Commit aa3b2b4c authored by Beau Belgrave's avatar Beau Belgrave Committed by Steven Rostedt (Google)
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user_events: Add print_fmt generation support for basic types 

Addes print_fmt format generation for basic types that are supported for
user processes. Only supports sizes that are the same on 32 and 64 bit.

Link: https://lkml.kernel.org/r/20220118204326.2169-3-beaub@linux.microsoft.com



Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarBeau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 7f5a08c7

kernel/trace/trace_events_user.c

+113 −2
Original line number Diff line number Diff line
@@ -359,6 +359,114 @@ static int user_event_parse_fields(struct user_event *user, char *args) 


static struct trace_event_fields user_event_fields_array[1];



static const char *user_field_format(const char *type)

{

	if (strcmp(type, "s64") == 0)

		return "%lld";

	if (strcmp(type, "u64") == 0)

		return "%llu";

	if (strcmp(type, "s32") == 0)

		return "%d";

	if (strcmp(type, "u32") == 0)

		return "%u";

	if (strcmp(type, "int") == 0)

		return "%d";

	if (strcmp(type, "unsigned int") == 0)

		return "%u";

	if (strcmp(type, "s16") == 0)

		return "%d";

	if (strcmp(type, "u16") == 0)

		return "%u";

	if (strcmp(type, "short") == 0)

		return "%d";

	if (strcmp(type, "unsigned short") == 0)

		return "%u";

	if (strcmp(type, "s8") == 0)

		return "%d";

	if (strcmp(type, "u8") == 0)

		return "%u";

	if (strcmp(type, "char") == 0)

		return "%d";

	if (strcmp(type, "unsigned char") == 0)

		return "%u";

	if (strstr(type, "char[") != 0)

		return "%s";



	/* Unknown, likely struct, allowed treat as 64-bit */

	return "%llu";

}



static bool user_field_is_dyn_string(const char *type, const char **str_func)

{

	if (str_has_prefix(type, "__data_loc ")) {

		*str_func = "__get_str";

		goto check;

	}



	if (str_has_prefix(type, "__rel_loc ")) {

		*str_func = "__get_rel_str";

		goto check;

	}



	return false;

check:

	return strstr(type, "char") != 0;

}



#define LEN_OR_ZERO (len ? len - pos : 0)

static int user_event_set_print_fmt(struct user_event *user, char *buf, int len)

{

	struct ftrace_event_field *field, *next;

	struct list_head *head = &user->fields;

	int pos = 0, depth = 0;

	const char *str_func;



	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");



	list_for_each_entry_safe_reverse(field, next, head, link) {

		if (depth != 0)

			pos += snprintf(buf + pos, LEN_OR_ZERO, " ");



		pos += snprintf(buf + pos, LEN_OR_ZERO, "%s=%s",

				field->name, user_field_format(field->type));



		depth++;

	}



	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");



	list_for_each_entry_safe_reverse(field, next, head, link) {

		if (user_field_is_dyn_string(field->type, &str_func))

			pos += snprintf(buf + pos, LEN_OR_ZERO,

					", %s(%s)", str_func, field->name);

		else

			pos += snprintf(buf + pos, LEN_OR_ZERO,

					", REC->%s", field->name);

	}



	return pos + 1;

}

#undef LEN_OR_ZERO



static int user_event_create_print_fmt(struct user_event *user)

{

	char *print_fmt;

	int len;



	len = user_event_set_print_fmt(user, NULL, 0);



	print_fmt = kmalloc(len, GFP_KERNEL);



	if (!print_fmt)

		return -ENOMEM;



	user_event_set_print_fmt(user, print_fmt, len);



	user->call.print_fmt = print_fmt;



	return 0;

}



static enum print_line_t user_event_print_trace(struct trace_iterator *iter,

						int flags,

						struct trace_event *event)
@@ -392,6 +500,7 @@ static int destroy_user_event(struct user_event *user) 
	clear_bit(user->index, page_bitmap);

	hash_del(&user->node);



	kfree(user->call.print_fmt);

	kfree(EVENT_NAME(user));

	kfree(user);
@@ -669,8 +778,10 @@ static int user_event_parse(char *name, char *args, char *flags, 
	if (ret)

		goto put_user;



	/* Minimal print format */

	user->call.print_fmt = "\"\"";

	ret = user_event_create_print_fmt(user);



	if (ret)

		goto put_user;



	user->call.data = user;

	user->call.class = &user->class;