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authorMichael Neuling <mikey@neuling.org>2013-09-26 13:29:09 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-10-03 17:25:51 +1000
commite9bdc3d6143d1c4b8d8ce5231fc958268331f983 (patch)
tree1892620b40d70713d28dfdaf266ad993e41248eb
parentc69e63b0f135fa51d6e1c38b5ac8a1def15ea3fa (diff)
downloadlinux-stericsson-e9bdc3d6143d1c4b8d8ce5231fc958268331f983.tar.gz
powerpc/tm: Switch out userspace PPR and DSCR sooner
When we do a treclaim or trecheckpoint we end up running with userspace PPR and DSCR values. Currently we don't do anything special to avoid running with user values which could cause a severe performance degradation. This patch moves the PPR and DSCR save and restore around treclaim and trecheckpoint so that we run with user values for a much shorter period. More care is taken with the PPR as it's impact is greater than the DSCR. This is similar to user exceptions, where we run HTM_MEDIUM early to ensure that we don't run with a userspace PPR values in the kernel. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> # 3.9+ Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/kernel/tm.S94
1 files changed, 63 insertions, 31 deletions
diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S
index 8ece1908be1a..cd809eaa8b5c 100644
--- a/arch/powerpc/kernel/tm.S
+++ b/arch/powerpc/kernel/tm.S
@@ -79,6 +79,11 @@ _GLOBAL(tm_abort)
TABORT(R3)
blr
+ .section ".toc","aw"
+DSCR_DEFAULT:
+ .tc dscr_default[TC],dscr_default
+
+ .section ".text"
/* void tm_reclaim(struct thread_struct *thread,
* unsigned long orig_msr,
@@ -188,11 +193,18 @@ dont_backup_fp:
std r1, PACATMSCRATCH(r13)
ld r1, PACAR1(r13)
+ /* Store the PPR in r11 and reset to decent value */
+ std r11, GPR11(r1) /* Temporary stash */
+ mfspr r11, SPRN_PPR
+ HMT_MEDIUM
+
/* Now get some more GPRS free */
std r7, GPR7(r1) /* Temporary stash */
std r12, GPR12(r1) /* '' '' '' */
ld r12, STACK_PARAM(0)(r1) /* Param 0, thread_struct * */
+ std r11, THREAD_TM_PPR(r12) /* Store PPR and free r11 */
+
addi r7, r12, PT_CKPT_REGS /* Thread's ckpt_regs */
/* Make r7 look like an exception frame so that we
@@ -204,15 +216,19 @@ dont_backup_fp:
SAVE_GPR(0, r7) /* user r0 */
SAVE_GPR(2, r7) /* user r2 */
SAVE_4GPRS(3, r7) /* user r3-r6 */
- SAVE_4GPRS(8, r7) /* user r8-r11 */
+ SAVE_GPR(8, r7) /* user r8 */
+ SAVE_GPR(9, r7) /* user r9 */
+ SAVE_GPR(10, r7) /* user r10 */
ld r3, PACATMSCRATCH(r13) /* user r1 */
ld r4, GPR7(r1) /* user r7 */
- ld r5, GPR12(r1) /* user r12 */
- GET_SCRATCH0(6) /* user r13 */
+ ld r5, GPR11(r1) /* user r11 */
+ ld r6, GPR12(r1) /* user r12 */
+ GET_SCRATCH0(8) /* user r13 */
std r3, GPR1(r7)
std r4, GPR7(r7)
- std r5, GPR12(r7)
- std r6, GPR13(r7)
+ std r5, GPR11(r7)
+ std r6, GPR12(r7)
+ std r8, GPR13(r7)
SAVE_NVGPRS(r7) /* user r14-r31 */
@@ -235,14 +251,12 @@ dont_backup_fp:
std r6, _XER(r7)
- /* ******************** TAR, PPR, DSCR ********** */
+ /* ******************** TAR, DSCR ********** */
mfspr r3, SPRN_TAR
- mfspr r4, SPRN_PPR
- mfspr r5, SPRN_DSCR
+ mfspr r4, SPRN_DSCR
std r3, THREAD_TM_TAR(r12)
- std r4, THREAD_TM_PPR(r12)
- std r5, THREAD_TM_DSCR(r12)
+ std r4, THREAD_TM_DSCR(r12)
/* MSR and flags: We don't change CRs, and we don't need to alter
* MSR.
