ioremap_nocache() and other interfaces that set the uncached memory type use _PAGE_CACHE_UC_MINUS in order to support legacy graphics drivers using MTRRs to overwrite it to WC. _PAGE_CACHE_UC is defined, but is unused on the systems with the PAT feature.
This patch redefines _PAGE_CACHE_UC to _PAGE_CACHE_UC_MINUS, and and frees up the PA3/7 slot in the PAT MSR that was used for _PAGE_CACHE_UC. This keeps _PAGE_CACHE_UC defined in case out-of-tree drivers refer it. Note: The legacy code in phys_mem_access_prot_allowed() that sets _PAGE_CACHE_UC for Pentiums and earlier processors is changed to set the PCD & PWT bits in order to avoid any change. They do not support PAT and MTRRs. Signed-off-by: Toshi Kani <[email protected]> --- arch/x86/include/asm/pgtable_types.h | 10 +++++----- arch/x86/mm/ioremap.c | 14 +++++--------- arch/x86/mm/pat.c | 9 +-------- arch/x86/mm/pat_internal.h | 1 - 4 files changed, 11 insertions(+), 23 deletions(-) diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index f216963..03d40da 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -133,7 +133,7 @@ #define _PAGE_CACHE_WB (0) #define _PAGE_CACHE_WC (_PAGE_PWT) #define _PAGE_CACHE_UC_MINUS (_PAGE_PCD) -#define _PAGE_CACHE_UC (_PAGE_PCD | _PAGE_PWT) +#define _PAGE_CACHE_UC (_PAGE_CACHE_UC_MINUS) #define PAGE_NONE __pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED) #define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | \ @@ -157,13 +157,13 @@ #define __PAGE_KERNEL_RO (__PAGE_KERNEL & ~_PAGE_RW) #define __PAGE_KERNEL_RX (__PAGE_KERNEL_EXEC & ~_PAGE_RW) -#define __PAGE_KERNEL_EXEC_NOCACHE (__PAGE_KERNEL_EXEC | _PAGE_PCD | _PAGE_PWT) +#define __PAGE_KERNEL_EXEC_NOCACHE (__PAGE_KERNEL_EXEC | _PAGE_CACHE_UC) #define __PAGE_KERNEL_WC (__PAGE_KERNEL | _PAGE_CACHE_WC) -#define __PAGE_KERNEL_NOCACHE (__PAGE_KERNEL | _PAGE_PCD | _PAGE_PWT) -#define __PAGE_KERNEL_UC_MINUS (__PAGE_KERNEL | _PAGE_PCD) +#define __PAGE_KERNEL_NOCACHE (__PAGE_KERNEL | _PAGE_CACHE_UC) +#define __PAGE_KERNEL_UC_MINUS (__PAGE_KERNEL | _PAGE_CACHE_UC_MINUS) #define __PAGE_KERNEL_VSYSCALL (__PAGE_KERNEL_RX | _PAGE_USER) #define __PAGE_KERNEL_VVAR (__PAGE_KERNEL_RO | _PAGE_USER) -#define __PAGE_KERNEL_VVAR_NOCACHE (__PAGE_KERNEL_VVAR | _PAGE_PCD | _PAGE_PWT) +#define __PAGE_KERNEL_VVAR_NOCACHE (__PAGE_KERNEL_VVAR | _PAGE_CACHE_UC) #define __PAGE_KERNEL_LARGE (__PAGE_KERNEL | _PAGE_PSE) #define __PAGE_KERNEL_LARGE_NOCACHE (__PAGE_KERNEL | _PAGE_CACHE_UC | _PAGE_PSE) #define __PAGE_KERNEL_LARGE_EXEC (__PAGE_KERNEL_EXEC | _PAGE_PSE) diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index baff1da..282829f 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -35,7 +35,7 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size, int err; switch (prot_val) { - case _PAGE_CACHE_UC: + case _PAGE_CACHE_UC_MINUS: default: err = _set_memory_uc(vaddr, nrpages); break; @@ -142,11 +142,8 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr, } switch (prot_val) { - case _PAGE_CACHE_UC: - default: - prot = PAGE_KERNEL_IO_NOCACHE; - break; case _PAGE_CACHE_UC_MINUS: + default: prot = PAGE_KERNEL_IO_UC_MINUS; break; case _PAGE_CACHE_WC: @@ -218,11 +215,10 @@ void __iomem *ioremap_nocache(resource_size_t phys_addr, unsigned long size) * pat_enabled ? _PAGE_CACHE_UC : _PAGE_CACHE_UC_MINUS; * * Till we fix all X drivers to use ioremap_wc(), we will use - * UC MINUS. + * UC MINUS. _PAGE_CACHE_UC is also defined as _PAGE_CACHE_UC_MINUS + * in pgtable_types.h. */ - unsigned long val = _PAGE_CACHE_UC_MINUS; - - return __ioremap_caller(phys_addr, size, val, + return __ioremap_caller(phys_addr, size, _PAGE_CACHE_UC_MINUS, __builtin_return_address(0)); } EXPORT_SYMBOL(ioremap_nocache); diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 6574388..c3567a5 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -213,12 +213,6 @@ static int reserve_ram_pages_type(u64 start, u64 end, unsigned long req_type, struct page *page; u64 pfn; - if (req_type == _PAGE_CACHE_UC) { - /* We do not support strong UC */ - WARN_ON_ONCE(1); - req_type = _PAGE_CACHE_UC_MINUS; - } - for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) { unsigned long type; @@ -261,7 +255,6 @@ static int free_ram_pages_type(u64 start, u64 end) * - _PAGE_CACHE_WB * - _PAGE_CACHE_WC * - _PAGE_CACHE_UC_MINUS - * - _PAGE_CACHE_UC * * If new_type is NULL, function will return an error if it cannot reserve the * region with req_type. If new_type is non-NULL, function will return @@ -543,7 +536,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, boot_cpu_has(X86_FEATURE_CYRIX_ARR) || boot_cpu_has(X86_FEATURE_CENTAUR_MCR)) && (pfn << PAGE_SHIFT) >= __pa(high_memory)) { - flags = _PAGE_CACHE_UC; + flags = _PAGE_PCD | _PAGE_PWT; /* UC w/o PAT */ } #endif diff --git a/arch/x86/mm/pat_internal.h b/arch/x86/mm/pat_internal.h index 77e5ba1..2593d40 100644 --- a/arch/x86/mm/pat_internal.h +++ b/arch/x86/mm/pat_internal.h @@ -17,7 +17,6 @@ struct memtype { static inline char *cattr_name(unsigned long flags) { switch (flags & _PAGE_CACHE_MASK) { - case _PAGE_CACHE_UC: return "uncached"; case _PAGE_CACHE_UC_MINUS: return "uncached-minus"; case _PAGE_CACHE_WB: return "write-back"; case _PAGE_CACHE_WC: return "write-combining"; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
