diff options
Diffstat (limited to 'include/linux/highmem.h')
| -rw-r--r-- | include/linux/highmem.h | 81 |
1 files changed, 75 insertions, 6 deletions
diff --git a/include/linux/highmem.h b/include/linux/highmem.h index ea5cdbd8c2c3..d6e82e3de027 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -32,8 +32,65 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size) #include <asm/kmap_types.h> #ifdef CONFIG_HIGHMEM +extern void *kmap_atomic_high_prot(struct page *page, pgprot_t prot); +extern void kunmap_atomic_high(void *kvaddr); #include <asm/highmem.h> +#ifndef ARCH_HAS_KMAP_FLUSH_TLB +static inline void kmap_flush_tlb(unsigned long addr) { } +#endif + +#ifndef kmap_prot +#define kmap_prot PAGE_KERNEL +#endif + +void *kmap_high(struct page *page); +static inline void *kmap(struct page *page) +{ + void *addr; + + might_sleep(); + if (!PageHighMem(page)) + addr = page_address(page); + else + addr = kmap_high(page); + kmap_flush_tlb((unsigned long)addr); + return addr; +} + +void kunmap_high(struct page *page); + +static inline void kunmap(struct page *page) +{ + might_sleep(); + if (!PageHighMem(page)) + return; + kunmap_high(page); +} + +/* + * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because + * no global lock is needed and because the kmap code must perform a global TLB + * invalidation when the kmap pool wraps. + * + * However when holding an atomic kmap is is not legal to sleep, so atomic + * kmaps are appropriate for short, tight code paths only. + * + * The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap + * gives a more generic (and caching) interface. But kmap_atomic can + * be used in IRQ contexts, so in some (very limited) cases we need + * it. + */ +static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot) +{ + preempt_disable(); + pagefault_disable(); + if (!PageHighMem(page)) + return page_address(page); + return kmap_atomic_high_prot(page, prot); +} +#define kmap_atomic(page) kmap_atomic_prot(page, kmap_prot) + /* declarations for linux/mm/highmem.c */ unsigned int nr_free_highpages(void); extern atomic_long_t _totalhigh_pages; @@ -77,15 +134,21 @@ static inline struct page *kmap_to_page(void *addr) static inline unsigned long totalhigh_pages(void) { return 0UL; } -#ifndef ARCH_HAS_KMAP static inline void *kmap(struct page *page) { might_sleep(); return page_address(page); } +static inline void kunmap_high(struct page *page) +{ +} + static inline void kunmap(struct page *page) { +#ifdef ARCH_HAS_FLUSH_ON_KUNMAP + kunmap_flush_on_unmap(page_address(page)); +#endif } static inline void *kmap_atomic(struct page *page) @@ -96,16 +159,20 @@ static inline void *kmap_atomic(struct page *page) } #define kmap_atomic_prot(page, prot) kmap_atomic(page) -static inline void __kunmap_atomic(void *addr) +static inline void kunmap_atomic_high(void *addr) { - pagefault_enable(); - preempt_enable(); + /* + * Mostly nothing to do in the CONFIG_HIGHMEM=n case as kunmap_atomic() + * handles re-enabling faults + preemption + */ +#ifdef ARCH_HAS_FLUSH_ON_KUNMAP + kunmap_flush_on_unmap(addr); +#endif } #define kmap_atomic_pfn(pfn) kmap_atomic(pfn_to_page(pfn)) #define kmap_flush_unused() do {} while(0) -#endif #endif /* CONFIG_HIGHMEM */ @@ -149,7 +216,9 @@ static inline void kmap_atomic_idx_pop(void) #define kunmap_atomic(addr) \ do { \ BUILD_BUG_ON(__same_type((addr), struct page *)); \ - __kunmap_atomic(addr); \ + kunmap_atomic_high(addr); \ + pagefault_enable(); \ + preempt_enable(); \ } while (0) |