Quelle  ftrace.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
#include <inttypes.h>
#include <pthread.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <unistd.h>
#include "../../../../../include/linux/kernel.h"
#include "aolib.h"

static char ftrace_path[] = "ksft-ftrace-XXXXXX";
static bool ftrace_mounted;
uint64_t ns_cookie1, ns_cookie2;

struct test_ftracer {
 pthread_t tracer_thread;
 int error;
 char *instance_path;
 FILE *trace_pipe;

 enum ftracer_op (*process_line)(const char *line);
 void (*destructor)(struct test_ftracer *tracer);
 bool (*expecting_more)(void);

 char **saved_lines;
 size_t saved_lines_size;
 size_t next_line_ind;

 pthread_cond_t met_all_expected;
 pthread_mutex_t met_all_expected_lock;

 struct test_ftracer *next;
};

static struct test_ftracer *ftracers;
static pthread_mutex_t ftracers_lock = PTHREAD_MUTEX_INITIALIZER;

static int mount_ftrace(void)
{
 if (!mkdtemp(ftrace_path))
  test_error("Can't create temp dir");

 if (mount("tracefs", ftrace_path, "tracefs", 0, "rw"))
  return -errno;

 ftrace_mounted = true;

 return 0;
}

static void unmount_ftrace(void)
{
 if (ftrace_mounted && umount(ftrace_path))
  test_print("Failed on cleanup: can't unmount tracefs: %m");

 if (rmdir(ftrace_path))
  test_error("Failed on cleanup: can't remove ftrace dir %s",
      ftrace_path);
}

struct opts_list_t {
 char *opt_name;
 struct opts_list_t *next;
};

static int disable_trace_options(const char *ftrace_path)
{
 struct opts_list_t *opts_list = NULL;
 char *fopts, *line = NULL;
 size_t buf_len = 0;
 ssize_t line_len;
 int ret = 0;
 FILE *opts;

 fopts = test_sprintf("%s/%s", ftrace_path, "trace_options");
 if (!fopts)
  return -ENOMEM;

 opts = fopen(fopts, "r+");
 if (!opts) {
  ret = -errno;
  goto out_free;
 }

 while ((line_len = getline(&line, &buf_len, opts)) != -1) {
  struct opts_list_t *tmp;

  if (!strncmp(line, "no", 2))
   continue;

  tmp = malloc(sizeof(*tmp));
  if (!tmp) {
   ret = -ENOMEM;
   goto out_free_opts_list;
  }
  tmp->next = opts_list;
  tmp->opt_name = test_sprintf("no%s", line);
  if (!tmp->opt_name) {
   ret = -ENOMEM;
   free(tmp);
   goto out_free_opts_list;
  }
  opts_list = tmp;
 }

 while (opts_list) {
  struct opts_list_t *tmp = opts_list;

  fseek(opts, 0, SEEK_SET);
  fwrite(tmp->opt_name, 1, strlen(tmp->opt_name), opts);

  opts_list = opts_list->next;
  free(tmp->opt_name);
  free(tmp);
 }

out_free_opts_list:
 while (opts_list) {
  struct opts_list_t *tmp = opts_list;

  opts_list = opts_list->next;
  free(tmp->opt_name);
  free(tmp);
 }
 free(line);
 fclose(opts);
out_free:
 free(fopts);
 return ret;
}

static int setup_buffer_size(const char *ftrace_path, size_t sz)
{
 char *fbuf_size = test_sprintf("%s/buffer_size_kb", ftrace_path);
 int ret;

 if (!fbuf_size)
  return -1;

 ret = test_echo(fbuf_size, 0, "%zu", sz);
 free(fbuf_size);
 return ret;
}

static int setup_ftrace_instance(struct test_ftracer *tracer, const char *name)
{
 char *tmp;

 tmp = test_sprintf("%s/instances/ksft-%s-XXXXXX", ftrace_path, name);
 if (!tmp)
  return -ENOMEM;

 tracer->instance_path = mkdtemp(tmp);
 if (!tracer->instance_path) {
  free(tmp);
  return -errno;
 }

 return 0;
}

static void remove_ftrace_instance(struct test_ftracer *tracer)
{
 if (rmdir(tracer->instance_path))
  test_print("Failed on cleanup: can't remove ftrace instance %s",
      tracer->instance_path);
 free(tracer->instance_path);
}

static void tracer_cleanup(void *arg)
{
 struct test_ftracer *tracer = arg;

 fclose(tracer->trace_pipe);
}

static void tracer_set_error(struct test_ftracer *tracer, int error)
{
 if (!tracer->error)
  tracer->error = error;
}

const size_t tracer_get_savedlines_nr(struct test_ftracer *tracer)
{
 return tracer->next_line_ind;
}

const char **tracer_get_savedlines(struct test_ftracer *tracer)
{
 return (const char **)tracer->saved_lines;
}

static void *tracer_thread_func(void *arg)
{
 struct test_ftracer *tracer = arg;

