Introduce phys_mem_access_prot_allowed(), which checks whether the mapping is possible, without any conflicts and returns success or failure based on that. phys_mem_access_prot() by itself does not allow failure case. This ability to return error is needed for PAT where we may have aliasing conflicts. x86 setup __HAVE_PHYS_MEM_ACCESS_PROT and move x86 specific code out of /dev/mem into arch specific area. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Suresh Siddha Index: linux-2.6-x86.git/arch/x86/mm/pat.c =================================================================== --- linux-2.6-x86.git.orig/arch/x86/mm/pat.c 2008-03-18 03:11:03.000000000 -0700 +++ linux-2.6-x86.git/arch/x86/mm/pat.c 2008-03-18 09:20:33.000000000 -0700 @@ -400,3 +400,42 @@ return err; } + +/* /dev/mem interface. Use the previous mapping */ +pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, + unsigned long size, pgprot_t vma_prot) +{ + return vma_prot; +} + +int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, + unsigned long size, pgprot_t *vma_prot) +{ + + if (file->f_flags & O_SYNC) { + *vma_prot = pgprot_noncached(*vma_prot); + return 1; + } + +#ifdef CONFIG_X86_32 + /* + * On the PPro and successors, the MTRRs are used to set + * memory types for physical addresses outside main memory, + * so blindly setting UC or PWT on those pages is wrong. + * For Pentiums and earlier, the surround logic should disable + * caching for the high addresses through the KEN pin, but + * we maintain the tradition of paranoia in this code. + */ + if (!pat_wc_enabled && + ! ( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) || + test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) || + test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) || + test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability)) && + (pfn << PAGE_SHIFT) >= __pa(high_memory)) { + *vma_prot = pgprot_noncached(*vma_prot); + return 1; + } +#endif + + return 1; +} Index: linux-2.6-x86.git/include/asm-x86/pgtable.h =================================================================== --- linux-2.6-x86.git.orig/include/asm-x86/pgtable.h 2008-03-18 02:16:04.000000000 -0700 +++ linux-2.6-x86.git/include/asm-x86/pgtable.h 2008-03-18 09:20:25.000000000 -0700 @@ -205,6 +205,15 @@ #define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask) +#ifndef __ASSEMBLY__ +#define __HAVE_PHYS_MEM_ACCESS_PROT +struct file; +pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, + unsigned long size, pgprot_t vma_prot); +int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, + unsigned long size, pgprot_t *vma_prot); +#endif + #ifdef CONFIG_PARAVIRT #include #else /* !CONFIG_PARAVIRT */ Index: linux-2.6-x86.git/drivers/char/mem.c =================================================================== --- linux-2.6-x86.git.orig/drivers/char/mem.c 2008-03-18 03:11:12.000000000 -0700 +++ linux-2.6-x86.git/drivers/char/mem.c 2008-03-18 09:20:33.000000000 -0700 @@ -41,36 +41,7 @@ */ static inline int uncached_access(struct file *file, unsigned long addr) { -#if defined(__i386__) && !defined(__arch_um__) - /* - * On the PPro and successors, the MTRRs are used to set - * memory types for physical addresses outside main memory, - * so blindly setting PCD or PWT on those pages is wrong. - * For Pentiums and earlier, the surround logic should disable - * caching for the high addresses through the KEN pin, but - * we maintain the tradition of paranoia in this code. - */ - if (file->f_flags & O_SYNC) - return 1; - return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) || - test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) || - test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) || - test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) ) - && addr >= __pa(high_memory); -#elif defined(__x86_64__) && !defined(__arch_um__) - /* - * This is broken because it can generate memory type aliases, - * which can cause cache corruptions - * But it is only available for root and we have to be bug-to-bug - * compatible with i386. - */ - if (file->f_flags & O_SYNC) - return 1; - /* same behaviour as i386. PAT always set to cached and MTRRs control the - caching behaviour. - Hopefully a full PAT implementation will fix that soon. */ - return 0; -#elif defined(CONFIG_IA64) +#if defined(CONFIG_IA64) /* * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases. */ @@ -283,6 +254,12 @@ return written; } +int __attribute__((weak)) phys_mem_access_prot_allowed(struct file *file, + unsigned long pfn, unsigned long size, pgprot_t *vma_prot) +{ + return 1; +} + #ifndef __HAVE_PHYS_MEM_ACCESS_PROT static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) @@ -336,6 +313,10 @@ if (!range_is_allowed(vma->vm_pgoff, size)) return -EPERM; + if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, + &vma->vm_page_prot)) + return -EINVAL; + vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, size, vma->vm_page_prot); -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/