From 597781f3e51f48ef8e67be772196d9e9673752c4 Mon Sep 17 00:00:00 2001 From: Cesar Eduardo Barros Date: Mon, 9 Aug 2010 17:18:32 -0700 Subject: [PATCH] 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 Cc: Russell King (arch/arm) Cc: Ralf Baechle (arch/mips) Cc: David Howells (arch/frv, arch/mn10300) Cc: Koichi Yasutake (arch/mn10300) Cc: Kyle McMartin (arch/parisc) Cc: Helge Deller (arch/parisc) Cc: "James E.J. Bottomley" (arch/parisc) Cc: Benjamin Herrenschmidt (arch/powerpc) Cc: Paul Mackerras (arch/powerpc) Cc: "David S. Miller" (arch/sparc) Cc: Thomas Gleixner (arch/x86) Cc: Ingo Molnar (arch/x86) Cc: "H. Peter Anvin" (arch/x86) Cc: Arnd Bergmann (include/asm-generic) Cc: Rusty Russell ("Hard To Misuse" list) Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arm/include/asm/highmem.h | 2 +- arch/arm/mm/highmem.c | 4 ++-- arch/frv/include/asm/highmem.h | 2 +- arch/mips/include/asm/highmem.h | 4 ++-- arch/mips/mm/highmem.c | 4 ++-- arch/mn10300/include/asm/highmem.h | 2 +- arch/parisc/include/asm/cacheflush.h | 2 +- arch/powerpc/include/asm/highmem.h | 2 +- arch/powerpc/mm/highmem.c | 4 ++-- arch/sparc/include/asm/highmem.h | 2 +- arch/sparc/mm/highmem.c | 4 ++-- arch/x86/include/asm/highmem.h | 2 +- arch/x86/mm/highmem_32.c | 4 ++-- include/linux/highmem.h | 10 +++++++++- 14 files changed, 28 insertions(+), 20 deletions(-) diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h index feb988a7ec37..5aff58126602 100644 --- a/arch/arm/include/asm/highmem.h +++ b/arch/arm/include/asm/highmem.h @@ -36,7 +36,7 @@ extern void kunmap_high_l1_vipt(struct page *page, pte_t saved_pte); extern void *kmap(struct page *page); extern void kunmap(struct page *page); extern void *kmap_atomic(struct page *page, enum km_type type); -extern void kunmap_atomic(void *kvaddr, enum km_type type); +extern void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type); extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type); extern struct page *kmap_atomic_to_page(const void *ptr); #endif diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c index 6ab244062b4a..1fbdb55bfd1b 100644 --- a/arch/arm/mm/highmem.c +++ b/arch/arm/mm/highmem.c @@ -82,7 +82,7 @@ void *kmap_atomic(struct page *page, enum km_type type) } EXPORT_SYMBOL(kmap_atomic); -void kunmap_atomic(void *kvaddr, enum km_type type) +void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type) { unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; unsigned int idx = type + KM_TYPE_NR * smp_processor_id(); @@ -103,7 +103,7 @@ void kunmap_atomic(void *kvaddr, enum km_type type) } pagefault_enable(); } -EXPORT_SYMBOL(kunmap_atomic); +EXPORT_SYMBOL(kunmap_atomic_notypecheck); void *kmap_atomic_pfn(unsigned long pfn, enum km_type type) { diff --git a/arch/frv/include/asm/highmem.h b/arch/frv/include/asm/highmem.h index 68e4677fb9e7..cb4c317eaecc 100644 --- a/arch/frv/include/asm/highmem.h +++ b/arch/frv/include/asm/highmem.h @@ -152,7 +152,7 @@ do { \ asm volatile("tlbpr %0,gr0,#4,#1" : : "r"(vaddr) : "memory"); \ } while(0) -static inline void kunmap_atomic(void *kvaddr, enum km_type type) +static inline void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type) { switch (type) { case 0: __kunmap_atomic_primary(0, 2); break; diff --git a/arch/mips/include/asm/highmem.h b/arch/mips/include/asm/highmem.h index 25adfb02923d..75753ca73bfd 100644 --- a/arch/mips/include/asm/highmem.h +++ b/arch/mips/include/asm/highmem.h @@ -48,14 +48,14 @@ extern void kunmap_high(struct page *page); extern void *__kmap(struct