mirror of https://gitee.com/openkylin/linux.git
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 <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linuxfoundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Andrew Morton <akpm@linux-foundation.org> Link: https://lore.kernel.org/r/20201103095858.827582066@linutronix.de
This commit is contained in:
Thomas Gleixner
parent
9bf6f7bab3
commit
13f876ba77
|
|
@ -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 <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);
|
||||
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
|
||||
|
|
@ -11,6 +11,108 @@
|
|||
|
||||
#include <asm/cacheflush.h>
|
||||
|
||||
#include "highmem-internal.h"
|
||||
|
||||
/**
|
||||
* kmap - Map a page for long term usage
|
||||
* @page: Pointer to the page to be mapped
|
||||
*
|
||||
* Returns: The virtual address of the mapping
|
||||
*
|
||||
* Can only be invoked from preemptible task context because on 32bit
|
||||
* systems with CONFIG_HIGHMEM enabled this function might sleep.
|
||||
*
|
||||
* For systems with CONFIG_HIGHMEM=n and for pages in the low memory area
|
||||
* this returns the virtual address of the direct kernel mapping.
|
||||
*
|
||||
* The returned virtual address is globally visible and valid up to the
|
||||
* point where it is unmapped via kunmap(). The pointer can be handed to
|
||||
* other contexts.
|
||||
*
|
||||
* For highmem pages on 32bit systems this can be slow as the mapping space
|
||||
* is limited and protected by a global lock. In case that there is no
|
||||
* mapping slot available the function blocks until a slot is released via
|
||||
* kunmap().
|
||||
*/
|
||||
static inline void *kmap(struct page *page);
|
||||
|
||||
/**
|
||||
* kunmap - Unmap the virtual address mapped by kmap()
|
||||
* @addr: Virtual address to be unmapped
|
||||
*
|
||||
* Counterpart to kmap(). A NOOP for CONFIG_HIGHMEM=n and for mappings of
|
||||
* pages in the low memory area.
|
||||
*/
|
||||
static inline void kunmap(struct page *page);
|
||||
|
||||
/**
|
||||
* kmap_to_page - Get the page for a kmap'ed address
|
||||
* @addr: The address to look up
|
||||
*
|
||||
* Returns: The page which is mapped to @addr.
|
||||
*/
|
||||
static inline struct page *kmap_to_page(void *addr);
|
||||
|
||||
/**
|
||||
* kmap_flush_unused - Flush all unused kmap mappings in order to
|
||||
* remove stray mappings
|
||||
*/
|
||||
static inline void kmap_flush_unused(void);
|
||||
|
||||
/**
|
||||
* kmap_atomic - Atomically map a page for temporary usage
|
||||
* @page: Pointer to the page to be mapped
|
||||
*
|
||||
* Returns: The virtual address of the mapping
|
||||
*
|
||||
* Side effect: On return pagefaults and preemption are disabled.
|
||||
*
|
||||
* Can be invoked from any context.
|
||||
*
|
||||
* Requires careful handling when nesting multiple mappings because the map
|
||||
* management is stack based. The unmap has to be in the reverse order of
|
||||
* the map operation:
|
||||
*
|
||||
* addr1 = kmap_atomic(page1);
|
||||
* addr2 = kmap_atomic(page2);
|
||||
* ...
|
||||
* kunmap_atomic(addr2);
|
||||
* kunmap_atomic(addr1);
|
||||
*
|
||||
* Unmapping addr1 before addr2 is invalid and causes malfunction.
|
||||
*
|
||||
* Contrary to kmap() mappings the mapping is only valid in the context of
|
||||
* the caller and cannot be handed to other contexts.
|
||||
*
|
||||
* On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the
|
||||
* virtual address of the direct mapping. Only real highmem pages are
|
||||
* temporarily mapped.
|
||||
*
|
||||
* While it is significantly faster than kmap() it comes with restrictions
|
||||
* about the pointer validity and the side effects of disabling page faults
|
||||
* and preemption. Use it only when absolutely necessary, e.g. from non
|
||||
* preemptible contexts.
|
||||
*/
|
||||
static inline void *kmap_atomic(struct page *page);
|
||||
|
||||
/**
|
||||
* kunmap_atomic - Unmap the virtual address mapped by kmap_atomic()
|
||||
* @addr: Virtual address to be unmapped
|
||||
*
|
||||
* Counterpart to kmap_atomic().
|
||||
*
|
||||
* Undoes the side effects of kmap_atomic(), i.e. reenabling pagefaults and
|
||||
* preemption.
