[Bug gprofng/30575] New: gprofng cannot profile application with clone3()

[vladimir.mezentsev at oracle dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=30575

            Bug ID: 30575
           Summary: gprofng cannot profile application with clone3()
           Product: binutils
           Version: unspecified
            Status: NEW
          Severity: minor
          Priority: P2
         Component: gprofng
          Assignee: vladimir.mezentsev at oracle dot com
          Reporter: vladimir.mezentsev at oracle dot com
  Target Milestone: ---

% cat clone.c
#define _GNU_SOURCE
#include <linux/sched.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/syscall.h>
#include <stdlib.h>
#include <errno.h>
#include <stdint.h>
#include <sys/wait.h>
#include <time.h>

#ifndef __NR_clone3
#define __NR_clone3 -1
#endif

static pid_t sys_clone3(struct clone_args *args)
{
        return syscall(__NR_clone3, args, sizeof(struct clone_args));
}

#define ptr_to_u64(ptr) ((unsigned long)((uintptr_t)(ptr)))

time_t
gethrtime (void)
{
  struct timespec tp;
  time_t rc = 0;
#ifdef CLOCK_MONOTONIC_RAW
  int r = clock_gettime (CLOCK_MONOTONIC_RAW, &tp);
#else
  int r = clock_gettime (CLOCK_MONOTONIC, &tp);
#endif

  if (r == 0)
    rc = ((time_t) tp.tv_sec) * 1e9 + (time_t) tp.tv_nsec;
  return rc;
}

volatile long ax; /* temp variable for long calculation */
static void aaa()
{
  long long count = 0;
  time_t start = gethrtime ();
  do {
    ax = 0;
    for (int j = 0; j < 1000000; j++)
      ax = ax + 1;
    count++;
  }
  while (start + 1e9 > gethrtime ());
  char buf[256];
  snprintf(buf, sizeof (buf),
    "aaa(): Child process with pid: %lld count=%lld  ax=%lld\n",
    (long long) getpid(), count, ax);
  write(1, buf, strlen(buf));
}

volatile long bx; /* temp variable for long calculation */
static void bbb()
{
  long long count = 0;
  time_t start = gethrtime ();
  do {
    bx = 0;
    for (int j = 0; j < 1000000; j++)
      bx = bx + 1;
    count++;
  }
  while (start + 1e9 > gethrtime ());
  char buf[256];
  snprintf(buf, sizeof (buf),
    "bbb(): Parent process with pid: %lld count=%lld  bx=%lld\n",
    (long long) getpid(), count, bx);
  write(1, buf, strlen(buf));
}

int
main (int argc, char **argv)
{
  int pidfd = -1;
  pid_t parent_tid = -1, pid = -1;
  struct clone_args args;
  memset(&args, 0, sizeof(args));

  args.parent_tid = ptr_to_u64(&parent_tid); /* CLONE_PARENT_SETTID */
  args.pidfd = ptr_to_u64(&pidfd); /* CLONE_PIDFD */
  args.flags = CLONE_PIDFD | CLONE_PARENT_SETTID;
  args.exit_signal = SIGCHLD;

  pid = sys_clone3(&args);
//  pid = clone3(&args, sizeof(args));
  if (pid < 0) {
    fprintf(stderr, "%s - Failed to create new process\n", strerror(errno));
    exit(EXIT_FAILURE);
  }

  if (pid == 0) {
    printf("Child process with pid %d\n", getpid());
    aaa();
    exit(EXIT_SUCCESS);
  }
  bbb();
  printf("Parent process received child's pid %d as return value\n", pid);
  printf("Parent process received child's pidfd %d\n", *(int *)args.pidfd);
  printf("Parent process received child's pid %d as return argument\n",
      *(pid_t *)args.parent_tid);

  if (waitid(P_ALL, pid, NULL, 0) == 0) {
    fprintf(stderr, "Managed to wait on CLONE_NO_WAITALL process with
waitid(P_ALL)\n");
  }
  return 0;
}


% gcc clone3.c
% gprofng collect app -O t.er ./a.out
Creating experiment directory t.er (Process ID: 535114) ...
Child process with pid 535117
bbb(): Parent process with pid: 535114 count=331  bx=1000000
Parent process received child's pid 535117 as return value
Parent process received child's pidfd 3
Parent process received child's pid 535117 as return argument
aaa(): Child process with pid: 535117 count=336  ax=1000000


 aaa is not in the function list:
% gprofng display text -func t.er/
Functions sorted by metric: Exclusive Total CPU Time

Excl. Total   Incl. Total    Name
CPU           CPU
 sec.      %   sec.      %
0.650 100.00  0.650 100.00   <Total>
0.650 100.00  0.650 100.00   bbb
0.      0.    0.650 100.00   __libc_start_call_main
0.      0.    0.650 100.00   main

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