Function perf_event_open [src]
Prototype
pub fn perf_event_open( attr: *system.perf_event_attr, pid: pid_t, cpu: i32, group_fd: fd_t, flags: usize, ) PerfEventOpenError!fd_t Parameters
attr: *system.perf_event_attrpid: pid_tcpu: i32group_fd: fd_tflags: usize Possible Errors
Returned if another event already has exclusive access to the PMU.
Returned if an event requiring a specific hardware feature is requested but there is no hardware support. This includes re‐ questing low-skid events if not supported, branch tracing if it is not available, sampling if no PMU interrupt is available, and branch stacks for software events.
Returned when the requested event requires CAP_SYS_ADMIN permis‐ sions (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; moni‐ toring all processes on a given CPU (i.e., specifying the pid argument as -1); and not setting exclude_kernel when the para‐ noid setting requires it. Also: Returned on many (but not all) architectures when an unsupported exclude_hv, exclude_idle, exclude_user, or exclude_kernel set‐ ting is specified. It can also happen, as with EACCES, when the requested event re‐ quires CAP_SYS_ADMIN permissions (or a more permissive perf_event paranoid setting). This includes setting a break‐ point on a kernel address, and (since Linux 3.13) setting a ker‐ nel function-trace tracepoint.
Returned if attempting to attach to a process that does not exist.
Each opened event uses one file descriptor. If a large number of events are opened, the per-process limit on the number of open file descriptors will be reached, and no more events can be created.
Returned if PERF_SAMPLE_CALLCHAIN is requested and sam‐ ple_max_stack is larger than the maximum specified in /proc/sys/kernel/perf_event_max_stack.
Returned if PERF_SAMPLE_STACK_USER is set in sample_type and it is not supported by hardware.
Returned if the perf_event_attr size value is too small (smaller than PERF_ATTR_SIZE_VER0), too big (larger than the page size), or larger than the kernel supports and the extra bytes are not zero. When E2BIG is returned, the perf_event_attr size field is overwritten by the kernel to be the size of the structure it was expecting.
Returned if you try to add more breakpoint events than supported by the hardware.
The Operating System returned an undocumented error code.
This error is in theory not possible, but it would be better to handle this error than to invoke undefined behavior.
When this error code is observed, it usually means the Zig Standard Library needs a small patch to add the error code to the error set for the respective function.
Source
pub fn perf_event_open(
attr: *system.perf_event_attr,
pid: pid_t,
cpu: i32,
group_fd: fd_t,
flags: usize,
) PerfEventOpenError!fd_t {
if (native_os == .linux) {
// There is no syscall wrapper for this function exposed by libcs
const rc = linux.perf_event_open(attr, pid, cpu, group_fd, flags);
switch (errno(rc)) {
.SUCCESS => return @intCast(rc),
.@"2BIG" => return error.TooBig,
.ACCES => return error.PermissionDenied,
.BADF => unreachable, // group_fd file descriptor is not valid.
.BUSY => return error.DeviceBusy,
.FAULT => unreachable, // Segmentation fault.
.INVAL => unreachable, // Bad attr settings.
.INTR => unreachable, // Mixed perf and ftrace handling for a uprobe.
.MFILE => return error.ProcessResources,
.NODEV => return error.EventRequiresUnsupportedCpuFeature,
.NOENT => unreachable, // Invalid type setting.
.NOSPC => return error.TooManyBreakpoints,
.NOSYS => return error.SampleStackNotSupported,
.OPNOTSUPP => return error.EventNotSupported,
.OVERFLOW => return error.SampleMaxStackOverflow,
.PERM => return error.PermissionDenied,
.SRCH => return error.ProcessNotFound,
else => |err| return unexpectedErrno(err),
}
}
}