Re: [PATCH v2 3/3] powerpc: machine check interrupt is a non-maskable interrupt
From: Christophe LEROY <hidden>
Date: 2018-10-08 16:19:46
Hi Nick, Le 19/07/2017 à 08:59, Nicholas Piggin a écrit :
quoted hunk ↗ jump to hunk
Use nmi_enter similarly to system reset interrupts. This uses NMI printk NMI buffers and turns off various debugging facilities that helps avoid tripping on ourselves or other CPUs. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/traps.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 2849c4f50324..6d31f9d7c333 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c@@ -789,8 +789,10 @@ int machine_check_generic(struct pt_regs *regs) void machine_check_exception(struct pt_regs *regs) { - enum ctx_state prev_state = exception_enter(); int recover = 0; + bool nested = in_nmi(); + if (!nested) + nmi_enter();
This alters preempt_count, then when die() is called in_interrupt() returns true allthough the trap didn't happen in interrupt, so oops_end() panics for "fatal exception in interrupt" instead of gently sending SIGBUS the faulting app. Any idea on how to fix this ? Christophe
quoted hunk ↗ jump to hunk
__this_cpu_inc(irq_stat.mce_exceptions);@@ -820,10 +822,11 @@ void machine_check_exception(struct pt_regs *regs) /* Must die if the interrupt is not recoverable */ if (!(regs->msr & MSR_RI)) - panic("Unrecoverable Machine check"); + nmi_panic(regs, "Unrecoverable Machine check"); bail: - exception_exit(prev_state); + if (!nested) + nmi_exit(); } void SMIException(struct pt_regs *regs)