| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Add-on to transform csum_partial_copy_nocheck in checksumcopy.S into |
| 3 | * csum_partial_copy_from_user by adding exception records. |
| 4 | * |
| 5 | * Copyright (C) 2001 Axis Communications AB. |
| 6 | * |
| 7 | * Author: Hans-Peter Nilsson. |
| 8 | */ |
| 9 | |
| 10 | #include <asm/errno.h> |
| 11 | |
| 12 | /* Same function body, but a different name. If we just added exception |
| 13 | records to _csum_partial_copy_nocheck and made it generic, we wouldn't |
| 14 | know a user fault from a kernel fault and we would have overhead in |
| 15 | each kernel caller for the error-pointer argument. |
| 16 | |
| 17 | unsigned int csum_partial_copy_from_user |
| 18 | (const char *src, char *dst, int len, unsigned int sum, int *errptr); |
| 19 | |
| 20 | Note that the errptr argument is only set if we encounter an error. |
| 21 | It is conveniently located on the stack, so the normal function body |
| 22 | does not have to handle it. */ |
| 23 | |
| 24 | #define csum_partial_copy_nocheck csum_partial_copy_from_user |
| 25 | |
| 26 | /* There are local labels numbered 1, 2 and 3 present to mark the |
| 27 | different from-user accesses. */ |
| 28 | #include "checksumcopy.S" |
| 29 | |
| 30 | .section .fixup,"ax" |
| 31 | |
| 32 | ;; Here from the movem loop; restore stack. |
| 33 | 4: |
| 34 | movem [$sp+],$r8 |
| 35 | ;; r12 is already decremented. Add back chunk_size-2. |
| 36 | addq 40-2,$r12 |
| 37 | |
| 38 | ;; Here from the word loop; r12 is off by 2; add it back. |
| 39 | 5: |
| 40 | addq 2,$r12 |
| 41 | |
| 42 | ;; Here from a failing single byte. |
| 43 | 6: |
| 44 | |
| 45 | ;; Signal in *errptr that we had a failing access. |
| 46 | moveq -EFAULT,$r9 |
| 47 | move.d $r9,[[$sp]] |
| 48 | |
| 49 | ;; Clear the rest of the destination area using memset. Preserve the |
| 50 | ;; checksum for the readable bytes. |
| 51 | push $srp |
| 52 | push $r13 |
| 53 | move.d $r11,$r10 |
| 54 | clear.d $r11 |
| 55 | jsr memset |
| 56 | pop $r10 |
| 57 | jump [$sp+] |
| 58 | |
| 59 | .previous |
| 60 | .section __ex_table,"a" |
| 61 | .dword 1b,4b |
| 62 | .dword 2b,5b |
| 63 | .dword 3b,6b |
| 64 | .previous |