[PATCH AUTOSEL 6.14 40/44] tracing: probe-events: Log error for exceeding the number of arguments

[PATCH AUTOSEL 6.14 40/44] tracing: probe-events: Log error for exceeding the number of arguments

[Sasha Levin]

From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>

[ Upstream commit 57faaa04804ccbf16582f7fc7a6b986fd0c0e78c ]

Add error message when the number of arguments exceeds the limitation.

Link: https://lore.kernel.org/all/174055075075.4079315.10916648136898316476.stgit@mhiramat.tok.corp.google.com/

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/trace/trace_eprobe.c | 2 ++
 kernel/trace/trace_fprobe.c | 5 ++++-
 kernel/trace/trace_kprobe.c | 5 ++++-
 kernel/trace/trace_probe.h  | 1 +
 kernel/trace/trace_uprobe.c | 9 +++++++--
 5 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
index 82fd637cfc19e..af9fa0632b574 100644
--- a/kernel/trace/trace_eprobe.c
+++ b/kernel/trace/trace_eprobe.c
@@ -913,6 +913,8 @@ static int __trace_eprobe_create(int argc, const char *argv[])
 	}
 
 	if (argc - 2 > MAX_TRACE_ARGS) {
+		trace_probe_log_set_index(2);
+		trace_probe_log_err(0, TOO_MANY_ARGS);
 		ret = -E2BIG;
 		goto error;
 	}
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 985ff98272da8..5d7ca80173ea2 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -1199,8 +1199,11 @@ static int trace_fprobe_create_internal(int argc, const char *argv[],
 		argc = new_argc;
 		argv = new_argv;
 	}
-	if (argc > MAX_TRACE_ARGS)
+	if (argc > MAX_TRACE_ARGS) {
+		trace_probe_log_set_index(2);
+		trace_probe_log_err(0, TOO_MANY_ARGS);
 		return -E2BIG;
+	}
 
 	ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
 	if (ret)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d8d5f18a141ad..8287b175667f3 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1007,8 +1007,11 @@ static int trace_kprobe_create_internal(int argc, const char *argv[],
 		argc = new_argc;
 		argv = new_argv;
 	}
-	if (argc > MAX_TRACE_ARGS)
+	if (argc > MAX_TRACE_ARGS) {
+		trace_probe_log_set_index(2);
+		trace_probe_log_err(0, TOO_MANY_ARGS);
 		return -E2BIG;
+	}
 
 	ret = traceprobe_expand_dentry_args(argc, argv, &dbuf);
 	if (ret)
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 96792bc4b0924..854e5668f5ee5 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -545,6 +545,7 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	C(BAD_BTF_TID,		"Failed to get BTF type info."),\
 	C(BAD_TYPE4STR,		"This type does not fit for string."),\
 	C(NEED_STRING_TYPE,	"$comm and immediate-string only accepts string type"),\
+	C(TOO_MANY_ARGS,	"Too many arguments are specified"),	\
 	C(TOO_MANY_EARGS,	"Too many entry arguments specified"),
 
 #undef C
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index ccc762fbb69cd..3386439ec9f67 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -562,8 +562,14 @@ static int __trace_uprobe_create(int argc, const char **argv)
 
 	if (argc < 2)
 		return -ECANCELED;
-	if (argc - 2 > MAX_TRACE_ARGS)
+
+	trace_probe_log_init("trace_uprobe", argc, argv);
+
+	if (argc - 2 > MAX_TRACE_ARGS) {
+		trace_probe_log_set_index(2);
+		trace_probe_log_err(0, TOO_MANY_ARGS);
 		return -E2BIG;
+	}
 
 	if (argv[0][1] == ':')
 		event = &argv[0][2];
@@ -582,7 +588,6 @@ static int __trace_uprobe_create(int argc, const char **argv)
 		return -ECANCELED;
 	}
 
-	trace_probe_log_init("trace_uprobe", argc, argv);
 	trace_probe_log_set_index(1);	/* filename is the 2nd argument */
 
 	*arg++ = '\0';
-- 
2.39.5

[PATCH AUTOSEL 6.14 41/44] tracing: probe-events: Add comments about entry data storing code

[Sasha Levin]

From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>

[ Upstream commit bb9c6020f4c3a07a90dc36826cb5fbe83f09efd5 ]

Add comments about entry data storing code to __store_entry_arg() and
traceprobe_get_entry_data_size(). These are a bit complicated because of
building the entry data storing code and scanning it.

This just add comments, no behavior change.

Link: https://lore.kernel.org/all/174061715004.501424.333819546601401102.stgit@devnote2/

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Closes: https://lore.kernel.org/all/20250226102223.586d7119@gandalf.local.home/
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/trace/trace_probe.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 8f58ee1e8858a..2eeecb6c95eea 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -770,6 +770,10 @@ static int check_prepare_btf_string_fetch(char *typename,
 
 #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
 
+/*
+ * Add the entry code to store the 'argnum'th parameter and return the offset
+ * in the entry data buffer where the data will be stored.
+ */
 static int __store_entry_arg(struct trace_probe *tp, int argnum)
 {
 	struct probe_entry_arg *earg = tp->entry_arg;
@@ -793,6 +797,20 @@ static int __store_entry_arg(struct trace_probe *tp, int argnum)
 		tp->entry_arg = earg;
 	}
 
+	/*
+	 * The entry code array is repeating the pair of
+	 * [FETCH_OP_ARG(argnum)][FETCH_OP_ST_EDATA(offset of entry data buffer)]
+	 * and the rest of entries are filled with [FETCH_OP_END].
+	 *
+	 * To reduce the redundant function parameter fetching, we scan the entry
+	 * code array to find the FETCH_OP_ARG which already fetches the 'argnum'
+	 * parameter. If it doesn't match, update 'offset' to find the last
+	 * offset.
+	 * If we find the FETCH_OP_END without matching FETCH_OP_ARG entry, we
+	 * will save the entry with FETCH_OP_ARG and FETCH_OP_ST_EDATA, and
+	 * return data offset so that caller can find the data offset in the entry
+	 * data buffer.
+	 */
 	offset = 0;
 	for (i = 0; i < earg->size - 1; i++) {
 		switch (earg->code[i].op) {
@@ -826,6 +844,16 @@ int traceprobe_get_entry_data_size(struct trace_probe *tp)
 	if (!earg)
 		return 0;
 
+	/*
+	 * earg->code[] array has an operation sequence which is run in
+	 * the entry handler.
+	 * The sequence stopped by FETCH_OP_END and each data stored in
+	 * the entry data buffer by FETCH_OP_ST_EDATA. The FETCH_OP_ST_EDATA
+	 * stores the data at the data buffer + its offset, and all data are
+	 * "unsigned long" size. The offset must be increased when a data is
+	 * stored. Thus we need to find the last FETCH_OP_ST_EDATA in the
+	 * code array.
+	 */
 	for (i = 0; i < earg->size; i++) {
 		switch (earg->code[i].op) {
 		case FETCH_OP_END:
-- 
2.39.5