traps */
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+	check_success("Test icebp\n");
+
+	/* Int 3 traps */
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+	check_success("Test int 3 trap\n");
+
+	ptrace(PTRACE_CONT, child_pid, NULL, 0);
+}
+
+int main(int argc, char **argv)
+{
+	pid_t pid;
+	int ret;
+
+	ksft_print_header();
+
+	pid = fork();
+	if (!pid) {
+		trigger_tests();
+		exit(0);
+	}
+
+	child_pid = pid;
+
+	wait(NULL);
+
+	launch_tests();
+
+	wait(NULL);
+
+	ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/breakpoints/breakpoint_test_arm64.c b/tools/testing/selftests/breakpoints/breakpoint_test_arm64.c
new file mode 100644
index 000000000..5fc0f37f3
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/breakpoint_test_arm64.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * Original Code by Pavel Labath <labath@google.com>
+ *
+ * Code modified by Pratyush Anand <panand@redhat.com>
+ * for testing different byte select for each access size.
+ */
+
+#define _GNU_SOURCE
+
+#include <asm/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/ptrace.h>
+#include <sys/param.h>
+#include <sys/uio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <elf.h>
+#include <errno.h>
+#include <signal.h>
+
+#include "kselftest.h"
+
+static volatile uint8_t var[96] __attribute__((__aligned__(32)));
+
+static void child(int size, int wr)
+{
+	volatile uint8_t *addr = &var[32 + wr];
+
+	if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_TRACEME) failed: %s\n",
+			strerror(errno));
+		_exit(1);
+	}
+
+	if (raise(SIGSTOP) != 0) {
+		ksft_print_msg(
+			"raise(SIGSTOP) failed: %s\n", strerror(errno));
+		_exit(1);
+	}
+
+	if ((uintptr_t) addr % size) {
+		ksft_print_msg(
+			 "Wrong address write for the given size: %s\n",
+			 strerror(errno));
+		_exit(1);
+	}
+
+	switch (size) {
+	case 1:
+		*addr = 47;
+		break;
+	case 2:
+		*(uint16_t *)addr = 47;
+		break;
+	case 4:
+		*(uint32_t *)addr = 47;
+		break;
+	case 8:
+		*(uint64_t *)addr = 47;
+		break;
+	case 16:
+		__asm__ volatile ("stp x29, x30, %0" : "=m" (addr[0]));
+		break;
+	case 32:
+		__asm__ volatile ("stp q29, q30, %0" : "=m" (addr[0]));
+		break;
+	}
+
+	_exit(0);
+}
+
+static bool set_watchpoint(pid_t pid, int size, int wp)
+{
+	const volatile uint8_t *addr = &var[32 + wp];
+	const int offset = (uintptr_t)addr % 8;
+	const unsigned int byte_mask = ((1 << size) - 1) << offset;
+	const unsigned int type = 2; /* Write */
+	const unsigned int enable = 1;
+	const unsigned int control = byte_mask << 5 | type << 3 | enable;
+	struct user_hwdebug_state dreg_state;
+	struct iovec iov;
+
+	memset(&dreg_state, 0, sizeof(dreg_state));
+	dreg_state.dbg_regs[0].addr = (uintptr_t)(addr - offset);
+	dreg_state.dbg_regs[0].ctrl = control;
+	iov.iov_base = &dreg_state;
+	iov.iov_len = offsetof(struct user_hwdebug_state, dbg_regs) +
+				sizeof(dreg_state.dbg_regs[0]);
+	if (ptrace(PTRACE_SETREGSET, pid, NT_ARM_HW_WATCH, &iov) == 0)
+		return true;
+
+	if (errno == EIO)
+		ksft_print_msg(
+			"ptrace(PTRACE_SETREGSET, NT_ARM_HW_WATCH) not supported on this hardware: %s\n",
+			strerror(errno));
+
+	ksft_print_msg(
+		"ptrace(PTRACE_SETREGSET, NT_ARM_HW_WATCH) failed: %s\n",
+		strerror(errno));
+	return false;
+}
+
+static bool run_test(int wr_size, int wp_size, int wr, int wp)
+{
+	int status;
+	siginfo_t siginfo;
+	pid_t pid = fork();
+	pid_t wpid;
+
+	if (pid < 0) {
+		ksft_test_result_fail(
+			"fork() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (pid == 0)
+		child(wr_size, wr);
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg(
+			"child did not stop: %s\n", strerror(errno));
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGSTOP) {
+		ksft_print_msg("child did not stop with SIGSTOP\n");
+		return false;
+	}
+
+	if (!set_watchpoint(pid, wp_size, wp))
+		return false;
+
+	if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_CONT) failed: %s\n",
+			strerror(errno));
+		return false;
+	}
+
+	alarm(3);
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	alarm(0);
+	if (WIFEXITED(status)) {
+		ksft_print_msg("child exited prematurely\n");
+		return false;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop\n");
+		return false;
+	}
+	if (WSTOPSIG(status) != SIGTRAP) {
+		ksft_print_msg("child did not stop with SIGTRAP\n");
+		return false;
+	}
+	if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo) != 0) {
+		ksft_print_msg(
+			"ptrace(PTRACE_GETSIGINFO): %s\n",
+			strerror(errno));
+		return false;
+	}
