UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

libbpf: Use available_filter_functions_addrs with multi-kprobes 

Now that kernel provides a new available_filter_functions_addrs file
which can help us avoid the need to cross-validate
available_filter_functions and kallsyms, we can improve efficiency of
multi-attach kprobes. For example, on my device, the sample program [1]
of start time:

$ sudo ./funccount "tcp_*"

before   after
1.2s     1.0s

  [1]: https://github.com/JackieLiu1/ketones/tree/master/src/funccount

Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230705091209.3803873-2-liu.yun@linux.dev
This commit is contained in:
Jackie Liu 2023-07-05 17:12:09 +08:00 committed by Andrii Nakryiko
parent 8a3fe76f87
commit 56baeeba0a
1 changed files with 61 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
tools/lib/bpf/libbpf.c
View File

@ -10234,6 +10234,12 @@ static const char *tracefs_available_filter_functions(void)
: TRACEFS"/available_filter_functions";
}
static const char *tracefs_available_filter_functions_addrs(void)
{
return use_debugfs() ? DEBUGFS"/available_filter_functions_addrs"
: TRACEFS"/available_filter_functions_addrs";
}
static void gen_kprobe_legacy_event_name(char *buf, size_t buf_sz,
const char *kfunc_name, size_t offset)
{
@ -10650,6 +10656,57 @@ cleanup:
return err;
}
static bool has_available_filter_functions_addrs(void)
{
return access(tracefs_available_filter_functions_addrs(), R_OK) != -1;
}
static int libbpf_available_kprobes_parse(struct kprobe_multi_resolve *res)
{
const char *available_path = tracefs_available_filter_functions_addrs();
char sym_name[500];
FILE *f;
int ret, err = 0;
unsigned long long sym_addr;
f = fopen(available_path, "re");
if (!f) {
err = -errno;
pr_warn("failed to open %s: %d\n", available_path, err);
return err;
}
while (true) {
ret = fscanf(f, "%llx %499s%*[^\n]\n", &sym_addr, sym_name);
if (ret == EOF && feof(f))
break;
if (ret != 2) {
pr_warn("failed to parse available_filter_functions_addrs entry: %d\n",
ret);
err = -EINVAL;
goto cleanup;
}
if (!glob_match(sym_name, res->pattern))
continue;
err = libbpf_ensure_mem((void **)&res->addrs, &res->cap,
sizeof(*res->addrs), res->cnt + 1);
if (err)
goto cleanup;
res->addrs[res->cnt++] = (unsigned long)sym_addr;
}
if (res->cnt == 0)
err = -ENOENT;
cleanup:
fclose(f);
return err;
}
struct bpf_link *
bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
const char *pattern,
@ -10686,7 +10743,10 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
return libbpf_err_ptr(-EINVAL);
if (pattern) {
err = libbpf_available_kallsyms_parse(&res);
if (has_available_filter_functions_addrs())
err = libbpf_available_kprobes_parse(&res);
else
err = libbpf_available_kallsyms_parse(&res);
if (err)
goto error;
addrs = res.addrs;