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 37 .text 38ENTRY(__get_user_1) 39 CFI_STARTPROC 40 GET_THREAD_INFO(%_ASM_DX) 41 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 42 jae bad_get_user 431: movzb (%_ASM_AX),%edx 44 xor %eax,%eax 45 ret 46 CFI_ENDPROC 47ENDPROC(__get_user_1) 48 49ENTRY(__get_user_2) 50 CFI_STARTPROC 51 add $1,%_ASM_AX 52 jc bad_get_user 53 GET_THREAD_INFO(%_ASM_DX) 54 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 55 jae bad_get_user 562: movzwl -1(%_ASM_AX),%edx 57 xor %eax,%eax 58 ret 59 CFI_ENDPROC 60ENDPROC(__get_user_2) 61 62ENTRY(__get_user_4) 63 CFI_STARTPROC 64 add $3,%_ASM_AX 65 jc bad_get_user 66 GET_THREAD_INFO(%_ASM_DX) 67 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 68 jae bad_get_user 693: mov -3(%_ASM_AX),%edx 70 xor %eax,%eax 71 ret 72 CFI_ENDPROC 73ENDPROC(__get_user_4) 74 75#ifdef CONFIG_X86_64 76ENTRY(__get_user_8) 77 CFI_STARTPROC 78 add $7,%_ASM_AX 79 jc bad_get_user 80 GET_THREAD_INFO(%_ASM_DX) 81 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX 82 jae bad_get_user 834: movq -7(%_ASM_AX),%_ASM_DX 84 xor %eax,%eax 85 ret 86 CFI_ENDPROC 87ENDPROC(__get_user_8) 88#endif 89 90bad_get_user: 91 CFI_STARTPROC 92 xor %edx,%edx 93 mov $(-EFAULT),%_ASM_AX 94 ret 95 CFI_ENDPROC 96END(bad_get_user) 97 98 _ASM_EXTABLE(1b,bad_get_user) 99 _ASM_EXTABLE(2b,bad_get_user) 100 _ASM_EXTABLE(3b,bad_get_user) 101#ifdef CONFIG_X86_64 102 _ASM_EXTABLE(4b,bad_get_user) 103#endif 104