ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

8 files changed, 521 insertions, 0 deletions

diff --git a/tools/testing/selftests/prctl/.gitignore b/tools/testing/selftests/prctl/.gitignore
new file mode 100644
index 000000000..05d5e3166
--- /dev/null
+++ b/tools/testing/selftests/prctl/.gitignore
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
+disable-tsc-ctxt-sw-stress-test
+disable-tsc-on-off-stress-test
+disable-tsc-test
+set-anon-vma-name-test
+set-process-name
diff --git a/tools/testing/selftests/prctl/Makefile b/tools/testing/selftests/prctl/Makefile
new file mode 100644
index 000000000..e770e86fa
--- /dev/null
+++ b/tools/testing/selftests/prctl/Makefile
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+ifndef CROSS_COMPILE
+ARCH ?= $(shell uname -m 2>/dev/null || echo not)
+override ARCH := $(shell echo $(ARCH) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
+
+ifeq ($(ARCH),x86)
+TEST_PROGS := disable-tsc-ctxt-sw-stress-test disable-tsc-on-off-stress-test \
+		disable-tsc-test set-anon-vma-name-test set-process-name
+all: $(TEST_PROGS)
+
+include ../lib.mk
+
+endif
+endif
diff --git a/tools/testing/selftests/prctl/config b/tools/testing/selftests/prctl/config
new file mode 100644
index 000000000..c6ed03c54
--- /dev/null
+++ b/tools/testing/selftests/prctl/config
@@ -0,0 +1 @@
+CONFIG_ANON_VMA_NAME=y
diff --git a/tools/testing/selftests/prctl/disable-tsc-ctxt-sw-stress-test.c b/tools/testing/selftests/prctl/disable-tsc-ctxt-sw-stress-test.c
new file mode 100644
index 000000000..6d1a5ee8e
--- /dev/null
+++ b/tools/testing/selftests/prctl/disable-tsc-ctxt-sw-stress-test.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
+ *
+ * Tests if the control register is updated correctly
+ * at context switches
+ *
+ * Warning: this test will cause a very high load for a few seconds
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <inttypes.h>
+#include <wait.h>
+
+
+#include <sys/prctl.h>
+#include <linux/prctl.h>
+
+/* Get/set the process' ability to use the timestamp counter instruction */
+#ifndef PR_GET_TSC
+#define PR_GET_TSC 25
+#define PR_SET_TSC 26
+# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */
+# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */
+#endif
+
+static uint64_t rdtsc(void)
+{
+uint32_t lo, hi;
+/* We cannot use "=A", since this would use %rax on x86_64 */
+__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+return (uint64_t)hi << 32 | lo;
+}
+
+static void sigsegv_expect(int sig)
+{
+	/* */
+}
+
+static void segvtask(void)
+{
+	if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)
+	{
+		perror("prctl");
+		exit(0);
+	}
+	signal(SIGSEGV, sigsegv_expect);
+	alarm(10);
+	rdtsc();
+	fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");
+	exit(0);
+}
+
+
+static void sigsegv_fail(int sig)
+{
+	fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");
+	exit(0);
+}
+
+static void rdtsctask(void)
+{
+	if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)
+	{
+		perror("prctl");
+		exit(0);
+	}
+	signal(SIGSEGV, sigsegv_fail);
+	alarm(10);
+	for(;;) rdtsc();
+}
+
+
+int main(void)
+{
+	int n_tasks = 100, i;
+
+	fprintf(stderr, "[No further output means we're all right]\n");
+
+	for (i=0; i<n_tasks; i++)
+		if (fork() == 0)
+		{
+			if (i & 1)
