[PATCH] ARM: 2655/1: ARM1136 SWP instruction abort handler fix

Patch from George G. Davis

As noted in http://www.arm.com/linux/patch-2.6.9-arm1.gz, the "Faulty SWP instruction on 1136 doesn't set bit 11 in DFSR." So the v6_early_abort handler does not report the correct rd/wr direction for the SWP instruction which may result in SEGVS or hangs. In order to work around this problem, this patch merely updates the fix contained in the ARM Ltd. patch to use the macroised abort handler fixups.

Signed-off-by: George G. Davis
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 16 insertions, 0 deletions

diff --git a/arch/arm/mm/abort-ev6.S b/arch/arm/mm/abort-ev6.S
index 38b2cbb89be..8f76f3df7b4 100644
--- a/arch/arm/mm/abort-ev6.S
+++ b/arch/arm/mm/abort-ev6.S
@@ -1,5 +1,6 @@
 #include <linux/linkage.h>
 #include <asm/assembler.h>
+#include "abort-macro.S"
 /*
  * Function: v6_early_abort
  *
@@ -13,11 +14,26 @@
  *         : sp = pointer to registers
  *
  * Purpose : obtain information about current aborted instruction.
+ * Note: we read user space.  This means we might cause a data
+ * abort here if the I-TLB and D-TLB aren't seeing the same
+ * picture.  Unfortunately, this does happen.  We live with it.
  */
         .align  5
 ENTRY(v6_early_abort)
         mrc     p15, 0, r1, c5, c0, 0           @ get FSR
         mrc     p15, 0, r0, c6, c0, 0           @ get FAR
+/*
+ * Faulty SWP instruction on 1136 doesn't set bit 11 in DFSR.
+ * The test below covers all the write situations, including Java bytecodes
+ */
+        bic     r1, r1, #1 << 11 | 1 << 10      @ clear bits 11 and 10 of FSR
+        tst     r3, #PSR_J_BIT                  @ Java?
+        movne   pc, lr
+        do_thumb_abort
+        ldreq   r3, [r2]                        @ read aborted ARM instruction
+        do_ldrd_abort
+        tst     r3, #1 << 20                    @ L = 0 -> write
+        orreq   r1, r1, #1 << 11                @ yes.
         mov     pc, lr