From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- tools/perf/util/vdso.c | 369 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 369 insertions(+) create mode 100644 tools/perf/util/vdso.c (limited to 'tools/perf/util/vdso.c') diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c new file mode 100644 index 000000000..c12f5d8c4 --- /dev/null +++ b/tools/perf/util/vdso.c @@ -0,0 +1,369 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "vdso.h" +#include "dso.h" +#include +#include "map.h" +#include "symbol.h" +#include "machine.h" +#include "thread.h" +#include "linux/string.h" +#include +#include "debug.h" + +/* + * Include definition of find_map() also used in perf-read-vdso.c for + * building perf-read-vdso32 and perf-read-vdsox32. + */ +#include "find-map.c" + +#define VDSO__TEMP_FILE_NAME "/tmp/perf-vdso.so-XXXXXX" + +struct vdso_file { + bool found; + bool error; + char temp_file_name[sizeof(VDSO__TEMP_FILE_NAME)]; + const char *dso_name; + const char *read_prog; +}; + +struct vdso_info { + struct vdso_file vdso; +#if BITS_PER_LONG == 64 + struct vdso_file vdso32; + struct vdso_file vdsox32; +#endif +}; + +static struct vdso_info *vdso_info__new(void) +{ + static const struct vdso_info vdso_info_init = { + .vdso = { + .temp_file_name = VDSO__TEMP_FILE_NAME, + .dso_name = DSO__NAME_VDSO, + }, +#if BITS_PER_LONG == 64 + .vdso32 = { + .temp_file_name = VDSO__TEMP_FILE_NAME, + .dso_name = DSO__NAME_VDSO32, + .read_prog = "perf-read-vdso32", + }, + .vdsox32 = { + .temp_file_name = VDSO__TEMP_FILE_NAME, + .dso_name = DSO__NAME_VDSOX32, + .read_prog = "perf-read-vdsox32", + }, +#endif + }; + + return memdup(&vdso_info_init, sizeof(vdso_info_init)); +} + +static char *get_file(struct vdso_file *vdso_file) +{ + char *vdso = NULL; + char *buf = NULL; + void *start, *end; + size_t size; + int fd; + + if (vdso_file->found) + return vdso_file->temp_file_name; + + if (vdso_file->error || find_map(&start, &end, VDSO__MAP_NAME)) + return NULL; + + size = end - start; + + buf = memdup(start, size); + if (!buf) + return NULL; + + fd = mkstemp(vdso_file->temp_file_name); + if (fd < 0) + goto out; + + if (size == (size_t) write(fd, buf, size)) + vdso = vdso_file->temp_file_name; + + close(fd); + + out: + free(buf); + + vdso_file->found = (vdso != NULL); + vdso_file->error = !vdso_file->found; + return vdso; +} + +void machine__exit_vdso(struct machine *machine) +{ + struct vdso_info *vdso_info = machine->vdso_info; + + if (!vdso_info) + return; + + if (vdso_info->vdso.found) + unlink(vdso_info->vdso.temp_file_name); +#if BITS_PER_LONG == 64 + if (vdso_info->vdso32.found) + unlink(vdso_info->vdso32.temp_file_name); + if (vdso_info->vdsox32.found) + unlink(vdso_info->vdsox32.temp_file_name); +#endif + + zfree(&machine->vdso_info); +} + +static struct dso *__machine__addnew_vdso(struct machine *machine, const char *short_name, + const char *long_name) +{ + struct dso *dso; + + dso = dso__new(short_name); + if (dso != NULL) { + __dsos__add(&machine->dsos, dso); + dso__set_long_name(dso, long_name, false); + } + + return dso; +} + +struct machine__thread_dso_type_maps_cb_args { + struct machine *machine; + enum dso_type dso_type; +}; + +static int machine__thread_dso_type_maps_cb(struct map *map, void *data) +{ + struct machine__thread_dso_type_maps_cb_args *args = data; + struct dso *dso = map__dso(map); + + if (!dso || dso__long_name(dso)[0] != '/') + return 0; + + args->dso_type = dso__type(dso, args->machine); + return (args->dso_type != DSO__TYPE_UNKNOWN) ? 