* Request for comments version (still needs polishing).
* Based on Andrii Nakryiko's suggestion.
* Using bpf_program__set_priv in attach_kprobe() for kprobe cleanup.
Signed-off-by: Rafael David Tinoco <rafaeldtinoco@xxxxxxxxxx>
---
src/libbpf.c | 100 +++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 90 insertions(+), 10 deletions(-)
diff --git a/src/libbpf.c b/src/libbpf.c
index 2f351d3..4dc09d3 100644
--- a/src/libbpf.c
+++ b/src/libbpf.c
@@ -9677,8 +9677,14 @@ static int parse_uint_from_file(const char *file, const char *fmt)
static int determine_kprobe_perf_type(void)
{
+ int ret = 0;
+ struct stat s;
const char *file = "/sys/bus/event_source/devices/kprobe/type";
+ ret = stat(file, &s);
+ if (ret < 0)
+ return -errno;
+
return parse_uint_from_file(file, "%d\n");
}
@@ -9703,25 +9709,87 @@ static int determine_uprobe_retprobe_bit(void)
return parse_uint_from_file(file, "config:%d\n");
}
+static int determine_kprobe_perf_type_legacy(const char *func_name)
+{
+ char file[256];
+ const char *fname = "/sys/kernel/debug/tracing/events/kprobes/%s/id";
+
+ snprintf(file, sizeof(file), fname, func_name);
+
+ return parse_uint_from_file(file, "%d\n");
+}
+
+static int poke_kprobe_events(bool add, const char *name, bool kretprobe)
+{
+ int fd, ret = 0;
+ char given[256], buf[256];
+ const char *file = "/sys/kernel/debug/tracing/kprobe_events";
+
+ if (kretprobe && add)
+ snprintf(given, sizeof(given), "kprobes/%s_ret", name);
+ else
+ snprintf(given, sizeof(given), "kprobes/%s", name);
+ if (add)
+ snprintf(buf, sizeof(buf),"%c:%s %s\n", kretprobe ? 'r' : 'p', given, name);
+ else
+ snprintf(buf, sizeof(buf), "-:%s\n", given);
+
+ fd = open(file, O_WRONLY|O_APPEND, 0);
+ if (!fd)
+ return -errno;
+ ret = write(fd, buf, strlen(buf));
+ if (ret < 0) {
+ ret = -errno;
+ }
+ close(fd);
+
+ return ret;
+}
+
+static inline int add_kprobe_event_legacy(const char* func_name, bool kretprobe)
+{
+ return poke_kprobe_events(true /*add*/, func_name, kretprobe);
+}
+
+static inline int remove_kprobe_event_legacy(const char* func_name, bool kretprobe)
+{
+ return poke_kprobe_events(false /*remove*/, func_name, kretprobe);
+}
+
static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
uint64_t offset, int pid)
{
struct perf_event_attr attr = {};
char errmsg[STRERR_BUFSIZE];
int type, pfd, err;
+ bool legacy = false;
type = uprobe ? determine_uprobe_perf_type()
: determine_kprobe_perf_type();
if (type < 0) {
- pr_warn("failed to determine %s perf type: %s\n",
- uprobe ? "uprobe" : "kprobe",
- libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
- return type;
+ if (uprobe) {
+ pr_warn("failed to determine %s perf type: %s\n",
+ uprobe ? "uprobe" : "kprobe",
+ libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
+ return type;
+ }
+ err = add_kprobe_event_legacy(name, retprobe);
+ if (err < 0) {
+ pr_warn("failed to add legacy kprobe events: %s\n",
+ libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+ return err;
+ }
+ type = uprobe ? type : determine_kprobe_perf_type_legacy(name);
+ if (type < 0) {
+ remove_kprobe_event_legacy(name, retprobe);
+ pr_warn("failed to determine kprobe perf type: %s\n",
+ libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
+ }
+ legacy = true;
}
- if (retprobe) {
+ if (retprobe && !legacy) {
int bit = uprobe ? determine_uprobe_retprobe_bit()
: determine_kprobe_retprobe_bit();
-
if (bit < 0) {
pr_warn("failed to determine %s retprobe bit: %s\n",
uprobe ? "uprobe" : "kprobe",
@@ -9731,10 +9799,14 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
attr.config |= 1 << bit;
}
attr.size = sizeof(attr);
- attr.type = type;
- attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
- attr.config2 = offset; /* kprobe_addr or probe_offset */
-
+ if (!legacy) {
+ attr.type = type;
+ attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
+ attr.config2 = offset; /* kprobe_addr or probe_offset */
+ } else {
+ attr.config = type;
+ attr.type = PERF_TYPE_TRACEPOINT;
+ }
/* pid filter is meaningful only for uprobes */
pfd = syscall(__NR_perf_event_open, &attr,
pid < 0 ? -1 : pid /* pid */,
@@ -9750,6 +9822,11 @@ static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
return pfd;
}
+void bpf_program__detach_kprobe_legacy(struct bpf_program *prog, void *retprobe)
+{
+ remove_kprobe_event_legacy(prog->name, (bool) retprobe);
+}
+
struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
bool retprobe,
const char *func_name)
@@ -9766,6 +9843,9 @@ struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
return ERR_PTR(pfd);
}
+
+ bpf_program__set_priv(prog, (void *) retprobe, bpf_program__detach_kprobe_legacy);
+
link = bpf_program__attach_perf_event(prog, pfd);
if (IS_ERR(link)) {
close(pfd);
--
2.27.0
