Low-level functions have many call paths, and sometimes we only care about the calls on a specific call path. Add a new filter to filter based on the call stack.
Usage: 1. echo 'caller=="$function_name"' > events/../filter Only support OP_EQ and OP_NE Signed-off-by: Chen Jun <[email protected]> --- include/linux/trace_events.h | 1 + kernel/trace/trace.h | 3 ++- kernel/trace/trace_events.c | 1 + kernel/trace/trace_events_filter.c | 40 ++++++++++++++++++++++++++++-- 4 files changed, 42 insertions(+), 3 deletions(-) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 40a43a4c7caf..1f109669a391 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -851,6 +851,7 @@ enum { FILTER_COMM, FILTER_CPU, FILTER_STACKTRACE, + FILTER_CALLER, }; extern int trace_event_raw_init(struct trace_event_call *call); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 80fe152af1dd..4e4b92ce264f 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1825,7 +1825,8 @@ static inline bool is_string_field(struct ftrace_event_field *field) field->filter_type == FILTER_RDYN_STRING || field->filter_type == FILTER_STATIC_STRING || field->filter_type == FILTER_PTR_STRING || - field->filter_type == FILTER_COMM; + field->filter_type == FILTER_COMM || + field->filter_type == FILTER_CALLER; } static inline bool is_function_field(struct ftrace_event_field *field) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index c46e623e7e0d..6d220d7eec73 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -199,6 +199,7 @@ static int trace_define_generic_fields(void) __generic_field(char *, comm, FILTER_COMM); __generic_field(char *, stacktrace, FILTER_STACKTRACE); __generic_field(char *, STACKTRACE, FILTER_STACKTRACE); + __generic_field(char *, caller, FILTER_CALLER); return ret; } diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 609325f57942..1cf040065abe 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -72,6 +72,7 @@ enum filter_pred_fn { FILTER_PRED_FN_CPUMASK, FILTER_PRED_FN_CPUMASK_CPU, FILTER_PRED_FN_FUNCTION, + FILTER_PRED_FN_CALLER, FILTER_PRED_FN_, FILTER_PRED_TEST_VISITED, }; @@ -1009,6 +1010,21 @@ static int filter_pred_function(struct filter_pred *pred, void *event) return pred->op == OP_EQ ? ret : !ret; } +/* Filter predicate for caller. */ +static int filter_pred_caller(struct filter_pred *pred, void *event) +{ + unsigned long entries[32]; + unsigned int nr_entries; + int i; + + nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0); + for (i = 0; i < nr_entries ; i++) + if (pred->val <= entries[i] && entries[i] < pred->val2) + return !pred->not; + + return pred->not; +} + /* * regex_match_foo - Basic regex callbacks * @@ -1617,6 +1633,8 @@ static int filter_pred_fn_call(struct filter_pred *pred, void *event) return filter_pred_cpumask_cpu(pred, event); case FILTER_PRED_FN_FUNCTION: return filter_pred_function(pred, event); + case FILTER_PRED_FN_CALLER: + return filter_pred_caller(pred, event); case FILTER_PRED_TEST_VISITED: return test_pred_visited_fn(pred, event); default: @@ -2002,10 +2020,28 @@ static int parse_pred(const char *str, void *data, } else if (field->filter_type == FILTER_DYN_STRING) { pred->fn_num = FILTER_PRED_FN_STRLOC; - } else if (field->filter_type == FILTER_RDYN_STRING) + } else if (field->filter_type == FILTER_RDYN_STRING) { pred->fn_num = FILTER_PRED_FN_STRRELLOC; - else { + } else if (field->filter_type == FILTER_CALLER) { + unsigned long caller; + + if (op == OP_GLOB) + goto err_free; + pred->fn_num = FILTER_PRED_FN_CALLER; + caller = kallsyms_lookup_name(pred->regex->pattern); + if (!caller) { + parse_error(pe, FILT_ERR_NO_FUNCTION, pos + i); + goto err_free; + } + /* Now find the function start and end address */ + if (!kallsyms_lookup_size_offset(caller, &size, &offset)) { + parse_error(pe, FILT_ERR_NO_FUNCTION, pos + i); + goto err_free; + } + pred->val = caller - offset; + pred->val2 = pred->val + size; + } else { if (!ustring_per_cpu) { /* Once allocated, keep it around for good */ ustring_per_cpu = alloc_percpu(struct ustring_buffer); -- 2.22.0
