Messages in this thread | | | Date | Thu, 29 Nov 2007 10:23:05 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 current task |
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Chuck Ebbert wrote: > 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. >
For i386-x86_64 sharing, getting to the user segments probably should be macroized. I'm thinking something like get_user_[cs|ds|es|fs|gs|ss](thread) in <asm/processor.h> doing the appropriate thing for different configurations.
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