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: 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>
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7bcdca1..ce96f1f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -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;
+}