On Thu, Jan 16, 2014 at 12:26:53PM +0000, Jean Pihet wrote:
On 16 January 2014 12:56, Will Deacon will.deacon@arm.com wrote:
In your previous series, compat backtracing is actually split out into a separate function (compat_user_backtrace), so it would be more consistent to have a compat_user_stack_pointer macro, rather than add this check here.
Do you mean this change instead?
I don't think so...
diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 569b2187..9b88d2e 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -185,7 +185,8 @@ static inline bool arch_perf_have_user_stack_dump(void) return true; }
-#define perf_user_stack_pointer(regs) user_stack_pointer(regs) +#define perf_user_stack_pointer(regs) \
(!compat_user_mode(regs)) ? ((regs)->sp) : ((regs)->compat_sp)
This doesn't belong in core code; compat_user_mode and the fields of regs are arm64-specific. So I suppose you need to rework your original patch to call compat_user_stack_pointer (which we already define in compat.h for arm64) if compat_user_mode(regs)).
The problem there is the inconsistency with respect to the regs argument:
user_stack_pointer(regs) // Returns user stack pointer for regs current_user_stack_pointer() // Returns current user stack pointer compat_user_stack_pointer() // Doesn't take a regs argument!
On top of that, x86 treats those last two functions differently when current is a compat task.
So the simplest thing would be to make compat_user_stack_pointer expand to user_stack_pointer(current_pt_regs()) on arm64 and merge that in with your original patch fixing user_stack_pointer.
Will