[PATCH 08/11] tracing: add func and symfunc to tag format

[Steven Rostedt]

From: Steven Rostedt <srostedt@xxxxxxxxxx>

This adds a way to print out a function name from a pointer the same way
that the Linux printf "%pF" does. Well the symfunc tag does.

If we change kmalloc and kfree formats to:

  TP_FORMAT("call_site=<symfunc:call_site> ptr=<ptr:ptr> bytes_req=<int:bytes_req> "

and

  TP_FORMAT("call_site=<func:call_site> ptr=<ptr:ptr>")

respectively, we would get something like:

   kmalloc: call_site=__alloc_skb+0x70/0x160 ptr=ffff88003d830800 bytes_req=680
   kfree: call_site=skb_release_data ptr=ffff88003d830800

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace_output.c      |    2 +-
 kernel/trace/trace_output.h      |    4 ++++
 kernel/trace/trace_read_binary.c |   27 +++++++++++++++++++++++++--
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 7938f3a..39d5eeb 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -326,7 +326,7 @@ static inline const char *kretprobed(const char *name)
 }
 #endif /* CONFIG_KRETPROBES */
 
-static int
+int
 seq_print_sym_short(struct trace_seq *s, const char *fmt, unsigned long address)
 {
 #ifdef CONFIG_KALLSYMS
diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h
index d38bec4..412eee8 100644
--- a/kernel/trace/trace_output.h
+++ b/kernel/trace/trace_output.h
@@ -47,5 +47,9 @@ do {							\
 		return TRACE_TYPE_PARTIAL_LINE;		\
 } while (0)
 
+/* until we have a way with sprintf to do this */
+int seq_print_sym_short(struct trace_seq *s, const char *fmt,
+			unsigned long address);
+
 #endif
 
diff --git a/kernel/trace/trace_read_binary.c b/kernel/trace/trace_read_binary.c
index f3fdac8..9ff4ed8 100644
--- a/kernel/trace/trace_read_binary.c
+++ b/kernel/trace/trace_read_binary.c
@@ -10,7 +10,7 @@
 #include <linux/module.h>
 #include <linux/ctype.h>
 
-#include "trace.h"
+#include "trace_output.h"
 
 static DEFINE_MUTEX(buffer_lock);
 static struct trace_seq buffer;
@@ -23,7 +23,8 @@ static struct trace_seq buffer;
  * COMMAND := <TYPE:FIELD> | <mask:FIELD:DELIM:MASKS> | <sym:FIELD:SYMBOLS> |
  *            <if:FIELD:TRUE:FALSE> | <ifmask:FIELD:MASK:TRUE:FALSE> |
  *            <nsec2sec:PRECISION:FIELD> | <nsec2usec:PRECISION:FIELD> |
- *            <nsec2msec:PRECISION:FIELD> | <major:FIELD> | <minor:FIELD>
+ *            <nsec2msec:PRECISION:FIELD> | <major:FIELD> | <minor:FIELD> |
+ *            <func:FIELD> | <symfunc:FIELD>
  * TYPE := int | uint | hex | ptr | string | strarray
  * FIELD := defined by the event structure
  * MASKS := MASK=NAME,MASKS | MASK=NAME
@@ -43,6 +44,8 @@ static struct trace_seq buffer;
  *  uint      : Same as int, but for unsigned.
  *  hex       : Print the field as a hex (ie. 0x4ab)
  *  ptr       : Print the field as a hex but without the '0x'.
+ *  symfunc   : Print a ptr like the "%pF" does.
+ *  func      : Like symfunc but without the address.
  *  string    : Used with dynamic sized strings (__string)
  *  strarray  : Used with static sized arrays (__array ( char , item, len)).
  *  if        : If the field is non zero, print the TRUE text,
@@ -80,6 +83,8 @@ enum field_types {
 	FIELD_IS_HEX,
 	FIELD_IS_MINOR,
 	FIELD_IS_MAJOR,
+	FIELD_IS_FUNC,
+	FIELD_IS_SYMFUNC,
 	FIELD_IS_NSEC2SEC,
 	FIELD_IS_NSEC2USEC,
 	FIELD_IS_NSEC2MSEC,
@@ -412,6 +417,8 @@ handle_field(struct ftrace_event_call *event,
 	case FIELD_IS_HEX:
 	case FIELD_IS_MINOR:
 	case FIELD_IS_MAJOR:
+	case FIELD_IS_FUNC:
+	case FIELD_IS_SYMFUNC:
 	case FIELD_IS_STRING:
 	case FIELD_IS_STRARRAY:
 		field = find_field(event, fmt, end - fmt);
@@ -594,6 +601,12 @@ ftrace_initialize_print(struct ftrace_event_call *event, const char *fmt, ...)
 		else if (strncmp(fmt, "ifmask:", 7) == 0)
 			field_type = FIELD_IS_IFMASK;
 
+		else if (strncmp(fmt, "func:", 5) == 0)
+			field_type = FIELD_IS_FUNC;
+
+		else if (strncmp(fmt, "symfunc:", 8) == 0)
+			field_type = FIELD_IS_SYMFUNC;
+
 		else if (strncmp(fmt, "nsec2sec:", 9) == 0)
 			field_type = FIELD_IS_NSEC2SEC;
 
@@ -785,6 +798,8 @@ ftrace_read_binary(struct trace_seq *s, struct ftrace_event_call *event,
 		case FIELD_IS_UINT:
 		case FIELD_IS_HEX:
 		case FIELD_IS_PTR:
+		case FIELD_IS_FUNC:
+		case FIELD_IS_SYMFUNC:
 		case FIELD_IS_MAJOR:
 		case FIELD_IS_MINOR:
 			field = info->data.field;
@@ -837,6 +852,14 @@ ftrace_read_binary(struct trace_seq *s, struct ftrace_event_call *event,
 				trace_seq_printf(s, "%u", MINOR(val));
 				break;
 
+			case FIELD_IS_SYMFUNC:
+				trace_seq_printf(s, "%pF", (void *)val);
+				break;
+
+			case FIELD_IS_FUNC:
+				seq_print_sym_short(s, "%s", val);
+				break;
+
 			default:
 				/* hex should only print the size specified */
 				if (mask)
-- 
1.6.3.1

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