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From: tip-bot for Masami Hiramatsu <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org,
	shuah@kernel.org, acme@redhat.com, mingo@kernel.org,
	mhiramat@kernel.org, ravi.bangoria@linux.vnet.ibm.com,
	tom.zanussi@linux.intel.com, hpa@zytor.com, tglx@linutronix.de,
	namhyung@kernel.org
Subject: [tip:perf/core] perf probe: Use right type to access array elements
Date: Mon, 19 Mar 2018 23:36:17 -0700	[thread overview]
Message-ID: <tip-d0461794a1dcaf552b507e23788777f718b736a1@git.kernel.org> (raw)
In-Reply-To: <152129114502.31874.2474068470011496356.stgit@devbox>

Commit-ID:  d0461794a1dcaf552b507e23788777f718b736a1
Gitweb:     https://git.kernel.org/tip/d0461794a1dcaf552b507e23788777f718b736a1
Author:     Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Sat, 17 Mar 2018 21:52:25 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 19 Mar 2018 13:51:53 -0300

perf probe: Use right type to access array elements

Current 'perf probe' converts the type of array-elements incorrectly. It
always converts the types as a pointer of array. This passes the "array"
type DIE to the type converter so that it can get correct "element of
array" type DIE from it.

E.g.
  ====
  $ cat hello.c
  #include <stdio.h>

  void foo(int a[])
  {
	  printf("%d\n", a[1]);
  }

  void main()
  {
	  int a[3] = {4, 5, 6};
	  printf("%d\n", a[0]);
	  foo(a);
  }

  $ gcc -g hello.c -o hello
  $ perf probe -x ./hello -D "foo a[1]"
  ====

Without this fix, above outputs
  ====
  p:probe_hello/foo /tmp/hello:0x4d3 a=+4(-8(%bp)):u64
  ====
The "u64" means "int *", but a[1] is "int".

With this,
  ====
  p:probe_hello/foo /tmp/hello:0x4d3 a=+4(-8(%bp)):s32
  ====
So, "int" correctly converted to "s32"

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
Cc: linux-kselftest@vger.kernel.org
Cc: linux-trace-users@vger.kernel.org
Fixes: b2a3c12b7442 ("perf probe: Support tracing an entry of array")
Link: http://lkml.kernel.org/r/152129114502.31874.2474068470011496356.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/probe-finder.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index a5731de0e5eb..c37fbef1711d 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -423,20 +423,20 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 		pr_warning("Failed to get the type of %s.\n", varname);
 		return -ENOENT;
 	}
-	pr_debug2("Var real type: (%x)\n", (unsigned)dwarf_dieoffset(&type));
+	pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type),
+		  (unsigned)dwarf_dieoffset(&type));
 	tag = dwarf_tag(&type);
 
 	if (field->name[0] == '[' &&
 	    (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
-		if (field->next)
-			/* Save original type for next field */
-			memcpy(die_mem, &type, sizeof(*die_mem));
+		/* Save original type for next field or type */
+		memcpy(die_mem, &type, sizeof(*die_mem));
 		/* Get the type of this array */
 		if (die_get_real_type(&type, &type) == NULL) {
 			pr_warning("Failed to get the type of %s.\n", varname);
 			return -ENOENT;
 		}
-		pr_debug2("Array real type: (%x)\n",
+		pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type),
 			 (unsigned)dwarf_dieoffset(&type));
 		if (tag == DW_TAG_pointer_type) {
 			ref = zalloc(sizeof(struct probe_trace_arg_ref));
@@ -448,9 +448,6 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 				*ref_ptr = ref;
 		}
 		ref->offset += dwarf_bytesize(&type) * field->index;
-		if (!field->next)
-			/* Save vr_die for converting types */
-			memcpy(die_mem, vr_die, sizeof(*die_mem));
 		goto next;
 	} else if (tag == DW_TAG_pointer_type) {
 		/* Check the pointer and dereference */

