From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gw1.transmode.se (gw1.transmode.se [195.58.98.146]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 55DD0B72BB for ; Mon, 10 Oct 2011 22:30:38 +1100 (EST) From: Joakim Tjernlund To: linuxppc-dev , Scott Wood , Willy Tarreau , Dan Malek Subject: [PATCH 05/14] 8xx: Update TLB asm so it behaves as linux mm expects. Date: Mon, 10 Oct 2011 13:30:11 +0200 Message-Id: <1318246220-4839-6-git-send-email-Joakim.Tjernlund@transmode.se> In-Reply-To: <1318246220-4839-1-git-send-email-Joakim.Tjernlund@transmode.se> References: <1318246220-4839-1-git-send-email-Joakim.Tjernlund@transmode.se> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Update the TLB asm to make proper use of _PAGE_DIRTY and _PAGE_ACCESSED. Get rid of _PAGE_HWWRITE too. Pros: - PRESENT is copied to ACCESSED, fixing accounting - DIRTY is mapped to 0x100, the changed bit, and is set directly when a page has been made dirty. - Proper RO/RW mapping of user space. - Free up 2 SW TLB bits in the linux pte(add back _PAGE_WRITETHRU ?) - kernel RO/user NA support. Not sure this is really needed, would save a few insn if not required. Cons: - A few more instructions in the DTLB Miss routine. Signed-off-by: Joakim Tjernlund --- arch/ppc/kernel/head_8xx.S | 53 ++++++++++++++++++++++++++----------------- include/asm-ppc/pgtable.h | 15 +++++------ 2 files changed, 39 insertions(+), 29 deletions(-) diff --git a/arch/ppc/kernel/head_8xx.S b/arch/ppc/kernel/head_8xx.S index 9d8a1b5..c9770b6 100644 --- a/arch/ppc/kernel/head_8xx.S +++ b/arch/ppc/kernel/head_8xx.S @@ -369,25 +369,27 @@ InstructionTLBMiss: */ tophys(r21,r21) ori r21,r21,1 /* Set valid bit */ - beq- 2f /* If zero, don't try to find a pte */ DO_8xx_CPU6(0x2b80, r3) mtspr MI_TWC, r21 /* Set segment attributes */ + beq- 2f /* If zero, don't try to find a pte */ DO_8xx_CPU6(0x3b80, r3) mtspr MD_TWC, r21 /* Load pte table base address */ mfspr r21, MD_TWC /* ....and get the pte address */ lwz r20, 0(r21) /* Get the pte */ - ori r20, r20, _PAGE_ACCESSED - stw r20, 0(r21) - +#if 1 + /* if !swap, you can delete this */ + rlwimi r20, r20, 5, _PAGE_PRESENT<<5 /* Copy PRESENT to ACCESSED */ + stw r20, 0(r21) /* Update pte */ +#endif /* The Linux PTE won't go exactly into the MMU TLB. - * Software indicator bits 21, 22 and 28 must be clear. + * Software indicator bits 21 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. */ 2: li r21, 0x00f0 - rlwimi r20, r21, 0, 24, 28 /* Set 24-27, clear 28 */ + rlwimi r20, r21, 0, 0x07f8 /* Set 24-27, clear 21-23,28 */ DO_8xx_CPU6(0x2d80, r3) mtspr MI_RPN, r20 /* Update TLB entry */ @@ -444,12 +446,25 @@ DataStoreTLBMiss: DO_8xx_CPU6(0x3b80, r3) mtspr MD_TWC, r21 - mfspr r21, MD_TWC /* get the pte address again */ - ori r20, r20, _PAGE_ACCESSED - stw r20, 0(r21) +#if 1 + /* if !swap, you can delete this */ + mfspr r21, MD_TWC /* get the pte address */ + rlwimi r20, r20, 5, _PAGE_PRESENT<<5 /* Copy PRESENT to ACCESSED */ + stw r20, 0(r21) /* Update pte */ +#endif + + /* Honour kernel RO, User NA */ + /* 0x200 == Extended encoding, bit 22 */ + /* r20 |= (r20 & _PAGE_USER) >> 2 */ + rlwimi r20, r20, 32-2, 0x200 + /* r21 = (r20 & _PAGE_RW) >> 1 */ + rlwinm r21, r20, 32-1, 0x200 + or r20, r21, r20 + /* invert RW and 0x200 bits */ + xori r20, r20, _PAGE_RW | 0x200 /* The Linux PTE won't go exactly into the MMU TLB. - * Software indicator bits 21, 22 and 28 must be clear. + * Software indicator bits 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. @@ -496,11 +511,12 @@ DataTLBError: stw r20, 0(r0) stw r21, 4(r0) - /* First, make sure this was a store operation. - */ mfspr r20, DSISR - andis. r21, r20, 0x0200 /* If set, indicates store op */ - beq 2f + andis. r21, r20, 0x4800 /* !translation or protection */ + bne- 2f + /* Only Change bit left now, do it here as it is faster + * than trapping to the C fault handler. + */ /* The EA of a data TLB miss is automatically stored in the MD_EPN * register. The EA of a data TLB error is automatically stored in @@ -550,17 +566,12 @@ DataTLBError: mfspr r21, MD_TWC /* ....and get the pte address */ lwz r20, 0(r21) /* Get the pte */ - andi. r21, r20, _PAGE_RW /* Is it writeable? */ - beq 2f /* Bail out if not */ - - /* Update 'changed', among others. - */ ori r20, r20, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE - mfspr r21, MD_TWC /* Get pte address again */ stw r20, 0(r21) /* and update pte in table */ + xori r20, r20, _PAGE_RW /* RW bit is inverted */ /* The Linux PTE won't go exactly into the MMU TLB. - * Software indicator bits 21, 22 and 28 must be clear. + * Software indicator bits 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. diff --git a/include/asm-ppc/pgtable.h b/include/asm-ppc/pgtable.h index 71b2165..2ba37d3 100644 --- a/include/asm-ppc/pgtable.h +++ b/include/asm-ppc/pgtable.h @@ -298,21 +298,20 @@ extern unsigned long vmalloc_start; #define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */ #define _PAGE_SHARED 0x0004 /* No ASID (context) compare */ -/* These five software bits must be masked out when the entry is loaded - * into the TLB. +/* These three software bits must be masked out when the entry is loaded + * into the TLB, 2 SW bits free. */ #define _PAGE_EXEC 0x0008 /* software: i-cache coherency required */ #define _PAGE_GUARDED 0x0010 /* software: guarded access */ -#define _PAGE_DIRTY 0x0020 /* software: page changed */ -#define _PAGE_RW 0x0040 /* software: user write access allowed */ -#define _PAGE_ACCESSED 0x0080 /* software: page referenced */ +#define _PAGE_ACCESSED 0x0020 /* software: page referenced */ /* Setting any bits in the nibble with the follow two controls will * require a TLB exception handler change. It is assumed unused bits - * are always zero. + * are always zero, encoding(bit 22). */ -#define _PAGE_HWWRITE 0x0100 /* h/w write enable: never set in Linux PTE */ -#define _PAGE_USER 0x0800 /* One of the PP bits, the other is USER&~RW */ +#define _PAGE_DIRTY 0x0100 /* Changed: page changed */ +#define _PAGE_RW 0x0400 /* PP lsb(bit 21), user write access allowed */ +#define _PAGE_USER 0x0800 /* PP msb(bit 20), user access allowed */ #define _PMD_PRESENT PAGE_MASK #define _PMD_PAGE_MASK 0x000c -- 1.7.3.4