linux-hardening - [PATCH v5 07/32] irqchip: nvic: Use GENERIC_IRQ_MULTI

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Date:   Mon, 24 Jan 2022 18:47:19 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux@...linux.org.uk, linux-arm-kernel@...ts.infradead.org
Cc:     linux-hardening@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
        Nicolas Pitre <nico@...xnic.net>,
        Arnd Bergmann <arnd@...db.de>,
        Kees Cook <keescook@...omium.org>,
        Keith Packard <keithpac@...zon.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tony Lindgren <tony@...mide.com>,
        Marc Zyngier <maz@...nel.org>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Jesse Taube <mr.bossman075@...il.com>,
        Mark Rutland <mark.rutland@....com>
Subject: [PATCH v5 07/32] irqchip: nvic: Use GENERIC_IRQ_MULTI_HANDLER

From: Vladimir Murzin <vladimir.murzin@....com>

Rather then restructuring the ARMv7M entrly logic per TODO, just move
NVIC to GENERIC_IRQ_MULTI_HANDLER.

Signed-off-by: Vladimir Murzin <vladimir.murzin@....com>
Acked-by: Mark Rutland <mark.rutland@....com>
Acked-by: Arnd Bergmann <arnd@...db.de>
Acked-by: Marc Zyngier <maz@...nel.org>
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
Tested-by: Marc Zyngier <maz@...nel.org>
Tested-by: Vladimir Murzin <vladimir.murzin@....com> # ARMv7M
---
 arch/arm/include/asm/v7m.h  |  3 ++-
 arch/arm/kernel/entry-v7m.S | 10 +++------
 drivers/irqchip/Kconfig     |  1 +
 drivers/irqchip/irq-nvic.c  | 22 +++++---------------
 4 files changed, 11 insertions(+), 25 deletions(-)

diff --git a/arch/arm/include/asm/v7m.h b/arch/arm/include/asm/v7m.h
index 2cb00d15831b..4512f7e1918f 100644
--- a/arch/arm/include/asm/v7m.h
+++ b/arch/arm/include/asm/v7m.h
@@ -13,6 +13,7 @@
 #define V7M_SCB_ICSR_PENDSVSET			(1 << 28)
 #define V7M_SCB_ICSR_PENDSVCLR			(1 << 27)
 #define V7M_SCB_ICSR_RETTOBASE			(1 << 11)
+#define V7M_SCB_ICSR_VECTACTIVE			0x000001ff
 
 #define V7M_SCB_VTOR			0x08
 
@@ -38,7 +39,7 @@
 #define V7M_SCB_SHCSR_MEMFAULTENA		(1 << 16)
 
 #define V7M_xPSR_FRAMEPTRALIGN			0x00000200
-#define V7M_xPSR_EXCEPTIONNO			0x000001ff
+#define V7M_xPSR_EXCEPTIONNO			V7M_SCB_ICSR_VECTACTIVE
 
 /*
  * When branching to an address that has bits [31:28] == 0xf an exception return
diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S
index 7bde93c10962..520dd43e7e08 100644
--- a/arch/arm/kernel/entry-v7m.S
+++ b/arch/arm/kernel/entry-v7m.S
@@ -39,14 +39,10 @@ __irq_entry:
 	@
 	@ Invoke the IRQ handler
 	@
-	mrs	r0, ipsr
-	ldr	r1, =V7M_xPSR_EXCEPTIONNO
-	and	r0, r1
-	sub	r0, #16
-	mov	r1, sp
+	mov	r0, sp
 	stmdb	sp!, {lr}
-	@ routine called with r0 = irq number, r1 = struct pt_regs *
-	bl	nvic_handle_irq
+	@ routine called with r0 = struct pt_regs *
+	bl	generic_handle_arch_irq
 
 	pop	{lr}
 	@
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 7038957f4a77..488eaa14d3a7 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -58,6 +58,7 @@ config ARM_NVIC
 	bool
 	select IRQ_DOMAIN_HIERARCHY
 	select GENERIC_IRQ_CHIP
+	select GENERIC_IRQ_MULTI_HANDLER
 
 config ARM_VIC
 	bool
diff --git a/drivers/irqchip/irq-nvic.c b/drivers/irqchip/irq-nvic.c
index ba4759b3e269..125f9c1cf0c3 100644
--- a/drivers/irqchip/irq-nvic.c
+++ b/drivers/irqchip/irq-nvic.c
@@ -37,25 +37,12 @@
 
 static struct irq_domain *nvic_irq_domain;
 
-static void __nvic_handle_irq(irq_hw_number_t hwirq)
+static void __irq_entry nvic_handle_irq(struct pt_regs *regs)
 {
-	generic_handle_domain_irq(nvic_irq_domain, hwirq);
-}
+	unsigned long icsr = readl_relaxed(BASEADDR_V7M_SCB + V7M_SCB_ICSR);
+	irq_hw_number_t hwirq = (icsr & V7M_SCB_ICSR_VECTACTIVE) - 16;
 
-/*
- * TODO: restructure the ARMv7M entry logic so that this entry logic can live
- * in arch code.
- */
-asmlinkage void __exception_irq_entry
-nvic_handle_irq(irq_hw_number_t hwirq, struct pt_regs *regs)
-{
-	struct pt_regs *old_regs;
-
-	irq_enter();
-	old_regs = set_irq_regs(regs);
-	__nvic_handle_irq(hwirq);
-	set_irq_regs(old_regs);
-	irq_exit();
+	generic_handle_domain_irq(nvic_irq_domain, hwirq);
 }
 
 static int nvic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
@@ -141,6 +128,7 @@ static int __init nvic_of_init(struct device_node *node,
 	for (i = 0; i < irqs; i += 4)
 		writel_relaxed(0, nvic_base + NVIC_IPR + i);
 
+	set_handle_irq(nvic_handle_irq);
 	return 0;
 }
 IRQCHIP_DECLARE(armv7m_nvic, "arm,armv7m-nvic", nvic_of_init);
-- 
2.30.2