[PATCH v2] powerpc/tm: Save and restore AMR on treclaim and trechkpt
From: Gustavo Romero <hidden>
Date: 2020-09-19 15:04:03
Althought AMR is stashed in the checkpoint area, currently we don't save it to the per thread checkpoint struct after a treclaim and so we don't restore it either from that struct when we trechkpt. As a consequence when the transaction is later rolled back the kernel space AMR value when the trechkpt was done appears in userspace. That commit saves and restores AMR accordingly on treclaim and trechkpt. Since AMR value is also used in kernel space in other functions, it also takes care of stashing kernel live AMR into the stack before treclaim and before trechkpt, restoring it later, just before returning from tm_reclaim and __tm_recheckpoint. Is also fixes two nonrelated comments about CR and MSR. Signed-off-by: Gustavo Romero <redacted> --- arch/powerpc/include/asm/processor.h | 1 + arch/powerpc/kernel/asm-offsets.c | 1 + arch/powerpc/kernel/tm.S | 35 ++++++++++++++++++++++++---- 3 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index ed0d633ab5aa..9f4f6cc033ac 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h@@ -220,6 +220,7 @@ struct thread_struct { unsigned long tm_tar; unsigned long tm_ppr; unsigned long tm_dscr; + unsigned long tm_amr; /* * Checkpointed FP and VSX 0-31 register set.
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 8711c2164b45..c2722ff36e98 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c@@ -176,6 +176,7 @@ int main(void) OFFSET(THREAD_TM_TAR, thread_struct, tm_tar); OFFSET(THREAD_TM_PPR, thread_struct, tm_ppr); OFFSET(THREAD_TM_DSCR, thread_struct, tm_dscr); + OFFSET(THREAD_TM_AMR, thread_struct, tm_amr); OFFSET(PT_CKPT_REGS, thread_struct, ckpt_regs); OFFSET(THREAD_CKVRSTATE, thread_struct, ckvr_state.vr); OFFSET(THREAD_CKVRSAVE, thread_struct, ckvrsave);
diff --git a/arch/powerpc/kernel/tm.S b/arch/powerpc/kernel/tm.S
index 6ba0fdd1e7f8..2b91f233b05d 100644
--- a/arch/powerpc/kernel/tm.S
+++ b/arch/powerpc/kernel/tm.S@@ -122,6 +122,13 @@ _GLOBAL(tm_reclaim) std r3, STK_PARAM(R3)(r1) SAVE_NVGPRS(r1) + /* + * Save kernel live AMR since it will be clobbered by treclaim + * but can be used elsewhere later in kernel space. + */ + mfspr r3, SPRN_AMR + std r3, TM_FRAME_L1(r1) + /* We need to setup MSR for VSX register save instructions. */ mfmsr r14 mr r15, r14
@@ -245,7 +252,7 @@ _GLOBAL(tm_reclaim) * but is used in signal return to 'wind back' to the abort handler. */ - /* ******************** CR,LR,CCR,MSR ********** */ + /* ***************** CTR, LR, CR, XER ********** */ mfctr r3 mflr r4 mfcr r5
@@ -256,7 +263,6 @@ _GLOBAL(tm_reclaim) std r5, _CCR(r7) std r6, _XER(r7) - /* ******************** TAR, DSCR ********** */ mfspr r3, SPRN_TAR mfspr r4, SPRN_DSCR
@@ -264,6 +270,10 @@ _GLOBAL(tm_reclaim) std r3, THREAD_TM_TAR(r12) std r4, THREAD_TM_DSCR(r12) + /* ******************** AMR **************** */ + mfspr r3, SPRN_AMR + std r3, THREAD_TM_AMR(r12) + /* * MSR and flags: We don't change CRs, and we don't need to alter MSR. */
@@ -308,7 +318,9 @@ _GLOBAL(tm_reclaim) std r3, THREAD_TM_TFHAR(r12) std r4, THREAD_TM_TFIAR(r12) - /* AMR is checkpointed too, but is unsupported by Linux. */ + /* Restore kernel live AMR */ + ld r8, TM_FRAME_L1(r1) + mtspr SPRN_AMR, r8 /* Restore original MSR/IRQ state & clear TM mode */ ld r14, TM_FRAME_L0(r1) /* Orig MSR */
@@ -355,6 +367,13 @@ _GLOBAL(__tm_recheckpoint) */ SAVE_NVGPRS(r1) + /* + * Save kernel live AMR since it will be clobbered for trechkpt + * but can be used elsewhere later in kernel space. + */ + mfspr r8, SPRN_AMR + std r8, TM_FRAME_L0(r1) + /* Load complete register state from ts_ckpt* registers */ addi r7, r3, PT_CKPT_REGS /* Thread's ckpt_regs */
@@ -404,7 +423,7 @@ _GLOBAL(__tm_recheckpoint) restore_gprs: - /* ******************** CR,LR,CCR,MSR ********** */ + /* ****************** CTR, LR, XER ************* */ ld r4, _CTR(r7) ld r5, _LINK(r7) ld r8, _XER(r7)
@@ -417,6 +436,10 @@ restore_gprs: ld r4, THREAD_TM_TAR(r3) mtspr SPRN_TAR, r4 + /* ******************** AMR ******************** */ + ld r4, THREAD_TM_AMR(r3) + mtspr SPRN_AMR, r4 + /* Load up the PPR and DSCR in GPRs only at this stage */ ld r5, THREAD_TM_DSCR(r3) ld r6, THREAD_TM_PPR(r3)
@@ -509,6 +532,10 @@ restore_gprs: li r4, MSR_RI mtmsrd r4, 1 + /* Restore kernel live AMR */ + ld r8, TM_FRAME_L0(r1) + mtspr SPRN_AMR, r8 + REST_NVGPRS(r1) addi r1, r1, TM_FRAME_SIZE
--
2.25.1