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authorYonghong Song <yhs@fb.com>2018-04-28 22:28:13 -0700
committerAlexei Starovoitov <ast@kernel.org>2018-04-29 08:45:54 -0700
commit28dbf861deacb0321604bf1c5e1ccc34dd215669 (patch)
treeae98045b9d24ea60e1034b08200d74e762dde8bb /tools/testing/selftests/bpf/trace_helpers.c
parenttools/bpf: add bpf_get_stack helper to tools headers (diff)
downloadlinux-dev-28dbf861deacb0321604bf1c5e1ccc34dd215669.tar.xz
linux-dev-28dbf861deacb0321604bf1c5e1ccc34dd215669.zip
samples/bpf: move common-purpose trace functions to selftests
There is no functionality change in this patch. The common-purpose trace functions, including perf_event polling and ksym lookup, are moved from trace_output_user.c and bpf_load.c to selftests/bpf/trace_helpers.c so that these function can be reused later in selftests. Acked-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/testing/selftests/bpf/trace_helpers.c')
-rw-r--r--tools/testing/selftests/bpf/trace_helpers.c180
1 files changed, 180 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
new file mode 100644
index 000000000000..ad025bd75f1c
--- /dev/null
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <errno.h>
+#include <poll.h>
+#include <unistd.h>
+#include <linux/perf_event.h>
+#include <sys/mman.h>
+#include "trace_helpers.h"
+
+#define MAX_SYMS 300000
+static struct ksym syms[MAX_SYMS];
+static int sym_cnt;
+
+static int ksym_cmp(const void *p1, const void *p2)
+{
+ return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
+}
+
+int load_kallsyms(void)
+{
+ FILE *f = fopen("/proc/kallsyms", "r");
+ char func[256], buf[256];
+ char symbol;
+ void *addr;
+ int i = 0;
+
+ if (!f)
+ return -ENOENT;
+
+ while (!feof(f)) {
+ if (!fgets(buf, sizeof(buf), f))
+ break;
+ if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
+ break;
+ if (!addr)
+ continue;
+ syms[i].addr = (long) addr;
+ syms[i].name = strdup(func);
+ i++;
+ }
+ sym_cnt = i;
+ qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
+ return 0;
+}
+
+struct ksym *ksym_search(long key)
+{
+ int start = 0, end = sym_cnt;
+ int result;
+
+ while (start < end) {
+ size_t mid = start + (end - start) / 2;
+
+ result = key - syms[mid].addr;
+ if (result < 0)
+ end = mid;
+ else if (result > 0)
+ start = mid + 1;
+ else
+ return &syms[mid];
+ }
+
+ if (start >= 1 && syms[start - 1].addr < key &&
+ key < syms[start].addr)
+ /* valid ksym */
+ return &syms[start - 1];
+
+ /* out of range. return _stext */
+ return &syms[0];
+}
+
+static int page_size;
+static int page_cnt = 8;
+static volatile struct perf_event_mmap_page *header;
+
+int perf_event_mmap(int fd)
+{
+ void *base;
+ int mmap_size;
+
+ page_size = getpagesize();
+ mmap_size = page_size * (page_cnt + 1);
+
+ base = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ if (base == MAP_FAILED) {
+ printf("mmap err\n");
+ return -1;
+ }
+
+ header = base;
+ return 0;
+}
+
+static int perf_event_poll(int fd)
+{
+ struct pollfd pfd = { .fd = fd, .events = POLLIN };
+
+ return poll(&pfd, 1, 1000);
+}
+
+struct perf_event_sample {
+ struct perf_event_header header;
+ __u32 size;
+ char data[];
+};
+
+static int perf_event_read(perf_event_print_fn fn)
+{
+ __u64 data_tail = header->data_tail;
+ __u64 data_head = header->data_head;
+ __u64 buffer_size = page_cnt * page_size;
+ void *base, *begin, *end;
+ char buf[256];
+ int ret;
+
+ asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */
+ if (data_head == data_tail)
+ return PERF_EVENT_CONT;
+
+ base = ((char *)header) + 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;
+
+ assert(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;
+ }
+
+ if (e->header.type == PERF_RECORD_SAMPLE) {
+ ret = fn(e->data, e->size);
+ if (ret != PERF_EVENT_CONT)
+ return ret;
+ } else if (e->header.type == PERF_RECORD_LOST) {
+ struct {
+ struct perf_event_header header;
+ __u64 id;
+ __u64 lost;
+ } *lost = (void *) e;
+ printf("lost %lld events\n", lost->lost);
+ } else {
+ printf("unknown event type=%d size=%d\n",
+ e->header.type, e->header.size);
+ }
+ }
+
+ __sync_synchronize(); /* smp_mb() */
+ header->data_tail = data_head;
+ return PERF_EVENT_CONT;
+}
+
+int perf_event_poller(int fd, perf_event_print_fn output_fn)
+{
+ int ret;
+
+ for (;;) {
+ perf_event_poll(fd);
+ ret = perf_event_read(output_fn);
+ if (ret != PERF_EVENT_CONT)
+ return ret;
+ }
+
+ return PERF_EVENT_DONE;
+}