 pthread_cleanup_push(tracer_cleanup, arg);

 while (tracer->next_line_ind < tracer->saved_lines_size) {
  char **lp = &tracer->saved_lines[tracer->next_line_ind];
  enum ftracer_op op;
  size_t buf_len = 0;
  ssize_t line_len;

  line_len = getline(lp, &buf_len, tracer->trace_pipe);
  if (line_len == -1)
   break;

  pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
  op = tracer->process_line(*lp);
  pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);

  if (tracer->expecting_more) {
   pthread_mutex_lock(&tracer->met_all_expected_lock);
   if (!tracer->expecting_more())
    pthread_cond_signal(&tracer->met_all_expected);
   pthread_mutex_unlock(&tracer->met_all_expected_lock);
  }

  if (op == FTRACER_LINE_DISCARD)
   continue;
  if (op == FTRACER_EXIT)
   break;
  if (op != FTRACER_LINE_PRESERVE)
   test_error("unexpected tracer command %d", op);

  tracer->next_line_ind++;
  buf_len = 0;
 }
 test_print("too many lines in ftracer buffer %zu, exiting tracer",
     tracer->next_line_ind);

 pthread_cleanup_pop(1);
 return NULL;
}

static int setup_trace_thread(struct test_ftracer *tracer)
{
 int ret = 0;
 char *path;

 path = test_sprintf("%s/trace_pipe", tracer->instance_path);
 if (!path)
  return -ENOMEM;

 tracer->trace_pipe = fopen(path, "r");
 if (!tracer->trace_pipe) {
  ret = -errno;
  goto out_free;
 }

 if (pthread_create(&tracer->tracer_thread, NULL,
      tracer_thread_func, (void *)tracer)) {
  ret = -errno;
  fclose(tracer->trace_pipe);
 }

out_free:
 free(path);
 return ret;
}

static void stop_trace_thread(struct test_ftracer *tracer)
{
 void *res;

 if (pthread_cancel(tracer->tracer_thread)) {
  test_print("Can't stop tracer pthread: %m");
  tracer_set_error(tracer, -errno);
 }
 if (pthread_join(tracer->tracer_thread, &res)) {
  test_print("Can't join tracer pthread: %m");
  tracer_set_error(tracer, -errno);
 }
 if (res != PTHREAD_CANCELED) {
  test_print("Tracer thread wasn't canceled");
  tracer_set_error(tracer, -errno);
 }
 if (tracer->error)
  test_fail("tracer errored by %s", strerror(tracer->error));
}

static void final_wait_for_events(struct test_ftracer *tracer,
      unsigned timeout_sec)
{
 struct timespec timeout;
 struct timeval now;
 int ret = 0;

 if (!tracer->expecting_more)
  return;

 pthread_mutex_lock(&tracer->met_all_expected_lock);
 gettimeofday(&now, NULL);
 timeout.tv_sec = now.tv_sec + timeout_sec;
 timeout.tv_nsec = now.tv_usec * 1000;

 while (tracer->expecting_more() && ret != ETIMEDOUT)
  ret = pthread_cond_timedwait(&tracer->met_all_expected,
    &tracer->met_all_expected_lock, &timeout);
 pthread_mutex_unlock(&tracer->met_all_expected_lock);
}

int setup_trace_event(struct test_ftracer *tracer,
        const char *event, const char *filter)
{
 char *enable_path, *filter_path, *instance = tracer->instance_path;
 int ret;

 enable_path = test_sprintf("%s/events/%s/enable", instance, event);
 if (!enable_path)
  return -ENOMEM;

 filter_path = test_sprintf("%s/events/%s/filter", instance, event);
 if (!filter_path) {
  ret = -ENOMEM;
  goto out_free;
 }

 ret = test_echo(filter_path, 0, "%s", filter);
 if (!ret)
  ret = test_echo(enable_path, 0, "1");

out_free:
 free(filter_path);
 free(enable_path);
 return ret;
}

struct test_ftracer *create_ftracer(const char *name,
        enum ftracer_op (*process_line)(const char *line),
        void (*destructor)(struct test_ftracer *tracer),
        bool (*expecting_more)(void),
        size_t lines_buf_sz, size_t buffer_size_kb)
{
 struct test_ftracer *tracer;
 int err;