+				segvtask();
+			else
+				rdtsctask();
+		}
+
+	for (i=0; i<n_tasks; i++)
+		wait(NULL);
+
+	exit(0);
+}
+
diff --git a/tools/testing/selftests/prctl/disable-tsc-on-off-stress-test.c b/tools/testing/selftests/prctl/disable-tsc-on-off-stress-test.c
new file mode 100644
index 000000000..d39511eb9
--- /dev/null
+++ b/tools/testing/selftests/prctl/disable-tsc-on-off-stress-test.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
+ *
+ * Tests if the control register is updated correctly
+ * when set with prctl()
+ *
+ * Warning: this test will cause a very high load for a few seconds
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <inttypes.h>
+#include <wait.h>
+
+
+#include <sys/prctl.h>
+#include <linux/prctl.h>
+
+/* Get/set the process' ability to use the timestamp counter instruction */
+#ifndef PR_GET_TSC
+#define PR_GET_TSC 25
+#define PR_SET_TSC 26
+# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */
+# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */
+#endif
+
+/* snippet from wikipedia :-) */
+
+static uint64_t rdtsc(void)
+{
+uint32_t lo, hi;
+/* We cannot use "=A", since this would use %rax on x86_64 */
+__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+return (uint64_t)hi << 32 | lo;
+}
+
+int should_segv = 0;
+
+static void sigsegv_cb(int sig)
+{
+	if (!should_segv)
+	{
+		fprintf(stderr, "FATAL ERROR, rdtsc() failed while enabled\n");
+		exit(0);
+	}
+	if (prctl(PR_SET_TSC, PR_TSC_ENABLE) < 0)
+	{
+		perror("prctl");
+		exit(0);
+	}
+	should_segv = 0;
+
+	rdtsc();
+}
+
+static void task(void)
+{
+	signal(SIGSEGV, sigsegv_cb);
+	alarm(10);
+	for(;;)
+	{
+		rdtsc();
+		if (should_segv)
+		{
+			fprintf(stderr, "FATAL ERROR, rdtsc() succeeded while disabled\n");
+			exit(0);
+		}
+		if (prctl(PR_SET_TSC, PR_TSC_SIGSEGV) < 0)
+		{
+			perror("prctl");
+			exit(0);
+		}
+		should_segv = 1;
+	}
+}
+
+
+int main(void)
+{
+	int n_tasks = 100, i;
+
+	fprintf(stderr, "[No further output means we're all right]\n");
+
+	for (i=0; i<n_tasks; i++)
+		if (fork() == 0)
+			task();
+
+	for (i=0; i<n_tasks; i++)
+		wait(NULL);
+
+	exit(0);
+}
+
diff --git a/tools/testing/selftests/prctl/disable-tsc-test.c b/tools/testing/selftests/prctl/disable-tsc-test.c
new file mode 100644
index 000000000..f84d4ee11
--- /dev/null
+++ b/tools/testing/selftests/prctl/disable-tsc-test.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tests for prctl(PR_GET_TSC, ...) / prctl(PR_SET_TSC, ...)
+ *
+ * Basic test to test behaviour of PR_GET_TSC and PR_SET_TSC
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <inttypes.h>
+
+
+#include <sys/prctl.h>
+#include <linux/prctl.h>
+
+/* Get/set the process' ability to use the timestamp counter instruction */
+#ifndef PR_GET_TSC
+#define PR_GET_TSC 25
+#define PR_SET_TSC 26
+# define PR_TSC_ENABLE		1   /* allow the use of the timestamp counter */
+# define PR_TSC_SIGSEGV		2   /* throw a SIGSEGV instead of reading the TSC */
+#endif
+
+const char *tsc_names[] =
+{
+	[0] = "[not set]",
+	[PR_TSC_ENABLE] = "PR_TSC_ENABLE",
+	[PR_TSC_SIGSEGV] = "PR_TSC_SIGSEGV",
+};
+
+static uint64_t rdtsc(void)
+{
+uint32_t lo, hi;
+/* We cannot use "=A", since this would use %rax on x86_64 */
+__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+return (uint64_t)hi << 32 | lo;
