From 7711ece9b31f0f3cf15ca16005dfd78988ea8f7e Mon Sep 17 00:00:00 2001 From: Chris Zankel Date: Mon, 20 May 2013 11:09:13 -0700 Subject: xtensa: fix TLB multihit exceptions - set _PAGE_USER in the pte_clear to avoid having TLB multihit exceptions (see following threads for more details); http://lists.linux-xtensa.org/pipermail/linux-xtensa/Week-of-Mon-20130401/ http://lists.linux-xtensa.org/pipermail/linux-xtensa/Week-of-Mon-20130408/ - improved documentation of the PTE layout - fix PTE mapping for present and 'prot_none' pages for T1050 hw and earlier - fix pte_file offset and size - add check for the correct number of bits for swap type CC: piet.delaney@gmail.com CC: jcmvbkbc@gmail.com Signed-off-by: Chris Zankel --- arch/xtensa/include/asm/pgtable.h | 140 ++++++++++++++++++++++---------------- 1 file changed, 83 insertions(+), 57 deletions(-) (limited to 'arch/xtensa') diff --git a/arch/xtensa/include/asm/pgtable.h b/arch/xtensa/include/asm/pgtable.h index d7546c94da52..7e09f7011370 100644 --- a/arch/xtensa/include/asm/pgtable.h +++ b/arch/xtensa/include/asm/pgtable.h @@ -5,7 +5,7 @@ * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * - * Copyright (C) 2001 - 2007 Tensilica Inc. + * Copyright (C) 2001 - 2013 Tensilica Inc. */ #ifndef _XTENSA_PGTABLE_H @@ -64,41 +64,82 @@ * Virtual memory area. We keep a distance to other memory regions to be * on the safe side. We also use this area for cache aliasing. */ - #define VMALLOC_START 0xC0000000 #define VMALLOC_END 0xC7FEFFFF #define TLBTEMP_BASE_1 0xC7FF0000 #define TLBTEMP_BASE_2 0xC7FF8000 /* - * Xtensa Linux config PTE layout (when present): - * 31-12: PPN - * 11-6: Software - * 5-4: RING - * 3-0: CA + * For the Xtensa architecture, the PTE layout is as follows: + * + * 31------12 11 10-9 8-6 5-4 3-2 1-0 + * +-----------------------------------------+ + * | | Software | HARDWARE | + * | PPN | ADW | RI |Attribute| + * +-----------------------------------------+ + * pte_none | MBZ | 01 | 11 | 00 | + * +-----------------------------------------+ + * present | PPN | 0 | 00 | ADW | RI | CA | wx | + * +- - - - - - - - - - - - - - - - - - - - -+ + * (PAGE_NONE)| PPN | 0 | 00 | ADW | 01 | 11 | 11 | + * +-----------------------------------------+ + * swap | index | type | 01 | 11 | 00 | + * +- - - - - - - - - - - - - - - - - - - - -+ + * file | file offset | 01 | 11 | 10 | + * +-----------------------------------------+ + * + * For T1050 hardware and earlier the layout differs for present and (PAGE_NONE) + * +-----------------------------------------+ + * present | PPN | 0 | 00 | ADW | RI | CA | w1 | + * +-----------------------------------------+ + * (PAGE_NONE)| PPN | 0 | 00 | ADW | 01 | 01 | 00 | + * +-----------------------------------------+ * - * Similar to the Alpha and MIPS ports, we need to keep track of the ref - * and mod bits in software. We have a software "you can read - * from this page" bit, and a hardware one which actually lets the - * process read from the page. On the same token we have a software - * writable bit and