From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> In order to move pointer checks like IS_ERR_VALUE() out of the hotpath and into the reader path of a trace event, user space tools need to be able to parse that. IS_ERR_VALUE() is defined as: #define IS_ERR_VALUE() unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO) Which eventually turns into: __builtin_expect(!!((unsigned long)(void *)(x) >= (unsigned long)-4095), 0) Now the traceevent parser can handle most of that except for the __builtin_expect(), which needs to be added. Link: https://lore.kernel.org/linux-mm/20200320055823.27089-3-jaewon31.kim@xxxxxxxxxxx/ Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> --- tools/lib/traceevent/event-parse.c | 35 ++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c index 010e60d5a081..5b36c589a029 100644 --- a/tools/lib/traceevent/event-parse.c +++ b/tools/lib/traceevent/event-parse.c @@ -3084,6 +3084,37 @@ process_func_handler(struct tep_event *event, struct tep_function_handler *func, return TEP_EVENT_ERROR; } +static enum tep_event_type +process_builtin_expect(struct tep_event *event, struct tep_print_arg *arg, char **tok) +{ + enum tep_event_type type; + char *token = NULL; + + /* Handle __builtin_expect( cond, #) */ + type = process_arg(event, arg, &token); + + if (type != TEP_EVENT_DELIM || token[0] != ',') + goto out_free; + + free_token(token); + + /* We don't care what the second parameter is of the __builtin_expect() */ + if (read_expect_type(TEP_EVENT_ITEM, &token) < 0) + goto out_free; + + if (read_expected(TEP_EVENT_DELIM, ")") < 0) + goto out_free; + + free_token(token); + type = read_token_item(tok); + return type; + +out_free: + free_token(token); + *tok = NULL; + return TEP_EVENT_ERROR; +} + static enum tep_event_type process_function(struct tep_event *event, struct tep_print_arg *arg, char *token, char **tok) @@ -3128,6 +3159,10 @@ process_function(struct tep_event *event, struct tep_print_arg *arg, free_token(token); return process_dynamic_array_len(event, arg, tok); } + if (strcmp(token, "__builtin_expect") == 0) { + free_token(token); + return process_builtin_expect(event, arg, tok); + } func = find_func_handler(event->tep, token); if (func) { -- 2.25.1
