| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * The ARM LDRD and Thumb LDRSB instructions use bit 20/11 (ARM/Thumb) |
| 3 | * differently than every other instruction, so it is set to 0 (write) |
| 4 | * even though the instructions are read instructions. This means that |
| 5 | * during an abort the instructions will be treated as a write and the |
| 6 | * handler will raise a signal from unwriteable locations if they |
| 7 | * fault. We have to specifically check for these instructions |
| 8 | * from the abort handlers to treat them properly. |
| 9 | * |
| 10 | */ |
| 11 | |
| 12 | .macro do_thumb_abort |
| 13 | tst r3, #PSR_T_BIT |
| 14 | beq not_thumb |
| 15 | ldrh r3, [r2] @ Read aborted Thumb instruction |
| 16 | and r3, r3, # 0xfe00 @ Mask opcode field |
| 17 | cmp r3, # 0x5600 @ Is it ldrsb? |
| 18 | orreq r3, r3, #1 << 11 @ Set L-bit if yes |
| 19 | tst r3, #1 << 11 @ L = 0 -> write |
| 20 | orreq r1, r1, #1 << 11 @ yes. |
| 21 | mov pc, lr |
| 22 | not_thumb: |
| 23 | .endm |
| 24 | |
| 25 | /* |
| 26 | * We check for the following insturction encoding for LDRD. |
| 27 | * |
| 28 | * [27:25] == 0 |
| 29 | * [7:4] == 1101 |
| 30 | * [20] == 0 |
| 31 | */ |
| 32 | .macro do_ldrd_abort |
| 33 | tst r3, #0x0e000000 @ [27:25] == 0 |
| 34 | bne not_ldrd |
| 35 | and r2, r3, #0x000000f0 @ [7:4] == 1101 |
| 36 | cmp r2, #0x000000d0 |
| 37 | bne not_ldrd |
| 38 | tst r3, #1 << 20 @ [20] == 0 |
| 39 | moveq pc, lr |
| 40 | not_ldrd: |
| 41 | .endm |
| 42 | |