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From: Ye Bin <yebin10@huawei.com>
To: <rostedt@goodmis.org>, <mhiramat@kernel.org>,
	<mathieu.desnoyers@efficios.com>, <linux-trace-kernel@vger.kernel.org>
CC: <linux-kernel@vger.kernel.org>, <yebin10@huawei.com>
Subject: [PATCH v7 1/5] tracing/probes: support '%pd' type for print struct dentry's name
Date: Wed, 20 Mar 2024 21:29:20 +0800
Message-ID: <20240320132924.2802187-2-yebin10@huawei.com>
In-Reply-To: <20240320132924.2802187-1-yebin10@huawei.com>
References: <20240320132924.2802187-1-yebin10@huawei.com>
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Support print type '%pd' for print dentry's  name.

Signed-off-by: Ye Bin <yebin10@huawei.com>
---
 kernel/trace/trace.c        |  2 +-
 kernel/trace/trace_fprobe.c |  6 +++++
 kernel/trace/trace_kprobe.c |  6 +++++
 kernel/trace/trace_probe.c  | 50 +++++++++++++++++++++++++++++++++++++
 kernel/trace/trace_probe.h  |  2 ++
 5 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b12f8384a36a..ac26b8446337 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5510,7 +5510,7 @@ static const char readme_msg[] =
 	"\t           +|-[u]<offset>(<fetcharg>), \\imm-value, \\\"imm-string\"\n"
 	"\t     type: s8/16/32/64, u8/16/32/64, x8/16/32/64, char, string, symbol,\n"
 	"\t           b<bit-width>@<bit-offset>/<container-size>, ustring,\n"
-	"\t           symstr, <type>\\[<array-size>\\]\n"
+	"\t           symstr, %pd, <type>\\[<array-size>\\]\n"
 #ifdef CONFIG_HIST_TRIGGERS
 	"\t    field: <stype> <name>;\n"
 	"\t    stype: u8/u16/u32/u64, s8/s16/s32/s64, pid_t,\n"
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 7d2ddbcfa377..988d68e906ad 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -976,6 +976,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	char gbuf[MAX_EVENT_NAME_LEN];
 	char sbuf[KSYM_NAME_LEN];
 	char abuf[MAX_BTF_ARGS_LEN];
+	char *dbuf = NULL;
 	bool is_tracepoint = false;
 	struct tracepoint *tpoint = NULL;
 	struct traceprobe_parse_context ctx = {
@@ -1086,6 +1087,10 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 		argv = new_argv;
 	}
 
+	ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
+	if (ret)
+		goto out;
+
 	/* setup a probe */
 	tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive,
 				argc, is_return);
@@ -1131,6 +1136,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
 	trace_probe_log_clear();
 	kfree(new_argv);
 	kfree(symbol);
+	kfree(dbuf);
 	return ret;
 
 parse_error:
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index c4c6e0e0068b..7cbb43740b4f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -779,6 +779,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
 	char buf[MAX_EVENT_NAME_LEN];
 	char gbuf[MAX_EVENT_NAME_LEN];
 	char abuf[MAX_BTF_ARGS_LEN];
+	char *dbuf = NULL;
 	struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL };
 
 	switch (argv[0][0]) {
@@ -930,6 +931,10 @@ static int __trace_kprobe_create(int argc, const char *argv[])
 		argv = new_argv;
 	}
 
+	ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
+	if (ret)
+		goto out;
+
 	/* setup a probe */
 	tk = alloc_trace_kprobe(group, event, addr, symbol, offset, maxactive,
 				argc, is_return);
@@ -971,6 +976,7 @@ static int __trace_kprobe_create(int argc, const char *argv[])
 	trace_probe_log_clear();
 	kfree(new_argv);
 	kfree(symbol);
+	kfree(dbuf);
 	return ret;
 
 parse_error:
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 34289f9c6707..a27567e16c36 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -1569,6 +1569,56 @@ 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;
+	const 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 c1877d018269..3d22fba4b63f 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