the real hardware one which actually lets the - * process write to the page. + * Legend: + * PPN Physical Page Number + * ADW software: accessed (young) / dirty / writable + * RI ring (0=privileged, 1=user, 2 and 3 are unused) + * CA cache attribute: 00 bypass, 01 writeback, 10 writethrough + * (11 is invalid and used to mark pages that are not present) + * w page is writable (hw) + * x page is executable (hw) + * index swap offset / PAGE_SIZE (bit 11-31: 21 bits -> 8 GB) + * (note that the index is always non-zero) + * type swap type (5 bits -> 32 types) + * file offset 26-bit offset into the file, in increments of PAGE_SIZE * - * See further below for PTE layout for swapped-out pages. + * Notes: + * - (PROT_NONE) is a special case of 'present' but causes an exception for + * any access (read, write, and execute). + * - 'multihit-exception' has the highest priority of all MMU exceptions, + * so the ring must be set to 'RING_USER' even for 'non-present' pages. + * - on older hardware, the exectuable flag was not supported and + * used as a 'valid' flag, so it needs to be always set. + * - we need to keep track of certain flags in software (dirty and young) + * to do this, we use write exceptions and have a separate software w-flag. + * - attribute value 1101 (and 1111 on T1050 and earlier) is reserved */ +#define _PAGE_ATTRIB_MASK 0xf + #define _PAGE_HW_EXEC (1<<0) /* hardware: page is executable */ #define _PAGE_HW_WRITE (1<<1) /* hardware: page is writable */ -#define _PAGE_FILE (1<<1) /* non-linear mapping, if !present */ -#define _PAGE_PROTNONE (3<<0) /* special case for VM_PROT_NONE */ - -/* None of these cache modes include MP coherency: */ #define _PAGE_CA_BYPASS (0<<2) /* bypass, non-speculative */ #define _PAGE_CA_WB (1<<2) /* write-back */ #define _PAGE_CA_WT (2<<2) /* write-through */ #define _PAGE_CA_MASK (3<<2) -#define _PAGE_INVALID (3<<2) +#define _PAGE_CA_INVALID (3<<2) + +/* We use invalid attribute values to distinguish special pte entries */ +#if XCHAL_HW_VERSION_MAJOR < 2000 +#define _PAGE_HW_VALID 0x01 /* older HW needed this bit set */ +#define _PAGE_NONE 0x04 +#else +#define _PAGE_HW_VALID 0x00 +#define _PAGE_NONE 0x0f +#endif +#define _PAGE_FILE (1<<1) /* file mapped page, only if !present */ #define _PAGE_USER (1<<4) /* user access (ring=1) */ @@ -108,19 +149,12 @@ #define _PAGE_DIRTY (1<<7) /* software: page dirty */ #define _PAGE_ACCESSED (1<<8) /* software: page accessed (read) */ -/* On older HW revisions, we always have to set bit 0 */ -#if XCHAL_HW_VERSION_MAJOR < 2000 -# define _PAGE_VALID (1<<0) -#else -# define _PAGE_VALID 0 -#endif - -#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY) -#define _PAGE_PRESENT (_PAGE_VALID | _PAGE_CA_WB | _PAGE_ACCESSED) - #ifdef CONFIG_MMU -#define PAGE_NONE __pgprot(_PAGE_INVALID | _PAGE_USER | _PAGE_PROTNONE) +#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY) +#define _PAGE_PRESENT (_PAGE_HW_VALID | _PAGE_CA_WB | _PAGE_ACCESSED) + +#define PAGE_NONE __pgprot(_PAGE_NONE | _PAGE_USER) #define PAGE_COPY __pgprot(_PAGE_PRESENT | _PAGE_USER) #define PAGE_COPY_EXEC __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_HW_EXEC) #define PAGE_READONLY __pgprot(_PAGE_PRESENT | _PAGE_USER) @@ -132,9 +166,9 @@ #define PAGE_KERNEL_EXEC __pgprot(_PAGE_PRESENT|_PAGE_HW_WRITE|_PAGE_HW_EXEC) #if (DCACHE_WAY_SIZE > PAGE_SIZE) -# define _PAGE_DIRECTORY (_PAGE_VALID | _PAGE_ACCESSED) +# define _PAGE_DIRECTORY (_PAGE_HW_VALID | _PAGE_ACCESSED | _PAGE_CA_BYPASS) #else -# define _PAGE_DIRECTORY (_PAGE_VALID | _PAGE_ACCESSED | _PAGE_CA_WB) +# define _PAGE_DIRECTORY (_PAGE_HW_VALID | _PAGE_ACCESSED | _PAGE_CA_WB) #endif #else /* no mmu */ @@ -202,12 +236,16 @@ static inline void pgtable_cache_init(void) { } /* * pte status. */ -#define pte_none(pte) (pte_val(pte) == _PAGE_INVALID) -#define pte_present(pte) \ - (((pte_val(pte) & _PAGE_CA_MASK) != _PAGE_INVALID) \ - || ((pte_val(pte) & _PAGE_PROTNONE) == _PAGE_PROTNONE)) +# define pte_none(pte) (pte_val(pte) == (_PAGE_CA_INVALID | _PAGE_USER)) +#if XCHAL_HW_VERSION_MAJOR < 2000 +# define pte_present(pte) ((pte_val(pte) & _PAGE_CA_MASK) != _PAGE_CA_INVALID) +#else +# define pte_present(pte) \ + (((pte_val(pte) & _PAGE_CA_MASK) != _PAGE_CA_INVALID) \ + || ((pte_val(pte) & _PAGE_ATTRIB_MASK) == _PAGE_NONE)) +#endif #define pte_clear(mm,addr,ptep) \ - do { update_pte(ptep, __pte(_PAGE_INVALID)); } while(0) + do { update_pte(ptep, __pte(_PAGE_CA_INVALID | _PAGE_USER)); } while (0) #define pmd_none(pmd) (!pmd_val(pmd)) #define pmd_present(pmd) (pmd_val(pmd) & PAGE_MASK) @@ -328,35 +366,23 @@ ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep) /* - * Encode and decode a swap entry. - * - * Format of swap pte: - * bit 0 MBZ - * bit 1 page-file (must be zero) - * bits 2 - 3 page hw access mode (must be 11: _PAGE_INVALID) - * bits 4 - 5 ring protection (must be 01: _PAGE_USER) - * bits 6 - 10 swap type (5 bits -> 32 types) - * bits 11 - 31 swap offset / PAGE_SIZE (21 bits -> 8GB) - - * Format of file pte: - * bit 0 MBZ - * bit 1 page-file (must be one: _PAGE_FILE) - * bits 2 - 3 page hw access mode (must be 11: _PAGE_INVALID) - * bits 4 - 5 ring protection (must be 01: _PAGE_USER) - * bits 6 - 31 file offset / PAGE_SIZE + * Encode and decode a swap and file entry. */ +#define SWP_TYPE_BITS 5 +#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS) #define __swp_type(entry) (((entry).val >> 6) & 0x1f) #define __swp_offset(entry) ((entry).val >> 11) #define __swp_entry(type,offs) \ - ((swp_entry_t) {((type) << 6) | ((offs) << 11) | _PAGE_INVALID}) + ((swp_entry_t){((type) << 6) | ((offs) << 11) | \ + _PAGE_CA_INVALID | _PAGE_USER}) #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(x) ((pte_t) { (x).val }) -#define PTE_FILE_MAX_BITS 28 -#define pte_to_pgoff(pte) (pte_val(pte) >> 4) +#define PTE_FILE_MAX_BITS 26 +#define pte_to_pgoff(pte) (pte_val(pte) >> 6) #define pgoff_to_pte(off) \ - ((pte_t) { ((off) << 4) | _PAGE_INVALID | _PAGE_FILE }) + ((pte_t) { ((off) << 6) | _PAGE_CA_INVALID | _PAGE_FILE | _PAGE_USER }) #endif /* !defined (__ASSEMBLY__) */ -- cgit v1.2.1