This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH][BZ #19490] Add unwind descriptors for x86_64 _mcount and __fentry__
- From: Andi Kleen <andi at firstfloor dot org>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Paul Pluzhnikov <ppluzhnikov at google dot com>, Andreas Schwab <schwab at suse dot de>, GLIBC Devel <libc-alpha at sourceware dot org>, Andi Kleen <andi at firstfloor dot org>
- Date: Thu, 3 Mar 2016 19:29:33 +0100
- Subject: Re: [PATCH][BZ #19490] Add unwind descriptors for x86_64 _mcount and __fentry__
- Authentication-results: sourceware.org; auth=none
- References: <CALoOobPzA=QaRyua2KVLR5CtKoks_Tz=c45SwWBg18sY0X4kWg at mail dot gmail dot com> <20160222091457 dot GJ19841 at vapier dot lan> <CALoOobMWtqPyM99G4mX56nV=ymqNGFKEwWMAmc0h_Uff_K2yjA at mail dot gmail dot com> <20160226034043 dot GM19841 at vapier dot lan> <CALoOobMtV8tWzW5rxU-UUN0Q7Pc3TCVUpfXXr3kOUoodr+0n0w at mail dot gmail dot com> <CAMe9rOpAgpdPTPz7ac_kyfkCG19YQwQTyhQzPRWuN8BEg5aS-Q at mail dot gmail dot com> <CALoOobOYv1i+D41VOECjQtyKeDF3LBGdT=z37gH3zMEJ=jctQQ at mail dot gmail dot com> <mvmio14neuh dot fsf at hawking dot suse dot de> <CALoOobMRss18H48kOngTdyXWO1tJf=YahxqJavLyuZcXQVzW8g at mail dot gmail dot com> <CAMe9rOohY-RvA3dVJTxGQdU8NaP3ALwuSvN3xGgCBpKdawe8Lg at mail dot gmail dot com>
> Why do we need __fentry__ different from _mcount in glibc? Can we
> make __fentry__ an alias of _mcount?
The stack frame is different, and mcount needs to look at the
stack frame. mcount is after the frame pointer, __fentry__ before.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.