From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26665 invoked by alias); 26 Nov 2001 20:43:36 -0000 Mailing-List: contact gdb-patches-help@sourceware.cygnus.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 26597 invoked from network); 26 Nov 2001 20:43:33 -0000 Received: from unknown (HELO nevyn.them.org) (128.2.145.6) by hostedprojects.ges.redhat.com with SMTP; 26 Nov 2001 20:43:33 -0000 Received: from drow by nevyn.them.org with local (Exim 3.32 #1 (Debian)) id 168SbT-0002M4-00; Mon, 26 Nov 2001 15:43:47 -0500 Date: Tue, 13 Nov 2001 08:19:00 -0000 From: Daniel Jacobowitz To: Andrew Cagney Cc: Jakub Jelinek , gdb-patches@sources.redhat.com Subject: Re: [PATCH] Fix sparc-*-linux register fetching/storing Message-ID: <20011126154347.A8899@nevyn.them.org> Mail-Followup-To: Andrew Cagney , Jakub Jelinek , gdb-patches@sources.redhat.com References: <20011123154220.A562@sunsite.ms.mff.cuni.cz> <20011125020147.A32180@nevyn.them.org> <20011125113201.C4087@devserv.devel.redhat.com> <20011125115446.A15038@nevyn.them.org> <3C02795A.9000104@cygnus.com> <20011126150435.A6212@nevyn.them.org> <3C02A761.4030003@cygnus.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3C02A761.4030003@cygnus.com> User-Agent: Mutt/1.3.23i X-SW-Source: 2001-11/txt/msg00242.txt.bz2 On Mon, Nov 26, 2001 at 03:34:41PM -0500, Andrew Cagney wrote: > > >>That sounds like overkill. If you need to be doing sign/zero extension > >>stuff then I'd be looking at explicit calls to extract_signed_integer() > >>and/or extract_unsigned_integer() in the nat code. > >> > >>A sequence like: > >> > >>void *buf = alloca (MAX_REGISTER_RAW_SIZE); > >>regcache_collect (my reg, buf); > >>LONGEST val = extract_unsigned_integer (buf, REGISTER_RAW_SIZE(my reg)); > >>store_unsigned_integer (dest, dest size, val); > >> > >>should insulate it from the current problems. > > > > > >But won't we want this absolutely every time we extract a CORE_ADDR? > >And for that matter, I'm talking about getting a target memory address > >out of a register; is store_*signed_integer right for that? Is there > >an extract_pointer or so? > > In *-nat.c? Now I'm confused :-) > > Doesn't the *-nat.c file just copy raw register bytes between the > regcache and the /proc or ptrace() interface? The only complication I > could see is if someone used 32 bit ptrace calls to get the values for a > regcache that had space for 64 bit registers - the above code snipit > would handle that. > > The reason for suggesting extract/store signed/unsigned integer is that > they have clear, machine independant, semantics that work on > uninterpreted (well apart from assuming they are integers :-) bytes. Well, remember that we can't cast things to (CORE_ADDR *) reliably. With --enable-64-bit-bfd, that has a tendency to turn into a 'long long *'. What was happening was reading $sp out of the regcache, and then passing it to target_read_memory. If this were MIPS, I think we'd have to sign extend there, for "correctness". We'd eventually truncate it back down with a cast in infptrace.c, though. I just don't like duplicating that above code sequence everywhere we get a pointer out of a register into a CORE_ADDR. It seems like a very frequent operation, in nat or in tdep. -- Daniel Jacobowitz Carnegie Mellon University MontaVista Software Debian GNU/Linux Developer From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Jacobowitz To: Andrew Cagney Cc: Jakub Jelinek , gdb-patches@sources.redhat.com Subject: Re: [PATCH] Fix sparc-*-linux register fetching/storing Date: Mon, 26 Nov 2001 12:43:00 -0000 Message-ID: <20011126154347.A8899@nevyn.them.org> References: <20011123154220.A562@sunsite.ms.mff.cuni.cz> <20011125020147.A32180@nevyn.them.org> <20011125113201.C4087@devserv.devel.redhat.com> <20011125115446.A15038@nevyn.them.org> <3C02795A.9000104@cygnus.com> <20011126150435.A6212@nevyn.them.org> <3C02A761.4030003@cygnus.com> X-SW-Source: 2001-11/msg00457.html Message-ID: <20011126124300.XiERSxi2JbdBoqQNmM1D96sca4MFVI8pkBAQj5RAUH4@z> On Mon, Nov 26, 2001 at 03:34:41PM -0500, Andrew Cagney wrote: > > >>That sounds like overkill. If you need to be doing sign/zero extension > >>stuff then I'd be looking at explicit calls to extract_signed_integer() > >>and/or extract_unsigned_integer() in the nat code. > >> > >>A sequence like: > >> > >>void *buf = alloca (MAX_REGISTER_RAW_SIZE); > >>regcache_collect (my reg, buf); > >>LONGEST val = extract_unsigned_integer (buf, REGISTER_RAW_SIZE(my reg)); > >>store_unsigned_integer (dest, dest size, val); > >> > >>should insulate it from the current problems. > > > > > >But won't we want this absolutely every time we extract a CORE_ADDR? > >And for that matter, I'm talking about getting a target memory address > >out of a register; is store_*signed_integer right for that? Is there > >an extract_pointer or so? > > In *-nat.c? Now I'm confused :-) > > Doesn't the *-nat.c file just copy raw register bytes between the > regcache and the /proc or ptrace() interface? The only complication I > could see is if someone used 32 bit ptrace calls to get the values for a > regcache that had space for 64 bit registers - the above code snipit > would handle that. > > The reason for suggesting extract/store signed/unsigned integer is that > they have clear, machine independant, semantics that work on > uninterpreted (well apart from assuming they are integers :-) bytes. Well, remember that we can't cast things to (CORE_ADDR *) reliably. With --enable-64-bit-bfd, that has a tendency to turn into a 'long long *'. What was happening was reading $sp out of the regcache, and then passing it to target_read_memory. If this were MIPS, I think we'd have to sign extend there, for "correctness". We'd eventually truncate it back down with a cast in infptrace.c, though. I just don't like duplicating that above code sequence everywhere we get a pointer out of a register into a CORE_ADDR. It seems like a very frequent operation, in nat or in tdep. -- Daniel Jacobowitz Carnegie Mellon University MontaVista Software Debian GNU/Linux Developer