  reply	other threads:[~2018-03-20  6:36 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-17 12:37 [PATCH v6 00/21] tracing: probeevent: Improve fetcharg features Masami Hiramatsu
2018-03-17 12:38 ` [PATCH v6 01/21] [BUGFIX] tracing: probeevent: Fix to support minus offset from symbol Masami Hiramatsu
2018-03-17 12:38 ` [PATCH v6 02/21] selftests: ftrace: Add probe event argument syntax testcase Masami Hiramatsu
2018-03-17 12:39 ` [PATCH v6 03/21] selftests: ftrace: Add a testcase for string type with kprobe_event Masami Hiramatsu
2018-03-17 12:40 ` [PATCH v6 04/21] selftests: ftrace: Add a testcase for probepoint Masami Hiramatsu
2018-03-23 16:19   ` Steven Rostedt
2018-03-17 12:41 ` [PATCH v6 05/21] tracing: probeevent: Cleanup print argument functions Masami Hiramatsu
2018-03-23 16:36   ` Steven Rostedt
2018-03-26  4:17     ` Masami Hiramatsu
2018-03-26 17:28       ` Steven Rostedt
2018-03-28  4:21         ` Masami Hiramatsu
2018-03-17 12:41 ` [PATCH v6 06/21] tracing: probeevent: Cleanup argument field definition Masami Hiramatsu
2018-03-17 12:42 ` [PATCH v6 07/21] tracing: probeevent: Remove NOKPROBE_SYMBOL from print functions Masami Hiramatsu
2018-03-17 12:43 ` [PATCH v6 08/21] tracing: probeevent: Introduce new argument fetching code Masami Hiramatsu
2018-03-17 12:44 ` [PATCH v6 09/21] tracing: probeevent: Unify fetch type tables Masami Hiramatsu
2018-03-17 12:44 ` [PATCH v6 10/21] tracing: probeevent: Return consumed bytes of dynamic area Masami Hiramatsu
2018-04-02 20:02   ` Steven Rostedt
2018-04-03 14:41     ` Masami Hiramatsu
2018-03-17 12:45 ` [PATCH v6 11/21] tracing: probeevent: Append traceprobe_ for exported function Masami Hiramatsu
2018-03-17 12:46 ` [PATCH v6 12/21] tracing: probeevent: Unify fetch_insn processing common part Masami Hiramatsu
2018-03-17 12:47 ` [PATCH v6 13/21] tracing: probeevent: Add symbol type Masami Hiramatsu
2018-03-17 12:47 ` [PATCH v6 14/21] x86: ptrace: Add function argument access API Masami Hiramatsu
2018-03-17 12:48 ` [PATCH v6 15/21] tracing: probeevent: Add $argN for accessing function args Masami Hiramatsu
2018-03-17 12:49 ` [PATCH v6 16/21] tracing: probeevent: Add array type support Masami Hiramatsu
2018-03-17 12:50 ` [PATCH v6 17/21] selftests: ftrace: Add a testcase for symbol type Masami Hiramatsu
2018-03-17 12:50 ` [PATCH v6 18/21] selftests: ftrace: Add a testcase for $argN with kprobe_event Masami Hiramatsu
2018-03-17 12:51 ` [PATCH v6 19/21] selftests: ftrace: Add a testcase for array type " Masami Hiramatsu
2018-03-17 12:52 ` [PATCH v6 20/21] [RESEND] perf-probe: Fix to convert array type collectly Masami Hiramatsu
2018-03-20  6:36   ` tip-bot for Masami Hiramatsu [this message]
2018-03-17 12:53 ` [PATCH v6 21/21] perf-probe: Add array argument support Masami Hiramatsu
2018-03-19  7:59   ` Ravi Bangoria
2018-03-22 10:23     ` Masami Hiramatsu
2018-03-22 10:49       ` Ravi Bangoria
2018-03-26  3:53         ` Masami Hiramatsu
2018-03-17 14:06 ` [PATCH v6 00/21] tracing: probeevent: Improve fetcharg features Masami Hiramatsu

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