![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>
183 lines
5.3 KiB
C
183 lines
5.3 KiB
C
/* highmem.h: virtual kernel memory mappings for high memory
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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* - Derived from include/asm-i386/highmem.h
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*
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* See Documentation/frv/mmu-layout.txt for more information.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_HIGHMEM_H
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#define _ASM_HIGHMEM_H
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#ifdef __KERNEL__
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#include <linux/init.h>
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#include <linux/highmem.h>
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#include <asm/mem-layout.h>
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#include <asm/spr-regs.h>
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#include <asm/mb-regs.h>
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#define NR_TLB_LINES 64 /* number of lines in the TLB */
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#ifndef __ASSEMBLY__
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#include <linux/interrupt.h>
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#include <asm/kmap_types.h>
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#include <asm/pgtable.h>
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#ifdef CONFIG_DEBUG_HIGHMEM
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#define HIGHMEM_DEBUG 1
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#else
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#define HIGHMEM_DEBUG 0
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#endif
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/* declarations for highmem.c */
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extern unsigned long highstart_pfn, highend_pfn;
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#define kmap_prot PAGE_KERNEL
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#define kmap_pte ______kmap_pte_in_TLB
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extern pte_t *pkmap_page_table;
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#define flush_cache_kmaps() do { } while (0)
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/*
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* Right now we initialize only a single pte table. It can be extended
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* easily, subsequent pte tables have to be allocated in one physical
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* chunk of RAM.
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*/
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#define LAST_PKMAP PTRS_PER_PTE
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#define LAST_PKMAP_MASK (LAST_PKMAP - 1)
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#define PKMAP_NR(virt) ((virt - PKMAP_BASE) >> PAGE_SHIFT)
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#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
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extern void *kmap_high(struct page *page);
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extern void kunmap_high(struct page *page);
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extern void *kmap(struct page *page);
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extern void kunmap(struct page *page);
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extern struct page *kmap_atomic_to_page(void *ptr);
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#endif /* !__ASSEMBLY__ */
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/*
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* The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
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* gives a more generic (and caching) interface. But kmap_atomic can
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* be used in IRQ contexts, so in some (very limited) cases we need
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* it.
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*/
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#define KMAP_ATOMIC_CACHE_DAMR 8
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#ifndef __ASSEMBLY__
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#define __kmap_atomic_primary(type, paddr, ampr) \
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({ \
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unsigned long damlr, dampr; \
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\
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dampr = paddr | xAMPRx_L | xAMPRx_M | xAMPRx_S | xAMPRx_SS_16Kb | xAMPRx_V; \
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\
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if (type != __KM_CACHE) \
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asm volatile("movgs %0,dampr"#ampr :: "r"(dampr) : "memory"); \
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else \
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asm volatile("movgs %0,iampr"#ampr"\n" \
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"movgs %0,dampr"#ampr"\n" \
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:: "r"(dampr) : "memory" \
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); \
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\
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asm("movsg damlr"#ampr",%0" : "=r"(damlr)); \
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\
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/*printk("DAMR"#ampr": PRIM sl=%d L=%08lx P=%08lx\n", type, damlr, dampr);*/ \
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\
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(void *) damlr; \
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})
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#define __kmap_atomic_secondary(slot, paddr) \
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({ \
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unsigned long damlr = KMAP_ATOMIC_SECONDARY_FRAME + (slot) * PAGE_SIZE; \
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unsigned long dampr = paddr | xAMPRx_L | xAMPRx_M | xAMPRx_S | xAMPRx_SS_16Kb | xAMPRx_V; \
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\
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asm volatile("movgs %0,tplr \n" \
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"movgs %1,tppr \n" \
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"tlbpr %0,gr0,#2,#1" \
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: : "r"(damlr), "r"(dampr) : "memory"); \
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\
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/*printk("TLB: SECN sl=%d L=%08lx P=%08lx\n", slot, damlr, dampr);*/ \
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\
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(void *) damlr; \
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})
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static inline void *kmap_atomic(struct page *page, enum km_type type)
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{
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unsigned long paddr;
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pagefault_disable();
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debug_kmap_atomic(type);
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paddr = page_to_phys(page);
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switch (type) {
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case 0: return __kmap_atomic_primary(0, paddr, 2);
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case 1: return __kmap_atomic_primary(1, paddr, 3);
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case 2: return __kmap_atomic_primary(2, paddr, 4);
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case 3: return __kmap_atomic_primary(3, paddr, 5);
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case 4: return __kmap_atomic_primary(4, paddr, 6);
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case 5: return __kmap_atomic_primary(5, paddr, 7);
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case 6: return __kmap_atomic_primary(6, paddr, 8);
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case 7: return __kmap_atomic_primary(7, paddr, 9);
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case 8: return __kmap_atomic_primary(8, paddr, 10);
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case 9 ... 9 + NR_TLB_LINES - 1:
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return __kmap_atomic_secondary(type - 9, paddr);
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default:
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BUG();
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return NULL;
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}
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}
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#define __kunmap_atomic_primary(type, ampr) \
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do { \
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asm volatile("movgs gr0,dampr"#ampr"\n" ::: "memory"); \
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if (type == __KM_CACHE) \
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asm volatile("movgs gr0,iampr"#ampr"\n" ::: "memory"); \
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} while(0)
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#define __kunmap_atomic_secondary(slot, vaddr) \
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do { \
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asm volatile("tlbpr %0,gr0,#4,#1" : : "r"(vaddr) : "memory"); \
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} while(0)
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static inline void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
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{
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switch (type) {
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case 0: __kunmap_atomic_primary(0, 2); break;
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case 1: __kunmap_atomic_primary(1, 3); break;
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case 2: __kunmap_atomic_primary(2, 4); break;
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case 3: __kunmap_atomic_primary(3, 5); break;
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case 4: __kunmap_atomic_primary(4, 6); break;
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case 5: __kunmap_atomic_primary(5, 7); break;
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case 6: __kunmap_atomic_primary(6, 8); break;
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case 7: __kunmap_atomic_primary(7, 9); break;
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case 8: __kunmap_atomic_primary(8, 10); break;
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case 9 ... 9 + NR_TLB_LINES - 1:
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__kunmap_atomic_secondary(type - 9, kvaddr);
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break;
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default:
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BUG();
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}
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pagefault_enable();
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_HIGHMEM_H */
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