Re: [PATCH 1/1] [PPC] 8xx swap bug-fix
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2008-02-05 07:37:34
On Sat, 2008-02-02 at 10:47 +0300, Yuri Tikhonov wrote:
Hello, Here is the patch which makes Linux-2.6 swap routines operate correctly on the ppc-8xx-based machines.
Best is to just remove writeback completely and let the generic code handle it. Ben.
quoted hunk ↗ jump to hunk
Signed-off-by: Yuri Tikhonov <redacted> --diff --git a/arch/ppc/kernel/head_8xx.S b/arch/ppc/kernel/head_8xx.S index eb8d26f..321bda2 100644 --- a/arch/ppc/kernel/head_8xx.S +++ b/arch/ppc/kernel/head_8xx.S@@ -329,8 +329,18 @@ InstructionTLBMiss: mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ lwz r10, 0(r11) /* Get the pte */ +#ifdef CONFIG_SWAP + /* do not set the _PAGE_ACCESSED bit of a non-present page */ + andi. r11, r10, _PAGE_PRESENT + beq 4f + ori r10, r10, _PAGE_ACCESSED + mfspr r11, SPRN_MD_TWC /* get the pte address again */ + stw r10, 0(r11) +4: +#else ori r10, r10, _PAGE_ACCESSED stw r10, 0(r11) +#endif /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 21, 22 and 28 must be clear.@@ -395,8 +405,17 @@ DataStoreTLBMiss: DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 - mfspr r11, SPRN_MD_TWC /* get the pte address again */ +#ifdef CONFIG_SWAP + /* do not set the _PAGE_ACCESSED bit of a non-present page */ + andi. r11, r10, _PAGE_PRESENT + beq 4f + ori r10, r10, _PAGE_ACCESSED +4: + /* and update pte in table */ +#else ori r10, r10, _PAGE_ACCESSED +#endif + mfspr r11, SPRN_MD_TWC /* get the pte address again */ stw r10, 0(r11) /* The Linux PTE won't go exactly into the MMU TLB.@@ -575,7 +594,16 @@ DataTLBError: /* Update 'changed', among others. */ +#ifdef CONFIG_SWAP + ori r10, r10, _PAGE_DIRTY|_PAGE_HWWRITE + /* do not set the _PAGE_ACCESSED bit of a non-present page */ + andi. r11, r10, _PAGE_PRESENT + beq 4f + ori r10, r10, _PAGE_ACCESSED +4: +#else ori r10, r10, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE +#endif mfspr r11, SPRN_MD_TWC /* Get pte address again */ stw r10, 0(r11) /* and update pte in table */diff --git a/include/asm-ppc/pgtable.h b/include/asm-ppc/pgtable.h index c159315..76717ff 100644 --- a/include/asm-ppc/pgtable.h +++ b/include/asm-ppc/pgtable.h@@ -341,14 +341,6 @@ extern unsigned long ioremap_bot, ioremap_base; #define _PMD_PAGE_MASK 0x000c #define _PMD_PAGE_8M 0x000c -/* - * The 8xx TLB miss handler allegedly sets _PAGE_ACCESSED in the PTE - * for an address even if _PAGE_PRESENT is not set, as a performance - * optimization. This is a bug if you ever want to use swap unless - * _PAGE_ACCESSED is 2, which it isn't, or unless you have 8xx-specific - * definitions for __swp_entry etc. below, which would be gross. - * -- paulus - */ #define _PTE_NONE_MASK _PAGE_ACCESSED #else /* CONFIG_6xx */