+	if (siginfo.si_code != TRAP_HWBKPT) {
+		ksft_print_msg(
+			"Unexpected si_code %d\n", siginfo.si_code);
+		return false;
+	}
+
+	kill(pid, SIGKILL);
+	wpid = waitpid(pid, &status, 0);
+	if (wpid != pid) {
+		ksft_print_msg(
+			"waitpid() failed: %s\n", strerror(errno));
+		return false;
+	}
+	return true;
+}
+
+static void sigalrm(int sig)
+{
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+	bool succeeded = true;
+	struct sigaction act;
+	int wr, wp, size;
+	bool result;
+
+	ksft_print_header();
+	ksft_set_plan(213);
+
+	act.sa_handler = sigalrm;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	sigaction(SIGALRM, &act, NULL);
+	for (size = 1; size <= 32; size = size*2) {
+		for (wr = 0; wr <= 32; wr = wr + size) {
+			for (wp = wr - size; wp <= wr + size; wp = wp + size) {
+				result = run_test(size, MIN(size, 8), wr, wp);
+				if ((result && wr == wp) ||
+				    (!result && wr != wp))
+					ksft_test_result_pass(
+						"Test size = %d write offset = %d watchpoint offset = %d\n",
+						size, wr, wp);
+				else {
+					ksft_test_result_fail(
+						"Test size = %d write offset = %d watchpoint offset = %d\n",
+						size, wr, wp);
+					succeeded = false;
+				}
+			}
+		}
+	}
+
+	for (size = 1; size <= 32; size = size*2) {
+		if (run_test(size, 8, -size, -8))
+			ksft_test_result_pass(
+				"Test size = %d write offset = %d watchpoint offset = -8\n",
+				size, -size);
+		else {
+			ksft_test_result_fail(
+				"Test size = %d write offset = %d watchpoint offset = -8\n",
+				size, -size);
+			succeeded = false;
+		}
+	}
+
+	if (succeeded)
+		ksft_exit_pass();
+	else
+		ksft_exit_fail();
+}
diff --git a/tools/testing/selftests/breakpoints/step_after_suspend_test.c b/tools/testing/selftests/breakpoints/step_after_suspend_test.c
new file mode 100644
index 000000000..ca2aaab9e
--- /dev/null
+++ b/tools/testing/selftests/breakpoints/step_after_suspend_test.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 Google, Inc.
+ */
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/ptrace.h>
+#include <sys/stat.h>
+#include <sys/timerfd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "kselftest.h"
+
+void child(int cpu)
+{
+	cpu_set_t set;
+
+	CPU_ZERO(&set);
+	CPU_SET(cpu, &set);
+	if (sched_setaffinity(0, sizeof(set), &set) != 0) {
+		ksft_print_msg("sched_setaffinity() failed: %s\n",
+			strerror(errno));
+		_exit(1);
+	}
+
+	if (ptrace(PTRACE_TRACEME, 0, NULL, NULL) != 0) {
+		ksft_print_msg("ptrace(PTRACE_TRACEME) failed: %s\n",
+			strerror(errno));
+		_exit(1);
+	}
+
+	if (raise(SIGSTOP) != 0) {
+		ksft_print_msg("raise(SIGSTOP) failed: %s\n", strerror(errno));
+		_exit(1);
+	}
+
+	_exit(0);
+}
+
+int run_test(int cpu)
+{
+	int status;
+	pid_t pid = fork();
+	pid_t wpid;
+
+	if (pid < 0) {
+		ksft_print_msg("fork() failed: %s\n", strerror(errno));
+		return KSFT_FAIL;
+	}
+	if (pid == 0)
+		child(cpu);
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return KSFT_FAIL;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop: %s\n", strerror(errno));
+		return KSFT_FAIL;
+	}
+	if (WSTOPSIG(status) != SIGSTOP) {
+		ksft_print_msg("child did not stop with SIGSTOP: %s\n",
+			strerror(errno));
+		return KSFT_FAIL;
+	}
+
+	if (ptrace(PTRACE_SINGLESTEP, pid, NULL, NULL) < 0) {
+		if (errno == EIO) {
+			ksft_print_msg(
+				"ptrace(PTRACE_SINGLESTEP) not supported on this architecture: %s\n",
+				strerror(errno));
+			return KSFT_SKIP;
+		}
+		ksft_print_msg("ptrace(PTRACE_SINGLESTEP) failed: %s\n",
+			strerror(errno));
+		return KSFT_FAIL;
+	}
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return KSFT_FAIL;
+	}
+	if (WIFEXITED(status)) {
+		ksft_print_msg("child did not single-step: %s\n",
+			strerror(errno));
+		return KSFT_FAIL;
+	}
+	if (!WIFSTOPPED(status)) {
+		ksft_print_msg("child did not stop: %s\n", strerror(errno));
+		return KSFT_FAIL;
+	}
+	if (WSTOPSIG(status) != SIGTRAP) {
+		ksft_print_msg("child did not stop with SIGTRAP: %s\n",
+			strerror(errno));
+		return KSFT_FAIL;
+	}
+
+	if (ptrace(PTRACE_CONT, pid, NULL, NULL) < 0) {
+		ksft_print_msg("ptrace(PTRACE_CONT) failed: %s\n",
+			strerror(errno));
+		return KSFT_FAIL;
+	}
+
+	wpid = waitpid(pid, &status, __WALL);
+	if (wpid != pid) {
+		ksft_print_msg("waitpid() failed: %s\n", strerror(errno));
+		return KSFT_FAIL;
+	}
+	if (!WIFEXITED(status)) {
+		ksft_print_msg("child did not exit after PTRACE_CONT: %s\n",
+			strerror(errno));
+		return KSFT_FAIL;
+	}
+
+	return KSFT_PASS;
+}
+
+/*
+ * Reads the suspend success count from sysfs.