+}
+
+static void sigsegv_cb(int sig)
+{
+	int tsc_val = 0;
+
+	printf("[ SIG_SEGV ]\n");
+	printf("prctl(PR_GET_TSC, &tsc_val); ");
+	fflush(stdout);
+
+	if ( prctl(PR_GET_TSC, &tsc_val) == -1)
+		perror("prctl");
+
+	printf("tsc_val == %s\n", tsc_names[tsc_val]);
+	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
+	fflush(stdout);
+	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
+		perror("prctl");
+
+	printf("rdtsc() == ");
+}
+
+int main(void)
+{
+	int tsc_val = 0;
+
+	signal(SIGSEGV, sigsegv_cb);
+
+	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
+	printf("prctl(PR_GET_TSC, &tsc_val); ");
+	fflush(stdout);
+
+	if ( prctl(PR_GET_TSC, &tsc_val) == -1)
+		perror("prctl");
+
+	printf("tsc_val == %s\n", tsc_names[tsc_val]);
+	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
+	printf("prctl(PR_SET_TSC, PR_TSC_ENABLE)\n");
+	fflush(stdout);
+
+	if ( prctl(PR_SET_TSC, PR_TSC_ENABLE) == -1)
+		perror("prctl");
+
+	printf("rdtsc() == %llu\n", (unsigned long long)rdtsc());
+	printf("prctl(PR_SET_TSC, PR_TSC_SIGSEGV)\n");
+	fflush(stdout);
+
+	if ( prctl(PR_SET_TSC, PR_TSC_SIGSEGV) == -1)
+		perror("prctl");
+
+	printf("rdtsc() == ");
+	fflush(stdout);
+	printf("%llu\n", (unsigned long long)rdtsc());
+	fflush(stdout);
+
+	exit(EXIT_SUCCESS);
+}
+
diff --git a/tools/testing/selftests/prctl/set-anon-vma-name-test.c b/tools/testing/selftests/prctl/set-anon-vma-name-test.c
new file mode 100644
index 000000000..5f9589534
--- /dev/null
+++ b/tools/testing/selftests/prctl/set-anon-vma-name-test.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This test covers the anonymous VMA naming functionality through prctl calls
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/prctl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "kselftest_harness.h"
+
+#define AREA_SIZE 1024
+
+#define GOOD_NAME "goodname"
+#define BAD_NAME "badname\1"
+
+#ifndef PR_SET_VMA
+#define PR_SET_VMA 0x53564d41
+#define PR_SET_VMA_ANON_NAME 0
+#endif
+
+
+int rename_vma(unsigned long addr, unsigned long size, char *name)
+{
+	int res;
+
+	res = prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, addr, size, name);
+	if (res < 0)
+		return -errno;
+	return res;
+}
+
+int was_renaming_successful(char *target_name, unsigned long ptr)
+{
+	FILE *maps_file;
+
+	char line_buf[512], name[128], mode[8];
+	unsigned long start_addr, end_addr, offset;
+	unsigned int major_id, minor_id, node_id;
+
+	char target_buf[128];
+	int res = 0, sscanf_res;
+
+	// The entry name in maps will be in format [anon:<target_name>]
+	sprintf(target_buf, "[anon:%s]", target_name);
+	maps_file = fopen("/proc/self/maps", "r");
+	if (!maps_file) {
+		printf("## /proc/self/maps file opening error\n");
+		return 0;
+	}
+
+	// Parse the maps file to find the entry we renamed
+	while (fgets(line_buf, sizeof(line_buf), maps_file)) {
+		sscanf_res = sscanf(line_buf, "%lx-%lx %7s %lx %u:%u %u %s", &start_addr,
+					&end_addr, mode, &offset, &major_id,
+					&minor_id, &node_id, name);
+		if (sscanf_res == EOF) {
+			res = 0;
+			printf("## EOF while parsing the maps file\n");
+			break;
+		}
+		if (!strcmp(name, target_buf) && start_addr == ptr) {
+			res = 1;
+			break;
+		}
+	}
+	fclose(maps_file);
+	return res;
+}
+
+FIXTURE(vma) {
