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>
This commit is contained in:
Michael Neuling
Benjamin Herrenschmidt
parent
c69e63b0f1
commit
e9bdc3d614
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@ -79,6 +79,11 @@ _GLOBAL(tm_abort)
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TABORT(R3)
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blr
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.section ".toc","aw"
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DSCR_DEFAULT:
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.tc dscr_default[TC],dscr_default
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.section ".text"
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/* void tm_reclaim(struct thread_struct *thread,
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* unsigned long orig_msr,
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@ -188,11 +193,18 @@ dont_backup_fp:
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std r1, PACATMSCRATCH(r13)
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ld r1, PACAR1(r13)
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/* Store the PPR in r11 and reset to decent value */
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std r11, GPR11(r1) /* Temporary stash */
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mfspr r11, SPRN_PPR
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HMT_MEDIUM
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/* Now get some more GPRS free */
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std r7, GPR7(r1) /* Temporary stash */
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std r12, GPR12(r1) /* '' '' '' */
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ld r12, STACK_PARAM(0)(r1) /* Param 0, thread_struct * */
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std r11, THREAD_TM_PPR(r12) /* Store PPR and free r11 */
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addi r7, r12, PT_CKPT_REGS /* Thread's ckpt_regs */
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/* Make r7 look like an exception frame so that we
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@ -204,15 +216,19 @@ dont_backup_fp:
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SAVE_GPR(0, r7) /* user r0 */
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SAVE_GPR(2, r7) /* user r2 */
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SAVE_4GPRS(3, r7) /* user r3-r6 */
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SAVE_4GPRS(8, r7) /* user r8-r11 */
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SAVE_GPR(8, r7) /* user r8 */
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SAVE_GPR(9, r7) /* user r9 */
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SAVE_GPR(10, r7) /* user r10 */
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ld r3, PACATMSCRATCH(r13) /* user r1 */
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ld r4, GPR7(r1) /* user r7 */
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ld r5, GPR12(r1) /* user r12 */
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GET_SCRATCH0(6) /* user r13 */
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ld r5, GPR11(r1) /* user r11 */
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ld r6, GPR12(r1) /* user r12 */
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GET_SCRATCH0(8) /* user r13 */
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std r3, GPR1(r7)
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std r4, GPR7(r7)
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std r5, GPR12(r7)
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std r6, GPR13(r7)
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std r5, GPR11(r7)
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std r6, GPR12(r7)
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std r8, GPR13(r7)
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SAVE_NVGPRS(r7) /* user r14-r31 */
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@ -235,14 +251,12 @@ dont_backup_fp:
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std r6, _XER(r7)
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/* ******************** TAR, PPR, DSCR ********** */
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/* ******************** TAR, DSCR ********** */
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mfspr r3, SPRN_TAR
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mfspr r4, SPRN_PPR
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mfspr r5, SPRN_DSCR
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mfspr r4, SPRN_DSCR
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std r3, THREAD_TM_TAR(r12)
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std r4, THREAD_TM_PPR(r12)
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std r5, THREAD_TM_DSCR(r12)
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std r4, THREAD_TM_DSCR(r12)
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/* MSR and flags: We don't change CRs, and we don't need to alter
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* MSR.
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@ -259,7 +273,7 @@ dont_backup_fp:
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std r3, THREAD_TM_TFHAR(r12)
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std r4, THREAD_TM_TFIAR(r12)
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/* AMR and PPR are checkpointed too, but are unsupported by Linux. */
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/* AMR is checkpointed too, but is unsupported by Linux. */
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/* Restore original MSR/IRQ state & clear TM mode */
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ld r14, TM_FRAME_L0(r1) /* Orig MSR */
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@ -275,6 +289,12 @@ dont_backup_fp:
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mtcr r4
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mtlr r0
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ld r2, 40(r1)
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/* Load system default DSCR */
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ld r4, DSCR_DEFAULT@toc(r2)
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ld r0, 0(r4)
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mtspr SPRN_DSCR, r0
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blr
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@ -359,25 +379,24 @@ dont_restore_fp:
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restore_gprs:
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/* ******************** TAR, PPR, DSCR ********** */
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ld r4, THREAD_TM_TAR(r3)
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ld r5, THREAD_TM_PPR(r3)
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ld r6, THREAD_TM_DSCR(r3)
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mtspr SPRN_TAR, r4
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mtspr SPRN_PPR, r5
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mtspr SPRN_DSCR, r6
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/* ******************** CR,LR,CCR,MSR ********** */
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ld r3, _CTR(r7)
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ld r4, _LINK(r7)
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ld r5, _CCR(r7)
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ld r6, _XER(r7)
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ld r4, _CTR(r7)
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ld r5, _LINK(r7)
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ld r6, _CCR(r7)
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ld r8, _XER(r7)
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mtctr r3
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mtlr r4
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mtcr r5
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mtxer r6
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mtctr r4
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mtlr r5
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mtcr r6
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mtxer r8
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/* ******************** TAR ******************** */
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ld r4, THREAD_TM_TAR(r3)
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mtspr SPRN_TAR, r4
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/* Load up the PPR and DSCR in GPRs only at this stage */
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ld r5, THREAD_TM_DSCR(r3)
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ld r6, THREAD_TM_PPR(r3)
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/* Clear the MSR RI since we are about to change R1. EE is already off
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*/
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@ -385,19 +404,26 @@ restore_gprs:
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mtmsrd r4, 1
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REST_4GPRS(0, r7) /* GPR0-3 */
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REST_GPR(4, r7) /* GPR4-6 */
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REST_GPR(5, r7)
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REST_GPR(6, r7)
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REST_GPR(4, r7) /* GPR4 */
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REST_4GPRS(8, r7) /* GPR8-11 */
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REST_2GPRS(12, r7) /* GPR12-13 */
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REST_NVGPRS(r7) /* GPR14-31 */
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ld r7, GPR7(r7) /* GPR7 */
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/* Load up PPR and DSCR here so we don't run with user values for long
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*/
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mtspr SPRN_DSCR, r5
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mtspr SPRN_PPR, r6
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REST_GPR(5, r7) /* GPR5-7 */
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REST_GPR(6, r7)
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ld r7, GPR7(r7)
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/* Commit register state as checkpointed state: */
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TRECHKPT
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HMT_MEDIUM
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/* Our transactional state has now changed.
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*
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* Now just get out of here. Transactional (current) state will be
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@ -420,6 +446,12 @@ restore_gprs:
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mtcr r4
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mtlr r0
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ld r2, 40(r1)
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/* Load system default DSCR */
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ld r4, DSCR_DEFAULT@toc(r2)
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ld r0, 0(r4)
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mtspr SPRN_DSCR, r0
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blr
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/* ****************************************************************** */
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