diff options
Diffstat (limited to 'arch/x86/mm/pat.c')
| -rw-r--r-- | arch/x86/mm/pat.c | 103 |
1 files changed, 48 insertions, 55 deletions
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index 277446cd30b..06b7a1c90fb 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -25,31 +25,24 @@ #include <asm/mtrr.h> #include <asm/io.h> -int pat_wc_enabled = 1; +#ifdef CONFIG_X86_PAT +int __read_mostly pat_wc_enabled = 1; -static u64 __read_mostly boot_pat_state; - -static int nopat(char *str) +void __cpuinit pat_disable(char *reason) { pat_wc_enabled = 0; - printk(KERN_INFO "x86: PAT support disabled.\n"); - - return 0; + printk(KERN_INFO "%s\n", reason); } -early_param("nopat", nopat); -static int pat_known_cpu(void) +static int __init nopat(char *str) { - if (!pat_wc_enabled) - return 0; - - if (cpu_has_pat) - return 1; - - pat_wc_enabled = 0; - printk(KERN_INFO "CPU and/or kernel does not support PAT.\n"); + pat_disable("PAT support disabled."); return 0; } +early_param("nopat", nopat); +#endif + +static u64 __read_mostly boot_pat_state; enum { PAT_UC = 0, /* uncached */ @@ -66,17 +59,19 @@ void pat_init(void) { u64 pat; -#ifndef CONFIG_X86_PAT - nopat(NULL); -#endif - - /* Boot CPU enables PAT based on CPU feature */ - if (!smp_processor_id() && !pat_known_cpu()) + if (!pat_wc_enabled) return; - /* APs enable PAT iff boot CPU has enabled it before */ - if (smp_processor_id() && !pat_wc_enabled) - return; + /* Paranoia check. */ + if (!cpu_has_pat) { + printk(KERN_ERR "PAT enabled, but CPU feature cleared\n"); + /* + * Panic if this happens on the secondary CPU, and we + * switched to PAT on the boot CPU. We have no way to + * undo PAT. + */ + BUG_ON(boot_pat_state); + } /* Set PWT to Write-Combining. All other bits stay the same */ /* @@ -95,9 +90,8 @@ void pat_init(void) PAT(4,WB) | PAT(5,WC) | PAT(6,UC_MINUS) | PAT(7,UC); /* Boot CPU check */ - if (!smp_processor_id()) { + if (!boot_pat_state) rdmsrl(MSR_IA32_CR_PAT, boot_pat_state); - } wrmsrl(MSR_IA32_CR_PAT, pat); printk(KERN_INFO "x86 PAT enabled: cpu %d, old 0x%Lx, new 0x%Lx\n", @@ -157,32 +151,33 @@ static int pat_x_mtrr_type(u64 start, u64 end, unsigned long prot, unsigned long pat_type; u8 mtrr_type; - mtrr_type = mtrr_type_lookup(start, end); - if (mtrr_type == 0xFF) { /* MTRR not enabled */ - *ret_prot = prot; - return 0; - } - if (mtrr_type == 0xFE) { /* MTRR match error */ - *ret_prot = _PAGE_CACHE_UC; - return -1; - } - if (mtrr_type != MTRR_TYPE_UNCACHABLE && - mtrr_type != MTRR_TYPE_WRBACK && - mtrr_type != MTRR_TYPE_WRCOMB) { /* MTRR type unhandled */ - *ret_prot = _PAGE_CACHE_UC; - return -1; - } - pat_type = prot & _PAGE_CACHE_MASK; prot &= (~_PAGE_CACHE_MASK); - /* Currently doing intersection by hand. Optimize it later. */ + /* + * We return the PAT request directly for types where PAT takes + * precedence with respect to MTRR and for UC_MINUS. + * Consistency checks with other PAT requests is done later + * while going through memtype list. + */ if (pat_type == _PAGE_CACHE_WC) { *ret_prot = prot | _PAGE_CACHE_WC; + return 0; } else if (pat_type == _PAGE_CACHE_UC_MINUS) { *ret_prot = prot | _PAGE_CACHE_UC_MINUS; - } else if (pat_type == _PAGE_CACHE_UC || - mtrr_type == MTRR_TYPE_UNCACHABLE) { + return 0; + } else if (pat_type == _PAGE_CACHE_UC) { + *ret_prot = prot | _PAGE_CACHE_UC; + return 0; + } + + /* + * Look for MTRR hint to get the effective type in case where PAT + * request is for WB. + */ + mtrr_type = mtrr_type_lookup(start, end); + + if (mtrr_type == MTRR_TYPE_UNCACHABLE) { *ret_prot = prot | _PAGE_CACHE_UC; } else if (mtrr_type == MTRR_TYPE_WRCOMB) { *ret_prot = prot | _PAGE_CACHE_WC; @@ -239,14 +234,12 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type, if (req_type == -1) { /* - * Special case where caller wants to inherit from mtrr or - * existing pat mapping, defaulting to UC_MINUS in case of - * no match. + * Call mtrr_lookup to get the type hint. This is an + * optimization for /dev/mem mmap'ers into WB memory (BIOS + * tools and ACPI tools). Use WB request for WB memory and use + * UC_MINUS otherwise. */ u8 mtrr_type = mtrr_type_lookup(start, end); - if (mtrr_type == 0xFE) { /* MTRR match error */ - err = -1; - } if (mtrr_type == MTRR_TYPE_WRBACK) { req_type = _PAGE_CACHE_WB; @@ -561,7 +554,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, "%s:%d /dev/mem ioremap_change_attr failed %s for %Lx-%Lx\n", current->comm, current->pid, cattr_name(flags), - offset, offset + size); + offset, (unsigned long long)(offset + size)); return 0; } @@ -582,7 +575,7 @@ void map_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot) "%s:%d /dev/mem expected mapping type %s for %Lx-%Lx, got %s\n", current->comm, current->pid, cattr_name(want_flags), - addr, addr + size, + addr, (unsigned long long)(addr + size), cattr_name(flags)); } } |