Messages in this thread | | | Subject | Re: [PATCH] x86: Use v8086_mode helper, trivial unification | From | Harvey Harrison <> | Date | Thu, 17 Jan 2008 18:21:02 -0800 |
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On Thu, 2008-01-17 at 20:36 -0500, H. Peter Anvin wrote: > Roland McGrath wrote: > > It's indeed true that &pt_regs is truly the esp value for x86-32 > > kernel-mode trap frames. Because this nonobvious calculation is > > only right for a kernel mode pt_regs and not for a user-mode one, > > I think it would be better to use a name for the inline/macro that > > makes this quite clear, rather than one so generic as "stack_addr". > > Indeed. This was certainly highly nonobvious in the current code. >
What do you think of:
/* * (unsigned long)regs looks strange, but it's correct for x86_32. x86_32 CPUs * don't save the ss and esp registers if the CPU is already in kernel mode * when it traps. So ®s happens to be esp. Valid only for kernel-mode * pt_regs. */ static inline unsigned long stack_pointer(struct pt_regs *regs) { #ifdef CONFIG_X86_32 return (unsigned long)regs; #else return regs->sp; #endif }
Harvey
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