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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/mm/abort-macro.S
downloadlinux-stericsson-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * 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
+