+ * Returns the count on success or exits on failure.
+ */
+static int get_suspend_success_count_or_fail(void)
+{
+	FILE *fp;
+	int val;
+
+	fp = fopen("/sys/power/suspend_stats/success", "r");
+	if (!fp)
+		ksft_exit_fail_msg(
+			"Failed to open suspend_stats/success: %s\n",
+			strerror(errno));
+
+	if (fscanf(fp, "%d", &val) != 1) {
+		fclose(fp);
+		ksft_exit_fail_msg(
+			"Failed to read suspend success count\n");
+	}
+
+	fclose(fp);
+	return val;
+}
+
+void suspend(void)
+{
+	int timerfd;
+	int err;
+	int count_before;
+	int count_after;
+	struct itimerspec spec = {};
+
+	if (getuid() != 0)
+		ksft_exit_skip("Please run the test as root - Exiting.\n");
+
+	timerfd = timerfd_create(CLOCK_BOOTTIME_ALARM, 0);
+	if (timerfd < 0)
+		ksft_exit_fail_msg("timerfd_create() failed\n");
+
+	spec.it_value.tv_sec = 5;
+	err = timerfd_settime(timerfd, 0, &spec, NULL);
+	if (err < 0)
+		ksft_exit_fail_msg("timerfd_settime() failed\n");
+
+	count_before = get_suspend_success_count_or_fail();
+
+	system("(echo mem > /sys/power/state) 2> /dev/null");
+
+	count_after = get_suspend_success_count_or_fail();
+	if (count_after <= count_before)
+		ksft_exit_fail_msg("Failed to enter Suspend state\n");
+
+	close(timerfd);
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+	bool do_suspend = true;
+	bool succeeded = true;
+	unsigned int tests = 0;
+	cpu_set_t available_cpus;
+	int err;
+	int cpu;
+
+	ksft_print_header();
+
+	while ((opt = getopt(argc, argv, "n")) != -1) {
+		switch (opt) {
+		case 'n':
+			do_suspend = false;
+			break;
+		default:
+			printf("Usage: %s [-n]\n", argv[0]);
+			printf("        -n: do not trigger a suspend/resume cycle before the test\n");
+			return -1;
+		}
+	}
+
+	err = sched_getaffinity(0, sizeof(available_cpus), &available_cpus);
+	if (err < 0)
+		ksft_exit_fail_msg("sched_getaffinity() failed\n");
+
+	for (cpu = 0; cpu < CPU_SETSIZE; cpu++) {
+		if (!CPU_ISSET(cpu, &available_cpus))
+			continue;
+		tests++;
+	}
+
+	if (do_suspend)
+		suspend();
+
+	ksft_set_plan(tests);
+	for (cpu = 0; cpu < CPU_SETSIZE; cpu++) {
+		int test_success;
+
+		if (!CPU_ISSET(cpu, &available_cpus))
+			continue;
+
+		test_success = run_test(cpu);
+		switch (test_success) {
+		case KSFT_PASS:
+			ksft_test_result_pass("CPU %d\n", cpu);
+			break;
+		case KSFT_SKIP:
+			ksft_test_result_skip("CPU %d\n", cpu);
+			break;
+		case KSFT_FAIL:
+			ksft_test_result_fail("CPU %d\n", cpu);
+			succeeded = false;
+			break;
+		}
+	}
+
+	if (succeeded)
+		ksft_exit_pass();
+	else
+		ksft_exit_fail();
+}