recordmcount: Fix handling of elf64 big-endian objects.
David Daney [Tue, 20 Dec 2011 01:42:42 +0000 (17:42 -0800)]
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

index f40a6af..54e35c1 100644 (file)
@@ -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;
 }