From: Steven Rostedt (Google) Date: Tue, 17 Jan 2023 15:21:27 +0000 (-0500) Subject: tracing: Allow stacktraces to be saved as histogram variables X-Git-Tag: v6.6.7~3258^2~38 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=288709c9f3b0236000754824bcabc9a9ffaa3738;p=platform%2Fkernel%2Flinux-starfive.git tracing: Allow stacktraces to be saved as histogram variables Allow to save stacktraces into a histogram variable. This will be used by synthetic events to allow a stacktrace from one event to be passed and displayed by another event. The special keyword "stacktrace" is to be used to trigger a stack trace for the event that the histogram trigger is attached to. echo 'hist:keys=pid:st=stacktrace" > events/sched/sched_waking/trigger Currently nothing can get access to the "$st" variable above that contains the stack trace, but that will soon change. Link: https://lkml.kernel.org/r/20230117152235.856323729@goodmis.org Cc: Masami Hiramatsu Cc: Andrew Morton Cc: Tom Zanussi Cc: Ross Zwisler Cc: Ching-lin Yu Signed-off-by: Steven Rostedt (Google) --- diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 5edbf6b1da3f..f8f67e17898a 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -1360,6 +1360,8 @@ static const char *hist_field_name(struct hist_field *field, field_name = field->name; } else if (field->flags & HIST_FIELD_FL_TIMESTAMP) field_name = "common_timestamp"; + else if (field->flags & HIST_FIELD_FL_STACKTRACE) + field_name = "stacktrace"; else if (field->flags & HIST_FIELD_FL_HITCOUNT) field_name = "hitcount"; @@ -1980,6 +1982,10 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data, if (flags & HIST_FIELD_FL_STACKTRACE) { hist_field->fn_num = HIST_FIELD_FN_NOP; + hist_field->size = HIST_STACKTRACE_SIZE; + hist_field->type = kstrdup_const("unsigned long[]", GFP_KERNEL); + if (!hist_field->type) + goto free; goto out; } @@ -2351,6 +2357,8 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file, hist_data->enable_timestamps = true; if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS) hist_data->attrs->ts_in_usecs = true; + } else if (strcmp(field_name, "stacktrace") == 0) { + *flags |= HIST_FIELD_FL_STACKTRACE; } else if (strcmp(field_name, "common_cpu") == 0) *flags |= HIST_FIELD_FL_CPU; else if (strcmp(field_name, "hitcount") == 0) @@ -3119,13 +3127,24 @@ static inline void __update_field_vars(struct tracing_map_elt *elt, var_val = hist_fn_call(val, elt, buffer, rbe, rec); var_idx = var->var.idx; - if (val->flags & HIST_FIELD_FL_STRING) { + if (val->flags & (HIST_FIELD_FL_STRING | + HIST_FIELD_FL_STACKTRACE)) { char *str = elt_data->field_var_str[j++]; char *val_str = (char *)(uintptr_t)var_val; unsigned int size; - size = min(val->size, STR_VAR_LEN_MAX); - strscpy(str, val_str, size); + if (val->flags & HIST_FIELD_FL_STRING) { + size = min(val->size, STR_VAR_LEN_MAX); + strscpy(str, val_str, size); + } else { + int e; + + e = stack_trace_save((void *)str, + HIST_STACKTRACE_DEPTH, + HIST_STACKTRACE_SKIP); + if (e < HIST_STACKTRACE_DEPTH - 1) + ((unsigned long *)str)[e] = 0; + } var_val = (u64)(uintptr_t)str; } tracing_map_set_var(elt, var_idx, var_val); @@ -3824,7 +3843,8 @@ static void save_field_var(struct hist_trigger_data *hist_data, { hist_data->field_vars[hist_data->n_field_vars++] = field_var; - if (field_var->val->flags & HIST_FIELD_FL_STRING) + /* Stack traces are saved in the string storage too */ + if (field_var->val->flags & (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) hist_data->n_field_var_str++; } @@ -4103,7 +4123,8 @@ static int action_create(struct hist_trigger_data *hist_data, } hist_data->save_vars[hist_data->n_save_vars++] = field_var; - if (field_var->val->flags & HIST_FIELD_FL_STRING) + if (field_var->val->flags & + (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) hist_data->n_save_var_str++; kfree(param); } @@ -4351,7 +4372,8 @@ static int create_var_field(struct hist_trigger_data *hist_data, if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_EXECNAME) update_var_execname(hist_data->fields[val_idx]); - if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING) + if (!ret && hist_data->fields[val_idx]->flags & + (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) hist_data->fields[val_idx]->var_str_idx = hist_data->n_var_str++; return ret; @@ -5092,7 +5114,8 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data, if (hist_field->flags & HIST_FIELD_FL_VAR) { var_idx = hist_field->var.idx; - if (hist_field->flags & HIST_FIELD_FL_STRING) { + if (hist_field->flags & + (HIST_FIELD_FL_STRING | HIST_FIELD_FL_STACKTRACE)) { unsigned int str_start, var_str_idx, idx; char *str, *val_str; unsigned int size; @@ -5105,9 +5128,18 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data, str = elt_data->field_var_str[idx]; val_str = (char *)(uintptr_t)hist_val; - size = min(hist_field->size, STR_VAR_LEN_MAX); - strscpy(str, val_str, size); - + if (hist_field->flags & HIST_FIELD_FL_STRING) { + size = min(hist_field->size, STR_VAR_LEN_MAX); + strscpy(str, val_str, size); + } else { + int e; + + e = stack_trace_save((void *)str, + HIST_STACKTRACE_DEPTH, + HIST_STACKTRACE_SKIP); + if (e < HIST_STACKTRACE_DEPTH - 1) + ((unsigned long *)str)[e] = 0; + } hist_val = (u64)(uintptr_t)str; } tracing_map_set_var(elt, var_idx, hist_val);