From 2fff0a48416af891dce38fd425246e337831e0bb Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Thu, 7 Dec 2006 02:14:05 +0100 Subject: [PATCH] Generic: Move __user cast into probe_kernel_address Caller of probe_kernel_address shouldn't need to know that pka is internally implemented with __get_user. So move the __user cast into pka. Signed-off-by: Andi Kleen --- include/linux/uaccess.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/uaccess.h') diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index a48d7f11c7be..65a68da8bd5d 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -36,7 +36,7 @@ static inline unsigned long __copy_from_user_nocache(void *to, long ret; \ \ inc_preempt_count(); \ - ret = __get_user(retval, addr); \ + ret = __get_user(retval, (__force typeof(*addr) __user *)addr);\ dec_preempt_count(); \ ret; \ }) -- cgit v1.2.3 From a866374aecc90c7d90619727ccd851ac096b2fc7 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 6 Dec 2006 20:32:20 -0800 Subject: [PATCH] mm: pagefault_{disable,enable}() Introduce pagefault_{disable,enable}() and use these where previously we did manual preempt increments/decrements to make the pagefault handler do the atomic thing. Currently they still rely on the increased preempt count, but do not rely on the disabled preemption, this might go away in the future. (NOTE: the extra barrier() in pagefault_disable might fix some holes on machines which have too many registers for their own good) [heiko.carstens@de.ibm.com: s390 fix] Signed-off-by: Peter Zijlstra Acked-by: Nick Piggin Cc: Martin Schwidefsky Signed-off-by: Heiko Carstens Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/uaccess.h | 39 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 37 insertions(+), 2 deletions(-) (limited to 'include/linux/uaccess.h') diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index a48d7f11c7be..67918c22339c 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -1,8 +1,43 @@ #ifndef __LINUX_UACCESS_H__ #define __LINUX_UACCESS_H__ +#include #include +/* + * These routines enable/disable the pagefault handler in that + * it will not take any locks and go straight to the fixup table. + * + * They have great resemblance to the preempt_disable/enable calls + * and in fact they are identical; this is because currently there is + * no other way to make the pagefault handlers do this. So we do + * disable preemption but we don't necessarily care about that. + */ +static inline void pagefault_disable(void) +{ + inc_preempt_count(); + /* + * make sure to have issued the store before a pagefault + * can hit. + */ + barrier(); +} + +static inline void pagefault_enable(void) +{ + /* + * make sure to issue those last loads/stores before enabling + * the pagefault handler again. + */ + barrier(); + dec_preempt_count(); + /* + * make sure we do.. + */ + barrier(); + preempt_check_resched(); +} + #ifndef ARCH_HAS_NOCACHE_UACCESS static inline unsigned long __copy_from_user_inatomic_nocache(void *to, @@ -35,9 +70,9 @@ static inline unsigned long __copy_from_user_nocache(void *to, ({ \ long ret; \ \ - inc_preempt_count(); \ + pagefault_disable(); \ ret = __get_user(retval, addr); \ - dec_preempt_count(); \ + pagefault_enable(); \ ret; \ }) -- cgit v1.2.3 From 20aa7b21b1cbd1aa3fbf5fc14da5f7484a61a824 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 6 Dec 2006 20:36:40 -0800 Subject: [PATCH] probe_kernel_address() needs to do set_fs() probe_kernel_address() purports to be generic, only it forgot to select KERNEL_DS, so it presently won't work right on all architectures. Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/uaccess.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux/uaccess.h') diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 67918c22339c..76c3fe325101 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -65,14 +65,22 @@ static inline unsigned long __copy_from_user_nocache(void *to, * do_page_fault() doesn't attempt to take mmap_sem. This makes * probe_kernel_address() suitable for use within regions where the caller * already holds mmap_sem, or other locks which nest inside mmap_sem. + * This must be a macro because __get_user() needs to know the types of the + * args. + * + * We don't include enough header files to be able to do the set_fs(). We + * require that the probe_kernel_address() caller will do that. */ #define probe_kernel_address(addr, retval) \ ({ \ long ret; \ + mm_segment_t old_fs = get_fs(); \ \ + set_fs(KERNEL_DS); \ pagefault_disable(); \ ret = __get_user(retval, addr); \ pagefault_enable(); \ + set_fs(old_fs); \ ret; \ }) -- cgit v1.2.3