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

[Liu Yuan]

On Mon, Jul 29, 2013 at 04:18:05PM +0800, YunQiang Su wrote:
> On Mon, Jul 29, 2013 at 4:06 PM, Hitoshi Mitake
> <mitake.hitoshi at gmail.com> 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 don't know ABIs of other architectures supported in YunQiang's
> > # patch. Do you know their ABIs?
> Will use backtrace(3) be a good idea?

We indeed use backtrace(3) for sd_backtrace(), this stack pointer is needed
to dump stack frame with more information, such as local variables.

Thanks
Yuan