diff options
Diffstat (limited to 'arch/x86/include/asm/uaccess_32.h')
| -rw-r--r-- | arch/x86/include/asm/uaccess_32.h | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h new file mode 100644 index 00000000000..5e06259e90e --- /dev/null +++ b/arch/x86/include/asm/uaccess_32.h @@ -0,0 +1,218 @@ +#ifndef _ASM_X86_UACCESS_32_H +#define _ASM_X86_UACCESS_32_H + +/* + * User space memory access functions + */ +#include <linux/errno.h> +#include <linux/thread_info.h> +#include <linux/prefetch.h> +#include <linux/string.h> +#include <asm/asm.h> +#include <asm/page.h> + +unsigned long __must_check __copy_to_user_ll + (void __user *to, const void *from, unsigned long n); +unsigned long __must_check __copy_from_user_ll + (void *to, const void __user *from, unsigned long n); +unsigned long __must_check __copy_from_user_ll_nozero + (void *to, const void __user *from, unsigned long n); +unsigned long __must_check __copy_from_user_ll_nocache + (void *to, const void __user *from, unsigned long n); +unsigned long __must_check __copy_from_user_ll_nocache_nozero + (void *to, const void __user *from, unsigned long n); + +/** + * __copy_to_user_inatomic: - Copy a block of data into user space, with less checking. + * @to: Destination address, in user space. + * @from: Source address, in kernel space. + * @n: Number of bytes to copy. + * + * Context: User context only. + * + * Copy data from kernel space to user space. Caller must check + * the specified block with access_ok() before calling this function. + * The caller should also make sure he pins the user space address + * so that the we don't result in page fault and sleep. + * + * Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault + * we return the initial request size (1, 2 or 4), as copy_*_user should do. + * If a store crosses a page boundary and gets a fault, the x86 will not write + * anything, so this is accurate. + */ + +static __always_inline unsigned long __must_check +__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) +{ + if (__builtin_constant_p(n)) { + unsigned long ret; + + switch (n) { + case 1: + __put_user_size(*(u8 *)from, (u8 __user *)to, + 1, ret, 1); + return ret; + case 2: + __put_user_size(*(u16 *)from, (u16 __user *)to, + 2, ret, 2); + return ret; + case 4: + __put_user_size(*(u32 *)from, (u32 __user *)to, + 4, ret, 4); + return ret; + } + } + return __copy_to_user_ll(to, from, n); +} + +/** + * __copy_to_user: - Copy a block of data into user space, with less checking. + * @to: Destination address, in user space. + * @from: Source address, in kernel space. + * @n: Number of bytes to copy. + * + * Context: User context only. This function may sleep. + * + * Copy data from kernel space to user space. Caller must check + * the specified block with access_ok() before calling this function. + * + * Returns number of bytes that could not be copied. + * On success, this will be zero. + */ +static __always_inline unsigned long __must_check +__copy_to_user(void __user *to, const void *from, unsigned long n) +{ + might_fault(); + return __copy_to_user_inatomic(to, from, n); +} + +static __always_inline unsigned long +__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n) +{ + /* Avoid zeroing the tail if the copy fails.. + * If 'n' is constant and 1, 2, or 4, we do still zero on a failure, + * but as the zeroing behaviour is only significant when n is not + * constant, that shouldn't be a problem. + */ + if (__builtin_constant_p(n)) { + unsigned long ret; + + switch (n) { + case 1: + __get_user_size(*(u8 *)to, from, 1, ret, 1); + return ret; + case 2: + __get_user_size(*(u16 *)to, from, 2, ret, 2); + return ret; + case 4: + __get_user_size(*(u32 *)to, from, 4, ret, 4); + return ret; + } + } + return __copy_from_user_ll_nozero(to, from, n); +} + +/** + * __copy_from_user: - Copy a block of data from user space, with less checking. + * @to: Destination address, in kernel space. + * @from: Source address, in user space. + * @n: Number of bytes to copy. + * + * Context: User context only. This function may sleep. + * + * Copy data from user space to kernel space. Caller must check + * the specified block with access_ok() before calling this function. + * + * Returns number of bytes that could not be copied. + * On success, this will be zero. + * + * If some data could not be copied, this function will pad the copied + * data to the requested size using zero bytes. + * + * An alternate version - __copy_from_user_inatomic() - may be called from + * atomic context and will fail rather than sleep. In this case the + * uncopied bytes will *NOT* be padded with zeros. See fs/filemap.h + * for explanation of why this is needed. + */ +static __always_inline unsigned long +__copy_from_user(void *to, const void __user *from, unsigned long n) +{ + might_fault(); + if (__builtin_constant_p(n)) { + unsigned long ret; + + switch (n) { + case 1: + __get_user_size(*(u8 *)to, from, 1, ret, 1); + return ret; + case 2: + __get_user_size(*(u16 *)to, from, 2, ret, 2); + return ret; + case 4: + __get_user_size(*(u32 *)to, from, 4, ret, 4); + return ret; + } + } + return __copy_from_user_ll(to, from, n); +} + +static __always_inline unsigned long __copy_from_user_nocache(void *to, + const void __user *from, unsigned long n) +{ + might_fault(); + if (__builtin_constant_p(n)) { + unsigned long ret; + + switch (n) { + case 1: + __get_user_size(*(u8 *)to, from, 1, ret, 1); + return ret; + case 2: + __get_user_size(*(u16 *)to, from, 2, ret, 2); + return ret; + case 4: + __get_user_size(*(u32 *)to, from, 4, ret, 4); + return ret; + } + } + return __copy_from_user_ll_nocache(to, from, n); +} + +static __always_inline unsigned long +__copy_from_user_inatomic_nocache(void *to, const void __user *from, + unsigned long n) +{ + return __copy_from_user_ll_nocache_nozero(to, from, n); +} + +unsigned long __must_check copy_to_user(void __user *to, + const void *from, unsigned long n); +unsigned long __must_check copy_from_user(void *to, + const void __user *from, + unsigned long n); +long __must_check strncpy_from_user(char *dst, const char __user *src, + long count); +long __must_check __strncpy_from_user(char *dst, + const char __user *src, long count); + +/** + * strlen_user: - Get the size of a string in user space. + * @str: The string to measure. + * + * Context: User context only. This function may sleep. + * + * Get the size of a NUL-terminated string in user space. + * + * Returns the size of the string INCLUDING the terminating NUL. + * On exception, returns 0. + * + * If there is a limit on the length of a valid string, you may wish to + * consider using strnlen_user() instead. + */ +#define strlen_user(str) strnlen_user(str, LONG_MAX) + +long strnlen_user(const char __user *str, long n); +unsigned long __must_check clear_user(void __user *mem, unsigned long len); +unsigned long __must_check __clear_user(void __user *mem, unsigned long len); + +#endif /* _ASM_X86_UACCESS_32_H */ |