| /* |
| * Copyright 2008 Vitaly Mayatskikh <vmayatsk@redhat.com> |
| * Copyright 2002 Andi Kleen, SuSE Labs. |
| * Subject to the GNU Public License v2. |
| * |
| * Functions to copy from and to user space. |
| */ |
| |
| #include <linux/linkage.h> |
| #include <asm/dwarf2.h> |
| |
| #define FIX_ALIGNMENT 1 |
| |
| #include <asm/current.h> |
| #include <asm/asm-offsets.h> |
| #include <asm/thread_info.h> |
| #include <asm/cpufeature.h> |
| #include <asm/alternative-asm.h> |
| #include <asm/asm.h> |
| |
| /* |
| * By placing feature2 after feature1 in altinstructions section, we logically |
| * implement: |
| * If CPU has feature2, jmp to alt2 is used |
| * else if CPU has feature1, jmp to alt1 is used |
| * else jmp to orig is used. |
| */ |
| .macro ALTERNATIVE_JUMP feature1,feature2,orig,alt1,alt2 |
| 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 \alt1-1b /* offset */ /* or alternatively to alt1 */ |
| 3: .byte 0xe9 /* near jump with 32bit immediate */ |
| .long \alt2-1b /* offset */ /* or alternatively to alt2 */ |
| .previous |
| |
| .section .altinstructions,"a" |
| altinstruction_entry 0b,2b,\feature1,5,5 |
| altinstruction_entry 0b,3b,\feature2,5,5 |
| .previous |
| .endm |
| |
| .macro ALIGN_DESTINATION |
| #ifdef FIX_ALIGNMENT |
| /* check for bad alignment of destination */ |
| movl %edi,%ecx |
| andl $7,%ecx |
| jz 102f /* already aligned */ |
| subl $8,%ecx |
| negl %ecx |
| subl %ecx,%edx |
| 100: movb (%rsi),%al |
| 101: movb %al,(%rdi) |
| incq %rsi |
| incq %rdi |
| decl %ecx |
| jnz 100b |
| 102: |
| .section .fixup,"ax" |
| 103: addl %ecx,%edx /* ecx is zerorest also */ |
| jmp copy_user_handle_tail |
| .previous |
| |
| _ASM_EXTABLE(100b,103b) |
| _ASM_EXTABLE(101b,103b) |
| #endif |
| .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 TI_addr_limit(%rax),%rcx |
| ja bad_to_user |
| ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,X86_FEATURE_ERMS, \ |
| copy_user_generic_unrolled,copy_user_generic_string, \ |
| copy_user_enhanced_fast_string |
| CFI_ENDPROC |
| ENDPROC(_copy_to_user) |
| |
| /* 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 TI_addr_limit(%rax),%rcx |
| ja bad_from_user |
| ALTERNATIVE_JUMP X86_FEATURE_REP_GOOD,X86_FEATURE_ERMS, \ |
| copy_user_generic_unrolled,copy_user_generic_string, \ |
| copy_user_enhanced_fast_string |
| CFI_ENDPROC |
| ENDPROC(_copy_from_user) |
| |
| .section .fixup,"ax" |
| /* must zero dest */ |
| ENTRY(bad_from_user) |
| bad_from_user: |
| CFI_STARTPROC |
| movl %edx,%ecx |
| xorl %eax,%eax |
| rep |
| stosb |
| bad_to_user: |
| movl %edx,%eax |
| ret |
| CFI_ENDPROC |
| ENDPROC(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 |
| * |
| * Output: |
| * eax uncopied bytes or 0 if successful. |
| */ |
| ENTRY(copy_user_generic_unrolled) |
| CFI_STARTPROC |
| cmpl $8,%edx |
| jb 20f /* less then 8 bytes, go to byte copy loop */ |
| ALIGN_DESTINATION |
| movl %edx,%ecx |
| andl $63,%edx |
| shrl $6,%ecx |
| jz 17f |
| 1: movq (%rsi),%r8 |
| 2: movq 1*8(%rsi),%r9 |
| 3: movq 2*8(%rsi),%r10 |
| 4: movq 3*8(%rsi),%r11 |
| 5: movq %r8,(%rdi) |
| 6: movq %r9,1*8(%rdi) |
