From b7d9ccec3056913528690c5fae7cc86a5ea3dffc Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Fri, 2 Aug 2019 20:56:39 +1000 Subject: [PATCH] powerpc/64s/exception: machine check move unrecoverable handling out of line Similarly to the previous change, all callers of the unrecoverable handler run relocated so can reach it with a direct branch. This makes it easy to move out of line, which makes the "normal" path less cluttered and easier to follow. MSR[ME] manipulation still requires the rfi, so that is moved out of line to its own function. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190802105709.27696-15-npiggin@gmail.com --- arch/powerpc/kernel/exceptions-64s.S | 87 ++++++++++++++-------------- 1 file changed, 44 insertions(+), 43 deletions(-) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index bbbcab88cf78..af18d0f1d4ab 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -992,9 +992,9 @@ EXC_COMMON_BEGIN(machine_check_early_common) bne 1f /* First machine check entry */ ld r1,PACAMCEMERGSP(r13) /* Use MC emergency stack */ -1: subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */ - /* Limit nested MCE to level 4 to avoid stack overflow */ - bge cr1,2f /* Check if we hit limit of 4 */ +1: /* Limit nested MCE to level 4 to avoid stack overflow */ + bgt cr1,unrecoverable_mce /* Check if we hit limit of 4 */ + subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */ EXCEPTION_PROLOG_COMMON_1() /* We don't touch AMR here, we never go to virtual mode */ @@ -1013,21 +1013,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) mtmsrd r10,1 b machine_check_handle_early -2: - /* Stack overflow. Stay on emergency stack and panic. - * Keep the ME bit off while panic-ing, so that if we hit - * another machine check we checkstop. - */ - addi r1,r1,INT_FRAME_SIZE /* go back to previous stack frame */ - ld r11,PACAKMSR(r13) - LOAD_HANDLER(r12, unrecover_mce) - li r10,MSR_ME - andc r11,r11,r10 /* Turn off MSR_ME */ - mtspr SPRN_SRR0,r12 - mtspr SPRN_SRR1,r11 - RFI_TO_KERNEL - b . /* prevent speculative execution */ - EXC_COMMON_BEGIN(machine_check_common) /* * Machine check is different because we use a different @@ -1141,32 +1126,15 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206) * If yes, then stay on emergency stack and panic. */ andi. r11,r12,MSR_RI - bne 2f -1: mfspr r11,SPRN_SRR0 - LOAD_HANDLER(r10,unrecover_mce) - mtspr SPRN_SRR0,r10 - ld r10,PACAKMSR(r13) - /* - * We are going down. But there are chances that we might get hit by - * another MCE during panic path and we may run into unstable state - * with no way out. Hence, turn ME bit off while going down, so that - * when another MCE is hit during panic path, system will checkstop - * and hypervisor will get restarted cleanly by SP. - */ - li r3,MSR_ME - andc r10,r10,r3 /* Turn off MSR_ME */ - mtspr SPRN_SRR1,r10 - RFI_TO_KERNEL - b . -2: + beq unrecoverable_mce + /* * Check if we have successfully handled/recovered from error, if not * then stay on emergency stack and panic. */ ld r3,RESULT(r1) /* Load result */ cmpdi r3,0 /* see if we handled MCE successfully */ - - beq 1b /* if !handled then panic */ + beq unrecoverable_mce /* if !handled then panic */ /* * Return from MC interrupt. @@ -1189,17 +1157,35 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR) EXCEPTION_PROLOG_1 EXC_STD, PACA_EXMC, 1, 0x200, 1, 1, 0 EXCEPTION_PROLOG_2_REAL machine_check_common, EXC_STD, 0 -EXC_COMMON_BEGIN(unrecover_mce) +EXC_COMMON_BEGIN(unrecoverable_mce) + /* + * We are going down. But there are chances that we might get hit by + * another MCE during panic path and we may run into unstable state + * with no way out. Hence, turn ME bit off while going down, so that + * when another MCE is hit during panic path, system will checkstop + * and hypervisor will get restarted cleanly by SP. + */ +BEGIN_FTR_SECTION + li r10,0 /* clear MSR_RI */ + mtmsrd r10,1 + bl disable_machine_check +END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) + ld r10,PACAKMSR(r13) + li r3,MSR_ME + andc r10,r10,r3 + mtmsrd r10 + /* Invoke machine_check_exception to print MCE event and panic. */ addi r3,r1,STACK_FRAME_OVERHEAD bl machine_check_exception + /* - * We will not reach here. Even if we did, there is no way out. Call - * unrecoverable_exception and die. + * We will not reach here. Even if we did, there is no way out. + * Call unrecoverable_exception and die. */ -1: addi r3,r1,STACK_FRAME_OVERHEAD + addi r3,r1,STACK_FRAME_OVERHEAD bl unrecoverable_exception - b 1b + b . EXC_REAL_BEGIN(data_access, 0x300, 0x80) @@ -2282,6 +2268,21 @@ enable_machine_check: 1: mtlr r0 blr +/* MSR[RI] should be clear because this uses SRR[01] */ +disable_machine_check: + mflr r0 + bcl 20,31,$+4 +0: mflr r3 + addi r3,r3,(1f - 0b) + mtspr SPRN_SRR0,r3 + mfmsr r3 + li r4,MSR_ME + andc r3,r3,r4 + mtspr SPRN_SRR1,r3 + RFI_TO_KERNEL +1: mtlr r0 + blr + /* * Hash table stuff */ -- 2.30.2