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SubjectRe: [PATCH] perf tools: Fix compilation on powerpc
Em Tue, Sep 28, 2021 at 10:39:05PM +0200, Mark Wielaard escreveu:
> Hi,
>
> On Tue, Sep 28, 2021 at 09:52:53PM +0200, Jiri Olsa wrote:
> > Got following build fail on powerpc:
> >
> > CC arch/powerpc/util/skip-callchain-idx.o
> > In function ‘check_return_reg’,
> > inlined from ‘check_return_addr’ at arch/powerpc/util/skip-callchain-idx.c:213:7,
> > inlined from ‘arch_skip_callchain_idx’ at arch/powerpc/util/skip-callchain-idx.c:265:7:
> > arch/powerpc/util/skip-callchain-idx.c:54:18: error: ‘dwarf_frame_register’ accessing 96 bytes \
> > in a region of size 64 [-Werror=stringop-overflow=]
> > 54 | result = dwarf_frame_register(frame, ra_regno, ops_mem, &ops, &nops);
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > arch/powerpc/util/skip-callchain-idx.c: In function ‘arch_skip_callchain_idx’:
> > arch/powerpc/util/skip-callchain-idx.c:54:18: note: referencing argument 3 of type ‘Dwarf_Op *’
> > In file included from /usr/include/elfutils/libdwfl.h:32,
> > from arch/powerpc/util/skip-callchain-idx.c:10:
> > /usr/include/elfutils/libdw.h:1069:12: note: in a call to function ‘dwarf_frame_register’
> > 1069 | extern int dwarf_frame_register (Dwarf_Frame *frame, int regno,
> > | ^~~~~~~~~~~~~~~~~~~~
> > cc1: all warnings being treated as errors
> >
> > The dwarf_frame_register args changed with [1],
> > Updating ops_mem accordingly.
> >
> > [1] https://sourceware.org/git/?p=elfutils.git;a=commit;h=5621fe5443da23112170235dd5cac161e5c75e65
>
> The warning (new with GCC11) and the fix are correct.

I'm taking this as an Acked-by, ok?

- Arnaldo

> The code probably worked fine before because the next var on the stack
> was the dummy Dwarf_Op which would have been as if the ops_mem[2] was
> actually ops_mem[3] already. You don't need the dummy var now and
> Dwarf_Op *ops doesn't need to be initialized (the dwarf_frame_register
> will initialize it).
>
> Note that [1] didn't change the args of the dwarf_frame_register, but
> did fix a similar bug in one of the elfutils own tests (and updated
> the comment on the function to hopefully be more clear).
>
> Cheers,
>
> Mark
>
> > Cc: Mark Wielaard <mjw@redhat.com>
> > Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> > Signed-off-by: Jiri Olsa <jolsa@redhat.com>
> > ---
> > tools/perf/arch/powerpc/util/skip-callchain-idx.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
> > index 3018a054526a..20cd6244863b 100644
> > --- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
> > +++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
> > @@ -45,7 +45,7 @@ static const Dwfl_Callbacks offline_callbacks = {
> > */
> > static int check_return_reg(int ra_regno, Dwarf_Frame *frame)
> > {
> > - Dwarf_Op ops_mem[2];
> > + Dwarf_Op ops_mem[3];
> > Dwarf_Op dummy;
> > Dwarf_Op *ops = &dummy;
> > size_t nops;
> > --
> > 2.31.1
> >

--

- Arnaldo

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