From 13f876ba77ebd5125799bb042201f22cf73df154 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 3 Nov 2020 10:27:34 +0100 Subject: highmem: High implementation details and document API Move the gory details of kmap & al into a private header and only document the interfaces which are usable by drivers. Signed-off-by: Thomas Gleixner Cc: Linus Torvalds Cc: Christoph Hellwig Cc: Andrew Morton Link: https://lore.kernel.org/r/20201103095858.827582066@linutronix.de --- include/linux/highmem-internal.h | 174 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 174 insertions(+) create mode 100644 include/linux/highmem-internal.h (limited to 'include/linux/highmem-internal.h') diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h new file mode 100644 index 000000000000..6ceed907b14e --- /dev/null +++ b/include/linux/highmem-internal.h @@ -0,0 +1,174 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_HIGHMEM_INTERNAL_H +#define _LINUX_HIGHMEM_INTERNAL_H + +/* + * Outside of CONFIG_HIGHMEM to support X86 32bit iomap_atomic() cruft. + */ +#ifdef CONFIG_KMAP_LOCAL +void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot); +void *__kmap_local_page_prot(struct page *page, pgprot_t prot); +void kunmap_local_indexed(void *vaddr); +#endif + +#ifdef CONFIG_HIGHMEM +#include + +#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); +void kunmap_high(struct page *page); +void __kmap_flush_unused(void); +struct page *__kmap_to_page(void *addr); + +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; +} + +static inline void kunmap(struct page *page) +{ + might_sleep(); + if (!PageHighMem(page)) + return; + kunmap_high(page); +} + +static inline struct page *kmap_to_page(void *addr) +{ + return __kmap_to_page(addr); +} + +static inline void kmap_flush_unused(void) +{ + __kmap_flush_unused(); +} + +static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot) +{ + preempt_disable(); + pagefault_disable(); + return __kmap_local_page_prot(page, prot); +} + +static inline void *kmap_atomic(struct page *page) +{ + return kmap_atomic_prot(page, kmap_prot); +} + +static inline void *kmap_atomic_pfn(unsigned long pfn) +{ + preempt_disable(); + pagefault_disable(); + return __kmap_local_pfn_prot(pfn, kmap_prot); +} + +static inline void __kunmap_atomic(void *addr) +{ + kunmap_local_indexed(addr); + pagefault_enable(); + preempt_enable(); +} + +unsigned int __nr_free_highpages(void); +extern atomic_long_t _totalhigh_pages; + +static inline unsigned int nr_free_highpages(void) +{ + return __nr_free_highpages(); +} + +static inline unsigned long totalhigh_pages(void) +{ + return (unsigned long)atomic_long_read(&_totalhigh_pages); +} + +static inline void totalhigh_pages_inc(void) +{ + atomic_long_inc(&_totalhigh_pages); +} + +static inline void totalhigh_pages_add(long count) +{ + atomic_long_add(count, &_totalhigh_pages); +} + +#else /* CONFIG_HIGHMEM */ + +static inline struct page *kmap_to_page(void *addr) +{ + return virt_to_page(addr); +} + +static inline void *kmap(struct page *page) +{ + might_sleep(); + return page_address(page); +} + +static inline void kunmap_high(struct page *page) { } +static inline void kmap_flush_unused(void) { } + +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) +{ + preempt_disable(); + pagefault_disable(); + return page_address(page); +} + +static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot) +{ + return kmap_atomic(page); +} + +static inline void *kmap_atomic_pfn(unsigned long pfn) +{ + return kmap_atomic(pfn_to_page(pfn)); +} + +static inline void __kunmap_atomic(void *addr) +{ +#ifdef ARCH_HAS_FLUSH_ON_KUNMAP + kunmap_flush_on_unmap(addr); +#endif + pagefault_enable(); + preempt_enable(); +} + +static inline unsigned int nr_free_highpages(void) { return 0; } +static inline unsigned long totalhigh_pages(void) { return 0UL; } + +#endif /* CONFIG_HIGHMEM */ + +/* + * Prevent people trying to call kunmap_atomic() as if it were kunmap() + * kunmap_atomic() should get the return value of kmap_atomic, not the page. + */ +#define kunmap_atomic(__addr) \ +do { \ + BUILD_BUG_ON(__same_type((__addr), struct page *)); \ + __kunmap_atomic(__addr); \ +} while (0) + +#endif -- cgit v1.2.3