1/* 2 * __get_user functions. 3 * 4 * (C) Copyright 1998 Linus Torvalds 5 * (C) Copyright 2005 Andi Kleen 6 * (C) Copyright 2008 Glauber Costa 7 * 8 * These functions have a non-standard call interface 9 * to make them more efficient, especially as they 10 * return an error value in addition to the "real" 11 * return value. 12 */ 13 14/* 15 * __get_user_X 16 * 17 * Inputs: %[r|e]ax contains the address. 18 * The register is modified, but all changes are undone 19 * before returning because the C code doesn't know about it. 20 * 21 * Outputs: %[r|e]ax is error code (0 or -EFAULT) 22 * %[r|e]dx contains zero-extended value 23 * 24 * 25 * These functions should not modify any other registers, 26 * as they get called from within inline assembly. 27 */ 28 29#include <linux/linkage.h> 30#include <asm/dwarf2.h> 31#include <asm/page_types.h> 32#include <asm/errno.h> 33#include <asm/asm-offsets.h> 34#include <asm/thread_info.h> 35#include <asm/asm.h> 36#include <asm/smap.h> 37 38 .text 39ENTRY(__get_user_1) 40 CFI_STARTPROC 41 GET_THREAD_INFO(%_ASM_DX) 42 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 43 jae bad_get_user 44 ASM_STAC 451: movzb (%_ASM_AX),%edx 46 xor %eax,%eax 47 ASM_CLAC 48 ret 49 CFI_ENDPROC 50ENDPROC(__get_user_1) 51 52ENTRY(__get_user_2) 53 CFI_STARTPROC 54 add $1,%_ASM_AX 55 jc bad_get_user 56 GET_THREAD_INFO(%_ASM_DX) 57 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 58 jae bad_get_user 59 ASM_STAC 602: movzwl -1(%_ASM_AX),%edx 61 xor %eax,%eax 62 ASM_CLAC 63 ret 64 CFI_ENDPROC 65ENDPROC(__get_user_2) 66 67ENTRY(__get_user_4) 68 CFI_STARTPROC 69 add $3,%_ASM_AX 70 jc bad_get_user 71 GET_THREAD_INFO(%_ASM_DX) 72 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 73 jae bad_get_user 74 ASM_STAC 753: mov -3(%_ASM_AX),%edx 76 xor %eax,%eax 77 ASM_CLAC 78 ret 79 CFI_ENDPROC 80ENDPROC(__get_user_4) 81 82#ifdef CONFIG_X86_64 83ENTRY(__get_user_8) 84 CFI_STARTPROC 85 add $7,%_ASM_AX 86 jc bad_get_user 87 GET_THREAD_INFO(%_ASM_DX) 88 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 89 jae bad_get_user 90 ASM_STAC 914: movq -7(%_ASM_AX),%_ASM_DX 92 xor %eax,%eax 93 ASM_CLAC 94 ret 95 CFI_ENDPROC 96ENDPROC(__get_user_8) 97#endif 98 99bad_get_user: 100 CFI_STARTPROC 101 xor %edx,%edx 102 mov $(-EFAULT),%_ASM_AX 103 ASM_CLAC 104 ret 105 CFI_ENDPROC 106END(bad_get_user) 107 108 _ASM_EXTABLE(1b,bad_get_user) 109 _ASM_EXTABLE(2b,bad_get_user) 110 _ASM_EXTABLE(3b,bad_get_user) 111#ifdef CONFIG_X86_64 112 _ASM_EXTABLE(4b,bad_get_user) 113#endif 114