From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 7C2D8B7B76 for ; Thu, 8 Oct 2009 08:18:30 +1100 (EST) Subject: Re: [PATCH 4/6] 8xx: Tag DAR with 0x00f0 to catch buggy instructions. From: Benjamin Herrenschmidt To: Joakim Tjernlund In-Reply-To: <1254948364-30074-5-git-send-email-Joakim.Tjernlund@transmode.se> References: <1254948364-30074-1-git-send-email-Joakim.Tjernlund@transmode.se> <1254948364-30074-2-git-send-email-Joakim.Tjernlund@transmode.se> <1254948364-30074-3-git-send-email-Joakim.Tjernlund@transmode.se> <1254948364-30074-4-git-send-email-Joakim.Tjernlund@transmode.se> <1254948364-30074-5-git-send-email-Joakim.Tjernlund@transmode.se> Content-Type: text/plain; charset="UTF-8" Date: Thu, 08 Oct 2009 08:18:21 +1100 Message-Id: <1254950301.2409.11.camel@pasglop> Mime-Version: 1.0 Cc: Scott Wood , "linuxppc-dev@ozlabs.org" , Rex Feany List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2009-10-07 at 22:46 +0200, Joakim Tjernlund wrote: > dcbz, dcbf, dcbi, dcbst and icbi do not set DAR when they > cause a DTLB Error. Dectect this by tagging DAR with 0x00f0 > at every exception exit that modifies DAR. > Test for DAR=0x00f0 in DataTLBError and bail > to handle_page_fault(). Why not -1 ? :-) Ben. > --- > arch/powerpc/kernel/head_8xx.S | 19 ++++++++++++++++--- > 1 files changed, 16 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S > index 3cf1289..37aa7d0 100644 > --- a/arch/powerpc/kernel/head_8xx.S > +++ b/arch/powerpc/kernel/head_8xx.S > @@ -206,6 +206,8 @@ MachineCheck: > EXCEPTION_PROLOG > mfspr r4,SPRN_DAR > stw r4,_DAR(r11) > + li r5,0x00f0 > + mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */ > mfspr r5,SPRN_DSISR > stw r5,_DSISR(r11) > addi r3,r1,STACK_FRAME_OVERHEAD > @@ -222,6 +224,8 @@ DataAccess: > stw r10,_DSISR(r11) > mr r5,r10 > mfspr r4,SPRN_DAR > + li r10,0x00f0 > + mtspr SPRN_DAR,r10 /* Tag DAR, to be used in DTLB Error */ > EXC_XFER_EE_LITE(0x300, handle_page_fault) > > /* Instruction access exception. > @@ -244,6 +248,8 @@ Alignment: > EXCEPTION_PROLOG > mfspr r4,SPRN_DAR > stw r4,_DAR(r11) > + li r5,0x00f0 > + mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */ > mfspr r5,SPRN_DSISR > stw r5,_DSISR(r11) > addi r3,r1,STACK_FRAME_OVERHEAD > @@ -427,6 +433,7 @@ DataStoreTLBMiss: > * of the MMU. > */ > 2: li r11, 0x00f0 > + mtspr SPRN_DAR,r11 /* Tag DAR */ > rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ > DO_8xx_CPU6(0x3d80, r3) > mtspr SPRN_MD_RPN, r10 /* Update TLB entry */ > @@ -467,10 +474,14 @@ DataTLBError: > stw r10, 0(r0) > stw r11, 4(r0) > > + mfspr r10, SPRN_DAR > + cmpwi cr0, r10, 0x00f0 > + beq- 2f /* must be a buggy dcbX, icbi insn. */ > + > /* First, make sure this was a store operation. > */ > - mfspr r10, SPRN_DSISR > - andis. r11, r10, 0x4000 /* no translation */ > + mfspr r11, SPRN_DSISR > + andis. r11, r11, 0x4000 /* no translation */ > bne 2f /* branch if set */ > > /* The EA of a data TLB miss is automatically stored in the MD_EPN > @@ -489,7 +500,8 @@ DataTLBError: > * are initialized in mapin_ram(). This will avoid the problem, > * assuming we only use the dcbi instruction on kernel addresses. > */ > - mfspr r10, SPRN_DAR > + > + /* DAR is in r10 already */ > rlwinm r11, r10, 0, 0, 19 > ori r11, r11, MD_EVALID > mfspr r10, SPRN_M_CASID > @@ -539,6 +551,7 @@ DataTLBError: > * of the MMU. > */ > li r11, 0x00f0 > + mtspr SPRN_DAR,r11 /* Tag DAR */ > rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ > DO_8xx_CPU6(0x3d80, r3) > mtspr SPRN_MD_RPN, r10 /* Update TLB entry */