Re: [patch 1/1] ptrace POKEUSR: add comment about the DR7 check.

[Andi Kleen]

On Wed, Nov 03, 2004 at 12:20:26AM +0100, blaisorblade_spam@xxxxxxxx wrote:
> But since the original ia32 emulation code has this comment:
> 
> 	/* You are not expected to understand this ... I don't neither. */

That was a joke, I actually went through the bits.

> 
> I am dubious that the code in ptrace32.c is wrong: does x86_64 supports
> 8byte-wide watchpoints in 32-bit emulation? I've checked the AMD manual Vol.
> 2 (no. 24593), which says that to set the length to 8 bits "long mode must be
> enabled". This means, actually, that the current code is safe, notwithstanding

Yes, it does AFAIK. "long mode" just refers to the state of the whole
system.

>  			ret = 0;
>  			break;
>  		case offsetof(struct user, u_debugreg[7]):
> +			/* See arch/i386/kernel/ptrace.c for an explaination of
> +			 * this awkward check.*/

You have a typo there.

-Andi

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