perf_event_open 上的权限被拒绝，除了使用 sudo 或更改 perf_event_paranoid 文件之外，还有其他方法吗？

Question

我能找到的关于该主题的唯一信息是 link:，根据我的理解，建议使用 CONFIG_HW_PERF_EVENTS 配置，但我仍然遇到同样的问题.

我正在实施一个受 perf_event_open 手册页启发的程序：

static long
       perf_event_open(struct perf_event_attr *hw_event, pid_t pid,
                       int cpu, int group_fd, unsigned long flags)
       {
           int ret;

           ret= syscall(__NR_perf_event_open, hw_event, pid, cpu,
                          group_fd, flags);
           return ret;
       }
struct perf_event_attr pe;

int pid = fork();

if (pid > 0 ) {

memset(&pe, 0, sizeof(pe));
           pe.type = PERF_TYPE_HARDWARE;
           pe.size = sizeof(pe);
           pe.config = PERF_COUNT_HW_CPU_CYCLES;
           pe.disabled = 0;
           pe.exclude_kernel = 0;
           pe.exclude_hv = 0;   
            
           fd = perf_event_open(&pe, pid, -1, -1, 0);
if (fd == -1) {
               perror(0);
              exit(EXIT_FAILURE);
           }
}

对于 fd，我总是得到 -1 return，perror 表示权限被拒绝。

当然我可以使用 sudo 解决这个问题，但是有没有其他方法允许执行 perf_event_open?

PS：我不想更改perf_event_paranoid文件，它使程序在设置为-1时运行；我假设它会在 2.

Answer 1

RETURN VALUE section of the Linux perf_event_open() system call 部分陈述：

   ...

   EACCES Returned when the requested event requires CAP_PERFMON
          (since Linux 5.8) or CAP_SYS_ADMIN permissions (or a more
          permissive perf_event paranoid setting).  Some common
          cases where an unprivileged process may encounter this
          error: attaching to a process owned by a different user;
          monitoring all processes on a given CPU (i.e., specifying
          the pid argument as -1); and not setting exclude_kernel
          when the paranoid setting requires it.

   ...

   EPERM  Returned on many (but not all) architectures when an
          unsupported exclude_hv, exclude_idle, exclude_user, or
          exclude_kernel setting is specified.

          It can also happen, as with EACCES, when the requested
          event requires CAP_PERFMON (since Linux 5.8) or
          CAP_SYS_ADMIN permissions (or a more permissive perf_event
          paranoid setting).  This includes setting a breakpoint on
          a kernel address, and (since Linux 3.13) setting a kernel
          function-trace tracepoint.

根据发布的示例代码，值 pe.exclude_kernel = 0; 或 pe.exclude_hv = 0; 可能会导致权限问题，因为您对 paranoid 设置的声明。

perf_event_open 上的权限被拒绝，除了使用 sudo 或更改 perf_event_paranoid 文件之外，还有其他方法吗？

Permission denied on perf_event_open, is there another way than to use sudo or changing the perf_event_paranoid file?

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