[sheepdog] [PATCH] Fix hardcode AMD64 assembly code (RSP)

[Liu Yuan]

On Mon, Jul 29, 2013 at 05:21:47PM +0800, YunQiang Su wrote:
> On Mon, Jul 29, 2013 at 4:55 PM, Liu Yuan <namei.unix at gmail.com> wrote:
> > On Mon, Jul 29, 2013 at 04:19:08PM +0800, Liu Yuan wrote:
> >> On Mon, Jul 29, 2013 at 05:06:37PM +0900, Hitoshi Mitake wrote:
> >> > At Mon, 29 Jul 2013 14:41:35 +0800,
> >> > Liu Yuan wrote:
> >> > >
> >> > > On Sun, Jul 28, 2013 at 02:05:49AM +0800, YunQiang Su wrote:
> >> > > > RSP is a register name only for AMD64 (x86_64) platform,
> >> > > > while on other platform it may be another name.
> >> > > >
> >> > > > On i386 (x86_32) platform, it is "esp".
> >> > > > On most of RISC platform (PowerPC, SPARC, MIPS, ARM, etc),
> >> > > > it is "sp".
> >> > > > ---
> >> > > >  include/logger.h | 23 ++++++++++++++++++++++-
> >> > > >  lib/logger.c     |  5 -----
> >> > > >  2 files changed, 22 insertions(+), 6 deletions(-)
> >> > > >
> >> > > > diff --git a/include/logger.h b/include/logger.h
> >> > > > index 79eb108..81691b2 100644
> >> > > > --- a/include/logger.h
> >> > > > +++ b/include/logger.h
> >> > > > @@ -38,10 +38,31 @@ void log_write(int prio, const char *func, int line, const char *fmt, ...)
> >> > > >  void set_thread_name(const char *name, bool show_idx);
> >> > > >  void get_thread_name(char *name);
> >> > > >
> >> > > > +#ifdef __i386__
> >> > > > +#define SP_REG "esp"
> >> > > > +#elif defined(__x86_64__)
> >> > > > +#define SP_REG "rsp"
> >> > > > +#elif defined(__mips__) || defined(__sparc__) || \
> >> > > > +      defined (__arm__) || (defined __powerpc__) || \
> >> > > > +      defined (__s390__) || (defined __s390x__) || \
> >> > > > +      defined (__ia64__)
> >> > > > +#define SP_REG "sp"
> >> > > > +#endif
> >> > > > +
> >> > > > +#ifdef SP_REG
> >> > > > +#define dump_stack_frames() ({                 \
> >> > > > +       register void *current_sp asm(SP_REG);  \
> >> > > > +       __dump_stack_frames(current_sp);        \
> >> > > > +})
> >> > > >  #define sd_dump_variable(var) ({               \
> >> > > > -       register void *current_sp asm("rsp");   \
> >> > > > +       register void *current_sp asm(SP_REG);  \
> >> > > >         __sd_dump_variable(#var, current_sp);   \
> >> > > >  })
> >> > > > +#else
> >> > > > +#define dump_stack_frames() ()
> >> > > > +#define sd_dump_variable(var) ()
> >> > > > +#endif
> >> > > > +
> >> > > >  int __sd_dump_variable(const char *var, const void *base_sp);
> >> > > >  void sd_backtrace(void);
> >> > > >
> >> > > > diff --git a/lib/logger.c b/lib/logger.c
> >> > > > index 253163d..ba55adc 100644
> >> > > > --- a/lib/logger.c
> >> > > > +++ b/lib/logger.c
> >> > > > @@ -742,11 +742,6 @@ notrace int __sd_dump_variable(const char *var, const void *base_sp)
> >> > > >         return 0;
> >> > > >  }
> >> > > >
> >> > > > -#define dump_stack_frames() ({                 \
> >> > > > -       register void *current_sp asm("rsp");   \
> >> > > > -       __dump_stack_frames(current_sp);        \
> >> > > > -})
> >> > > > -
> >> > > >  __attribute__ ((__noinline__))
> >> > > >  static notrace int __dump_stack_frames(const void *base_sp)
> >> > > >  {
> >> > > > --
> >> > >
> >> > > I've come up with a better fix. Which use the gcc builtin function to get the
> >> > > stack pointer.
> >> > >
> >> > > From 44300c3fe580a677757803cc30838923ccc5b748 Mon Sep 17 00:00:00 2001
> >> > > From: Liu Yuan <namei.unix at gmail.com>
> >> > > Date: Mon, 29 Jul 2013 14:33:58 +0800
> >> > > Subject: [PATCH] sheep: use gcc builtin to get stack frame pointer
> >> > >
> >> > > This remove hardcoded assembly which is not portable.
> >> > >
> >> > > Signed-off-by: Liu Yuan <namei.unix at gmail.com>
> >> > >
> >> > > diff --git a/include/logger.h b/include/logger.h
> >> > > index 79eb108..9253548 100644
> >> > > --- a/include/logger.h
> >> > > +++ b/include/logger.h
> >> > > @@ -39,10 +39,9 @@ void set_thread_name(const char *name, bool show_idx);
> >> > >  void get_thread_name(char *name);
> >> > >
> >> > >  #define sd_dump_variable(var) ({         \
> >> > > - register void *current_sp asm("rsp");   \
> >> > > - __sd_dump_variable(#var, current_sp);   \
> >> > > + __sd_dump_variable(#var);               \
> >> > >  })
> >> > > -int __sd_dump_variable(const char *var, const void *base_sp);
> >> > > +int __sd_dump_variable(const char *var);
> >> > >  void sd_backtrace(void);
> >> > >
> >> > >  /* sheep log priorities, comliant with syslog spec */
> >> > > diff --git a/lib/logger.c b/lib/logger.c
> >> > > index 253163d..da1221b 100644
> >> > > --- a/lib/logger.c
> >> > > +++ b/lib/logger.c
> >> > > @@ -697,11 +697,15 @@ static bool check_gdb(void)
> >> > >   return system("which gdb > /dev/null") == 0;
> >> > >  }
> >> > >
> >> > > +#define STACK_POINTER    \
> >> > > + ((char *)__builtin_frame_address(0) + __SIZEOF_POINTER__ * 2)
> >> >
> >> > Doesn't this depend on the ABI of x86?
> >>
> >> I have no idea of other archs. I am not sure. But if this address is wrong, GDB
> >> just print nothing about the frames or variables.
> >
> > I think __builtin_frame_address is arch-netrual, but I didn't find out why we
> > need '+ __SIZEOF_POINTER__ * 2'. I get this by examining the address of
> > __builtin_frame_address and previous asm("esp") code.
> (char *)__builtin_frame_address(0)
> while http://gcc.gnu.org/onlinedocs/gcc/Return-Address.html said that
> This function should only be used with a nonzero argument for
> debugging purposes.

"Calling __builtin_frame_address with a value of 0 yields the frame address of the current function"

This is why I pass 0 for it.

Thanks
Yuan