page *page); extern void __kunmap(struct page *page); extern void *__kmap_atomic(struct page *page, enum km_type type); -extern void __kunmap_atomic(void *kvaddr, enum km_type type); +extern void __kunmap_atomic_notypecheck(void *kvaddr, enum km_type type); extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type); extern struct page *__kmap_atomic_to_page(void *ptr); #define kmap __kmap #define kunmap __kunmap #define kmap_atomic __kmap_atomic -#define kunmap_atomic __kunmap_atomic +#define kunmap_atomic_notypecheck __kunmap_atomic_notypecheck #define kmap_atomic_to_page __kmap_atomic_to_page #define flush_cache_kmaps() flush_cache_all() diff --git a/arch/mips/mm/highmem.c b/arch/mips/mm/highmem.c index 127d732474bf..6a2b1bf9ef11 100644 --- a/arch/mips/mm/highmem.c +++ b/arch/mips/mm/highmem.c @@ -64,7 +64,7 @@ void *__kmap_atomic(struct page *page, enum km_type type) } EXPORT_SYMBOL(__kmap_atomic); -void __kunmap_atomic(void *kvaddr, enum km_type type) +void __kunmap_atomic_notypecheck(void *kvaddr, enum km_type type) { #ifdef CONFIG_DEBUG_HIGHMEM unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; @@ -87,7 +87,7 @@ void __kunmap_atomic(void *kvaddr, enum km_type type) pagefault_enable(); } -EXPORT_SYMBOL(__kunmap_atomic); +EXPORT_SYMBOL(__kunmap_atomic_notypecheck); /* * This is the same as kmap_atomic() but can map memory that doesn't diff --git a/arch/mn10300/include/asm/highmem.h b/arch/mn10300/include/asm/highmem.h index 90f2abb04bfd..b0b187a29b88 100644 --- a/arch/mn10300/include/asm/highmem.h +++ b/arch/mn10300/include/asm/highmem.h @@ -91,7 +91,7 @@ static inline unsigned long kmap_atomic(struct page *page, enum km_type type) return vaddr; } -static inline void kunmap_atomic(unsigned long vaddr, enum km_type type) +static inline void kunmap_atomic_notypecheck(unsigned long vaddr, enum km_type type) { #if HIGHMEM_DEBUG enum fixed_addresses idx = type + KM_TYPE_NR * smp_processor_id(); diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h index 4556d820128a..dba11aedce1b 100644 --- a/arch/parisc/include/asm/cacheflush.h +++ b/arch/parisc/include/asm/cacheflush.h @@ -132,7 +132,7 @@ static inline void *kmap_atomic(struct page *page, enum km_type idx) return page_address(page); } -static inline void kunmap_atomic(void *addr, enum km_type idx) +static inline void kunmap_atomic_notypecheck(void *addr, enum km_type idx) { kunmap_parisc(addr); pagefault_enable(); diff --git a/arch/powerpc/include/asm/highmem.h b/arch/powerpc/include/asm/highmem.h index a74c4ee6c020..d10d64a4be38 100644 --- a/arch/powerpc/include/asm/highmem.h +++ b/arch/powerpc/include/asm/highmem.h @@ -62,7 +62,7 @@ extern void *kmap_high(struct page *page); extern void kunmap_high(struct page *page); extern void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot); -extern void kunmap_atomic(void *kvaddr, enum km_type type); +extern void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type); static inline void *kmap(struct page *page) { diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c index c2186c74c85a..857d4173f9c6 100644 --- a/arch/powerpc/mm/highmem.c +++ b/arch/powerpc/mm/highmem.c @@ -52,7 +52,7 @@ void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot) } EXPORT_SYMBOL(kmap_atomic_prot); -void kunmap_atomic(void *kvaddr, enum km_type type) +void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type) { #ifdef CONFIG_DEBUG_HIGHMEM unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; @@ -74,4 +74,4 @@ void kunmap_atomic(void *kvaddr, enum km_type