Messages in this thread | | | Subject | Re: [PATCH] recordmcount: Fix handling of elf64 big-endian objects. | From | Steven Rostedt <> | Date | Mon, 19 Dec 2011 22:09:02 -0500 |
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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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