Messages in this thread | | | Subject | Re: [PATCH v7 13/14] perf callchain: Support x86 target platform | From | Hekuang <> | Date | Wed, 1 Jun 2016 17:53:22 +0800 |
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在 2016/6/1 16:40, Jiri Olsa 写道: > On Tue, May 31, 2016 at 11:19:11AM +0000, He Kuang wrote: > > SNIP > >> 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.
> jirka >
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