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

[YunQiang Su]

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.
>
> Thanks
> Yuan



-- 
YunQiang Su