From 0fa6831811f62cfc10415d731bcf9fde2647ad81 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Tue, 4 Oct 2022 15:11:57 +1000 Subject: powerpc/64: Fix msr_check_and_set/clear MSR[EE] race irq soft-masking means that when Linux irqs are disabled, the MSR[EE] value can change from 1 to 0 asynchronously: if a masked interrupt of the PACA_IRQ_MUST_HARD_MASK variety fires while irqs are disabled, the masked handler will return with MSR[EE]=0. This means a sequence like mtmsr(mfmsr() | MSR_FP) is racy if it can be called with local irqs disabled, unless a hard_irq_disable has been done. Reported-by: Sachin Sant Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221004051157.308999-2-npiggin@gmail.com --- arch/powerpc/kernel/process.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/kernel/process.c') diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 0fbda89cd1bb..37df0428e4fb 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -127,7 +127,7 @@ unsigned long notrace msr_check_and_set(unsigned long bits) newmsr |= MSR_VSX; if (oldmsr != newmsr) - mtmsr_isync(newmsr); + newmsr = mtmsr_isync_irqsafe(newmsr); return newmsr; } @@ -145,7 +145,7 @@ void notrace __msr_check_and_clear(unsigned long bits) newmsr &= ~MSR_VSX; if (oldmsr != newmsr) - mtmsr_isync(newmsr); + mtmsr_isync_irqsafe(newmsr); } EXPORT_SYMBOL(__msr_check_and_clear); -- cgit