arm64: irq: allow FIQs to be handled
On contemporary platforms we don't use FIQ, and treat any stray FIQ as a
fatal event. However, some platforms have an interrupt controller wired
to FIQ, and need to handle FIQ as part of regular operation.
So that we can support both cases dynamically, this patch updates the
FIQ exception handling code to operate the same way as the IRQ handling
code, with its own handle_arch_fiq handler. Where an FIQ handler is not
registered, an unexpected FIQ exception will trigger the default FIQ
handler, which will panic() as today. Where a FIQ handler is registered,
handling of the FIQ is deferred to that handler.
As el0_fiq_invalid_compat is supplanted by el0_fiq, the former is
removed. For !CONFIG_COMPAT builds we never expect to take an exception
from AArch32 EL0, so we keep the common el0_fiq_invalid handler.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Hector Martin <marcan@marcan.st>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index 8391c6f..fac08e18 100644
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -10,6 +10,7 @@
int set_handle_irq(void (*handle_irq)(struct pt_regs *));
#define set_handle_irq set_handle_irq
+int set_handle_fiq(void (*handle_fiq)(struct pt_regs *));
static inline int nr_legacy_irqs(void)
{
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index af04ce5..fe9ab63 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -588,18 +588,18 @@
kernel_ventry 1, sync // Synchronous EL1h
kernel_ventry 1, irq // IRQ EL1h
- kernel_ventry 1, fiq_invalid // FIQ EL1h
+ kernel_ventry 1, fiq // FIQ EL1h
kernel_ventry 1, error // Error EL1h
kernel_ventry 0, sync // Synchronous 64-bit EL0
kernel_ventry 0, irq // IRQ 64-bit EL0
- kernel_ventry 0, fiq_invalid // FIQ 64-bit EL0
+ kernel_ventry 0, fiq // FIQ 64-bit EL0
kernel_ventry 0, error // Error 64-bit EL0
#ifdef CONFIG_COMPAT
kernel_ventry 0, sync_compat, 32 // Synchronous 32-bit EL0
kernel_ventry 0, irq_compat, 32 // IRQ 32-bit EL0
- kernel_ventry 0, fiq_invalid_compat, 32 // FIQ 32-bit EL0
+ kernel_ventry 0, fiq_compat, 32 // FIQ 32-bit EL0
kernel_ventry 0, error_compat, 32 // Error 32-bit EL0
#else
kernel_ventry 0, sync_invalid, 32 // Synchronous 32-bit EL0
@@ -665,12 +665,6 @@
inv_entry 0, BAD_ERROR
SYM_CODE_END(el0_error_invalid)
-#ifdef CONFIG_COMPAT
-SYM_CODE_START_LOCAL(el0_fiq_invalid_compat)
- inv_entry 0, BAD_FIQ, 32
-SYM_CODE_END(el0_fiq_invalid_compat)
-#endif
-
SYM_CODE_START_LOCAL(el1_sync_invalid)
inv_entry 1, BAD_SYNC
SYM_CODE_END(el1_sync_invalid)
@@ -705,6 +699,12 @@
kernel_exit 1
SYM_CODE_END(el1_irq)
+SYM_CODE_START_LOCAL_NOALIGN(el1_fiq)
+ kernel_entry 1
+ el1_interrupt_handler handle_arch_fiq
+ kernel_exit 1
+SYM_CODE_END(el1_fiq)
+
/*
* EL0 mode handlers.
*/
@@ -731,6 +731,11 @@
b el0_irq_naked
SYM_CODE_END(el0_irq_compat)
+SYM_CODE_START_LOCAL_NOALIGN(el0_fiq_compat)
+ kernel_entry 0, 32
+ b el0_fiq_naked
+SYM_CODE_END(el0_fiq_compat)
+
SYM_CODE_START_LOCAL_NOALIGN(el0_error_compat)
kernel_entry 0, 32
b el0_error_naked
@@ -745,6 +750,13 @@
b ret_to_user
SYM_CODE_END(el0_irq)
+SYM_CODE_START_LOCAL_NOALIGN(el0_fiq)
+ kernel_entry 0
+el0_fiq_naked:
+ el0_interrupt_handler handle_arch_fiq
+ b ret_to_user
+SYM_CODE_END(el0_fiq)
+
SYM_CODE_START_LOCAL(el1_error)
kernel_entry 1
mrs x1, esr_el1
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index 00bcf37..bc3215d 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -76,7 +76,13 @@
panic("IRQ taken without a registered IRQ controller\n");
}
+void default_handle_fiq(struct pt_regs *regs)
+{
+ panic("FIQ taken without a registered FIQ controller\n");
+}
+
void (*handle_arch_irq)(struct pt_regs *) __ro_after_init = default_handle_irq;
+void (*handle_arch_fiq)(struct pt_regs *) __ro_after_init = default_handle_fiq;
int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
{
@@ -87,6 +93,15 @@
return 0;
}
+int __init set_handle_fiq(void (*handle_fiq)(struct pt_regs *))
+{
+ if (handle_arch_fiq != default_handle_fiq)
+ return -EBUSY;
+
+ handle_arch_fiq = handle_fiq;
+ return 0;
+}
+
void __init init_IRQ(void)
{
init_irq_stacks();
