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SubjectRe: [PATCH] recordmcount: Fix handling of elf64 big-endian objects.
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On Mon, 2011-12-19 at 17:42 -0800, David Daney wrote:
> From: David Daney <david.daney@cavium.com>
>
> In ELF64, the sh_flags field is 64-bits wide. recordmcount was
> erroneously treating it as a 32-bit wide field. For little endian
> objects this works because the flags of interest (SHF_EXECINSTR)
> reside in the lower 32 bits of the word, and you get the same result
> with either a 32-bit or 64-bit read. Big endian objects on the
> other hand do not work at all with this error.
>
> The fix: Correctly treat sh_flags as 64-bits wide in elf64 objects.
>
> The symptom I observed was that my
> __start_mcount_loc..__stop_mcount_loc was empty even though ftrace
> function tracing was enabled.
>

OUCH!

This looks like something that needs to go to stable. Let me play with
this on my PPC64 tomorrow.

Thanks!

-- Steve

> Signed-off-by: David Daney <david.daney@cavium.com>
> ---
> scripts/recordmcount.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
> index f40a6af6..54e35c1 100644
> --- a/scripts/recordmcount.h
> +++ b/scripts/recordmcount.h
> @@ -462,7 +462,7 @@ __has_rel_mcount(Elf_Shdr const *const relhdr, /* is SHT_REL or SHT_RELA */
> succeed_file();
> }
> if (w(txthdr->sh_type) != SHT_PROGBITS ||
> - !(w(txthdr->sh_flags) & SHF_EXECINSTR))
> + !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
> return NULL;
> return txtname;
> }




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