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

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Date:	Thu, 29 Nov 2007 12:34:28 -0500
From:	Chuck Ebbert <cebbert@...hat.com>
To:	Roland McGrath <roland@...hat.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH x86/mm 6/6] x86-64 ia32 ptrace get/putreg32 current task

On 11/28/2007 07:42 PM, Roland McGrath wrote:
> --- a/arch/x86/ia32/ptrace32.c
> +++ b/arch/x86/ia32/ptrace32.c
> @@ -48,19 +48,27 @@ static int putreg32(struct task_struct *child, unsigned regno, u32 val)
>  		if (val && (val & 3) != 3)
>  			return -EIO;
>  		child->thread.fsindex = val & 0xffff;
> +		if (child == current)
> +			loadsegment(fs, child->thread.fsindex);
>  		break;
>  	case offsetof(struct user32, regs.gs):
>  		if (val && (val & 3) != 3)
>  			return -EIO;
>  		child->thread.gsindex = val & 0xffff;
> +		if (child == current)
> +			load_gs_index(child->thread.gsindex);
>  		break;
>  	case offsetof(struct user32, regs.ds):
>  		if (val && (val & 3) != 3)
>  			return -EIO;
>  		child->thread.ds = val & 0xffff;
> +		if (child == current)
> +			loadsegment(ds, child->thread.ds);
>  		break;
>  	case offsetof(struct user32, regs.es):
>  		child->thread.es = val & 0xffff;
> +		if (child == current)
> +			loadsegment(es, child->thread.ds);

                                        child->thread.es ??

> @@ -129,15 +137,23 @@ static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
>  	switch (regno) {
>  	case offsetof(struct user32, regs.fs):
>  		*val = child->thread.fsindex;
> +		if (child == current)
> +			asm("movl %%fs,%0" : "=r" (*val));
>  		break;
>  	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?
-
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