![Cesar Eduardo Barros](/assets/img/avatar_default.png)
kunmap_atomic() is currently at level -4 on Rusty's "Hard To Misuse" list[1] ("Follow common convention and you'll get it wrong"), except in some architectures when CONFIG_DEBUG_HIGHMEM is set[2][3]. kunmap() takes a pointer to a struct page; kunmap_atomic(), however, takes takes a pointer to within the page itself. This seems to once in a while trip people up (the convention they are following is the one from kunmap()). Make it much harder to misuse, by moving it to level 9 on Rusty's list[4] ("The compiler/linker won't let you get it wrong"). This is done by refusing to build if the type of its first argument is a pointer to a struct page. The real kunmap_atomic() is renamed to kunmap_atomic_notypecheck() (which is what you would call in case for some strange reason calling it with a pointer to a struct page is not incorrect in your code). The previous version of this patch was compile tested on x86-64. [1] http://ozlabs.org/~rusty/index.cgi/tech/2008-04-01.html [2] In these cases, it is at level 5, "Do it right or it will always break at runtime." [3] At least mips and powerpc look very similar, and sparc also seems to share a common ancestor with both; there seems to be quite some degree of copy-and-paste coding here. The include/asm/highmem.h file for these three archs mention x86 CPUs at its top. [4] http://ozlabs.org/~rusty/index.cgi/tech/2008-03-30.html [5] As an aside, could someone tell me why mn10300 uses unsigned long as the first parameter of kunmap_atomic() instead of void *? Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net> Cc: Russell King <linux@arm.linux.org.uk> (arch/arm) Cc: Ralf Baechle <ralf@linux-mips.org> (arch/mips) Cc: David Howells <dhowells@redhat.com> (arch/frv, arch/mn10300) Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com> (arch/mn10300) Cc: Kyle McMartin <kyle@mcmartin.ca> (arch/parisc) Cc: Helge Deller <deller@gmx.de> (arch/parisc) Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> (arch/parisc) Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> (arch/powerpc) Cc: Paul Mackerras <paulus@samba.org> (arch/powerpc) Cc: "David S. Miller" <davem@davemloft.net> (arch/sparc) Cc: Thomas Gleixner <tglx@linutronix.de> (arch/x86) Cc: Ingo Molnar <mingo@redhat.com> (arch/x86) Cc: "H. Peter Anvin" <hpa@zytor.com> (arch/x86) Cc: Arnd Bergmann <arnd@arndb.de> (include/asm-generic) Cc: Rusty Russell <rusty@rustcorp.com.au> ("Hard To Misuse" list) Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
77 lines
2.1 KiB
C
77 lines
2.1 KiB
C
/*
|
|
* highmem.h: virtual kernel memory mappings for high memory
|
|
*
|
|
* Used in CONFIG_HIGHMEM systems for memory pages which
|
|
* are not addressable by direct kernel virtual addresses.
|
|
*
|
|
* Copyright (C) 1999 Gerhard Wichert, Siemens AG
|
|
* Gerhard.Wichert@pdb.siemens.de
|
|
*
|
|
*
|
|
* Redesigned the x86 32-bit VM architecture to deal with
|
|
* up to 16 Terabyte physical memory. With current x86 CPUs
|
|
* we now support up to 64 Gigabytes physical RAM.
|
|
*
|
|
* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
|
|
*/
|
|
|
|
#ifndef _ASM_X86_HIGHMEM_H
|
|
#define _ASM_X86_HIGHMEM_H
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
#include <linux/interrupt.h>
|
|
#include <linux/threads.h>
|
|
#include <asm/kmap_types.h>
|
|
#include <asm/tlbflush.h>
|
|
#include <asm/paravirt.h>
|
|
#include <asm/fixmap.h>
|
|
|
|
/* declarations for highmem.c */
|
|
extern unsigned long highstart_pfn, highend_pfn;
|
|
|
|
/*
|
|
* Right now we initialize only a single pte table. It can be extended
|
|
* easily, subsequent pte tables have to be allocated in one physical
|
|
* chunk of RAM.
|
|
*/
|
|
/*
|
|
* Ordering is:
|
|
*
|
|
* FIXADDR_TOP
|
|
* fixed_addresses
|
|
* FIXADDR_START
|
|
* temp fixed addresses
|
|
* FIXADDR_BOOT_START
|
|
* Persistent kmap area
|
|
* PKMAP_BASE
|
|
* VMALLOC_END
|
|
* Vmalloc area
|
|
* VMALLOC_START
|
|
* high_memory
|
|
*/
|
|
#define LAST_PKMAP_MASK (LAST_PKMAP-1)
|
|
#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
|
|
#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
|
|
|
|
extern void *kmap_high(struct page *page);
|
|
extern void kunmap_high(struct page *page);
|
|
|
|
void *kmap(struct page *page);
|
|
void kunmap(struct page *page);
|
|
void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot);
|
|
void *kmap_atomic(struct page *page, enum km_type type);
|
|
void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type);
|
|
void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
|
|
void *kmap_atomic_prot_pfn(unsigned long pfn, enum km_type type, pgprot_t prot);
|
|
struct page *kmap_atomic_to_page(void *ptr);
|
|
|
|
#define flush_cache_kmaps() do { } while (0)
|
|
|
|
extern void add_highpages_with_active_regions(int nid, unsigned long start_pfn,
|
|
unsigned long end_pfn);
|
|
|
|
#endif /* __KERNEL__ */
|
|
|
|
#endif /* _ASM_X86_HIGHMEM_H */
|