| 7: movq %r10,2*8(%rdi) |
| 8: movq %r11,3*8(%rdi) |
| 9: movq 4*8(%rsi),%r8 |
| 10: movq 5*8(%rsi),%r9 |
| 11: movq 6*8(%rsi),%r10 |
| 12: movq 7*8(%rsi),%r11 |
| 13: movq %r8,4*8(%rdi) |
| 14: movq %r9,5*8(%rdi) |
| 15: movq %r10,6*8(%rdi) |
| 16: movq %r11,7*8(%rdi) |
| leaq 64(%rsi),%rsi |
| leaq 64(%rdi),%rdi |
| decl %ecx |
| jnz 1b |
| 17: movl %edx,%ecx |
| andl $7,%edx |
| shrl $3,%ecx |
| jz 20f |
| 18: movq (%rsi),%r8 |
| 19: movq %r8,(%rdi) |
| leaq 8(%rsi),%rsi |
| leaq 8(%rdi),%rdi |
| decl %ecx |
| jnz 18b |
| 20: andl %edx,%edx |
| jz 23f |
| movl %edx,%ecx |
| 21: movb (%rsi),%al |
| 22: movb %al,(%rdi) |
| incq %rsi |
| incq %rdi |
| decl %ecx |
| jnz 21b |
| 23: xor %eax,%eax |
| ret |
| |
| .section .fixup,"ax" |
| 30: shll $6,%ecx |
| addl %ecx,%edx |
| jmp 60f |
| 40: lea (%rdx,%rcx,8),%rdx |
| jmp 60f |
| 50: movl %ecx,%edx |
| 60: jmp copy_user_handle_tail /* ecx is zerorest also */ |
| .previous |
| |
| _ASM_EXTABLE(1b,30b) |
| _ASM_EXTABLE(2b,30b) |
| _ASM_EXTABLE(3b,30b) |
| _ASM_EXTABLE(4b,30b) |
| _ASM_EXTABLE(5b,30b) |
| _ASM_EXTABLE(6b,30b) |
| _ASM_EXTABLE(7b,30b) |
| _ASM_EXTABLE(8b,30b) |
| _ASM_EXTABLE(9b,30b) |
| _ASM_EXTABLE(10b,30b) |
| _ASM_EXTABLE(11b,30b) |
| _ASM_EXTABLE(12b,30b) |
| _ASM_EXTABLE(13b,30b) |
| _ASM_EXTABLE(14b,30b) |
| _ASM_EXTABLE(15b,30b) |
| _ASM_EXTABLE(16b,30b) |
| _ASM_EXTABLE(18b,40b) |
| _ASM_EXTABLE(19b,40b) |
| _ASM_EXTABLE(21b,50b) |
| _ASM_EXTABLE(22b,50b) |
| CFI_ENDPROC |
| ENDPROC(copy_user_generic_unrolled) |
| |
| /* Some CPUs run faster using the string copy instructions. |
| * This is also a lot simpler. Use them when possible. |
| * |
| * 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. |
| * |
| * Input: |
| * rdi destination |
| * rsi source |
| * rdx count |
| * |
| * Output: |
| * eax uncopied bytes or 0 if successful. |
| */ |
| ENTRY(copy_user_generic_string) |
| CFI_STARTPROC |
| andl %edx,%edx |
| jz 4f |
| cmpl $8,%edx |
| jb 2f /* less than 8 bytes, go to byte copy loop */ |
| ALIGN_DESTINATION |
| movl %edx,%ecx |
| shrl $3,%ecx |
| andl $7,%edx |
| 1: rep |
| movsq |
| 2: movl %edx,%ecx |
| 3: rep |
| movsb |
| 4: xorl %eax,%eax |
| ret |
| |
| .section .fixup,"ax" |
| 11: lea (%rdx,%rcx,8),%rcx |
| 12: movl %ecx,%edx /* ecx is zerorest also */ |
| jmp copy_user_handle_tail |
| .previous |
| |
| _ASM_EXTABLE(1b,11b) |
| _ASM_EXTABLE(3b,12b) |
| CFI_ENDPROC |
| ENDPROC(copy_user_generic_string) |
| |
| /* |
| * Some CPUs are adding enhanced REP MOVSB/STOSB instructions. |
| * It's recommended to use enhanced REP MOVSB/STOSB if it's enabled. |
| * |
| * Input: |
| * rdi destination |
| * rsi source |
| * rdx count |
| * |
| * Output: |
| * eax uncopied bytes or 0 if successful. |
| */ |
| ENTRY(copy_user_enhanced_fast_string) |
| CFI_STARTPROC |
| andl %edx,%edx |
| jz 2f |
| movl %edx,%ecx |
| 1: rep |
| movsb |
| 2: xorl %eax,%eax |
| ret |
| |
| .section .fixup,"ax" |
| 12: movl %ecx,%edx /* ecx is zerorest also */ |
| jmp copy_user_handle_tail |
| .previous |
| |
| _ASM_EXTABLE(1b,12b) |
| CFI_ENDPROC |
| ENDPROC(copy_user_enhanced_fast_string) |
