Commit 8eb858c4 authored by Qi Zheng's avatar Qi Zheng Committed by Catalin Marinas
Browse files

arm64: run softirqs on the per-CPU IRQ stack 



Currently arm64 supports per-CPU IRQ stack, but softirqs
are still handled in the task context.

Since any call to local_bh_enable() at any level in the task's
call stack may trigger a softirq processing run, which could
potentially cause a task stack overflow if the combined stack
footprints exceed the stack's size, let's run these softirqs
on the IRQ stack as well.

Signed-off-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220815124739.15948-1-zhengqi.arch@bytedance.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 3fc24ef3

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -230,6 +230,7 @@ config ARM64 
	select HAVE_ARCH_USERFAULTFD_MINOR if USERFAULTFD

	select TRACE_IRQFLAGS_SUPPORT

	select TRACE_IRQFLAGS_NMI_SUPPORT

	select HAVE_SOFTIRQ_ON_OWN_STACK

	help

	  ARM 64-bit (AArch64) Linux support.

arch/arm64/kernel/irq.c

+14 −0
Original line number Diff line number Diff line
@@ -21,7 +21,9 @@ 
#include <linux/seq_file.h>

#include <linux/vmalloc.h>

#include <asm/daifflags.h>

#include <asm/exception.h>

#include <asm/vmap_stack.h>

#include <asm/softirq_stack.h>



/* Only access this in an NMI enter/exit */

DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts);
@@ -71,6 +73,18 @@ static void init_irq_stacks(void) 
}

#endif



#ifndef CONFIG_PREEMPT_RT

static void ____do_softirq(struct pt_regs *regs)

{

	__do_softirq();

}



void do_softirq_own_stack(void)

{

	call_on_irq_stack(NULL, ____do_softirq);

}

#endif



static void default_handle_irq(struct pt_regs *regs)

{

	panic("IRQ taken without a root IRQ handler\n");