|author||Michael Neuling <email@example.com>||2013-05-26 18:09:39 +0000|
|committer||Benjamin Herrenschmidt <firstname.lastname@example.org>||2013-06-01 08:29:22 +1000|
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 <email@example.com> Cc: <firstname.lastname@example.org> # v3.9 Signed-off-by: Benjamin Herrenschmidt <email@example.com>
Diffstat (limited to 'Documentation')
1 files changed, 5 insertions, 2 deletions
diff --git a/Documentation/powerpc/transactional_memory.txt b/Documentation/powerpc/transactional_memory.txt
index 84e04a0db0f..c54bf312765 100644
@@ -161,9 +161,12 @@ kernel aborted a transaction:
transactions for consistency will use this.
TM_CAUSE_SIGNAL Signal delivered.
TM_CAUSE_MISC Currently unused.
+ TM_CAUSE_ALIGNMENT Alignment fault.
+ TM_CAUSE_EMULATE Emulation that touched memory.
-These can be checked by the user program's abort handler as TEXASR[0:7].
+These can be checked by the user program's abort handler as TEXASR[0:7]. If
+bit 7 is set, it indicates that the error is consider persistent. For example
+a TM_CAUSE_ALIGNMENT will be persistent while a TM_CAUSE_RESCHED will not.q