2024-01-23 09:20:18

by yebin (H)

Subject: [PATCH v4 2/7] tracing/probes: add traceprobe_expand_dentry_args() helper

Add traceprobe_expand_dentry_args() to expand dentry args. this API is
prepare to support "%pd" print format for kprobe.

Signed-off-by: Ye Bin <[email protected]>
---
kernel/trace/trace_probe.c | 36 ++++++++++++++++++++++++++++++++++++
kernel/trace/trace_probe.h | 2 ++
2 files changed, 38 insertions(+)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 4dc74d73fc1d..cc8bd7ea5341 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -1565,6 +1565,42 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
return ERR_PTR(ret);
}

+int traceprobe_expand_dentry_args(int argc, const char *argv[], char *buf,
+ int bufsize)
+{
+ int i, used, ret;
+
+ used = 0;
+ for (i = 0; i < argc; i++) {
+ size_t idx;
+
+ if (str_has_suffix(argv[i], ":%pd", &idx)) {
+ char *tmp = kstrdup(argv[i], GFP_KERNEL);
+ char *equal;
+
+ if (!tmp)
+ return -ENOMEM;
+
+ equal = strchr(tmp, '=');
+ if (equal)
+ *equal = '\0';
+ tmp[idx] = '\0';
+ ret = snprintf(buf + used, bufsize - used,
+ "%s%s+0x0(+0x%zx(%s)):string",
+ equal ? tmp : "", equal ? "=" : "",
+ offsetof(struct dentry, d_name.name),
+ equal ? equal + 1 : tmp);
+ kfree(tmp);
+ if (ret >= bufsize - used)
+ return -ENOMEM;
+ argv[i] = buf + used;
+ used += ret + 1;
+ }
+ }
+
+ return 0;
+}
+
void traceprobe_finish_parse(struct traceprobe_parse_context *ctx)
{
clear_btf_context(ctx);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 850d9ecb6765..553371a4e0b1 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -402,6 +402,8 @@ extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i,
const char **traceprobe_expand_meta_args(int argc, const char *argv[],
int *new_argc, char *buf, int bufsize,
struct traceprobe_parse_context *ctx);
+extern int traceprobe_expand_dentry_args(int argc, const char *argv[], char *buf,
+ int bufsize);

extern int traceprobe_update_arg(struct probe_arg *arg);
extern void traceprobe_free_probe_arg(struct probe_arg *arg);
--
2.31.1

2024-01-23 14:49:22

by Masami Hiramatsu

Subject: Re: [PATCH v4 2/7] tracing/probes: add traceprobe_expand_dentry_args() helper

Hi Ye,

On Tue, 23 Jan 2024 17:21:34 +0800
Ye Bin <[email protected]> wrote:

> Add traceprobe_expand_dentry_args() to expand dentry args. this API is
> prepare to support "%pd" print format for kprobe.
>
> Signed-off-by: Ye Bin <[email protected]>
> ---
> kernel/trace/trace_probe.c | 36 ++++++++++++++++++++++++++++++++++++
> kernel/trace/trace_probe.h | 2 ++
> 2 files changed, 38 insertions(+)
>
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 4dc74d73fc1d..cc8bd7ea5341 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -1565,6 +1565,42 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
> return ERR_PTR(ret);
> }
>
> +int traceprobe_expand_dentry_args(int argc, const char *argv[], char *buf,
> + int bufsize)
> +{
> + int i, used, ret;
> +
> + used = 0;
> + for (i = 0; i < argc; i++) {
> + size_t idx;
> +
> + if (str_has_suffix(argv[i], ":%pd", &idx)) {

Instead of using this, I recommend to use `glob_match("*:%pd", argv[i])`
so that you can simply expand the pattern as `glob_match("*:%p[dD]",...)`
(glob_match means wildcard match like shell does)

Thank you,

> + char *tmp = kstrdup(argv[i], GFP_KERNEL);
> + char *equal;
> +
> + if (!tmp)
> + return -ENOMEM;
> +
> + equal = strchr(tmp, '=');
> + if (equal)
> + *equal = '\0';
> + tmp[idx] = '\0';
> + ret = snprintf(buf + used, bufsize - used,
nb> + "%s%s+0x0(+0x%zx(%s)):string",
> + equal ? tmp : "", equal ? "=" : "",
> + offsetof(struct dentry, d_name.name),
> + equal ? equal + 1 : tmp);
> + kfree(tmp);
> + if (ret >= bufsize - used)
> + return -ENOMEM;
> + argv[i] = buf + used;
> + used += ret + 1;
> + }
> + }
> +
> + return 0;
> +}
> +
> void traceprobe_finish_parse(struct traceprobe_parse_context *ctx)
> {
> clear_btf_context(ctx);
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 850d9ecb6765..553371a4e0b1 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -402,6 +402,8 @@ extern int traceprobe_parse_probe_arg(struct trace_probe *tp, int i,
> const char **traceprobe_expand_meta_args(int argc, const char *argv[],
> int *new_argc, char *buf, int bufsize,
> struct traceprobe_parse_context *ctx);
> +extern int traceprobe_expand_dentry_args(int argc, const char *argv[], char *buf,
> + int bufsize);
>
> extern int traceprobe_update_arg(struct probe_arg *arg);
> extern void traceprobe_free_probe_arg(struct probe_arg *arg);
> --
> 2.31.1
>
>


--
Masami Hiramatsu (Google) <[email protected]>