Re: PTRACE_GET_THREAD_AREA

[Roland McGrath]

> 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.