linux-kernel - [PATCH AUTOSEL 5.2 40/59] arm64: Lower priority mask for GIC_PRIO

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Date:   Tue,  6 Aug 2019 17:33:00 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Julien Thierry <julien.thierry.kdev@...il.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.2 40/59] arm64: Lower priority mask for GIC_PRIO_IRQON

From: Julien Thierry <julien.thierry.kdev@...il.com>

[ Upstream commit 677379bc9139ac24b310a281fcb21a2f04288353 ]

On a system with two security states, if SCR_EL3.FIQ is cleared,
non-secure IRQ priorities get shifted to fit the secure view but
priority masks aren't.

On such system, it turns out that GIC_PRIO_IRQON masks the priority of
normal interrupts, which obviously ends up in a hang.

Increase GIC_PRIO_IRQON value (i.e. lower priority) to make sure
interrupts are not blocked by it.

Cc: Oleg Nesterov <oleg@...hat.com>
Fixes: bd82d4bd21880b7c ("arm64: Fix incorrect irqflag restore for priority masking")
Acked-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Julien Thierry <julien.thierry.kdev@...il.com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
[will: fixed Fixes: tag]
Signed-off-by: Will Deacon <will@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm64/include/asm/arch_gicv3.h | 6 ++++++
 arch/arm64/include/asm/ptrace.h     | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
index 79155a8cfe7c0..89e4c8b793490 100644
--- a/arch/arm64/include/asm/arch_gicv3.h
+++ b/arch/arm64/include/asm/arch_gicv3.h
@@ -155,6 +155,12 @@ static inline void gic_pmr_mask_irqs(void)
 	BUILD_BUG_ON(GICD_INT_DEF_PRI < (GIC_PRIO_IRQOFF |
 					 GIC_PRIO_PSR_I_SET));
 	BUILD_BUG_ON(GICD_INT_DEF_PRI >= GIC_PRIO_IRQON);
+	/*
+	 * Need to make sure IRQON allows IRQs when SCR_EL3.FIQ is cleared
+	 * and non-secure PMR accesses are not subject to the shifts that
+	 * are applied to IRQ priorities
+	 */
+	BUILD_BUG_ON((0x80 | (GICD_INT_DEF_PRI >> 1)) >= GIC_PRIO_IRQON);
 	gic_write_pmr(GIC_PRIO_IRQOFF);
 }
 
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index 81693244f58d6..701eaa7381876 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -30,7 +30,7 @@
  * in the  the priority mask, it indicates that PSR.I should be set and
  * interrupt disabling temporarily does not rely on IRQ priorities.
  */
-#define GIC_PRIO_IRQON			0xc0
+#define GIC_PRIO_IRQON			0xe0
 #define GIC_PRIO_IRQOFF			(GIC_PRIO_IRQON & ~0x80)
 #define GIC_PRIO_PSR_I_SET		(1 << 4)
 
-- 
2.20.1