| Message ID | 1502189757-11623-1-git-send-email-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 44a12806d010944a5727f1dc99123121e3e2c8c6 |
| Headers | show |
On Tue, 2017-08-08 at 10:55:57 UTC, Michael Ellerman wrote: > This reverts commit bc4f65e4cf9d6cc43e0e9ba0b8648cf9201cd55f. > > As reported by Andreas, this commit is causing unrecoverable SLB misses in the > system call exit path: > > Unrecoverable exception 4100 at c00000000000a1ec > Oops: Unrecoverable exception, sig: 6 [#1] > SMP NR_CPUS=2 PowerMac > ... > CPU: 0 PID: 18626 Comm: rm Not tainted 4.13.0-rc3 #1 > task: c00000018335e080 task.stack: c000000139e50000 > NIP: c00000000000a1ec LR: c00000000000a118 CTR: 0000000000000000 > REGS: c000000139e53bb0 TRAP: 4100 Not tainted (4.13.0-rc3) > MSR: 9000000000001030 <SF,HV,ME,IR,DR> CR: 24000044 XER: 20000000 SOFTE: 1 > GPR00: 0000000000000000 c000000139e53e30 c000000000abb500 fffffffffffffffe > GPR04: c0000001eb866298 0000000000000000 0000000000000000 c00000018335e080 > GPR08: 900000000000d032 0000000000000000 0000000000000002 fffffffffffff001 > GPR12: c000000139e50000 c00000000ffff000 00003fffa8c0dca0 00003fffa8c0dc88 > GPR16: 0000000010000000 0000000000000001 00003fffa8c0eaa0 0000000000000000 > GPR20: 00003fffa8c27528 00003fffa8c27b00 0000000000000000 0000000000000000 > GPR24: 00003fffa8c0d918 00003ffff1b3efa0 00003fffa8c26d68 0000000000000000 > GPR28: 00003fffa8c249e8 00003fffa8c263d0 00003fffa8c27550 00003ffff1b3ef10 > NIP [c00000000000a1ec] system_call_exit+0xc0/0x21c > LR [c00000000000a118] system_call+0x58/0x6c > Call Trace: > [c000000139e53e30] [c00000000000a118] system_call+0x58/0x6c (unreliable) > Instruction dump: > 64a51000 7c6300d0 f8a101a0 4bffff9c 3c000000 60000006 780007c6 64000000 > 60000000 7c004039 4082001c e8ed0170 <88070b78> 88c70b79 7c003214 2c200000 > > This is caused by us trying to load THREAD_LOAD_FP with MSR_RI=0, and taking an > SLB miss on the thread struct. > > Reported-by: Andreas Schwab <schwab@linux-m68k.org> > Diagnosed-by: Nicholas Piggin <npiggin@gmail.com> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Applied to powerpc fixes. https://git.kernel.org/powerpc/c/44a12806d010944a5727f1dc991231 cheers
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 49d8422767b4..e925c1c99c71 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -223,17 +223,27 @@ system_call_exit: andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) bne- .Lsyscall_exit_work - /* If MSR_FP and MSR_VEC are set in user msr, then no need to restore */ - li r7,MSR_FP + andi. r0,r8,MSR_FP + beq 2f #ifdef CONFIG_ALTIVEC - oris r7,r7,MSR_VEC@h + andis. r0,r8,MSR_VEC@h + bne 3f #endif - and r0,r8,r7 - cmpd r0,r7 - bne .Lsyscall_restore_math -.Lsyscall_restore_math_cont: +2: addi r3,r1,STACK_FRAME_OVERHEAD +#ifdef CONFIG_PPC_BOOK3S + li r10,MSR_RI + mtmsrd r10,1 /* Restore RI */ +#endif + bl restore_math +#ifdef CONFIG_PPC_BOOK3S + li r11,0 + mtmsrd r11,1 +#endif + ld r8,_MSR(r1) + ld r3,RESULT(r1) + li r11,-MAX_ERRNO - cmpld r3,r11 +3: cmpld r3,r11 ld r5,_CCR(r1) bge- .Lsyscall_error .Lsyscall_error_cont: @@ -267,40 +277,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) std r5,_CCR(r1) b .Lsyscall_error_cont -.Lsyscall_restore_math: - /* - * Some initial tests from restore_math to avoid the heavyweight - * C code entry and MSR manipulations. - */ - LOAD_REG_IMMEDIATE(r0, MSR_TS_MASK) - and. r0,r0,r8 - bne 1f - - ld r7,PACACURRENT(r13) - lbz r0,THREAD+THREAD_LOAD_FP(r7) -#ifdef CONFIG_ALTIVEC - lbz r6,THREAD+THREAD_LOAD_VEC(r7) - add r0,r0,r6 -#endif - cmpdi r0,0 - beq .Lsyscall_restore_math_cont - -1: addi r3,r1,STACK_FRAME_OVERHEAD -#ifdef CONFIG_PPC_BOOK3S - li r10,MSR_RI - mtmsrd r10,1 /* Restore RI */ -#endif - bl restore_math -#ifdef CONFIG_PPC_BOOK3S - li r11,0 - mtmsrd r11,1 -#endif - /* Restore volatiles, reload MSR from updated one */ - ld r8,_MSR(r1) - ld r3,RESULT(r1) - li r11,-MAX_ERRNO - b .Lsyscall_restore_math_cont - /* Traced system call support */ .Lsyscall_dotrace: bl save_nvgprs diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 9f3e2c932dcc..ec480966f9bf 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -511,10 +511,6 @@ void restore_math(struct pt_regs *regs) { unsigned long msr; - /* - * Syscall exit makes a similar initial check before branching - * to restore_math. Keep them in synch. - */ if (!msr_tm_active(regs->msr) && !current->thread.load_fp && !loadvec(current->thread)) return;
This reverts commit bc4f65e4cf9d6cc43e0e9ba0b8648cf9201cd55f. As reported by Andreas, this commit is causing unrecoverable SLB misses in the system call exit path: Unrecoverable exception 4100 at c00000000000a1ec Oops: Unrecoverable exception, sig: 6 [#1] SMP NR_CPUS=2 PowerMac ... CPU: 0 PID: 18626 Comm: rm Not tainted 4.13.0-rc3 #1 task: c00000018335e080 task.stack: c000000139e50000 NIP: c00000000000a1ec LR: c00000000000a118 CTR: 0000000000000000 REGS: c000000139e53bb0 TRAP: 4100 Not tainted (4.13.0-rc3) MSR: 9000000000001030 <SF,HV,ME,IR,DR> CR: 24000044 XER: 20000000 SOFTE: 1 GPR00: 0000000000000000 c000000139e53e30 c000000000abb500 fffffffffffffffe GPR04: c0000001eb866298 0000000000000000 0000000000000000 c00000018335e080 GPR08: 900000000000d032 0000000000000000 0000000000000002 fffffffffffff001 GPR12: c000000139e50000 c00000000ffff000 00003fffa8c0dca0 00003fffa8c0dc88 GPR16: 0000000010000000 0000000000000001 00003fffa8c0eaa0 0000000000000000 GPR20: 00003fffa8c27528 00003fffa8c27b00 0000000000000000 0000000000000000 GPR24: 00003fffa8c0d918 00003ffff1b3efa0 00003fffa8c26d68 0000000000000000 GPR28: 00003fffa8c249e8 00003fffa8c263d0 00003fffa8c27550 00003ffff1b3ef10 NIP [c00000000000a1ec] system_call_exit+0xc0/0x21c LR [c00000000000a118] system_call+0x58/0x6c Call Trace: [c000000139e53e30] [c00000000000a118] system_call+0x58/0x6c (unreliable) Instruction dump: 64a51000 7c6300d0 f8a101a0 4bffff9c 3c000000 60000006 780007c6 64000000 60000000 7c004039 4082001c e8ed0170 <88070b78> 88c70b79 7c003214 2c200000 This is caused by us trying to load THREAD_LOAD_FP with MSR_RI=0, and taking an SLB miss on the thread struct. Reported-by: Andreas Schwab <schwab@linux-m68k.org> Diagnosed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/kernel/entry_64.S | 60 +++++++++++++----------------------------- arch/powerpc/kernel/process.c | 4 --- 2 files changed, 18 insertions(+), 46 deletions(-)