kernel-fxtec-pro1x/arch/frv/include/asm/highmem.h
Cesar Eduardo Barros 597781f3e5 kmap_atomic: make kunmap_atomic() harder to misuse
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>
2010-08-09 20:44:54 -07:00

182 lines
5.3 KiB
C

/* highmem.h: virtual kernel memory mappings for high memory
*
* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* - Derived from include/asm-i386/highmem.h
*
* See Documentation/frv/mmu-layout.txt for more information.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _ASM_HIGHMEM_H
#define _ASM_HIGHMEM_H
#ifdef __KERNEL__
#include <linux/init.h>
#include <linux/highmem.h>
#include <asm/mem-layout.h>
#include <asm/spr-regs.h>
#include <asm/mb-regs.h>
#define NR_TLB_LINES 64 /* number of lines in the TLB */
#ifndef __ASSEMBLY__
#include <linux/interrupt.h>
#include <asm/kmap_types.h>
#include <asm/pgtable.h>
#ifdef CONFIG_DEBUG_HIGHMEM
#define HIGHMEM_DEBUG 1
#else
#define HIGHMEM_DEBUG 0
#endif
/* declarations for highmem.c */
extern unsigned long highstart_pfn, highend_pfn;
#define kmap_prot PAGE_KERNEL
#define kmap_pte ______kmap_pte_in_TLB
extern pte_t *pkmap_page_table;
#define flush_cache_kmaps() do { } while (0)
/*
* 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.
*/
#define LAST_PKMAP PTRS_PER_PTE
#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);
extern void *kmap(struct page *page);
extern void kunmap(struct page *page);
extern struct page *kmap_atomic_to_page(void *ptr);
#endif /* !__ASSEMBLY__ */
/*
* 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.
*/
#define KMAP_ATOMIC_CACHE_DAMR 8
#ifndef __ASSEMBLY__
#define __kmap_atomic_primary(type, paddr, ampr) \
({ \
unsigned long damlr, dampr; \
\
dampr = paddr | xAMPRx_L | xAMPRx_M | xAMPRx_S | xAMPRx_SS_16Kb | xAMPRx_V; \
\
if (type != __KM_CACHE) \
asm volatile("movgs %0,dampr"#ampr :: "r"(dampr) : "memory"); \
else \
asm volatile("movgs %0,iampr"#ampr"\n" \
"movgs %0,dampr"#ampr"\n" \
:: "r"(dampr) : "memory" \
); \
\
asm("movsg damlr"#ampr",%0" : "=r"(damlr)); \
\
/*printk("DAMR"#ampr": PRIM sl=%d L=%08lx P=%08lx\n", type, damlr, dampr);*/ \
\
(void *) damlr; \
})
#define __kmap_atomic_secondary(slot, paddr) \
({ \
unsigned long damlr = KMAP_ATOMIC_SECONDARY_FRAME + (slot) * PAGE_SIZE; \
unsigned long dampr = paddr | xAMPRx_L | xAMPRx_M | xAMPRx_S | xAMPRx_SS_16Kb | xAMPRx_V; \
\
asm volatile("movgs %0,tplr \n" \
"movgs %1,tppr \n" \
"tlbpr %0,gr0,#2,#1" \
: : "r"(damlr), "r"(dampr) : "memory"); \
\
/*printk("TLB: SECN sl=%d L=%08lx P=%08lx\n", slot, damlr, dampr);*/ \
\
(void *) damlr; \
})
static inline void *kmap_atomic(struct page *page, enum km_type type)
{
unsigned long paddr;
pagefault_disable();
debug_kmap_atomic(type);
paddr = page_to_phys(page);
switch (type) {
case 0: return __kmap_atomic_primary(0, paddr, 2);
case 1: return __kmap_atomic_primary(1, paddr, 3);
case 2: return __kmap_atomic_primary(2, paddr, 4);
case 3: return __kmap_atomic_primary(3, paddr, 5);
case 4: return __kmap_atomic_primary(4, paddr, 6);
case 5: return __kmap_atomic_primary(5, paddr, 7);
case 6: return __kmap_atomic_primary(6, paddr, 8);
case 7: return __kmap_atomic_primary(7, paddr, 9);
case 8: return __kmap_atomic_primary(8, paddr, 10);
case 9 ... 9 + NR_TLB_LINES - 1:
return __kmap_atomic_secondary(type - 9, paddr);
default:
BUG();
return NULL;
}
}
#define __kunmap_atomic_primary(type, ampr) \
do { \
asm volatile("movgs gr0,dampr"#ampr"\n" ::: "memory"); \
if (type == __KM_CACHE) \
asm volatile("movgs gr0,iampr"#ampr"\n" ::: "memory"); \
} while(0)
#define __kunmap_atomic_secondary(slot, vaddr) \
do { \
asm volatile("tlbpr %0,gr0,#4,#1" : : "r"(vaddr) : "memory"); \
} while(0)
static inline void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
{
switch (type) {
case 0: __kunmap_atomic_primary(0, 2); break;
case 1: __kunmap_atomic_primary(1, 3); break;
case 2: __kunmap_atomic_primary(2, 4); break;
case 3: __kunmap_atomic_primary(3, 5); break;
case 4: __kunmap_atomic_primary(4, 6); break;
case 5: __kunmap_atomic_primary(5, 7); break;
case 6: __kunmap_atomic_primary(6, 8); break;
case 7: __kunmap_atomic_primary(7, 9); break;
case 8: __kunmap_atomic_primary(8, 10); break;
case 9 ... 9 + NR_TLB_LINES - 1:
__kunmap_atomic_secondary(type - 9, kvaddr);
break;
default:
BUG();
}
pagefault_enable();
}
#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _ASM_HIGHMEM_H */