+	void *ptr_anon, *ptr_not_anon;
+	int fd_not_anon;
+};
+
+FIXTURE_SETUP(vma) {
+	char template[] = "./set-anon-vma-test-XXXXXX";
+
+	self->ptr_anon = mmap(NULL, AREA_SIZE, PROT_READ | PROT_WRITE,
+					MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	ASSERT_NE(self->ptr_anon, MAP_FAILED);
+
+	self->fd_not_anon = mkstemp(template);
+	ASSERT_NE(self->fd_not_anon, -1);
+	unlink(template);
+	ASSERT_EQ(ftruncate(self->fd_not_anon, AREA_SIZE), 0);
+	self->ptr_not_anon = mmap(NULL, AREA_SIZE, PROT_READ | PROT_WRITE,
+					MAP_PRIVATE, self->fd_not_anon, 0);
+	ASSERT_NE(self->ptr_not_anon, MAP_FAILED);
+	close(self->fd_not_anon);
+}
+
+FIXTURE_TEARDOWN(vma) {
+	munmap(self->ptr_anon, AREA_SIZE);
+	munmap(self->ptr_not_anon, AREA_SIZE);
+}
+
+TEST_F(vma, renaming) {
+	TH_LOG("Try to rename the VMA with correct parameters");
+	EXPECT_GE(rename_vma((unsigned long)self->ptr_anon, AREA_SIZE, GOOD_NAME), 0);
+	EXPECT_TRUE(was_renaming_successful(GOOD_NAME, (unsigned long)self->ptr_anon));
+
+	TH_LOG("Try to pass invalid name (with non-printable character \\1) to rename the VMA");
+	EXPECT_EQ(rename_vma((unsigned long)self->ptr_anon, AREA_SIZE, BAD_NAME), -EINVAL);
+
+	TH_LOG("Try to rename non-anonymous VMA");
+	EXPECT_EQ(rename_vma((unsigned long) self->ptr_not_anon, AREA_SIZE, GOOD_NAME), -EBADF);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/prctl/set-process-name.c b/tools/testing/selftests/prctl/set-process-name.c
new file mode 100644
index 000000000..3f7b146d3
--- /dev/null
+++ b/tools/testing/selftests/prctl/set-process-name.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This test covers the PR_SET_NAME functionality of prctl calls
+ */
+
+#include <errno.h>
+#include <sys/prctl.h>
+#include <string.h>
+
+#include "kselftest_harness.h"
+
+#define CHANGE_NAME "changename"
+#define EMPTY_NAME ""
+#define TASK_COMM_LEN 16
+#define MAX_PATH_LEN 50
+
+int set_name(char *name)
+{
+	int res;
+
+	res = prctl(PR_SET_NAME, name, NULL, NULL, NULL);
+
+	if (res < 0)
+		return -errno;
+	return res;
+}
+
+int check_is_name_correct(char *check_name)
+{
+	char name[TASK_COMM_LEN];
+	int res;
+
+	res = prctl(PR_GET_NAME, name, NULL, NULL, NULL);
+
+	if (res < 0)
+		return -errno;
+
+	return !strcmp(name, check_name);
+}
+
+int check_null_pointer(char *check_name)
+{
+	char *name = NULL;
+	int res;
+
+	res = prctl(PR_GET_NAME, name, NULL, NULL, NULL);
+
+	return res;
+}
+
+int check_name(void)
+{
+
+	int pid;
+
+	pid = getpid();
+	FILE *fptr = NULL;
+	char path[MAX_PATH_LEN] = {};
+	char name[TASK_COMM_LEN] = {};
+	char output[TASK_COMM_LEN] = {};
+	int j;
+
+	j = snprintf(path, MAX_PATH_LEN, "/proc/self/task/%d/comm", pid);
+	fptr = fopen(path, "r");
+	if (!fptr)
+		return -EIO;
+
+	fscanf(fptr, "%s", output);
+	if (ferror(fptr))
+		return -EIO;
+
+	int res = prctl(PR_GET_NAME, name, NULL, NULL, NULL);
+
+	if (res < 0)
+		return -errno;
+
+	return !strcmp(output, name);
+}
+
+TEST(rename_process) {
+
+	EXPECT_GE(set_name(CHANGE_NAME), 0);
+	EXPECT_TRUE(check_is_name_correct(CHANGE_NAME));
+
+	EXPECT_GE(set_name(EMPTY_NAME), 0);
+	EXPECT_TRUE(check_is_name_correct(EMPTY_NAME));
+
+	EXPECT_GE(set_name(CHANGE_NAME), 0);
+	EXPECT_LT(check_null_pointer(CHANGE_NAME), 0);
+
+	EXPECT_TRUE(check_name());
+}
+
+TEST_HARNESS_MAIN