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powerpc/tm: Clear MSR RI in non-recoverable TM code

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When we treclaim and trecheckpoint there's an unavoidable period when r1
will not be a valid kernel stack pointer.

This patch clears the MSR recoverable interrupt (RI) bit over these
regions to indicate we have an invalid kernel stack pointer.

For treclaim, the region over which we clear MSR RI is larger than
required to avoid the need for an extra costly mtmsrd.

Thanks to Paulus for suggesting this change.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Neuling 2013-06-28 18:17:09 +10:00 committed by Benjamin Herrenschmidt
parent 80aa0fb494
commit 090b9284d7
1 changed files with 16 additions and 2 deletions
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18
arch/powerpc/kernel/tm.S
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@ -112,9 +112,18 @@ _GLOBAL(tm_reclaim)
std r3, STACK_PARAM(0)(r1)
SAVE_NVGPRS(r1)
/* We need to setup MSR for VSX register save instructions. Here we
* also clear the MSR RI since when we do the treclaim, we won't have a
* valid kernel pointer for a while. We clear RI here as it avoids
* adding another mtmsr closer to the treclaim. This makes the region
* maked as non-recoverable wider than it needs to be but it saves on
* inserting another mtmsrd later.
*/
mfmsr r14
mr r15, r14
ori r15, r15, MSR_FP
li r16, MSR_RI
andc r15, r15, r16
oris r15, r15, MSR_VEC@h
#ifdef CONFIG_VSX
BEGIN_FTR_SECTION
@ -349,9 +358,10 @@ restore_gprs:
mtcr r5
mtxer r6
/* MSR and flags: We don't change CRs, and we don't need to alter
* MSR.
/* Clear the MSR RI since we are about to change R1. EE is already off
*/
li r4, 0
mtmsrd r4, 1
REST_4GPRS(0, r7) /* GPR0-3 */
REST_GPR(4, r7) /* GPR4-6 */
@ -377,6 +387,10 @@ restore_gprs:
GET_PACA(r13)
GET_SCRATCH0(r1)
/* R1 is restored, so we are recoverable again. EE is still off */
li r4, MSR_RI
mtmsrd r4, 1
REST_NVGPRS(r1)
addi r1, r1, TM_FRAME_SIZE