diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2021-10-04 16:56:42 +0200 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-10-07 10:54:55 +0200 |
| commit | f08fb25bc66986b0952724530a640d9970fa52c1 (patch) | |
| tree | 3770f39e25bf2a57936c4ea55609aaaf63870e4b /arch/powerpc/kernel/exceptions-64s.S | |
| parent | powerpc/64/interrupt: Reconcile soft-mask state in NMI and fix false BUG (diff) | |
| download | linux-f08fb25bc66986b0952724530a640d9970fa52c1.tar.xz linux-f08fb25bc66986b0952724530a640d9970fa52c1.zip | |
powerpc/64s: Fix unrecoverable MCE calling async handler from NMI
The machine check handler is not considered NMI on 64s. The early
handler is the true NMI handler, and then it schedules the
machine_check_exception handler to run when interrupts are enabled.
This works fine except the case of an unrecoverable MCE, where the true
NMI is taken when MSR[RI] is clear, it can not recover, so it calls
machine_check_exception directly so something might be done about it.
Calling an async handler from NMI context can result in irq state and
other things getting corrupted. This can also trigger the BUG at
arch/powerpc/include/asm/interrupt.h:168
BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));
Fix this by making an _async version of the handler which is called
in the normal case, and a NMI version that is called for unrecoverable
interrupts.
Fixes: 2b43dd7653cc ("powerpc/64: enable MSR[EE] in irq replay pt_regs")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Tested-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211004145642.1331214-6-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/kernel/exceptions-64s.S')
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 024d9231f88c..eaf1f72131a1 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1243,7 +1243,7 @@ EXC_COMMON_BEGIN(machine_check_common) li r10,MSR_RI mtmsrd r10,1 addi r3,r1,STACK_FRAME_OVERHEAD - bl machine_check_exception + bl machine_check_exception_async b interrupt_return_srr @@ -1303,7 +1303,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) subi r12,r12,1 sth r12,PACA_IN_MCE(r13) - /* Invoke machine_check_exception to print MCE event and panic. */ + /* + * Invoke machine_check_exception to print MCE event and panic. + * This is the NMI version of the handler because we are called from + * the early handler which is a true NMI. + */ addi r3,r1,STACK_FRAME_OVERHEAD bl machine_check_exception |