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Commit 22adedd3 authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Daniel Borkmann
Browse files

trace_helpers.c: Add helpers to poll multiple perf FDs for events 



Add two new helper functions to trace_helpers that supports polling
multiple perf file descriptors for events. These are used to the XDP
perf_event_output example, which needs to work with one perf fd per CPU.

Reviewed-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarToke Høiland-Jørgensen <toke@toke.dk>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent cc0dff6d

tools/testing/selftests/bpf/trace_helpers.c

+46 −2
Original line number Diff line number Diff line
@@ -88,7 +88,7 @@ static int page_size; 
static int page_cnt = 8;

static struct perf_event_mmap_page *header;



int perf_event_mmap(int fd)

int perf_event_mmap_header(int fd, struct perf_event_mmap_page **header)

{

	void *base;

	int mmap_size;
@@ -102,10 +102,15 @@ int perf_event_mmap(int fd) 
		return -1;

	}



	header = base;

	*header = base;

	return 0;

}



int perf_event_mmap(int fd)

{

	return perf_event_mmap_header(fd, &header);

}



static int perf_event_poll(int fd)

{

	struct pollfd pfd = { .fd = fd, .events = POLLIN };
@@ -163,3 +168,42 @@ int perf_event_poller(int fd, perf_event_print_fn output_fn) 


	return ret;

}



int perf_event_poller_multi(int *fds, struct perf_event_mmap_page **headers,

			    int num_fds, perf_event_print_fn output_fn)

{

	enum bpf_perf_event_ret ret;

	struct pollfd *pfds;

	void *buf = NULL;

	size_t len = 0;

	int i;



	pfds = calloc(num_fds, sizeof(*pfds));

	if (!pfds)

		return LIBBPF_PERF_EVENT_ERROR;



	for (i = 0; i < num_fds; i++) {

		pfds[i].fd = fds[i];

		pfds[i].events = POLLIN;

	}



	for (;;) {

		poll(pfds, num_fds, 1000);

		for (i = 0; i < num_fds; i++) {

			if (!pfds[i].revents)

				continue;



			ret = bpf_perf_event_read_simple(headers[i],

							 page_cnt * page_size,

							 page_size, &buf, &len,

							 bpf_perf_event_print,

							 output_fn);

			if (ret != LIBBPF_PERF_EVENT_CONT)

				break;

		}

	}

	free(buf);

	free(pfds);



	return ret;

}

tools/testing/selftests/bpf/trace_helpers.h

+4 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 
#define __TRACE_HELPER_H



#include <libbpf.h>

#include <linux/perf_event.h>



struct ksym {

	long addr;
@@ -16,6 +17,9 @@ long ksym_get_addr(const char *name); 
typedef enum bpf_perf_event_ret (*perf_event_print_fn)(void *data, int size);



int perf_event_mmap(int fd);

int perf_event_mmap_header(int fd, struct perf_event_mmap_page **header);

/* return LIBBPF_PERF_EVENT_DONE or LIBBPF_PERF_EVENT_ERROR */

int perf_event_poller(int fd, perf_event_print_fn output_fn);

int perf_event_poller_multi(int *fds, struct perf_event_mmap_page **headers,

			    int num_fds, perf_event_print_fn output_fn);

#endif