[PATCH v5 1/8] tracing/probes: add traceprobe_expand_dentry_args() helper

[Ye Bin]

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 <yebi...@huawei.com>
---
 kernel/trace/trace_probe.c | 50 ++++++++++++++++++++++++++++++++++++++
 kernel/trace/trace_probe.h |  2 ++
 2 files changed, 52 insertions(+)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 4dc74d73fc1d..0c1caf0f474a 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -1565,6 +1565,56 @@ const char **traceprobe_expand_meta_args(int argc, const 
char *argv[],
        return ERR_PTR(ret);
 }
 
+/* @buf: *buf must be equal to NULL. Caller must to free *buf */
+int traceprobe_expand_dentry_args(int argc, const char *argv[], char **buf)
+{
+       int i, used, ret;
+       int bufsize = MAX_DENTRY_ARGS_LEN;
+       char *tmpbuf = NULL;
+
+       if (*buf)
+               return -EINVAL;
+
+       used = 0;
+       for (i = 0; i < argc; i++) {
+               if (glob_match("*:%pd", argv[i])) {
+                       char *tmp;
+                       char *equal;
+
+                       if (!tmpbuf) {
+                               tmpbuf = kmalloc(bufsize, GFP_KERNEL);
+                               if (!tmpbuf)
+                                       return -ENOMEM;
+                       }
+
+                       tmp = kstrdup(argv[i], GFP_KERNEL);
+                       if (!tmp)
+                               goto nomem;
+
+                       equal = strchr(tmp, '=');
+                       if (equal)
+                               *equal = '\0';
+                       tmp[strlen(argv[i]) - 4] = '\0';
+                       ret = snprintf(tmpbuf + 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)
+                               goto nomem;
+                       argv[i] = tmpbuf + used;
+                       used += ret + 1;
+               }
+       }
+
+       *buf = tmpbuf;
+       return 0;
+nomem:
+       kfree(tmpbuf);
+       return -ENOMEM;
+}
+
 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..5800513439f3 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -34,6 +34,7 @@
 #define MAX_ARRAY_LEN          64
 #define MAX_ARG_NAME_LEN       32
 #define MAX_BTF_ARGS_LEN       128
+#define MAX_DENTRY_ARGS_LEN    256
 #define MAX_STRING_SIZE                PATH_MAX
 #define MAX_ARG_BUF_LEN                (MAX_TRACE_ARGS * MAX_ARG_NAME_LEN)
 
@@ -402,6 +403,7 @@ 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);
 
 extern int traceprobe_update_arg(struct probe_arg *arg);
 extern void traceprobe_free_probe_arg(struct probe_arg *arg);
-- 
2.31.1