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[PATCH v10 21/26] tracing: Remove restriction on string position in hist trigger keys

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If we assume the maximum size for a string field, we don't have to
worry about its position.  Since we only allow two keys in a compound
key and having more than one string key in a given compound key
doesn't make much sense anyway, trading a bit of extra space instead
of introducing an arbitrary restriction makes more sense.

We also need to use the event field size for static strings when
copying the contents, otherwise we get random garbage in the key.

Also, cast string return values to avoid warnings on 32-bit compiles.

Finally, rearrange the code without changing any functionality by
moving the compound key updating code into a separate function.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
 kernel/trace/trace_events_hist.c | 69 +++++++++++++++++++++++-----------------
 1 file changed, 39 insertions(+), 30 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 955bf2b..fe057d6 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -58,14 +58,14 @@ static u64 hist_field_dynstring(struct hist_field *hist_field, void *event)
 	int str_loc = str_item & 0xffff;
 	char *addr = (char *)(event + str_loc);
 
-	return (u64)addr;
+	return (u64)(unsigned long)addr;
 }
 
 static u64 hist_field_pstring(struct hist_field *hist_field, void *event)
 {
 	char **addr = (char **)(event + hist_field->field->offset);
 
-	return (u64)*addr;
+	return (u64)(unsigned long)*addr;
 }
 
 #define DEFINE_HIST_FIELD_FN(type)					\
@@ -508,8 +508,8 @@ static int create_key_field(struct hist_trigger_data *hist_data,
 			goto out;
 		}
 
-		if (is_string_field(field)) /* should be last key field */
-			key_size = HIST_KEY_SIZE_MAX - key_offset;
+		if (is_string_field(field))
+			key_size = MAX_FILTER_STR_VAL;
 		else
 			key_size = field->size;
 	}
@@ -781,9 +781,36 @@ static void hist_trigger_elt_update(struct hist_trigger_data *hist_data,
 	}
 }
 
+static inline void add_to_key(char *compound_key, void *key,
+			      struct hist_field *key_field, void *rec)
+{
+	size_t size = key_field->size;
+
+	if (key_field->flags & HIST_FIELD_STRING) {
+		struct ftrace_event_field *field;
+
+		/* ensure NULL-termination */
+		size--;
+
+		field = key_field->field;
+		if (field->filter_type == FILTER_DYN_STRING)
+			size = *(u32 *)(rec + field->offset) >> 16;
+		else if (field->filter_type == FILTER_PTR_STRING)
+			size = strlen(key);
+		else if (field->filter_type == FILTER_STATIC_STRING)
+			size = field->size;
+
+		if (size > key_field->size - 1)
+			size = key_field->size - 1;
+	}
+
+	memcpy(compound_key + key_field->offset, key, size);
+}
+
 static void event_hist_trigger(struct event_trigger_data *data, void *rec)
 {
 	struct hist_trigger_data *hist_data = data->private_data;
+	bool use_compound_key = (hist_data->n_keys > 1);
 	unsigned long entries[HIST_STACKTRACE_DEPTH];
 	char compound_key[HIST_KEY_SIZE_MAX];
 	struct stack_trace stacktrace;
@@ -798,8 +825,7 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec)
 		return;
 	}
 
-	if (hist_data->n_keys > 1)
-		memset(compound_key, 0, hist_data->key_size);
+	memset(compound_key, 0, hist_data->key_size);
 
 	for (i = hist_data->n_vals; i < hist_data->n_fields; i++) {
 		key_field = hist_data->fields[i];
@@ -816,35 +842,18 @@ static void event_hist_trigger(struct event_trigger_data *data, void *rec)
 			key = entries;
 		} else {
 			field_contents = key_field->fn(key_field, rec);
-			if (key_field->flags & HIST_FIELD_STRING)
+			if (key_field->flags & HIST_FIELD_STRING) {
 				key = (void *)(unsigned long)field_contents;
-			else
+				use_compound_key = true;
+			} else
 				key = (void *)&field_contents;
-
-			if (hist_data->n_keys > 1) {
-				/* ensure NULL-termination */
-				size_t size = key_field->size - 1;
-
-				if (key_field->flags & HIST_FIELD_STRING) {
-					struct ftrace_event_field *field;
-
-					field = key_field->field;
-					if (field->filter_type == FILTER_DYN_STRING)
-						size = *(u32 *)(rec + field->offset) >> 16;
-					else if (field->filter_type == FILTER_PTR_STRING)
-						size = strlen(key);
-
-					if (size > key_field->size - 1)
-						size = key_field->size - 1;
-				}
-
-				memcpy(compound_key + key_field->offset, key,
-				       size);
-			}
 		}
+
+		if (use_compound_key)
+			add_to_key(compound_key, key, key_field, rec);
 	}
 
-	if (hist_data->n_keys > 1)
+	if (use_compound_key)
 		key = compound_key;
 
 	elt = tracing_map_insert(hist_data->map, key);
-- 
1.9.3

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Thread

[PATCH 00/26] tracing: 'hist' triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 06/26] tracing: Add a per-event-trigger 'paused' field Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 12/26] tracing: Add hist trigger support for user-defined sorting ('sort=' param) Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 01/26] tracing: Update cond flag when enabling or disabling a trigger Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 22/26] tracing: Add enable_hist/disable_hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 13/26] tracing: Add hist trigger support for pausing and continuing a trace Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 17/26] tracing: Add hist trigger 'execname' modifier Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 19/26] tracing: Add hist trigger support for stacktraces as keys Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 18/26] tracing: Add hist trigger 'syscall' modifier Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 04/26] tracing: Add event record param to trigger_ops.func() Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 14/26] tracing: Add hist trigger support for clearing a trace Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 26/26] tracing: Add support for named hist triggers Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 21/26] tracing: Remove restriction on string position in hist trigger keys Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 16/26] tracing: Add hist trigger 'sym' and 'sym-offset' modifiers Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200
  [PATCH v10 11/26] tracing: Add hist trigger support for compound keys Tom Zanussi <tom.zanussi@linux.intel.com> - 2015-09-30 21:20 +0200

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