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

Chuck Ebbert
2007-11-29T18:18:49Z

On 11/29/2007 01:09 PM, Linus Torvalds 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?
>
> No, %gs is untouched by the kernel, so it contains user space version, and
> getting the value directly from %gs looks correct.
>

But this is x86_64, where swapgs is done on kernel entry.