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arm64: irq: allow FIQs to be handled

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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 a root FIQ handler is
not registered, an unexpected FIQ exception will trigger the default FIQ
handler, which will panic() as today. Where a root 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>
Tested-by: 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>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210315115629.57191-7-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland 2021-03-15 11:56:29 +00:00 committed by Catalin Marinas
parent f0098155d3
commit 3889ba7010
3 changed files with 38 additions and 9 deletions
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1
arch/arm64/include/asm/irq.h
View file

@ -10,6 +10,7 @@ struct pt_regs;
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)
{

30
arch/arm64/kernel/entry.S
View file

@ -588,18 +588,18 @@ SYM_CODE_START(vectors)
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 @@ SYM_CODE_START_LOCAL(el0_error_invalid)
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 @@ SYM_CODE_START_LOCAL_NOALIGN(el1_irq)
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 @@ SYM_CODE_START_LOCAL_NOALIGN(el0_irq_compat)
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 @@ el0_irq_naked:
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

16
arch/arm64/kernel/irq.c
View file

@ -76,7 +76,13 @@ static void default_handle_irq(struct pt_regs *regs)
panic("IRQ taken without a root IRQ handler\n");
}
static void default_handle_fiq(struct pt_regs *regs)
{
panic("FIQ taken without a root FIQ handler\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 *))
{
@ -88,6 +94,16 @@ int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
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;
pr_info("Root FIQ handler: %ps\n", handle_fiq);
return 0;
}
void __init init_IRQ(void)
{
init_irq_stacks();