Messages in this thread Patch in this message | | | Date | Tue, 21 Jan 2014 11:20:04 +0000 | From | Will Deacon <> | Subject | Re: [PATCH] ARM64: perf: support dwarf unwinding in compat mode |
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On Mon, Jan 20, 2014 at 05:05:14PM +0000, Jean Pihet wrote: > Hi Will, > > Here is an updated version of the change, which uses compat_sp at only > one place. > The drawback is that compat_user_mode is checked when calling > compat_user_stack_pointer, which seems unnecessary. Unfortunately the > check is not optimized out by the complier as I could check with > objdump -S. > > What do you think?
I think that's cleaner and really wouldn't worry about the couple of extra instructions.
Cheers,
Will
> diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h > index fda2704..e71f81f 100644 > --- a/arch/arm64/include/asm/compat.h > +++ b/arch/arm64/include/asm/compat.h > @@ -228,7 +228,7 @@ static inline compat_uptr_t ptr_to_compat(void __user *uptr) > return (u32)(unsigned long)uptr; > } > > -#define compat_user_stack_pointer() (current_pt_regs()->compat_sp) > +#define compat_user_stack_pointer() (user_stack_pointer(current_pt_regs())) > > static inline void __user *arch_compat_alloc_user_space(long len) > { > diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h > index fbb0020..86d5b54 100644 > --- a/arch/arm64/include/asm/ptrace.h > +++ b/arch/arm64/include/asm/ptrace.h > @@ -133,7 +133,7 @@ struct pt_regs { > (!((regs)->pstate & PSR_F_BIT)) > > #define user_stack_pointer(regs) \ > - ((regs)->sp) > + (!compat_user_mode(regs)) ? ((regs)->sp) : ((regs)->compat_sp) > > /* > * Are the current registers suitable for user mode? (used to maintain
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