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-rw-r--r--tools/lib/bpf/libbpf.c75
1 files changed, 32 insertions, 43 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index bd71efcc53be..b607be7236d3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -27,6 +27,7 @@
#include <linux/list.h>
#include <linux/limits.h>
#include <linux/perf_event.h>
+#include <linux/ring_buffer.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/vfs.h>
@@ -2414,61 +2415,49 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
}
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)
+bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
+ void **copy_mem, size_t *copy_size,
+ bpf_perf_event_print_t fn, void *private_data)
{
- volatile struct perf_event_mmap_page *header = mem;
+ struct perf_event_mmap_page *header = mmap_mem;
+ __u64 data_head = ring_buffer_read_head(header);
__u64 data_tail = header->data_tail;
- __u64 data_head = header->data_head;
- int ret = LIBBPF_PERF_EVENT_ERROR;
- void *base, *begin, *end;
-
- 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) {
+ void *base = ((__u8 *)header) + page_size;
+ int ret = LIBBPF_PERF_EVENT_CONT;
+ struct perf_event_header *ehdr;
+ size_t ehdr_size;
+
+ while (data_head != data_tail) {
+ ehdr = base + (data_tail & (mmap_size - 1));
+ ehdr_size = ehdr->size;
+
+ if (((void *)ehdr) + ehdr_size > base + mmap_size) {
+ void *copy_start = ehdr;
+ size_t len_first = base + mmap_size - copy_start;
+ size_t len_secnd = ehdr_size - len_first;
+
+ if (*copy_size < ehdr_size) {
+ free(*copy_mem);
+ *copy_mem = malloc(ehdr_size);
+ if (!*copy_mem) {
+ *copy_size = 0;
ret = LIBBPF_PERF_EVENT_ERROR;
break;
}
- *buf_len = ehdr->size;
+ *copy_size = 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;
+ memcpy(*copy_mem, copy_start, len_first);
+ memcpy(*copy_mem + len_first, base, len_secnd);
+ ehdr = *copy_mem;
}
- ret = fn(ehdr, priv);
+ ret = fn(ehdr, private_data);
+ data_tail += ehdr_size;
if (ret != LIBBPF_PERF_EVENT_CONT)
break;
-
- data_tail += ehdr->size;
}
- __sync_synchronize(); /* smp_mb() */
- header->data_tail = data_tail;
-
+ ring_buffer_write_tail(header, data_tail);
return ret;
}