Date: Sun, 5 Feb 2006 17:56:56 +0100 From: Marius Strobl <marius@alchemy.franken.de> To: Andreas Tobler <toa@pop.agri.ch> Cc: freebsd-sparc64@freebsd.org Subject: Re: profiling with cc Message-ID: <20060205175656.S68720@newtrinity.zeist.de> In-Reply-To: <43E60F45.4070004@pop.agri.ch>; from toa@pop.agri.ch on Sun, Feb 05, 2006 at 03:44:21PM %2B0100 References: <43E3D228.6060801@pop.agri.ch> <20060205112432.A3868@newtrinity.zeist.de> <43E5D988.2070009@pop.agri.ch> <20060205122153.O68720@newtrinity.zeist.de> <43E5E70D.1090209@pop.agri.ch> <20060205132234.P68720@newtrinity.zeist.de> <43E60F45.4070004@pop.agri.ch>
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On Sun, Feb 05, 2006 at 03:44:21PM +0100, Andreas Tobler wrote:
> Marius Strobl wrote:
> > On Sun, Feb 05, 2006 at 12:52:45PM +0100, Andreas Tobler wrote:
> >> Marius Strobl wrote:
> >>
> >>> I think all it takes is the MD _mcount() -> mcount() wrapper but I'm
> >>> not sure what it's actually supposed to do.
> >> Ok, thank you for the pointer. I try to read through the code and see if
> >> I can get something out of it.
> >>
> >> Build question, if I play around in this section, does it mean to
> >> rebuild the whole kernel/world everytime, or is it enough to just
> >> compile and install the modified parts ?
> >>
> >
> > AFAICT the wrapper has to go into the userland version of the MCOUNT
> > macro in <machine/profile.h> and you'll have to re-compile and re-
> > install libc, specifically libc_p.a, in order to test it.
>
> Good.
>
> To my understanding, the wrapper should look similar like in
> sys/amd64/include/profile.h?
>
Basically yes.
>
> #else /* !_KERNEL */
> #define _MCOUNT_DECL \
> static void _mcount(uintfptr_t frompc, uintfptr_t selfpc) __used; \
> static void _mcount
>
> #ifdef __GNUCLIKE_ASM
>
> #define MCOUNT \
> __asm(".global " _mcount);\
> __asm(_mcount ":");\
> __asm("add %o7, 8, %o1");\
> __asm("1: call 2f; nop; 2:");\
> __asm("add %o7," __mcount "-1b, %o2");\
> __asm("ld [%o2], %o2");\
> __asm("jmpl %o2, %g0");\
> __asm("add %i7, 8, %o0");
> #else /* !__GNUCLIKE_ASM */
> #define MCOUNT \
> void \
> mcount() \
> { \
> }
> #endif /* __GNUCLIKE_ASM */
>
> Or am I looking to far?
>
> The above asm code comes from NetBSD...
>
As far as I understand MCOUNT refers to the symbol generated by the
compiler and _MCOUNT_DECL to the name of the real function in libc.
As the compiler apparently generates calls to _mcount() on sparc64
the MCOUNT macro should define _mcount() for userland and _MCOUNT_DECL
mcount() or maybe better __mcount(). I'm not sure wheter the NetBSD
asm applies to FreeBSD.
If you let _MCOUNT_DECL define _mcount() as in your snippet above
you'll bypass the wrapper on sparc64 altogether.
Marius
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