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Sun, 20 Sep 2020 05:56:06 +0000 (GMT) X-Mailer: emacs 27.1 (via feedmail 11-beta-1 I) From: "Aneesh Kumar K.V" To: Gustavo Romero , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v2] powerpc/tm: Save and restore AMR on treclaim and trechkpt In-Reply-To: <20200919150025.9609-1-gromero@linux.ibm.com> References: <20200919150025.9609-1-gromero@linux.ibm.com> Date: Sun, 20 Sep 2020 11:26:01 +0530 Message-ID: <878sd5uh3i.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-09-20_01:2020-09-16, 2020-09-20 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 malwarescore=0 mlxscore=0 priorityscore=1501 phishscore=0 lowpriorityscore=0 spamscore=0 mlxlogscore=999 suspectscore=0 adultscore=0 bulkscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009200043 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mikey@neuling.org, gromero@linux.ibm.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Gustavo Romero writes: > 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. > Tested-by: Aneesh Kumar K.V > Signed-off-by: Gustavo Romero > --- > 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