Re: [PATCH v7 13/14] perf callchain: Support x86 target platform

From: Hekuang
Date: Wed Jun 01 2016 - 05:59:43 EST

å 2016/6/1 16:40, Jiri Olsa åé:
On Tue, May 31, 2016 at 11:19:11AM +0000, He Kuang wrote:


diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
index e183390..5774317 100644
--- a/tools/perf/util/unwind-libunwind.c
+++ b/tools/perf/util/unwind-libunwind.c
@@ -5,6 +5,7 @@
#include "arch/common.h"
struct unwind_libunwind_ops __weak *local_unwind_libunwind_ops;
+struct unwind_libunwind_ops __weak *x86_32_unwind_libunwind_ops;
void unwind__register_ops(struct thread *thread,
struct unwind_libunwind_ops *ops)
@@ -30,7 +31,13 @@ int unwind__prepare_access(struct thread *thread, struct map *map)
dso_type == DSO__TYPE_64BIT, map->dso->name);
arch = normalize_arch(thread->mg->machine->env->arch);
- pr_debug("unwind: target platform=%s\n", arch);
+ if (!strcmp(arch, "x86"))
+ if (dso_type != DSO__TYPE_64BIT)
+ ops = x86_32_unwind_libunwind_ops;
+ if (!ops)
+ pr_err("unwind: target platform=%s is not supported\n", arch);
how could ops become NULL in here? it starts with local_unwind_libunwind_ops
I dont think this check is needed in here

x86_32_unwind_libunwind_ops is a null pointer when x86_32
libunwind is not supported.

There's a weak defination if CONFIG_LIBUNWIND_X86 is not set.

struct unwind_libunwind_ops __weak *x86_32_unwind_libunwind_ops;

In this case, ops is null and "x86_32 is not supported" error
message is showed up.