Re: [RFC PATCH 06/36] arm64: irq: introduce a helper for GIC priority initialization

On 7/9/2026 8:13 PM, Vladimir Murzin wrote:

quoted

From: Ada Couprie Diaz <redacted>

Arm64's `init_IRQ()` calls `local_daif_restore()` to synchronize
interrupt masking via DAIF and switch to masking via PMR.  This
depends on a very specific behaviour of `local_daif_restore()` which
will clear DAIF if masking interrupts via PMR, which will get removed
in the future.

As `setup_arch()` cleared DA only earlier, introduce a dedicated
helper that explicitly initializes the PMR to mask interrupts and
clears DAIF, switching to IRQ priority masking.

I believe that the `local_daif_restore(DAIF_PROCCTX_NOIRQ)` inside
`setup_arch()` should be directly replaced with the following code.
Otherwise, since the pseudo NMI has not yet taken effect at this point,
it could lead to ambiguity.

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 23c05dc7a8f2..35c5310783f4 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c

@@ -311,7 +311,8 @@ void __init __no_sanitize_address setup_arch(char

**cmdline_p)
         * IRQ and FIQ will be unmasked after the root irqchip has been
         * detected and initialized.
         */
-       local_daif_restore(DAIF_PROCCTX_NOIRQ);
+       write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
+       trace_hardirqs_off();