From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 07 Feb 2005 21:13:53 +0000 (GMT) Received: from alg138.algor.co.uk ([IPv6:::ffff:62.254.210.138]:41176 "EHLO mail.linux-mips.net") by linux-mips.org with ESMTP id ; Mon, 7 Feb 2005 21:13:30 +0000 Received: from dea.linux-mips.net (localhost.localdomain [127.0.0.1]) by mail.linux-mips.net (8.13.1/8.13.1) with ESMTP id j17L8TEC013864; Mon, 7 Feb 2005 21:08:29 GMT Received: (from ralf@localhost) by dea.linux-mips.net (8.13.1/8.13.1/Submit) id j17L8QmP013850; Mon, 7 Feb 2005 21:08:26 GMT Date: Mon, 7 Feb 2005 21:08:25 +0000 From: Ralf Baechle To: David Daney Cc: andreev , linux-mips@linux-mips.org Subject: Re: Strace doesn't work on linux-2.4.28 and later Message-ID: <20050207210825.GA6703@linux-mips.org> References: <41FF876B.3070407@niisi.msk.ru> <4207C142.6070804@avtrex.com> <4207C3E0.7070405@avtrex.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4207C3E0.7070405@avtrex.com> User-Agent: Mutt/1.4.1i Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 7187 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Mon, Feb 07, 2005 at 11:39:12AM -0800, David Daney wrote: > > offset("#define PT_SCRATCH0 ", struct pt_regs, pad0[4]); > > offset("#define PT_SCRATCH1 ", struct pt_regs, pad0[5]); > > > >I am thinking of testing a patch where I change them to: > > > > offset("#define PT_SCRATCH0 ", struct pt_regs, pad0[0]); > > offset("#define PT_SCRATCH1 ", struct pt_regs, pad0[1]); > > > >Any needed argument registers are already saved in and restored from the > >regs array so overwriting the stack area reserved for them should be OK. > > > I now think that is bogus reasoning as the first four slots can be > clobbered by the compiler. > > It seems that t2 must be saved somewhere in the regs list. I am not > sure what the problem with PT_R1(sp) was, but it seems like a good > candidate. Perhaps PT_R26 or PT_R27 (k0, k1) would be a better place to > store t2 as I don't think k0 or k1 are ever stored. I was always planning to backport the newer fix from 2.6 which is simply storing the value in a caller saved register. You now reminded me of that omission ;-) Patch below, Ralf Index: arch/mips/kernel/scall_o32.S =================================================================== RCS file: /home/cvs/linux/arch/mips/kernel/Attic/scall_o32.S,v retrieving revision 1.18.2.14 diff -u -r1.18.2.14 scall_o32.S --- arch/mips/kernel/scall_o32.S 25 Nov 2004 09:43:59 -0000 1.18.2.14 +++ arch/mips/kernel/scall_o32.S 7 Feb 2005 21:12:53 -0000 @@ -121,15 +121,14 @@ trace_a_syscall: SAVE_STATIC - sw t2, PT_SCRATCH0(sp) + move s0, sp jal syscall_trace - lw t2, PT_SCRATCH0(sp) lw a0, PT_R4(sp) # Restore argument registers lw a1, PT_R5(sp) lw a2, PT_R6(sp) lw a3, PT_R7(sp) - jalr t2 + jalr s0 li t0, -EMAXERRNO - 1 # error? sltu t0, t0, v0 Index: arch/mips/tools/offset.c =================================================================== RCS file: /home/cvs/linux/arch/mips/tools/Attic/offset.c,v retrieving revision 1.16.4.12 diff -u -r1.16.4.12 offset.c --- arch/mips/tools/offset.c 25 Nov 2004 09:43:59 -0000 1.16.4.12 +++ arch/mips/tools/offset.c 7 Feb 2005 21:12:53 -0000 @@ -12,7 +12,6 @@ #include #include #include -#include #include #include @@ -37,9 +36,6 @@ void output_ptreg_defines(void) { text("/* MIPS pt_regs offsets. */"); - offset("#define PT_SCRATCH0 ", struct pt_regs, pad0[4]); - offset("#define PT_SCRATCH1 ", struct pt_regs, pad0[5]); - offset("#define PT_R0 ", struct pt_regs, regs[0]); offset("#define PT_R1 ", struct pt_regs, regs[1]); offset("#define PT_R2 ", struct pt_regs, regs[2]); Index: arch/mips64/kernel/scall_64.S =================================================================== RCS file: /home/cvs/linux/arch/mips64/kernel/Attic/scall_64.S,v retrieving revision 1.20.2.20 diff -u -r1.20.2.20 scall_64.S --- arch/mips64/kernel/scall_64.S 25 Nov 2004 09:43:59 -0000 1.20.2.20 +++ arch/mips64/kernel/scall_64.S 7 Feb 2005 21:12:53 -0000 @@ -102,15 +102,14 @@ trace_a_syscall: SAVE_STATIC - sd t2, PT_SCRATCH0(sp) + move s0, t2 jal syscall_trace - ld t2, PT_SCRATCH0(sp) ld a0, PT_R4(sp) # Restore argument registers ld a1, PT_R5(sp) ld a2, PT_R6(sp) ld a3, PT_R7(sp) - jalr t2 + jalr s0 li t0, -EMAXERRNO - 1 # error? sltu t0, t0, v0 Index: arch/mips64/kernel/scall_n32.S =================================================================== RCS file: /home/cvs/linux/arch/mips64/kernel/Attic/scall_n32.S,v retrieving revision 1.2.2.17 diff -u -r1.2.2.17 scall_n32.S --- arch/mips64/kernel/scall_n32.S 25 Nov 2004 09:43:59 -0000 1.2.2.17 +++ arch/mips64/kernel/scall_n32.S 7 Feb 2005 21:12:53 -0000 @@ -106,15 +106,14 @@ trace_a_syscall: SAVE_STATIC - sd t2, PT_SCRATCH0(sp) + move s0, t2 jal syscall_trace - ld t2, PT_SCRATCH0(sp) ld a0, PT_R4(sp) # Restore argument registers ld a1, PT_R5(sp) ld a2, PT_R6(sp) ld a3, PT_R7(sp) - jalr t2 + jalr s0 li t0, -EMAXERRNO - 1 # error? sltu t0, t0, v0 Index: arch/mips64/kernel/scall_o32.S =================================================================== RCS file: /home/cvs/linux/arch/mips64/kernel/Attic/scall_o32.S,v retrieving revision 1.48.2.33 diff -u -r1.48.2.33 scall_o32.S --- arch/mips64/kernel/scall_o32.S 25 Nov 2004 09:43:59 -0000 1.48.2.33 +++ arch/mips64/kernel/scall_o32.S 7 Feb 2005 21:12:53 -0000 @@ -118,9 +118,8 @@ sd a6, PT_R10(sp) sd a7, PT_R11(sp) - sd t2, PT_SCRATCH0(sp) + move s0, t2 jal syscall_trace - ld t2, PT_SCRATCH0(sp) ld a0, PT_R4(sp) # Restore argument registers ld a1, PT_R5(sp) @@ -129,7 +128,7 @@ ld a4, PT_R8(sp) ld a5, PT_R9(sp) - jalr t2 + jalr s0 li t0, -EMAXERRNO - 1 # error? sltu t0, t0, v0