From: "Connor O'Brien" <connoro@google.com>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Connor O'Brien" <connoro@google.com>
Subject: [PATCH bpf-next v2] libbpf: also check /sys/kernel/tracing for tracefs files
Date: Mon, 23 May 2022 21:28:08 +0000 [thread overview]
Message-ID: <20220523212808.603526-1-connoro@google.com> (raw)
libbpf looks for tracefs files only under debugfs, but tracefs may be
mounted even if debugfs is not. When /sys/kernel/debug/tracing is
absent, try looking under /sys/kernel/tracing instead.
Signed-off-by: Connor O'Brien <connoro@google.com>
---
v1->v2: cache result of debugfs check.
src/libbpf.c | 32 +++++++++++++++++++++++++-------
1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/src/libbpf.c b/src/libbpf.c
index 2262bcd..cc47c52 100644
--- a/src/libbpf.c
+++ b/src/libbpf.c
@@ -9945,10 +9945,22 @@ static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz,
__sync_fetch_and_add(&index, 1));
}
+static bool debugfs_available(void)
+{
+ static bool initialized = false, available;
+
+ if (!initialized) {
+ available = !access("/sys/kernel/debug/tracing", F_OK);
+ initialized = true;
+ }
+ return available;
+}
+
static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,
const char *kfunc_name, size_t offset)
{
- const char *file = "/sys/kernel/debug/tracing/kprobe_events";
+ const char *file = debugfs_available() ? "/sys/kernel/debug/tracing/kprobe_events" :
+ "/sys/kernel/tracing/kprobe_events";
return append_to_file(file, "%c:%s/%s %s+0x%zx",
retprobe ? 'r' : 'p',
@@ -9958,7 +9970,8 @@ static int add_kprobe_event_legacy(const char *probe_name, bool retprobe,
static int remove_kprobe_event_legacy(const char *probe_name, bool retprobe)
{
- const char *file = "/sys/kernel/debug/tracing/kprobe_events";
+ const char *file = debugfs_available() ? "/sys/kernel/debug/tracing/kprobe_events" :
+ "/sys/kernel/tracing/kprobe_events";
return append_to_file(file, "-:%s/%s", retprobe ? "kretprobes" : "kprobes", probe_name);
}
@@ -9968,7 +9981,8 @@ static int determine_kprobe_perf_type_legacy(const char *probe_name, bool retpro
char file[256];
snprintf(file, sizeof(file),
- "/sys/kernel/debug/tracing/events/%s/%s/id",
+ debugfs_available() ? "/sys/kernel/debug/tracing/events/%s/%s/id" :
+ "/sys/kernel/tracing/events/%s/%s/id",
retprobe ? "kretprobes" : "kprobes", probe_name);
return parse_uint_from_file(file, "%d\n");
@@ -10144,7 +10158,8 @@ static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
static inline int add_uprobe_event_legacy(const char *probe_name, bool retprobe,
const char *binary_path, size_t offset)
{
- const char *file = "/sys/kernel/debug/tracing/uprobe_events";
+ const char *file = debugfs_available() ? "/sys/kernel/debug/tracing/uprobe_events" :
+ "/sys/kernel/tracing/uprobe_events";
return append_to_file(file, "%c:%s/%s %s:0x%zx",
retprobe ? 'r' : 'p',
@@ -10154,7 +10169,8 @@ static inline int add_uprobe_event_legacy(const char *probe_name, bool retprobe,
static inline int remove_uprobe_event_legacy(const char *probe_name, bool retprobe)
{
- const char *file = "/sys/kernel/debug/tracing/uprobe_events";
+ const char *file = debugfs_available() ? "/sys/kernel/debug/tracing/uprobe_events" :
+ "/sys/kernel/tracing/uprobe_events";
return append_to_file(file, "-:%s/%s", retprobe ? "uretprobes" : "uprobes", probe_name);
}
@@ -10164,7 +10180,8 @@ static int determine_uprobe_perf_type_legacy(const char *probe_name, bool retpro
char file[512];
snprintf(file, sizeof(file),
- "/sys/kernel/debug/tracing/events/%s/%s/id",
+ debugfs_available() ? "/sys/kernel/debug/tracing/events/%s/%s/id" :
+ "/sys/kernel/tracing/events/%s/%s/id",
retprobe ? "uretprobes" : "uprobes", probe_name);
return parse_uint_from_file(file, "%d\n");
@@ -10295,7 +10312,8 @@ static int determine_tracepoint_id(const char *tp_category,
int ret;
ret = snprintf(file, sizeof(file),
- "/sys/kernel/debug/tracing/events/%s/%s/id",
+ debugfs_available() ? "/sys/kernel/debug/tracing/events/%s/%s/id" :
+ "/sys/kernel/tracing/events/%s/%s/id",
tp_category, tp_name);
if (ret < 0)
return -errno;
--
2.36.1.124.g0e6072fb45-goog
next reply other threads:[~2022-05-23 21:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 21:28 Connor O'Brien [this message]
2022-05-23 22:18 ` Andrii Nakryiko
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