From fe11dc3f9628e5393e932567b7e29d35cbbad136 Mon Sep 17 00:00:00 2001 From: Joakim Tjernlund Date: Fri, 20 Nov 2009 00:21:03 +0000 Subject: [PATCH] powerpc/8xx: Update TLB asm so it behaves as linux mm expects. Update the TLB asm to make proper use of _PAGE_DIRY and _PAGE_ACCESSED. Get rid of _PAGE_HWWRITE too. Pros: - I/D TLB Miss never needs to write to the linux pte. - _PAGE_ACCESSED is only set on TLB Error fixing accounting - _PAGE_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. Cons: - A few more instructions in the TLB Miss routines. Signed-off-by: Joakim Tjernlund Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/pte-8xx.h | 13 +++-- arch/powerpc/kernel/head_8xx.S | 99 ++++++++++++++++++++------------------ 2 files changed, 57 insertions(+), 55 deletions(-) diff --git a/arch/powerpc/include/asm/pte-8xx.h b/arch/powerpc/include/asm/pte-8xx.h index dd5ea95fe61..68ba861331e 100644 --- a/arch/powerpc/include/asm/pte-8xx.h +++ b/arch/powerpc/include/asm/pte-8xx.h @@ -33,21 +33,20 @@ #define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */ #define _PAGE_SHARED 0x0004 /* No ASID (context) compare */ #define _PAGE_SPECIAL 0x0008 /* SW entry, forced to 0 by the TLB miss */ +#define _PAGE_DIRTY 0x0100 /* C: page changed */ -/* These five software bits must be masked out when the entry is loaded - * into the TLB. +/* These 3 software bits must be masked out when the entry is loaded + * into the TLB, 2 SW bits left. */ #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. */ -#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_RW 0x0400 /* lsb PP bits, inverted in HW */ +#define _PAGE_USER 0x0800 /* msb PP bits */ #define _PMD_PRESENT 0x0001 #define _PMD_BAD 0x0ff0 diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 6ded19d0189..97bd523a027 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -333,26 +333,20 @@ 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 + andi. r11, r10, _PAGE_ACCESSED | _PAGE_PRESENT + cmpwi cr0, r11, _PAGE_ACCESSED | _PAGE_PRESENT + bne- cr0, 2f + + /* Clear PP lsb, 0x400 */ + rlwinm r10, r10, 0, 22, 20 /* 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. */ -2: li r11, 0x00f0 + li r11, 0x00f0 rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */ DO_8xx_CPU6(0x2d80, r3) mtspr SPRN_MI_RPN, r10 /* Update TLB entry */ @@ -365,6 +359,22 @@ InstructionTLBMiss: lwz r3, 8(r0) #endif rfi +2: + mfspr r11, SPRN_SRR1 + /* clear all error bits as TLB Miss + * sets a few unconditionally + */ + rlwinm r11, r11, 0, 0xffff + mtspr SPRN_SRR1, r11 + + mfspr r10, SPRN_M_TW /* Restore registers */ + lwz r11, 0(r0) + mtcr r11 + lwz r11, 4(r0) +#ifdef CONFIG_8xx_CPU6 + lwz r3, 8(r0) +#endif + b InstructionAccess . = 0x1200 DataStoreTLBMiss: @@ -409,21 +419,27 @@ DataStoreTLBMiss: DO_8xx_CPU6(0x3b80, r3) mtspr SPRN_MD_TWC, r11 -#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) + /* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set. + * We also need to know if the insn is a load/store, so: + * Clear _PAGE_PRESENT and load that which will + * trap into DTLB Error with store bit set accordinly. + */ + /* PRESENT=0x1, ACCESSED=0x20 + * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5)); + * r10 = (r10 & ~PRESENT) | r11; + */ + rlwinm r11, r10, 32-5, 31, 31 + and r11, r11, r10 + rlwimi r10, r11, 0, 31, 31 + + /* Honour kernel RO, User NA */ + andi. r11, r10, _PAGE_USER | _PAGE_RW + bne- cr0, 5f + ori r10,r10, 0x200 /* Extended encoding, bit 22 */ +5: xori r10, r10, _PAGE_RW /* invert RW bit */ /* 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. @@ -469,11 +485,12 @@ DataTLBError: stw r10, 0(r0) stw r11, 4(r0) - /* First, make sure this was a store operation. + mfspr r11, SPRN_DSISR + andis. r11, r11, 0x4800 /* !translation or protection */ + bne 2f /* branch if either is set */ + /* Only Change bit left now, do it here as it is faster + * than trapping to the C fault handler. */ - mfspr r10, SPRN_DSISR - andis. r11, r10, 0x0200 /* If set, indicates store op */ - beq 2f /* 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 @@ -522,26 +539,12 @@ DataTLBError: mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ lwz r10, 0(r11) /* Get the pte */ - andi. r11, r10, _PAGE_RW /* Is it writeable? */ - beq 2f /* Bail out if not */ - - /* 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 */ + ori r10, r10, _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_HWWRITE stw r10, 0(r11) /* and update pte in table */ + xori r10, r10, _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. -- 2.11.4.GIT