[PATCH bpf-next 4/5] libbpf: Set read_format PERF_FORMAT_LOST on kprobe perf fds

[Daniel Xu]

There is no way to get the nmissed count from kprobes that are created
using the perf API. The previous commits added read_format support for
this count. Enable it in this commit.

Signed-off-by: Daniel Xu <d...@dxuuu.xyz>
---
 tools/lib/bpf/libbpf.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 1ca0acd1d823..43f45f6d914d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5031,7 +5031,7 @@ static int determine_uprobe_retprobe_bit(void)
 }
 
 static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
-                                uint64_t offset, int pid)
+                                uint64_t offset, int pid, uint64_t read_format)
 {
        struct perf_event_attr attr = {};
        char errmsg[STRERR_BUFSIZE];
@@ -5060,6 +5060,7 @@ static int perf_event_open_probe(bool uprobe, bool 
retprobe, const char *name,
        }
        attr.size = sizeof(attr);
        attr.type = type;
+       attr.read_format = read_format;
        attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
        attr.config2 = offset;           /* kprobe_addr or probe_offset */
 
@@ -5087,7 +5088,8 @@ struct bpf_link *bpf_program__attach_kprobe(struct 
bpf_program *prog,
        int pfd, err;
 
        pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
-                                   0 /* offset */, -1 /* pid */);
+                                   0 /* offset */, -1 /* pid */,
+                                   PERF_FORMAT_LOST /* read_format */);
        if (pfd < 0) {
                pr_warning("program '%s': failed to create %s '%s' perf event: 
%s\n",
                           bpf_program__title(prog, false),
@@ -5118,7 +5120,8 @@ struct bpf_link *bpf_program__attach_uprobe(struct 
bpf_program *prog,
        int pfd, err;
 
        pfd = perf_event_open_probe(true /* uprobe */, retprobe,
-                                   binary_path, func_offset, pid);
+                                   binary_path, func_offset, pid,
+                                   0 /* read_format */);
        if (pfd < 0) {
                pr_warning("program '%s': failed to create %s '%s:0x%zx' perf 
event: %s\n",
                           bpf_program__title(prog, false),
-- 
2.21.0