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

[Roland McGrath]

> >  	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.


Thanks,
Roland
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