type) #endif pagefault_enable(); } -EXPORT_SYMBOL(kunmap_atomic); +EXPORT_SYMBOL(kunmap_atomic_notypecheck); diff --git a/arch/sparc/include/asm/highmem.h b/arch/sparc/include/asm/highmem.h index 3de42e776274..ec23b0a87b98 100644 --- a/arch/sparc/include/asm/highmem.h +++ b/arch/sparc/include/asm/highmem.h @@ -71,7 +71,7 @@ static inline void kunmap(struct page *page) } extern void *kmap_atomic(struct page *page, enum km_type type); -extern void kunmap_atomic(void *kvaddr, enum km_type type); +extern void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type); extern struct page *kmap_atomic_to_page(void *vaddr); #define flush_cache_kmaps() flush_cache_all() diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c index 7916feba6e4a..e139e9cbf5f7 100644 --- a/arch/sparc/mm/highmem.c +++ b/arch/sparc/mm/highmem.c @@ -65,7 +65,7 @@ void *kmap_atomic(struct page *page, enum km_type type) } EXPORT_SYMBOL(kmap_atomic); -void kunmap_atomic(void *kvaddr, enum km_type type) +void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type) { #ifdef CONFIG_DEBUG_HIGHMEM unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; @@ -100,7 +100,7 @@ void kunmap_atomic(void *kvaddr, enum km_type type) pagefault_enable(); } -EXPORT_SYMBOL(kunmap_atomic); +EXPORT_SYMBOL(kunmap_atomic_notypecheck); /* We may be fed a pagetable here by ptep_to_xxx and others. */ struct page *kmap_atomic_to_page(void *ptr) diff --git a/arch/x86/include/asm/highmem.h b/arch/x86/include/asm/highmem.h index a726650fc80f..8caac76ac324 100644 --- a/arch/x86/include/asm/highmem.h +++ b/arch/x86/include/asm/highmem.h @@ -61,7 +61,7 @@ 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(void *kvaddr, 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); diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c index 63a6ba66cbe0..5e8fa12ef861 100644 --- a/arch/x86/mm/highmem_32.c +++ b/arch/x86/mm/highmem_32.c @@ -53,7 +53,7 @@ void *kmap_atomic(struct page *page, enum km_type type) return kmap_atomic_prot(page, type, kmap_prot); } -void kunmap_atomic(void *kvaddr, enum km_type type) +void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type) { unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK; enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id(); @@ -102,7 +102,7 @@ struct page *kmap_atomic_to_page(void *ptr) EXPORT_SYMBOL(kmap); EXPORT_SYMBOL(kunmap); EXPORT_SYMBOL(kmap_atomic); -EXPORT_SYMBOL(kunmap_atomic); +EXPORT_SYMBOL(kunmap_atomic_notypecheck); EXPORT_SYMBOL(kmap_atomic_prot); EXPORT_SYMBOL(kmap_atomic_to_page); diff --git a/include/linux/highmem.h b/include/linux/highmem.h index caafd0561aa1..67460f010224 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -2,6 +2,7 @@ #define _LINUX_HIGHMEM_H #include +#include #include #include @@ -72,7 +73,7 @@ static inline void *kmap_atomic(struct page *page, enum km_type idx) } #define kmap_atomic_prot(page, idx, prot) kmap_atomic(page, idx) -#define kunmap_atomic(addr, idx) do { pagefault_enable(); } while (0) +#define kunmap_atomic_notypecheck(addr, idx) do { pagefault_enable(); } while (0) #define kmap_atomic_pfn(pfn, idx) kmap_atomic(pfn_to_page(pfn), (idx)) #define kmap_atomic_to_page(ptr) virt_to_page(ptr) @@ -81,6 +82,13 @@ static inline void *kmap_atomic(struct page *page, enum km_type idx) #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, idx) do { \ + BUILD_BUG_ON(__same_type((addr), struct page *)); \ + kunmap_atomic_notypecheck((addr), (idx)); \ + } 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) -- 2.39.5