RE: [PATCH 2/2] amd64-linux: expose system register FS_BASE and GS_BASE for Linux.

["Tedeschi, Walfred" <walfred.tedeschi@intel.com>]

-----Original Message-----
From: gdb-patches-owner@sourceware.org [mailto:gdb-patches-owner@sourceware.org] On Behalf Of Gary Benson
Sent: Thursday, November 10, 2016 12:36 PM
To: Tedeschi, Walfred <walfred.tedeschi@intel.com>
Cc: palves@redhat.com; eliz@gnu.org; brobecker@adacore.com; gdb-patches@sourceware.org
Subject: Re: [PATCH 2/2] amd64-linux: expose system register FS_BASE and GS_BASE for Linux.

Walfred Tedeschi wrote:
> This patch allows examination of the registers FS_BASE and GS_BASE for 
> Linux Systems running on 64bit. Tests for simple read and write of the 
> new registers is also added with this patch.

I tried to add this support a while back and failed, so naturally I think this is amazing--thank you for doing it!

> diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c index 
> 3f2a92b..a8a0b79 100644
> --- a/gdb/amd64-linux-tdep.c
> +++ b/gdb/amd64-linux-tdep.c
> @@ -103,7 +103,14 @@ int amd64_linux_gregset_reg_offset[] =
>    -1, -1, -1, -1, -1, -1, -1, -1,
>    -1, -1, -1, -1, -1, -1, -1, -1,
>    -1, -1, -1, -1, -1, -1, -1, -1,
> +  /* System register added at the end.  */ #ifdef 
> +HAVE_STRUCT_USER_REGS_STRUCT_FS_BASE
> +  21 * 8,  22 * 8,		/* fs_base and gs_base.  */
> +#else
> +  -1, -1,			/* fs_base and gs_base.  */
> +#endif
>    15 * 8			      /* "orig_rax" */
> +
>  };
>  

>  

What is the meaning of the comment?  And why did you add the new fields before orig_rax?  I'm not disputing what you've done, I'd just like to understand it.

I'm not a maintainer so can't approve this, but everything looks right about it in terms of formatting, etc.

Thanks,
Gary


Gary,

Thanks for your review! Usually the orig_rax was left as last register, i have tried to follow that.
On the other hand, since we are adding new szstem registers there is no reason to keep specifically orig_rax at the end.

I will move them around. 

Thanks again,
/Fred
--
http://gbenson.net/
Intel Deutschland GmbH
Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
Managing Directors: Christin Eisenschmid, Christian Lamprechter
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928