powerpc/tm: Abort on emulation and alignment faults

If we are emulating an instruction inside an active user transaction that
touches memory, the kernel can't emulate it as it operates in transactional
suspend context.  We need to abort these transactions and send them back to
userspace for the hardware to rollback.

We can service these if the user transaction is in suspend mode, since the
kernel will operate in the same suspend context.

This adds a check to all alignment faults and to specific instruction
emulations (only string instructions for now).  If the user process is in an
active (non-suspended) transaction, we abort the transaction go back to
userspace allowing the HW to roll back the transaction and tell the user of the
failure.  This also adds new tm abort cause codes to report the reason of the
persistent error to the user.

Crappy test case here http://neuling.org/devel/junkcode/aligntm.c

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> # v3.9
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 8f6a94b2dc99..d0528e0d6db8 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -122,6 +122,8 @@
 #define TM_CAUSE_SYSCALL        0xd8  /* future use */
 #define TM_CAUSE_MISC           0xd6  /* future use */
 #define TM_CAUSE_SIGNAL         0xd4
+#define TM_CAUSE_ALIGNMENT      0xd2
+#define TM_CAUSE_EMULATE        0xd0
 
 #if defined(CONFIG_PPC_BOOK3S_64)
 #define MSR_64BIT       MSR_SF