1 : 0; +} + +static enum dso_type machine__thread_dso_type(struct machine *machine, + struct thread *thread) +{ + struct machine__thread_dso_type_maps_cb_args args = { + .machine = machine, + .dso_type = DSO__TYPE_UNKNOWN, + }; + + maps__for_each_map(thread__maps(thread), machine__thread_dso_type_maps_cb, &args); + + return args.dso_type; +} + +#if BITS_PER_LONG == 64 + +static int vdso__do_copy_compat(FILE *f, int fd) +{ + char buf[4096]; + size_t count; + + while (1) { + count = fread(buf, 1, sizeof(buf), f); + if (ferror(f)) + return -errno; + if (feof(f)) + break; + if (count && writen(fd, buf, count) != (ssize_t)count) + return -errno; + } + + return 0; +} + +static int vdso__copy_compat(const char *prog, int fd) +{ + FILE *f; + int err; + + f = popen(prog, "r"); + if (!f) + return -errno; + + err = vdso__do_copy_compat(f, fd); + + if (pclose(f) == -1) + return -errno; + + return err; +} + +static int vdso__create_compat_file(const char *prog, char *temp_name) +{ + int fd, err; + + fd = mkstemp(temp_name); + if (fd < 0) + return -errno; + + err = vdso__copy_compat(prog, fd); + + if (close(fd) == -1) + return -errno; + + return err; +} + +static const char *vdso__get_compat_file(struct vdso_file *vdso_file) +{ + int err; + + if (vdso_file->found) + return vdso_file->temp_file_name; + + if (vdso_file->error) + return NULL; + + err = vdso__create_compat_file(vdso_file->read_prog, + vdso_file->temp_file_name); + if (err) { + pr_err("%s failed, error %d\n", vdso_file->read_prog, err); + vdso_file->error = true; + return NULL; + } + + vdso_file->found = true; + + return vdso_file->temp_file_name; +} + +static struct dso *__machine__findnew_compat(struct machine *machine, + struct vdso_file *vdso_file) +{ + const char *file_name; + struct dso *dso; + + dso = dsos__find(&machine->dsos, vdso_file->dso_name, true); + if (dso) + return dso; + + file_name = vdso__get_compat_file(vdso_file); + if (!file_name) + return NULL; + + return __machine__addnew_vdso(machine, vdso_file->dso_name, file_name); +} + +static int __machine__findnew_vdso_compat(struct machine *machine, + struct thread *thread, + struct vdso_info *vdso_info, + struct dso **dso) +{ + enum dso_type dso_type; + + dso_type = machine__thread_dso_type(machine, thread); + +#ifndef HAVE_PERF_READ_VDSO32 + if (dso_type == DSO__TYPE_32BIT) + return 0; +#endif +#ifndef HAVE_PERF_READ_VDSOX32 + if (dso_type == DSO__TYPE_X32BIT) + return 0; +#endif + + switch (dso_type) { + case DSO__TYPE_32BIT: + *dso = __machine__findnew_compat(machine, &vdso_info->vdso32); + return 1; + case DSO__TYPE_X32BIT: + *dso = __machine__findnew_compat(machine, &vdso_info->vdsox32); + return 1; + case DSO__TYPE_UNKNOWN: + case DSO__TYPE_64BIT: + default: + return 0; + } +} + +#endif + +static struct dso *machine__find_vdso(struct machine *machine, + struct thread *thread) +{ + struct dso *dso = NULL; + enum dso_type dso_type; + + dso_type = machine__thread_dso_type(machine, thread); + switch (dso_type) { + case DSO__TYPE_32BIT: + dso = dsos__find(&machine->dsos, DSO__NAME_VDSO32, true); + if (!dso) { + dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, + true); + if (dso && dso_type != dso__type(dso, machine)) { + dso__put(dso); + dso = NULL; + } + } + break; + case DSO__TYPE_X32BIT: + dso = dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true); + break; + case DSO__TYPE_64BIT: + case DSO__TYPE_UNKNOWN: + default: + dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, true); + break; + } + + return dso; +} + +struct dso *machine__findnew_vdso(struct machine *machine, + struct thread *thread) +{ + struct vdso_info *vdso_info; + struct dso *dso = NULL; + char *file; + + if (!machine->vdso_info) + machine->vdso_info = vdso_info__new(); + + vdso_info = machine->vdso_info; + if (!vdso_info) + return NULL; + + dso = machine__find_vdso(machine, thread); + if (dso) + return dso; + +#if BITS_PER_LONG == 64 + if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso)) + return dso; +#endif + + dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, true); + if (dso) + return dso; + + file = get_file(&vdso_info->vdso); + if (!file) + return NULL; + + return __machine__addnew_vdso(machine, DSO__NAME_VDSO, file); +} + +bool dso__is_vdso(struct dso *dso) +{ + return !strcmp(dso__short_name(dso), DSO__NAME_VDSO) || + !strcmp(dso__short_name(dso), DSO__NAME_VDSO32) || + !strcmp(dso__short_name(dso), DSO__NAME_VDSOX32); +} -- cgit v1.3.1