diff options
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 274a86d001c7..8a0292dbb5fc 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -439,9 +439,9 @@ BEGIN_FTR_SECTION * R9 = CR * Original R9 to R13 is saved on PACA_EXMC * - * Switch to mc_emergency stack and handle re-entrancy (though we - * currently don't test for overflow). Save MCE registers srr1, - * srr0, dar and dsisr and then set ME=1 + * Switch to mc_emergency stack and handle re-entrancy (we limit + * the nested MCE upto level 4 to avoid stack overflow). + * Save MCE registers srr1, srr0, dar and dsisr and then set ME=1 * * We use paca->in_mce to check whether this is the first entry or * nested machine check. We increment paca->in_mce to track nested @@ -464,6 +464,9 @@ BEGIN_FTR_SECTION 0: subi r1,r1,INT_FRAME_SIZE /* alloc stack frame */ addi r10,r10,1 /* increment paca->in_mce */ sth r10,PACA_IN_MCE(r13) + /* Limit nested MCE to level 4 to avoid stack overflow */ + cmpwi r10,4 + bgt 2f /* Check if we hit limit of 4 */ std r11,GPR1(r1) /* Save r1 on the stack. */ std r11,0(r1) /* make stack chain pointer */ mfspr r11,SPRN_SRR0 /* Save SRR0 */ @@ -482,10 +485,23 @@ BEGIN_FTR_SECTION ori r11,r11,MSR_RI /* turn on RI bit */ ld r12,PACAKBASE(r13) /* get high part of &label */ LOAD_HANDLER(r12, machine_check_handle_early) - mtspr SPRN_SRR0,r12 +1: mtspr SPRN_SRR0,r12 mtspr SPRN_SRR1,r11 rfid b . /* prevent speculative execution */ +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) + ld r12,PACAKBASE(r13) + LOAD_HANDLER(r12, unrecover_mce) + li r10,MSR_ME + andc r11,r11,r10 /* Turn off MSR_ME */ + b 1b + b . /* prevent speculative execution */ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) machine_check_pSeries: |