Re: [patch] Fix i386 memory-by-register access on amd64

[Mark Kettenis <mark.kettenis@xs4all.nl>]

> Date: Wed, 29 Apr 2009 12:27:19 +0200
> From: Jan Kratochvil <jan.kratochvil@redhat.com>
> 
> Hi,
> 
> original bugreport:
> 	https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=181390
> 
> (gdb) x/x $esp
> 0xffffce70:     0x00000001
> (gdb) x/x $ebx
> 0xffffce70:     Cannot access memory at address 0xffffce70
> (gdb) x/x 0xffffce70
> 0xffffce70:     0x00000001
> 
> One point is there should have been printed this error message instead:
> 0xffffffffffffce70:     Cannot access memory at address 0xffffffffffffce70
> but this problem is just a consequence of paddress() truncating the printed
> address width.  This printing issue is unrelated to the patch below.
> 
> The error happens because $ebx is considered signed while $esp unsigned, as
> initialized by i386_register_type (or also amd64_register_type).  Therefore
> the address width should be cut to the right size at the right point of
> processing, I hope I caught (one of) such points.

I'm not sure this is the right solution.  On 64-bit machines where
addresses are signed I think we actually want the sign extension to
happen.

> 2006-09-28  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	Fix signed 32bit inferior registers on 64bit GDB.
> 	* gdb/value.c (value_as_address): Make it static, rename it to ...
> 	(value_as_address1): ... this function.
> 	(value_as_address): New function.

What is your motiviation for using a wrapper function?