From 281d4078bec366d60990add9d91a952953bd0d72 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Mon, 3 Nov 2014 14:01:47 +0100 Subject: [PATCH] x86: Make page cache mode a real type At the moment there are a lot of places that handle setting or getting the page cache mode by treating the pgprot bits equal to the cache mode. This is only true because there are a lot of assumptions about the setup of the PAT MSR. Otherwise the cache type needs to get translated into pgprot bits and vice versa. This patch tries to prepare for that by introducing a separate type for the cache mode and adding functions to translate between those and pgprot values. To avoid too much performance penalty the translation between cache mode and pgprot values is done via tables which contain the relevant information. Write-back cache mode is hard-wired to be 0, all other modes are configurable via those tables. For large pages there are translation functions as the PAT bit is located at different positions in the ptes of 4k and large pages. Based-on-patch-by: Stefan Bader Signed-off-by: Juergen Gross Reviewed-by: Thomas Gleixner Cc: stefan.bader@canonical.com Cc: xen-devel@lists.xensource.com Cc: konrad.wilk@oracle.com Cc: ville.syrjala@linux.intel.com Cc: david.vrabel@citrix.com Cc: jbeulich@suse.com Cc: toshi.kani@hp.com Cc: plagnioj@jcrosoft.com Cc: tomi.valkeinen@ti.com Cc: bhelgaas@google.com Link: http://lkml.kernel.org/r/1415019724-4317-2-git-send-email-jgross@suse.com Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/pgtable_types.h | 73 +++++++++++++++++++++++++++- arch/x86/mm/init.c | 29 +++++++++++ 2 files changed, 101 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index 07789647bf33..512464227c09 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -128,12 +128,34 @@ _PAGE_SOFT_DIRTY | _PAGE_NUMA) #define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE | _PAGE_NUMA) -#define _PAGE_CACHE_MASK (_PAGE_PCD | _PAGE_PWT) #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) +/* + * The cache modes defined here are used to translate between pure SW usage + * and the HW defined cache mode bits and/or PAT entries. + * + * The resulting bits for PWT, PCD and PAT should be chosen in a way + * to have the WB mode at index 0 (all bits clear). This is the default + * right now and likely would break too much if changed. + */ +#ifndef __ASSEMBLY__ +enum page_cache_mode { + _PAGE_CACHE_MODE_WB = 0, + _PAGE_CACHE_MODE_WC = 1, + _PAGE_CACHE_MODE_UC_MINUS = 2, + _PAGE_CACHE_MODE_UC = 3, + _PAGE_CACHE_MODE_WT = 4, + _PAGE_CACHE_MODE_WP = 5, + _PAGE_CACHE_MODE_NUM = 8 +}; +#endif + +#define _PAGE_CACHE_MASK (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT) +#define _PAGE_NOCACHE (cachemode2protval(_PAGE_CACHE_MODE_UC)) + #define PAGE_NONE __pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED) #define PAGE_SHARED __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | \ _PAGE_ACCESSED | _PAGE_NX) @@ -341,6 +363,55 @@ static inline pmdval_t pmdnuma_flags(pmd_t pmd) #define pgprot_val(x) ((x).pgprot) #define __pgprot(x) ((pgprot_t) { (x) } ) +extern uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM]; +extern uint8_t __pte2cachemode_tbl[8]; + +#define __pte2cm_idx(cb) \ + ((((cb) >> (_PAGE_BIT_PAT - 2)) & 4) | \ + (((cb) >> (_PAGE_BIT_PCD - 1)) & 2) | \ + (((cb) >> _PAGE_BIT_PWT) & 1)) + +static inline unsigned long cachemode2protval(enum page_cache_mode pcm) +{ + if (likely(pcm == 0)) + return 0; + return __cachemode2pte_tbl[pcm]; +} +static inline pgprot_t cachemode2pgprot(enum page_cache_mode pcm) +{ + return __pgprot(cachemode2protval(pcm)); +} +static inline enum page_cache_mode pgprot2cachemode(pgprot_t pgprot) +{ + unsigned long masked; + + masked = pgprot_val(pgprot) & _PAGE_CACHE_MASK; + if (likely(masked == 0)) + return 0; + return __pte2cachemode_tbl[__pte2cm_idx(masked)]; +} +static inline pgprot_t pgprot_4k_2_large(pgprot_t pgprot) +{ + pgprot_t new; + unsigned long val; + + val = pgprot_val(pgprot); + pgprot_val(new) = (val & ~(_PAGE_PAT | _PAGE_PAT_LARGE)) | + ((val & _PAGE_PAT) << (_PAGE_BIT_PAT_LARGE - _PAGE_BIT_PAT)); + return new; +} +static inline pgprot_t pgprot_large_2_4k(pgprot_t pgprot) +{ + pgprot_t new; + unsigned long val; + + val = pgprot_val(pgprot); + pgprot_val(new) = (val & ~(_PAGE_PAT | _PAGE_PAT_LARGE)) | + ((val & _PAGE_PAT_LARGE) >> + (_PAGE_BIT_PAT_LARGE - _PAGE_BIT_PAT)); + return new; +} + typedef struct page *pgtable_t; diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 66dba36f2343..a9776ba475d4 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -27,6 +27,35 @@ #include "mm_internal.h" +/* + * Tables translating between page_cache_type_t and pte encoding. + * Minimal supported modes are defined statically, modified if more supported + * cache modes are available. + * Index into __cachemode2pte_tbl is the cachemode. + * Index into __pte2cachemode_tbl are the caching attribute bits of the pte + * (_PAGE_PWT, _PAGE_PCD, _PAGE_PAT) at index bit positions 0, 1, 2. + */ +uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = { + [_PAGE_CACHE_MODE_WB] = 0, + [_PAGE_CACHE_MODE_WC] = _PAGE_PWT, + [_PAGE_CACHE_MODE_UC_MINUS] = _PAGE_PCD, + [_PAGE_CACHE_MODE_UC] = _PAGE_PCD | _PAGE_PWT, + [_PAGE_CACHE_MODE_WT] = _PAGE_PCD, + [_PAGE_CACHE_MODE_WP] = _PAGE_PCD, +}; +EXPORT_SYMBOL_GPL(__cachemode2pte_tbl); +uint8_t __pte2cachemode_tbl[8] = { + [__pte2cm_idx(0)] = _PAGE_CACHE_MODE_WB, + [__pte2cm_idx(_PAGE_PWT)] = _PAGE_CACHE_MODE_WC, + [__pte2cm_idx(_PAGE_PCD)] = _PAGE_CACHE_MODE_UC_MINUS, + [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD)] = _PAGE_CACHE_MODE_UC, + [__pte2cm_idx(_PAGE_PAT)] = _PAGE_CACHE_MODE_WB, + [__pte2cm_idx(_PAGE_PWT | _PAGE_PAT)] = _PAGE_CACHE_MODE_WC, + [__pte2cm_idx(_PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS, + [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC, +}; +EXPORT_SYMBOL_GPL(__pte2cachemode_tbl); + static unsigned long __initdata pgt_buf_start; static unsigned long __initdata pgt_buf_end; static unsigned long __initdata pgt_buf_top; -- GitLab