Re: [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 current task

[Chuck Ebbert]

On 11/29/2007 05:21 PM, Roland McGrath wrote:
>>>  	case offsetof(struct user32, regs.gs):
>>>  		*val = child->thread.gsindex;
>>> +		if (child == current)
>>> +			asm("movl %%gs,%0" : "=r" (*val));
>> Won't this return the kernel's GS instead of the user's?
> [...]
>> But this is x86_64, where swapgs is done on kernel entry.
> 
> As I understand it, and from what the documentation I have says, swapgs has
> nothing to do with the %gs selector.  It affects the "GS base register",
> i.e. the MSR.
> 

Yep, I confused the GS selector with the base address in the descriptor.
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