2 * __get_user functions.
4 * (C) Copyright 1998 Linus Torvalds
5 * (C) Copyright 2005 Andi Kleen
7 * These functions have a non-standard call interface
8 * to make them more efficient, especially as they
9 * return an error value in addition to the "real"
16 * Inputs: %rax contains the address.
17 * The register is modified, but all changes are undone
18 * before returning because the C code doesn't know about it.
20 * Outputs: %rax is error code (0 or -EFAULT)
21 * %rdx contains zero-extended value
24 * These functions should not modify any other registers,
25 * as they get called from within inline assembly.
28 #include <linux/linkage.h>
29 #include <asm/dwarf2.h>
31 #include <asm/errno.h>
32 #include <asm/asm-offsets.h>
33 #include <asm/thread_info.h>
39 GET_THREAD_INFO(%_ASM_DX)
40 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
42 1: movzb (%_ASM_AX),%edx
52 GET_THREAD_INFO(%_ASM_DX)
53 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
55 2: movzwl -1(%_ASM_AX),%edx
65 GET_THREAD_INFO(%_ASM_DX)
66 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
68 3: mov -3(%_ASM_AX),%edx
78 GET_THREAD_INFO(%_ASM_DX)
79 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
81 4: movq -7(%_ASM_AX),%_ASM_DX
90 mov $(-EFAULT),%_ASM_AX
95 .section __ex_table,"a"
96 _ASM_PTR 1b,bad_get_user
97 _ASM_PTR 2b,bad_get_user
98 _ASM_PTR 3b,bad_get_user
99 _ASM_PTR 4b,bad_get_user