Messages in this thread | | | Date | Tue, 28 Sep 2021 22:39:05 +0200 | From | Mark Wielaard <> | Subject | Re: [PATCH] perf tools: Fix compilation on powerpc |
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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.
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 >
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