 /* XXX: separate __create_ftracer() helper and do here
 * if (!kernel_config_has(KCONFIG_FTRACE))
 * return NULL;
 */

 tracer = malloc(sizeof(*tracer));
 if (!tracer) {
  test_print("malloc()");
  return NULL;
 }

 memset(tracer, 0, sizeof(*tracer));

 err = setup_ftrace_instance(tracer, name);
 if (err) {
  test_print("setup_ftrace_instance(): %d", err);
  goto err_free;
 }

 err = disable_trace_options(tracer->instance_path);
 if (err) {
  test_print("disable_trace_options(): %d", err);
  goto err_remove;
 }

 err = setup_buffer_size(tracer->instance_path, buffer_size_kb);
 if (err) {
  test_print("disable_trace_options(): %d", err);
  goto err_remove;
 }

 tracer->saved_lines = calloc(lines_buf_sz, sizeof(tracer->saved_lines[0]));
 if (!tracer->saved_lines) {
  test_print("calloc()");
  goto err_remove;
 }
 tracer->saved_lines_size = lines_buf_sz;

 tracer->process_line = process_line;
 tracer->destructor = destructor;
 tracer->expecting_more = expecting_more;

 err = pthread_cond_init(&tracer->met_all_expected, NULL);
 if (err) {
  test_print("pthread_cond_init(): %d", err);
  goto err_free_lines;
 }

 err = pthread_mutex_init(&tracer->met_all_expected_lock, NULL);
 if (err) {
  test_print("pthread_mutex_init(): %d", err);
  goto err_cond_destroy;
 }

 err = setup_trace_thread(tracer);
 if (err) {
  test_print("setup_trace_thread(): %d", err);
  goto err_mutex_destroy;
 }

 pthread_mutex_lock(&ftracers_lock);
 tracer->next = ftracers;
 ftracers = tracer;
 pthread_mutex_unlock(&ftracers_lock);

 return tracer;

err_mutex_destroy:
 pthread_mutex_destroy(&tracer->met_all_expected_lock);
err_cond_destroy:
 pthread_cond_destroy(&tracer->met_all_expected);
err_free_lines:
 free(tracer->saved_lines);
err_remove:
 remove_ftrace_instance(tracer);
err_free:
 free(tracer);
 return NULL;
}

static void __destroy_ftracer(struct test_ftracer *tracer)
{
 size_t i;

 final_wait_for_events(tracer, TEST_TIMEOUT_SEC);
 stop_trace_thread(tracer);
 remove_ftrace_instance(tracer);
 if (tracer->destructor)
  tracer->destructor(tracer);
 for (i = 0; i < tracer->saved_lines_size; i++)
  free(tracer->saved_lines[i]);
 pthread_cond_destroy(&tracer->met_all_expected);
 pthread_mutex_destroy(&tracer->met_all_expected_lock);
 free(tracer);
}

void destroy_ftracer(struct test_ftracer *tracer)
{
 pthread_mutex_lock(&ftracers_lock);
 if (tracer == ftracers) {
  ftracers = tracer->next;
 } else {
  struct test_ftracer *f = ftracers;

  while (f->next != tracer) {
   if (!f->next)
    test_error("tracers list corruption or double free %p", tracer);
   f = f->next;
  }
  f->next = tracer->next;
 }
 tracer->next = NULL;
 pthread_mutex_unlock(&ftracers_lock);
 __destroy_ftracer(tracer);
}

static void destroy_all_ftracers(void)
{
 struct test_ftracer *f;

 pthread_mutex_lock(&ftracers_lock);
 f = ftracers;
 ftracers = NULL;
 pthread_mutex_unlock(&ftracers_lock);

 while (f) {
  struct test_ftracer *n = f->next;

  f->next = NULL;
  __destroy_ftracer(f);
  f = n;
 }
}

static void test_unset_tracing(void)
{
 destroy_all_ftracers();
 unmount_ftrace();
}

int test_setup_tracing(void)
{
 /*
 * Just a basic protection - this should be called only once from
 * lib/kconfig. Not thread safe, which is fine as it's early, before
 * threads are created.
 */
 static int already_set;
 int err;

 if (already_set)
  return -1;

 /* Needs net-namespace cookies for filters */
 if (ns_cookie1 == ns_cookie2) {
  test_print("net-namespace cookies: %" PRIu64 " == %" PRIu64 ", can't set up tracing",
      ns_cookie1, ns_cookie2);
  return -1;
 }

 already_set = 1;

 test_add_destructor(test_unset_tracing);

 err = mount_ftrace();
 if (err) {
  test_print("failed to mount_ftrace(): %d", err);
  return err;
 }

 return setup_aolib_ftracer();
}

static int get_ns_cookie(int nsfd, uint64_t *out)
{
 int old_ns = switch_save_ns(nsfd);
 socklen_t size = sizeof(*out);
 int sk;

 sk = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
 if (sk < 0) {
  test_print("socket(): %m");
  return -errno;
 }

 if (getsockopt(sk, SOL_SOCKET, SO_NETNS_COOKIE, out, &size)) {
  test_print("getsockopt(SO_NETNS_COOKIE): %m");
  close(sk);
  return -errno;
 }

 close(sk);
 switch_close_ns(old_ns);
 return 0;
}

void test_init_ftrace(int nsfd1, int nsfd2)
{
 get_ns_cookie(nsfd1, &ns_cookie1);
 get_ns_cookie(nsfd2, &ns_cookie2);
 /* Populate kernel config state */
 kernel_config_has(KCONFIG_FTRACE);
}