diff options
Diffstat (limited to 'arch/arm/mm/abort-macro.S')
| -rw-r--r-- | arch/arm/mm/abort-macro.S | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/arch/arm/mm/abort-macro.S b/arch/arm/mm/abort-macro.S new file mode 100644 index 0000000..d7cb1bf --- /dev/null +++ b/arch/arm/mm/abort-macro.S @@ -0,0 +1,42 @@ +/* + * The ARM LDRD and Thumb LDRSB instructions use bit 20/11 (ARM/Thumb) + * differently than every other instruction, so it is set to 0 (write) + * even though the instructions are read instructions. This means that + * during an abort the instructions will be treated as a write and the + * handler will raise a signal from unwriteable locations if they + * fault. We have to specifically check for these instructions + * from the abort handlers to treat them properly. + * + */ + + .macro do_thumb_abort + tst r3, #PSR_T_BIT + beq not_thumb + ldrh r3, [r2] @ Read aborted Thumb instruction + and r3, r3, # 0xfe00 @ Mask opcode field + cmp r3, # 0x5600 @ Is it ldrsb? + orreq r3, r3, #1 << 11 @ Set L-bit if yes + tst r3, #1 << 11 @ L = 0 -> write + orreq r1, r1, #1 << 11 @ yes. + mov pc, lr +not_thumb: + .endm + +/* + * We check for the following insturction encoding for LDRD. + * + * [27:25] == 0 + * [7:4] == 1101 + * [20] == 0 + */ + .macro do_ldrd_abort + tst r3, #0x0e000000 @ [27:25] == 0 + bne not_ldrd + and r2, r3, #0x000000f0 @ [7:4] == 1101 + cmp r2, #0x000000d0 + bne not_ldrd + tst r3, #1 << 20 @ [20] == 0 + moveq pc, lr +not_ldrd: + .endm + |