From: Tom Zanussi Date: Fri, 22 Sep 2017 14:58:23 -0500 Subject: [PATCH 09/42] tracing: Reimplement log2 Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/older/patches-4.14.1-rt3.tar.xz log2 as currently implemented applies only to u64 trace_event_field derived fields, and assumes that anything it's applied to is a u64 field. To prepare for synthetic fields like latencies, log2 should be applicable to those as well, so take the opportunity now to fix the current problems as well as expand to more general uses. log2 should be thought of as a chaining function rather than a field type. To enable this as well as possible future function implementations, add a hist_field operand array into the hist_field definition for this purpose, and make use of it to implement the log2 'function'. Signed-off-by: Tom Zanussi Signed-off-by: Sebastian Andrzej Siewior --- kernel/trace/trace_events_hist.c | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -28,12 +28,16 @@ struct hist_field; typedef u64 (*hist_field_fn_t) (struct hist_field *field, void *event); +#define HIST_FIELD_OPERANDS_MAX 2 + struct hist_field { struct ftrace_event_field *field; unsigned long flags; hist_field_fn_t fn; unsigned int size; unsigned int offset; + unsigned int is_signed; + struct hist_field *operands[HIST_FIELD_OPERANDS_MAX]; }; static u64 hist_field_none(struct hist_field *field, void *event) @@ -71,7 +75,9 @@ static u64 hist_field_pstring(struct his static u64 hist_field_log2(struct hist_field *hist_field, void *event) { - u64 val = *(u64 *)(event + hist_field->field->offset); + struct hist_field *operand = hist_field->operands[0]; + + u64 val = operand->fn(operand, event); return (u64) ilog2(roundup_pow_of_two(val)); } @@ -156,6 +162,8 @@ static const char *hist_field_name(struc if (field->field) field_name = field->field->name; + else if (field->flags & HIST_FIELD_FL_LOG2) + field_name = hist_field_name(field->operands[0], ++level); if (field_name == NULL) field_name = ""; @@ -357,8 +365,20 @@ static const struct tracing_map_ops hist .elt_init = hist_trigger_elt_comm_init, }; -static void destroy_hist_field(struct hist_field *hist_field) +static void destroy_hist_field(struct hist_field *hist_field, + unsigned int level) { + unsigned int i; + + if (level > 2) + return; + + if (!hist_field) + return; + + for (i = 0; i < HIST_FIELD_OPERANDS_MAX; i++) + destroy_hist_field(hist_field->operands[i], level + 1); + kfree(hist_field); } @@ -385,7 +405,10 @@ static struct hist_field *create_hist_fi } if (flags & HIST_FIELD_FL_LOG2) { + unsigned long fl = flags & ~HIST_FIELD_FL_LOG2; hist_field->fn = hist_field_log2; + hist_field->operands[0] = create_hist_field(field, fl); + hist_field->size = hist_field->operands[0]->size; goto out; } @@ -405,7 +428,7 @@ static struct hist_field *create_hist_fi hist_field->fn = select_value_fn(field->size, field->is_signed); if (!hist_field->fn) { - destroy_hist_field(hist_field); + destroy_hist_field(hist_field, 0); return NULL; } } @@ -422,7 +445,7 @@ static void destroy_hist_fields(struct h for (i = 0; i < TRACING_MAP_FIELDS_MAX; i++) { if (hist_data->fields[i]) { - destroy_hist_field(hist_data->fields[i]); + destroy_hist_field(hist_data->fields[i], 0); hist_data->fields[i] = NULL; } }