This is the mail archive of the
mailing list for the glibc project.
Re: [Patch] Add .size directives to x86_64 start.S, and possibly more
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Sterling Augustine <saugustine at google dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, carlos at redhat dot org
- Date: Fri, 21 Nov 2014 11:06:54 -0800
- Subject: Re: [Patch] Add .size directives to x86_64 start.S, and possibly more
- Authentication-results: sourceware.org; auth=none
- References: <CAEG7qUyQPNG1EtSwWSC77vUm+PZXUpDBtm5obab+Y5aa9Vv4-A at mail dot gmail dot com> <CAMe9rOq+bKtiJaAfa5sxx-PjiHLutdYBT1p=7K24KPcoB0pbug at mail dot gmail dot com> <CAEG7qUzM070Va4L1N=msw8t5uAFRp2WQmUryULen+99_zWpbKw at mail dot gmail dot com>
On Fri, Nov 21, 2014 at 11:02 AM, Sterling Augustine
> On Fri, Nov 21, 2014 at 10:52 AM, H.J. Lu <firstname.lastname@example.org> wrote:
>> On Fri, Nov 21, 2014 at 10:44 AM, Sterling Augustine
>> <email@example.com> wrote:
>>> sysdeps/x86_64/start.S doesn't have a .size elf directive for _start.
>>> This tripped up some analysis I was doing.
>>> This patch is the straightforward fix. Would you be interested in a
>>> similar fix for the ~150 assembly files inside x86_64 with similar
>>> 2014-11-21 Sterling Augustine <firstname.lastname@example.org>
>>> * sysdeps/x86_64/start.S: Add .size directive.
>>> diff --git a/sysdeps/x86_64/start.S b/sysdeps/x86_64/start.S
>>> index e3d4ff8..5106bd0 100644
>>> --- a/sysdeps/x86_64/start.S
>>> +++ b/sysdeps/x86_64/start.S
>>> @@ -124,6 +124,7 @@ _start:
>>> hlt /* Crash if somehow `exit' does return. */
>>> + .size _start, .-_start
>>> /* Define a symbol for the first piece of initialized data. */
>> Why not use ENTRY/END macros?
> I'm hazy here, but I don't think things are sufficiently initialized
> by _start to call mcount, which ENTRY does. You are right though, in
> that most of the other files do use END, and so the cleanup isn't as
> big as I thought.
> It probably doesn't make sense to use an END without a corresponding
> ENTRY in start.S, but I'm fine with whatever.
We can add
# define ENTRY_NO_MCOUNT
#define ENRTY ...
Then we can use ENTRY_NO_MCOUNT if needed.