/* Copyright 2002 Andi Kleen, SuSE Labs. * Subject to the GNU Public License v2. * * Functions to copy from and to user space. */ #include #include #define FIX_ALIGNMENT 1 #include #include #include #include .macro ALTERNATIVE_JUMP feature,orig,alt 0: .byte 0xe9 /* 32bit jump */ .long \orig-1f /* by default jump to orig */ 1: .section .altinstr_replacement,"ax" 2: .byte 0xe9 /* near jump with 32bit immediate */ .long \alt-1b /* offset */ /* or alternatively to alt */ .previous .section .altinstructions,"a" .align 8 .quad 0b .quad 2b .byte \feature /* when feature is set */ .byte 5 .byte 5 .previous .endm /* Standard copy_to_user with segment limit checking */ ENTRY(copy_to_user) CFI_STARTPROC GET_THREAD_INFO(%rax) movq %rdi,%rcx addq %rdx,%rcx jc bad_to_user cmpq threadinfo_addr_limit(%rax),%rcx jae bad_to_user xorl %eax,%eax /* clear zero flag */ ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string CFI_ENDPROC ENTRY(copy_user_generic) CFI_STARTPROC movl $1,%ecx /* set zero flag */ ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string CFI_ENDPROC ENTRY(__copy_from_user_inatomic) CFI_STARTPROC xorl %ecx,%ecx /* clear zero flag */ ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string CFI_ENDPROC /* Standard copy_from_user with segment limit checking */ ENTRY(copy_from_user) CFI_STARTPROC GET_THREAD_INFO(%rax) movq %rsi,%rcx addq %rdx,%rcx jc bad_from_user cmpq threadinfo_addr_limit(%rax),%rcx jae bad_from_user movl $1,%ecx /* set zero flag */ ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,copy_user_generic_unrolled,copy_user_generic_string CFI_ENDPROC ENDPROC(copy_from_user) .section .fixup,"ax" /* must zero dest */ bad_from_user: CFI_STARTPROC movl %edx,%ecx xorl %eax,%eax rep stosb bad_to_user: movl %edx,%eax ret CFI_ENDPROC END(bad_from_user) .previous /* * copy_user_generic_unrolled - memory copy with exception handling. * This version is for CPUs like P4 that don't have efficient micro code for rep movsq * * Input: * rdi destination * rsi source * rdx count * ecx zero flag -- if true zero destination on error * * Output: * eax uncopied bytes or 0 if successful. */ ENTRY(copy_user_generic_unrolled) CFI_STARTPROC pushq %rbx CFI_ADJUST_CFA_OFFSET 8 CFI_REL_OFFSET rbx, 0 pushq %rcx CFI_ADJUST_CFA_OFFSET 8 CFI_REL_OFFSET rcx, 0 xorl %eax,%eax /*zero for the exception handler */ #ifdef FIX_ALIGNMENT /* check for bad alignment of destination */ movl %edi,%ecx andl $7,%ecx jnz .Lbad_alignment .Lafter_bad_alignment: #endif movq %rdx,%rcx movl $64,%ebx shrq $6,%rdx decq %rdx js .Lhandle_tail .p2align 4 .Lloop: .Ls1: movq (%rsi),%r11 .Ls2: movq 1*8(%rsi),%r8 .Ls3: movq 2*8(%rsi),%r9 .Ls4: movq 3*8(%rsi),%r10 .Ld1: movq %r11,(%rdi) .Ld2: movq %r8,1*8(%rdi) .Ld3: movq %r9,2*8(%rdi) .Ld4: movq %r10,3*8(%rdi) .Ls5: movq 4*8(%rsi),%r11 .Ls6: movq 5*8(%rsi),%r8 .Ls7: movq 6*8(%rsi),%r9 .Ls8: movq 7*8(%rsi),%r10 .Ld5: movq %r11,4*8(%rdi) .Ld6: movq %r8,5*8(%rdi) .Ld7: movq %r9,6*8(%rdi) .Ld8: movq %r10,7*8(%rdi) decq %rdx leaq 64(%rsi),%rsi leaq 64(%rdi),%rdi jns .Lloop .p2align 4 .Lhandle_tail: movl %ecx,%edx andl $63,%ecx shrl $3,%ecx jz .Lhandle_7 movl $8,%ebx .p2align 4 .Lloop_8: .Ls9: movq (%rsi),%r8 .Ld9: movq %r8,(%rdi) decl %ecx leaq 8(%rdi),%rdi leaq 8(%rsi),%rsi jnz .Lloop_8 .Lhandle_7: movl %edx,%ecx andl $7,%ecx jz .Lende .p2align 4 .Lloop_1: .Ls10: movb (%rsi),%bl .Ld10: movb %bl,(%rdi) incq %rdi incq %rsi decl %ecx jnz .Lloop_1 CFI_REMEMBER_STATE .Lende: popq %rcx CFI_ADJUST_CFA_OFFSET -8 CFI_RESTORE rcx popq %rbx CFI_ADJUST_CFA_OFFSET -8 CFI_RESTORE rbx ret CFI_RESTORE_STATE #ifdef FIX_ALIGNMENT /* align destination */ .p2align 4 .Lbad_alignment: movl $8,%r9d subl %ecx,%r9d movl %r9d,%ecx cmpq %r9,%rdx jz .Lhandle_7 js .Lhandle_7 .Lalign_1: .Ls11: movb (%rsi),%bl .Ld11: movb %bl,(%rdi) incq %rsi incq %rdi decl %ecx jnz .Lalign_1 subq %r9,%rdx jmp .Lafter_bad_alignment #endif /* table sorted by exception address */ .section __ex_table,"a" .align 8 .quad .Ls1,.Ls1e .quad .Ls2,.Ls2e .quad .Ls3,.Ls3e .quad .Ls4,.Ls4e .quad .Ld1,.Ls1e .quad .Ld2,.Ls2e .quad .Ld3,.Ls3e .quad .Ld4,.Ls4e .quad .Ls5,.Ls5e .quad .Ls6,.Ls6e .quad .Ls7,.Ls7e .quad .Ls8,.Ls8e .quad .Ld5,.Ls5e .quad .Ld6,.Ls6e .quad .Ld7,.Ls7e .quad .Ld8,.Ls8e .quad .Ls9,.Le_quad .quad .Ld9,.Le_quad .quad .Ls10,.Le_byte .quad .Ld10,.Le_byte #ifdef FIX_ALIGNMENT .quad .Ls11,.Lzero_rest .quad .Ld11,.Lzero_rest #endif .quad .Le5,.Le_zero .previous /* compute 64-offset for main loop. 8 bytes accuracy with error on the pessimistic side. this is gross. it would be better to fix the interface. */ /* eax: zero, ebx: 64 */ .Ls1e: addl $8,%eax .Ls2e: addl $8,%eax .Ls3e: addl $8,%eax .Ls4e: addl $8,%eax .Ls5e: addl $8,%eax .Ls6e: addl $8,%eax .Ls7e: addl $8,%eax .Ls8e: addl $8,%eax addq %rbx,%rdi /* +64 */ subq %rax,%rdi /* correct destination with computed offset */ shlq $6,%rdx /* loop counter * 64 (stride length) */ addq %rax,%rdx /* add offset to loopcnt */ andl $63,%ecx /* remaining bytes */ addq %rcx,%rdx /* add them */ jmp .Lzero_rest /* exception on quad word loop in tail handling */ /* ecx: loopcnt/8, %edx: length, rdi: correct */ .Le_quad: shll $3,%ecx andl $7,%edx addl %ecx,%edx /* edx: bytes to zero, rdi: dest, eax:zero */ .Lzero_rest: cmpl $0,(%rsp) jz .Le_zero movq %rdx,%rcx .Le_byte: xorl %eax,%eax .Le5: rep stosb /* when there is another exception while zeroing the rest just return */ .Le_zero: movq %rdx,%rax jmp .Lende CFI_ENDPROC ENDPROC(copy_user_generic) /* Some CPUs run faster using the string copy instructions. This is also a lot simpler. Use them when possible. Patch in jmps to this code instead of copying it fully to avoid unwanted aliasing in the exception tables. */ /* rdi destination * rsi source * rdx count * ecx zero flag * * Output: * eax uncopied bytes or 0 if successfull. * * Only 4GB of copy is supported. This shouldn't be a problem * because the kernel normally only writes from/to page sized chunks * even if user space passed a longer buffer. * And more would be dangerous because both Intel and AMD have * errata with rep movsq > 4GB. If someone feels the need to fix * this please consider this. */ ENTRY(copy_user_generic_string) CFI_STARTPROC movl %ecx,%r8d /* save zero flag */ movl %edx,%ecx shrl $3,%ecx andl $7,%edx jz 10f 1: rep movsq movl %edx,%ecx 2: rep movsb 9: movl %ecx,%eax ret /* multiple of 8 byte */ 10: rep movsq xor %eax,%eax ret /* exception handling */ 3: lea (%rdx,%rcx,8),%rax /* exception on quad loop */ jmp 6f 5: movl %ecx,%eax /* exception on byte loop */ /* eax: left over bytes */ 6: testl %r8d,%r8d /* zero flag set? */ jz 7f movl %eax,%ecx /* initialize x86 loop counter */ push %rax xorl %eax,%eax 8: rep stosb /* zero the rest */ 11: pop %rax 7: ret CFI_ENDPROC END(copy_user_generic_c) .section __ex_table,"a" .quad 1b,3b .quad 2b,5b .quad 8b,11b .quad 10b,3b .previous