@@ -259,7 +273,7 @@ dont_backup_fp:
std r3, THREAD_TM_TFHAR(r12)
std r4, THREAD_TM_TFIAR(r12)
- /* AMR and PPR are checkpointed too, but are unsupported by Linux. */
+ /* AMR is checkpointed too, but is unsupported by Linux. */
/* Restore original MSR/IRQ state & clear TM mode */
ld r14, TM_FRAME_L0(r1) /* Orig MSR */
@@ -275,6 +289,12 @@ dont_backup_fp:
mtcr r4
mtlr r0
ld r2, 40(r1)
+
+ /* Load system default DSCR */
+ ld r4, DSCR_DEFAULT@toc(r2)
+ ld r0, 0(r4)
+ mtspr SPRN_DSCR, r0
+
blr
@@ -359,25 +379,24 @@ dont_restore_fp:
restore_gprs:
- /* ******************** TAR, PPR, DSCR ********** */
- ld r4, THREAD_TM_TAR(r3)
- ld r5, THREAD_TM_PPR(r3)
- ld r6, THREAD_TM_DSCR(r3)
+ /* ******************** CR,LR,CCR,MSR ********** */
+ ld r4, _CTR(r7)
+ ld r5, _LINK(r7)
+ ld r6, _CCR(r7)
+ ld r8, _XER(r7)
- mtspr SPRN_TAR, r4
- mtspr SPRN_PPR, r5
- mtspr SPRN_DSCR, r6
+ mtctr r4
+ mtlr r5
+ mtcr r6
+ mtxer r8
- /* ******************** CR,LR,CCR,MSR ********** */
- ld r3, _CTR(r7)
- ld r4, _LINK(r7)
- ld r5, _CCR(r7)
- ld r6, _XER(r7)
+ /* ******************** TAR ******************** */
+ ld r4, THREAD_TM_TAR(r3)
+ mtspr SPRN_TAR, r4
- mtctr r3
- mtlr r4
- mtcr r5
- mtxer r6
+ /* Load up the PPR and DSCR in GPRs only at this stage */
+ ld r5, THREAD_TM_DSCR(r3)
+ ld r6, THREAD_TM_PPR(r3)
/* Clear the MSR RI since we are about to change R1. EE is already off
*/
@@ -385,19 +404,26 @@ restore_gprs:
mtmsrd r4, 1
REST_4GPRS(0, r7) /* GPR0-3 */
- REST_GPR(4, r7) /* GPR4-6 */
- REST_GPR(5, r7)
- REST_GPR(6, r7)
+ REST_GPR(4, r7) /* GPR4 */
REST_4GPRS(8, r7) /* GPR8-11 */
REST_2GPRS(12, r7) /* GPR12-13 */
REST_NVGPRS(r7) /* GPR14-31 */
- ld r7, GPR7(r7) /* GPR7 */
+ /* Load up PPR and DSCR here so we don't run with user values for long
+ */
+ mtspr SPRN_DSCR, r5
+ mtspr SPRN_PPR, r6
+
+ REST_GPR(5, r7) /* GPR5-7 */
+ REST_GPR(6, r7)
+ ld r7, GPR7(r7)
/* Commit register state as checkpointed state: */
TRECHKPT
+ HMT_MEDIUM
+
/* Our transactional state has now changed.
*
* Now just get out of here. Transactional (current) state will be
@@ -420,6 +446,12 @@ restore_gprs:
mtcr r4
mtlr r0
ld r2, 40(r1)
+
+ /* Load system default DSCR */
+ ld r4, DSCR_DEFAULT@toc(r2)
+ ld r0, 0(r4)
+ mtspr SPRN_DSCR, r0
+
blr
/* ****************************************************************** */