Commit 8c427cc2 authored Jan 24, 2024 by Masami Hiramatsu (Google)

tracing/probes: Fix to show a parse error for bad type for $comm

Fix to show a parse error for bad type (non-string) for $comm/$COMM and
immediate-string. With this fix, error_log file shows appropriate error
message as below.

 /sys/kernel/tracing # echo 'p vfs_read $comm:u32' >> kprobe_events
sh: write error: Invalid argument
 /sys/kernel/tracing # echo 'p vfs_read \"hoge":u32' >> kprobe_events
sh: write error: Invalid argument
 /sys/kernel/tracing # cat error_log

[   30.144183] trace_kprobe: error: $comm and immediate-string only accepts string type
  Command: p vfs_read $comm:u32
                            ^
[   62.618500] trace_kprobe: error: $comm and immediate-string only accepts string type
  Command: p vfs_read \"hoge":u32
                              ^
Link: https://lore.kernel.org/all/170602215411.215583.2238016352271091852.stgit@devnote2/



Fixes: 3dd1f7f2 ("tracing: probeevent: Fix to make the type of $comm string")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

parent 54be6c6c

kernel/trace/trace_probe.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -1159,9 +1159,12 @@ static int traceprobe_parse_probe_arg_body(const char argv, ssize_t size,
		if (!(ctx->flags & TPARG_FL_TEVENT) &&
		(strcmp(arg, "$comm") == 0 \|\| strcmp(arg, "$COMM") == 0 \|\|
		strncmp(arg, "\\\"", 2) == 0)) {
		/* The type of $comm must be "string", and not an array. */
		if (parg->count \|\| (t && strcmp(t, "string")))
		/* The type of $comm must be "string", and not an array type. */
		if (parg->count \|\| (t && strcmp(t, "string"))) {
		trace_probe_log_err(ctx->offset + (t ? (t - arg) : 0),
		NEED_STRING_TYPE);
		goto out;
		}
		parg->type = find_fetch_type("string", ctx->flags);
		} else
		parg->type = find_fetch_type(t, ctx->flags);

kernel/trace/trace_probe.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -515,7 +515,8 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
		C(BAD_HYPHEN, "Failed to parse single hyphen. Forgot '>'?"), \
		C(NO_BTF_FIELD, "This field is not found."), \
		C(BAD_BTF_TID, "Failed to get BTF type info."),\
		C(BAD_TYPE4STR, "This type does not fit for string."),
		C(BAD_TYPE4STR, "This type does not fit for string."),\
		C(NEED_STRING_TYPE, "$comm and immediate-string only accepts string type"),

		#undef C
		#define C(a, b) TP_ERR_##a