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Diffstat (limited to 'include/linux/uaccess.h')
-rw-r--r-- | include/linux/uaccess.h | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h new file mode 100644 index 00000000..5ca0951e --- /dev/null +++ b/include/linux/uaccess.h @@ -0,0 +1,111 @@ +#ifndef __LINUX_UACCESS_H__ +#define __LINUX_UACCESS_H__ + +#include <linux/preempt.h> +#include <asm/uaccess.h> + +/* + * 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, + const void __user *from, unsigned long n) +{ + return __copy_from_user_inatomic(to, from, n); +} + +static inline unsigned long __copy_from_user_nocache(void *to, + const void __user *from, unsigned long n) +{ + return __copy_from_user(to, from, n); +} + +#endif /* ARCH_HAS_NOCACHE_UACCESS */ + +/** + * probe_kernel_address(): safely attempt to read from a location + * @addr: address to read from - its type is type typeof(retval)* + * @retval: read into this variable + * + * Safely read from address @addr into variable @revtal. If a kernel fault + * happens, handle that and return -EFAULT. + * We ensure that the __get_user() is executed in atomic context so that + * 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 = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \ + pagefault_enable(); \ + set_fs(old_fs); \ + ret; \ + }) + +/* + * probe_kernel_read(): safely attempt to read from a location + * @dst: pointer to the buffer that shall take the data + * @src: address to read from + * @size: size of the data chunk + * + * Safely read from address @src to the buffer at @dst. If a kernel fault + * happens, handle that and return -EFAULT. + */ +extern long probe_kernel_read(void *dst, const void *src, size_t size); +extern long __probe_kernel_read(void *dst, const void *src, size_t size); + +/* + * probe_kernel_write(): safely attempt to write to a location + * @dst: address to write to + * @src: pointer to the data that shall be written + * @size: size of the data chunk + * + * Safely write to address @dst from the buffer at @src. If a kernel fault + * happens, handle that and return -EFAULT. + */ +extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); +extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size); + +#endif /* __LINUX_UACCESS_H__ */ |