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Date: Mon, 13 Jan 2003 19:15:00 -0800
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From: Roland McGrath <roland@redhat.com>
To: theowl@freemail.hu
Cc: linux-kernel@vger.kernel.org
Subject: Re: PTRACE_GET_THREAD_AREA
In-Reply-To: theowl@freemail.hu's message of  Monday, 13 January 2003 12:37:04 +0100 <3E22B2F0.31397.E719685@localhost>
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> i've just seen your patch submitted to 2.5 and i think there's a mistake
> in there. this:
> 
> #define GET_32BIT(desc)		(((desc)->b >> 23) & 1)
> 
> should be
> 
> #define GET_32BIT(desc)		(((desc)->b >> 22) & 1)
> 
> i.e., bit 22 determines the segment bitness (default address/operand
> size), whereas bit 23 determines the granularity used to interpret the
> segment limit.

Those macros in my patch are copied directly from process.c where
get_thread_area is implemented.  Since the purpose of
PTRACE_GET_THREAD_AREA is to match what get_thread_area does, it's correct
that it match.  

But I think you are right that the definition is wrong.  It's obviously
suspect that two things are defined using the same bit:

#define GET_32BIT(desc)		(((desc)->b >> 23) & 1)
#define GET_LIMIT_PAGES(desc)	(((desc)->b >> 23) & 1)

This should be fixed in both process.c and ptrace.c together.
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