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tools: bpf: move the event reading loop to libbpf

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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: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Jakub Kicinski
2018-05-10 10:24:40 -07:00
committed by Daniel Borkmann
parent 5f9380572b
commit d0cabbb021
10 changed files with 138 additions and 122 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
tools/lib/bpf/Makefile
View File

@@ -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

61
tools/lib/bpf/libbpf.c
View File

@@ -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;
}

13
tools/lib/bpf/libbpf.h
View File

@@ -267,4 +267,17 @@ int bpf_prog_load(const char *file, enum bpf_prog_type type,
struct bpf_object **pobj, int *prog_fd);
int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);
enum bpf_perf_event_ret {
LIBBPF_PERF_EVENT_DONE = 0,
LIBBPF_PERF_EVENT_ERROR = -1,
LIBBPF_PERF_EVENT_CONT = -2,
};
typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(void *event,
void *priv);
int 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);
#endif