|
||||
*
|
||||
* Other than that a NOOP for CONFIG_HIGHMEM=n and for mappings of pages
|
||||
* in the low memory area. For real highmen pages the mapping which was
|
||||
* established with kmap_atomic() is destroyed.
|
||||
*/
|
||||
|
||||
/* Highmem related interfaces for management code */
|
||||
static inline unsigned int nr_free_highpages(void);
|
||||
static inline unsigned long totalhigh_pages(void);
|
||||
|
||||
#ifndef ARCH_HAS_FLUSH_ANON_PAGE
|
||||
static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
|
||||
{
|
||||
|
|
@ -29,182 +131,6 @@ static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
|
|||
}
|
||||
#endif
|
||||
|
||||
/*
|
||||
* 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 <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 it 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();
|
||||
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);
|
||||
}
|
||||
|
||||
/* declarations for linux/mm/highmem.c */
|
||||
unsigned int nr_free_highpages(void);
|
||||
extern atomic_long_t _totalhigh_pages;
|
||||
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);
|
||||
}
|
||||
|
||||
void kmap_flush_unused(void);
|
||||
|
||||
struct page *kmap_to_page(void *addr);
|
||||
|
||||
#else /* CONFIG_HIGHMEM */
|
||||
|
||||
static inline unsigned int nr_free_highpages(void) { return 0; }
|
||||
|
||||
static inline struct page *kmap_to_page(void *addr)
|
||||
{
|
||||
return virt_to_page(addr);
|
||||
}
|
||||
|
||||
static inline unsigned long totalhigh_pages(void) { return 0UL; }
|
||||
|
||||
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)
|
||||
{
|
||||
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)
|
||||
{
|
||||
/*
|
||||
* Mostly nothing to do in the CONFIG_HIGHMEM=n case as kunmap_atomic()
|
||||
* handles re-enabling faults and preemption
|
||||
*/
|
||||
#ifdef ARCH_HAS_FLUSH_ON_KUNMAP
|
||||
kunmap_flush_on_unmap(addr);
|
||||
#endif
|
||||
}
|
||||
|
||||
#define kmap_flush_unused() do {} while(0)
|
||||
|
||||
|
||||
#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); \
|
||||
pagefault_enable(); \
|
||||
preempt_enable(); \
|
||||
} while (0)
|
||||
|
||||
/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
|
||||
#ifndef clear_user_highpage
|
||||
static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
|
||||
|
|
|
|||
11
mm/highmem.c
11
mm/highmem.c
|
|
@ -104,7 +104,7 @@ static inline wait_queue_head_t *get_pkmap_wait_queue_head(unsigned int color)
|
|||
atomic_long_t _totalhigh_pages __read_mostly;
|
||||
EXPORT_SYMBOL(_totalhigh_pages);
|
||||
|
||||
unsigned int nr_free_highpages (void)
|
||||
unsigned int __nr_free_highpages (void)
|
||||
{
|
||||
struct zone *zone;
|
||||
unsigned int pages = 0;
|
||||
|
|
@ -141,7 +141,7 @@ pte_t * pkmap_page_table;
|
|||
do { spin_unlock(&kmap_lock); (void)(flags); } while (0)
|
||||
#endif
|
||||
|
||||
struct page *kmap_to_page(void *vaddr)
|
||||
struct page *__kmap_to_page(void *vaddr)
|
||||
{
|
||||
unsigned long addr = (unsigned long)vaddr;
|
||||
|
||||
|
|
@ -152,7 +152,7 @@ struct page *kmap_to_page(void *vaddr)
|
|||
|
||||
return virt_to_page(addr);
|
||||
}
|
||||
EXPORT_SYMBOL(kmap_to_page);
|
||||
EXPORT_SYMBOL(__kmap_to_page);
|
||||
|
||||
static void flush_all_zero_pkmaps(void)
|
||||
{
|
||||
|
|
@ -194,10 +194,7 @@ static void flush_all_zero_pkmaps(void)
|
|||
flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
|
||||
}
|
||||
|
||||
/**
|
||||
* kmap_flush_unused - flush all unused kmap mappings in order to remove stray mappings
|
||||
*/
|
||||
void kmap_flush_unused(void)
|
||||
void __kmap_flush_unused(void)
|
||||
{
|
||||
lock_kmap();
|
||||
flush_all_zero_pkmaps();
|
||||
|
|
|
|||
Loading…
Reference in New Issue