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Message-Id: <20131011193952.349521991@linuxfoundation.org> Date: Fri, 11 Oct 2013 12:39:06 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Michael Neuling <mikey@...ling.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org> Subject: [ 065/135] powerpc/tm: Switch out userspace PPR and DSCR sooner 3.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Neuling <mikey@...ling.org> commit e9bdc3d6143d1c4b8d8ce5231fc958268331f983 upstream. 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@...ling.org> Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- arch/powerpc/kernel/tm.S | 94 +++++++++++++++++++++++++++++++---------------- 1 file changed, 63 insertions(+), 31 deletions(-) --- 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, @@ -187,11 +192,18 @@ 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 @@ -203,15 +215,19 @@ 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 */ @@ -234,14 +250,12 @@ 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. @@ -258,7 +272,7 @@ 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 */ @@ -274,6 +288,12 @@ 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 @@ -358,25 +378,24 @@ 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) + + mtctr r4 + mtlr r5 + mtcr r6 + mtxer r8 + /* ******************** TAR ******************** */ + ld r4, THREAD_TM_TAR(r3) mtspr SPRN_TAR, r4 - mtspr SPRN_PPR, r5 - mtspr SPRN_DSCR, r6 - /* ******************** CR,LR,CCR,MSR ********** */ - ld r3, _CTR(r7) - ld r4, _LINK(r7) - ld r5, _CCR(r7) - ld r6, _XER(r7) - - 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 */ @@ -384,19 +403,26 @@ 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 @@ -419,6 +445,12 @@ 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 /* ****************************************************************** */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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