Re: [PATCH] uprobes/core: handle breakpoint and signal step exception.

[Srikar Dronamraju <srikar@linux.vnet.ibm.com>]

> >  
> >  #include <linux/kdebug.h>
> >  #include <asm/insn.h>
> >  
> > +#ifdef CONFIG_X86_32
> > +#define is_32bit_app(tsk) 1
> > +#else
> > +#define is_32bit_app(tsk) (test_tsk_thread_flag(tsk, TIF_IA32))
> > +#endif
> 
> Small detail, we prefer to use this variant:
> 
> #ifdef X
> # define foo()
> #else
> # define bar()
> #endif
> 
> to give the construct more visual structure.
> 
> Also, please put it into asm/compat.h and use it at other places 
> within arch/x86/ as well, there's half a dozen similar patterns 
> of TIP_IA32 tests in arch/x86/. Please make this a separate 
> patch, preceding this patch.

I am facing a problem doing the above.
I did some changes in arch/x86/kernel/signal.c and included compat.h 
and compilation fails on tip tree that the commit 
d1a797f388

In file included from ../arch/x86/kernel/signal.c:42:
../arch/x86/include/asm/compat.h: In function ‘arch_compat_alloc_user_space’:
../arch/x86/include/asm/compat.h:238: error: ‘old_rsp’ undeclared (first use in this function)
../arch/x86/include/asm/compat.h:238: error: (Each undeclared identifier is reported only once
../arch/x86/include/asm/compat.h:238: error: for each function it appears in.)
../arch/x86/include/asm/compat.h:238: warning: type defaults to ‘int’ in declaration of ‘pfo_ret__’            


I see old_rsp declared only under CONFIG_X86_64 in asm/processor.h 

The below helps resolve the problem.
---------
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 9c9b6dc..147e790 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -233,9 +233,11 @@ static inline void __user *arch_compat_alloc_user_space(long len)
 
 	if (test_thread_flag(TIF_IA32)) {
 		sp = task_pt_regs(current)->sp;
+#ifdef CONFIG_X86_64
 	} else {
 		/* -128 for the x32 ABI redzone */
 		sp = __this_cpu_read(old_rsp) - 128;
+#endif
 	}
 
 	return (void __user *)round_down(sp - len, 16);


-----------

But I wanted to check if there is any reason why we cant include asm/compat.h in arch/x86/kernel/signal.c.

-- 
Thanks and Regards
Srikar