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Commit d0cabbb0 authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Daniel Borkmann
Browse files

tools: bpf: move the event reading loop to libbpf 



There are two copies of event reading loop - in bpftool and
trace_helpers "library".  Consolidate them and move the code
to libbpf.  Return codes from trace_helpers are kept, but
renamed to include LIBBPF prefix.

Suggested-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 5f938057

samples/bpf/Makefile

+8 −0
Original line number Diff line number Diff line
@@ -165,6 +165,14 @@ HOSTCFLAGS += -I$(srctree)/tools/lib/ -I$(srctree)/tools/include 
HOSTCFLAGS += -I$(srctree)/tools/perf



HOSTCFLAGS_bpf_load.o += -I$(objtree)/usr/include -Wno-unused-variable

HOSTCFLAGS_trace_helpers.o += -I$(srctree)/tools/lib/bpf/



HOSTCFLAGS_trace_output_user.o += -I$(srctree)/tools/lib/bpf/

HOSTCFLAGS_offwaketime_user.o += -I$(srctree)/tools/lib/bpf/

HOSTCFLAGS_spintest_user.o += -I$(srctree)/tools/lib/bpf/

HOSTCFLAGS_trace_event_user.o += -I$(srctree)/tools/lib/bpf/

HOSTCFLAGS_sampleip_user.o += -I$(srctree)/tools/lib/bpf/



HOSTLOADLIBES_test_lru_dist += -lelf

HOSTLOADLIBES_sock_example += -lelf

HOSTLOADLIBES_fds_example += -lelf

samples/bpf/trace_output_user.c

+3 −3
Original line number Diff line number Diff line
@@ -48,7 +48,7 @@ static int print_bpf_output(void *data, int size) 
	if (e->cookie != 0x12345678) {

		printf("BUG pid %llx cookie %llx sized %d\n",

		       e->pid, e->cookie, size);

		return PERF_EVENT_ERROR;

		return LIBBPF_PERF_EVENT_ERROR;

	}



	cnt++;
@@ -56,10 +56,10 @@ static int print_bpf_output(void *data, int size) 
	if (cnt == MAX_CNT) {

		printf("recv %lld events per sec\n",

		       MAX_CNT * 1000000000ll / (time_get_ns() - start_time));

		return PERF_EVENT_DONE;

		return LIBBPF_PERF_EVENT_DONE;

	}



	return PERF_EVENT_CONT;

	return LIBBPF_PERF_EVENT_CONT;

}



static void test_bpf_perf_event(void)

tools/bpf/bpftool/map_perf_ring.c

+15 −51
Original line number Diff line number Diff line
@@ -50,14 +50,15 @@ static void int_exit(int signo) 
	stop = true;

}



static void

print_bpf_output(struct event_ring_info *ring, struct perf_event_sample *e)

static enum bpf_perf_event_ret print_bpf_output(void *event, void *priv)

{

	struct event_ring_info *ring = priv;

	struct perf_event_sample *e = event;

	struct {

		struct perf_event_header header;

		__u64 id;

		__u64 lost;

	} *lost = (void *)e;

	} *lost = event;



	if (json_output) {

		jsonw_start_object(json_wtr);
@@ -96,60 +97,23 @@ print_bpf_output(struct event_ring_info *ring, struct perf_event_sample *e) 
			       e->header.type, e->header.size);

		}

	}



	return LIBBPF_PERF_EVENT_CONT;

}



static void

perf_event_read(struct event_ring_info *ring, void **buf, size_t *buf_len)

{

	volatile struct perf_event_mmap_page *header = ring->mem;

	__u64 buffer_size = MMAP_PAGE_CNT * get_page_size();

	__u64 data_tail = header->data_tail;

	__u64 data_head = header->data_head;

	void *base, *begin, *end;



	asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */

	if (data_head == data_tail)

		return;



	base = ((char *)header) + get_page_size();



	begin = base + data_tail % buffer_size;

	end = base + data_head % buffer_size;



	while (begin != end) {

		struct perf_event_sample *e;



		e = begin;

		if (begin + e->header.size > base + buffer_size) {

			long len = base + buffer_size - begin;



			if (*buf_len < e->header.size) {

				free(*buf);

				*buf = malloc(e->header.size);

				if (!*buf) {

					fprintf(stderr,

						"can't allocate memory");

	enum bpf_perf_event_ret ret;



	ret = bpf_perf_event_read_simple(ring->mem,

					 MMAP_PAGE_CNT * get_page_size(),

					 get_page_size(), buf, buf_len,

					 print_bpf_output, ring);

	if (ret != LIBBPF_PERF_EVENT_CONT) {

		fprintf(stderr, "perf read loop failed with %d\n", ret);

		stop = true;

					return;

				}

				*buf_len = e->header.size;

	}



			memcpy(*buf, begin, len);

			memcpy(*buf + len, base, e->header.size - len);

			e = (void *)*buf;

			begin = base + e->header.size - len;

		} else if (begin + e->header.size == base + buffer_size) {

			begin = base;

		} else {

			begin += e->header.size;

		}



		print_bpf_output(ring, e);

	}



	__sync_synchronize(); /* smp_mb() */

	header->data_tail = data_head;

}



static int perf_mmap_size(void)

tools/lib/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ FEATURE_USER = .libbpf 
FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf

FEATURE_DISPLAY = libelf bpf



INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi

INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi -I$(srctree)/tools/perf

FEATURE_CHECK_CFLAGS-bpf = $(INCLUDES)



check_feat := 1

tools/lib/bpf/libbpf.c

+61 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include <perf-sys.h>

#include <asm/unistd.h>

#include <linux/err.h>

#include <linux/kernel.h>
@@ -2210,3 +2211,63 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, 
	*prog_fd = bpf_program__fd(first_prog);

	return 0;

}



enum bpf_perf_event_ret

bpf_perf_event_read_simple(void *mem, unsigned long size,

			   unsigned long page_size, void **buf, size_t *buf_len,

			   bpf_perf_event_print_t fn, void *priv)

{

	volatile struct perf_event_mmap_page *header = mem;

	__u64 data_tail = header->data_tail;

	__u64 data_head = header->data_head;

	void *base, *begin, *end;

	int ret;



	asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */

	if (data_head == data_tail)

		return LIBBPF_PERF_EVENT_CONT;



	base = ((char *)header) + page_size;



	begin = base + data_tail % size;

	end = base + data_head % size;



	while (begin != end) {

		struct perf_event_header *ehdr;



		ehdr = begin;

		if (begin + ehdr->size > base + size) {

			long len = base + size - begin;



			if (*buf_len < ehdr->size) {

				free(*buf);

				*buf = malloc(ehdr->size);

				if (!*buf) {

					ret = LIBBPF_PERF_EVENT_ERROR;

					break;

				}

				*buf_len = ehdr->size;

			}



			memcpy(*buf, begin, len);

			memcpy(*buf + len, base, ehdr->size - len);

			ehdr = (void *)*buf;

			begin = base + ehdr->size - len;

		} else if (begin + ehdr->size == base + size) {

			begin = base;

		} else {

			begin += ehdr->size;

		}



		ret = fn(ehdr, priv);

		if (ret != LIBBPF_PERF_EVENT_CONT)

			break;



		data_tail += ehdr->size;

	}



	__sync_synchronize(); /* smp_mb() */

	header->data_tail = data_tail;



	return ret;

}