| /* Copyright 2002 Andi Kleen, SuSE Labs. |
| * Subject to the GNU Public License v2. |
| * |
| * Functions to copy from and to user space. |
| */ |
| |
| #include <asm/current.h> |
| #include <asm/asm-offsets.h> |
| #include <asm/thread_info.h> |
| |
| /* Standard copy_to_user with segment limit checking */ |
| .globl copy_to_user |
| .p2align 4 |
| copy_to_user: |
| GET_THREAD_INFO(%rax) |
| movq %rdi,%rcx |
| addq %rdx,%rcx |
| jc bad_to_user |
| cmpq threadinfo_addr_limit(%rax),%rcx |
| jae bad_to_user |
| jmp copy_user_generic |
| |
| /* Standard copy_from_user with segment limit checking */ |
| .globl copy_from_user |
| .p2align 4 |
| copy_from_user: |
| GET_THREAD_INFO(%rax) |
| movq %rsi,%rcx |
| addq %rdx,%rcx |
| jc bad_from_user |
| cmpq threadinfo_addr_limit(%rax),%rcx |
| jae bad_from_user |
| /* FALL THROUGH to copy_user_generic */ |
| |
| .section .fixup,"ax" |
| /* must zero dest */ |
| bad_from_user: |
| movl %edx,%ecx |
| xorl %eax,%eax |
| rep |
| stosb |
| bad_to_user: |
| movl %edx,%eax |
| ret |
| .previous |
| |
| |
| /* |
| * copy_user_generic - memory copy with exception handling. |
| * |
| * Input: |
| * rdi destination |
| * rsi source |
| * rdx count |
| * |
| * 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. |
| * |
| * Output: |
| * eax uncopied bytes or 0 if successful. |
| */ |
| |
| .globl copy_user_generic |
| copy_user_generic: |
| movl %edx,%ecx |
| shrl $3,%ecx |
| andl $7,%edx |
| jz 5f |
| 1: rep |
| movsq |
| movl %edx,%ecx |
| xor %eax,%eax |
| 2: rep |
| movsb |
| ret |
| /* align here? */ |
| 5: xorl %eax,%eax |
| 6: rep movsq |
| ret |
| |
| .section .fixup,"ax" |
| 3: lea (%rdx,%rcx,8),%rax |
| ret |
| 4: movl %ecx,%eax |
| ret |
| .previous |
| |
| .section __ex_table,"a" |
| .quad 1b,3b |
| .quad 2b,4b |
| .quad 6b,4b |
| .previous |
