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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | /* * __get_user functions. * * (C) Copyright 1998 Linus Torvalds * (C) Copyright 2005 Andi Kleen * * These functions have a non-standard call interface * to make them more efficient, especially as they * return an error value in addition to the "real" * return value. */ /* * __get_user_X * * Inputs: %rcx contains the address. * The register is modified, but all changes are undone * before returning because the C code doesn't know about it. * * Outputs: %rax is error code (0 or -EFAULT) * %rdx contains zero-extended value * * %r8 is destroyed. * * These functions should not modify any other registers, * as they get called from within inline assembly. */ #include <linux/linkage.h> #include <asm/dwarf2.h> #include <asm/page.h> #include <asm/errno.h> #include <asm/asm-offsets.h> #include <asm/thread_info.h> .text ENTRY(__get_user_1) CFI_STARTPROC GET_THREAD_INFO(%r8) cmpq threadinfo_addr_limit(%r8),%rcx jae bad_get_user 1: movzb (%rcx),%edx xorl %eax,%eax ret CFI_ENDPROC ENDPROC(__get_user_1) ENTRY(__get_user_2) CFI_STARTPROC GET_THREAD_INFO(%r8) addq $1,%rcx jc 20f cmpq threadinfo_addr_limit(%r8),%rcx jae 20f decq %rcx 2: movzwl (%rcx),%edx xorl %eax,%eax ret 20: decq %rcx jmp bad_get_user CFI_ENDPROC ENDPROC(__get_user_2) ENTRY(__get_user_4) CFI_STARTPROC GET_THREAD_INFO(%r8) addq $3,%rcx jc 30f cmpq threadinfo_addr_limit(%r8),%rcx jae 30f subq $3,%rcx 3: movl (%rcx),%edx xorl %eax,%eax ret 30: subq $3,%rcx jmp bad_get_user CFI_ENDPROC ENDPROC(__get_user_4) ENTRY(__get_user_8) CFI_STARTPROC GET_THREAD_INFO(%r8) addq $7,%rcx jc 40f cmpq threadinfo_addr_limit(%r8),%rcx jae 40f subq $7,%rcx 4: movq (%rcx),%rdx xorl %eax,%eax ret 40: subq $7,%rcx jmp bad_get_user CFI_ENDPROC ENDPROC(__get_user_8) bad_get_user: CFI_STARTPROC xorl %edx,%edx movq $(-EFAULT),%rax ret CFI_ENDPROC END(bad_get_user) .section __ex_table,"a" .quad 1b,bad_get_user .quad 2b,bad_get_user .quad 3b,bad_get_user .quad 4b,bad_get_user .previous |