1/* 2 * __get_user functions. 3 * 4 * (C) Copyright 1998 Linus Torvalds 5 * (C) Copyright 2005 Andi Kleen 6 * 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" 10 * return value. 11 */ 12 13/* 14 * __get_user_X 15 * 16 * Inputs: %rcx 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. 19 * 20 * Outputs: %rax is error code (0 or -EFAULT) 21 * %rdx contains zero-extended value 22 * 23 * %r8 is destroyed. 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.h> 32#include <asm/errno.h> 33#include <asm/asm-offsets.h> 34#include <asm/thread_info.h> 35 36 .text 37ENTRY(__get_user_1) 38 CFI_STARTPROC 39 GET_THREAD_INFO(%r8) 40 cmpq threadinfo_addr_limit(%r8),%rcx 41 jae bad_get_user 421: movzb (%rcx),%edx 43 xorl %eax,%eax 44 ret 45 CFI_ENDPROC 46ENDPROC(__get_user_1) 47 48ENTRY(__get_user_2) 49 CFI_STARTPROC 50 GET_THREAD_INFO(%r8) 51 addq $1,%rcx 52 jc 20f 53 cmpq threadinfo_addr_limit(%r8),%rcx 54 jae 20f 55 decq %rcx 562: movzwl (%rcx),%edx 57 xorl %eax,%eax 58 ret 5920: decq %rcx 60 jmp bad_get_user 61 CFI_ENDPROC 62ENDPROC(__get_user_2) 63 64ENTRY(__get_user_4) 65 CFI_STARTPROC 66 GET_THREAD_INFO(%r8) 67 addq $3,%rcx 68 jc 30f 69 cmpq threadinfo_addr_limit(%r8),%rcx 70 jae 30f 71 subq $3,%rcx 723: movl (%rcx),%edx 73 xorl %eax,%eax 74 ret 7530: subq $3,%rcx 76 jmp bad_get_user 77 CFI_ENDPROC 78ENDPROC(__get_user_4) 79 80ENTRY(__get_user_8) 81 CFI_STARTPROC 82 GET_THREAD_INFO(%r8) 83 addq $7,%rcx 84 jc 40f 85 cmpq threadinfo_addr_limit(%r8),%rcx 86 jae 40f 87 subq $7,%rcx 884: movq (%rcx),%rdx 89 xorl %eax,%eax 90 ret 9140: subq $7,%rcx 92 jmp bad_get_user 93 CFI_ENDPROC 94ENDPROC(__get_user_8) 95 96bad_get_user: 97 CFI_STARTPROC 98 xorl %edx,%edx 99 movq $(-EFAULT),%rax 100 ret 101 CFI_ENDPROC 102END(bad_get_user) 103 104.section __ex_table,"a" 105 .quad 1b,bad_get_user 106 .quad 2b,bad_get_user 107 .quad 3b,bad_get_user 108 .quad 4b,bad_get_user 109.previous 110