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    Subject[tip:perf/core] recordmcount: Fix handling of elf64 big-endian objects.
    Commit-ID:  2e885057b7f75035f0b85e02f737891482815a81
    Gitweb: http://git.kernel.org/tip/2e885057b7f75035f0b85e02f737891482815a81
    Author: David Daney <david.daney@cavium.com>
    AuthorDate: Mon, 19 Dec 2011 17:42:42 -0800
    Committer: Steven Rostedt <rostedt@goodmis.org>
    CommitDate: Fri, 6 Jan 2012 17:06:42 -0500

    recordmcount: Fix handling of elf64 big-endian objects.

    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.

    Link: http://lkml.kernel.org/r/1324345362-12230-1-git-send-email-ddaney.cavm@gmail.com

    Cc: stable@kernel.org # 3.0+
    Signed-off-by: David Daney <david.daney@cavium.com>
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
    ---
    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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