From: Mark Brown <broonie@kernel.org> We have documentation at the top of irqflags.h which explains the DAIF masking. Since the additional masking with NMIs is related and also covers the IF in DAIF extend the comment to note what's going on with NMIs though none of the code in irqflags.h is updated to handle NMIs. Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Jie Liu <liujie375@h-partners.com> --- arch/arm64/include/asm/irqflags.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h index 1a59f0ed1ae3..2b2cdd7bb6fb 100644 --- a/arch/arm64/include/asm/irqflags.h +++ b/arch/arm64/include/asm/irqflags.h @@ -18,6 +18,16 @@ * side effects for other flags. Keeping to this order makes it easier for * entry.S to know which exceptions should be unmasked. * + * With the addition of the FEAT_NMI extension we gain an additional + * class of superpriority IRQ/FIQ which is separately masked with a + * choice of modes controlled by SCTLR_ELn.{SPINTMASK,NMI}. Linux + * sets SPINTMASK to 0 and NMI to 1 which results in ALLINT.ALLINT + * masking both superpriority interrupts and IRQ/FIQ regardless of the + * I and F settings. Since these superpriority interrupts are being + * used as NMIs we do not include them in the interrupt masking here, + * anything that requires that NMIs be masked needs to explicitly do + * so. + * * FIQ is never expected, but we mask it when we disable debug exceptions, and * unmask it at all other times. */ -- 2.25.1