Hiro Yoshioka | c22ce14 | 2006-06-23 02:04:16 -0700 | [diff] [blame] | 1 | #ifndef __LINUX_UACCESS_H__ |
| 2 | #define __LINUX_UACCESS_H__ |
| 3 | |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 4 | #include <linux/preempt.h> |
Hiro Yoshioka | c22ce14 | 2006-06-23 02:04:16 -0700 | [diff] [blame] | 5 | #include <asm/uaccess.h> |
| 6 | |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 7 | /* |
| 8 | * These routines enable/disable the pagefault handler in that |
| 9 | * it will not take any locks and go straight to the fixup table. |
| 10 | * |
| 11 | * They have great resemblance to the preempt_disable/enable calls |
| 12 | * and in fact they are identical; this is because currently there is |
| 13 | * no other way to make the pagefault handlers do this. So we do |
| 14 | * disable preemption but we don't necessarily care about that. |
| 15 | */ |
| 16 | static inline void pagefault_disable(void) |
| 17 | { |
| 18 | inc_preempt_count(); |
| 19 | /* |
| 20 | * make sure to have issued the store before a pagefault |
| 21 | * can hit. |
| 22 | */ |
| 23 | barrier(); |
| 24 | } |
| 25 | |
| 26 | static inline void pagefault_enable(void) |
| 27 | { |
| 28 | /* |
| 29 | * make sure to issue those last loads/stores before enabling |
| 30 | * the pagefault handler again. |
| 31 | */ |
| 32 | barrier(); |
| 33 | dec_preempt_count(); |
| 34 | /* |
| 35 | * make sure we do.. |
| 36 | */ |
| 37 | barrier(); |
| 38 | preempt_check_resched(); |
| 39 | } |
| 40 | |
Hiro Yoshioka | c22ce14 | 2006-06-23 02:04:16 -0700 | [diff] [blame] | 41 | #ifndef ARCH_HAS_NOCACHE_UACCESS |
| 42 | |
| 43 | static inline unsigned long __copy_from_user_inatomic_nocache(void *to, |
| 44 | const void __user *from, unsigned long n) |
| 45 | { |
| 46 | return __copy_from_user_inatomic(to, from, n); |
| 47 | } |
| 48 | |
| 49 | static inline unsigned long __copy_from_user_nocache(void *to, |
| 50 | const void __user *from, unsigned long n) |
| 51 | { |
| 52 | return __copy_from_user(to, from, n); |
| 53 | } |
| 54 | |
| 55 | #endif /* ARCH_HAS_NOCACHE_UACCESS */ |
| 56 | |
Andrew Morton | 1b79e55 | 2006-09-27 01:51:14 -0700 | [diff] [blame] | 57 | /** |
| 58 | * probe_kernel_address(): safely attempt to read from a location |
| 59 | * @addr: address to read from - its type is type typeof(retval)* |
| 60 | * @retval: read into this variable |
| 61 | * |
| 62 | * Safely read from address @addr into variable @revtal. If a kernel fault |
| 63 | * happens, handle that and return -EFAULT. |
| 64 | * We ensure that the __get_user() is executed in atomic context so that |
| 65 | * do_page_fault() doesn't attempt to take mmap_sem. This makes |
| 66 | * probe_kernel_address() suitable for use within regions where the caller |
| 67 | * already holds mmap_sem, or other locks which nest inside mmap_sem. |
Andrew Morton | 20aa7b2 | 2006-12-06 20:36:40 -0800 | [diff] [blame] | 68 | * This must be a macro because __get_user() needs to know the types of the |
| 69 | * args. |
| 70 | * |
| 71 | * We don't include enough header files to be able to do the set_fs(). We |
| 72 | * require that the probe_kernel_address() caller will do that. |
Andrew Morton | 1b79e55 | 2006-09-27 01:51:14 -0700 | [diff] [blame] | 73 | */ |
| 74 | #define probe_kernel_address(addr, retval) \ |
| 75 | ({ \ |
| 76 | long ret; \ |
Andrew Morton | 20aa7b2 | 2006-12-06 20:36:40 -0800 | [diff] [blame] | 77 | mm_segment_t old_fs = get_fs(); \ |
Andrew Morton | 1b79e55 | 2006-09-27 01:51:14 -0700 | [diff] [blame] | 78 | \ |
Andrew Morton | 20aa7b2 | 2006-12-06 20:36:40 -0800 | [diff] [blame] | 79 | set_fs(KERNEL_DS); \ |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 80 | pagefault_disable(); \ |
Linus Torvalds | 4522d58 | 2006-12-07 08:59:11 -0800 | [diff] [blame^] | 81 | ret = __get_user(retval, (__force typeof(retval) __user *)(addr)); \ |
Peter Zijlstra | a866374 | 2006-12-06 20:32:20 -0800 | [diff] [blame] | 82 | pagefault_enable(); \ |
Andrew Morton | 20aa7b2 | 2006-12-06 20:36:40 -0800 | [diff] [blame] | 83 | set_fs(old_fs); \ |
Andrew Morton | 1b79e55 | 2006-09-27 01:51:14 -0700 | [diff] [blame] | 84 | ret; \ |
| 85 | }) |
| 86 | |
Hiro Yoshioka | c22ce14 | 2006-06-23 02:04:16 -0700 | [diff] [blame] | 87 | #endif /* __LINUX_UACCESS_H__ */ |