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x86/softirq: Disable softirq stacks on PREEMPT_RT

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PREEMPT_RT preempts softirqs and the current implementation avoids
do_softirq_own_stack() and only uses __do_softirq().

Disable the unused softirqs stacks on PREEMPT_RT to safe some memory and
ensure that do_softirq_own_stack() is not used which is not expected.

 [ bigeasy: commit description. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210924161245.2357247-1-bigeasy@linutronix.de
This commit is contained in:
Thomas Gleixner 2021-09-24 18:12:45 +02:00 committed by Borislav Petkov
parent b70e13885c
commit 441e903693
2 changed files with 5 additions and 0 deletions
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3
arch/x86/include/asm/irq_stack.h
View File

@ -185,6 +185,7 @@
IRQ_CONSTRAINTS, regs, vector); \
}
#ifndef CONFIG_PREEMPT_RT
#define ASM_CALL_SOFTIRQ \
"call %P[__func] \n"
@ -201,6 +202,8 @@
__this_cpu_write(hardirq_stack_inuse, false); \
}
#endif
#else /* CONFIG_X86_64 */
/* System vector handlers always run on the stack they interrupted. */
#define run_sysvec_on_irqstack_cond(func, regs) \

2
arch/x86/kernel/irq_32.c
View File

@ -132,6 +132,7 @@ int irq_init_percpu_irqstack(unsigned int cpu)
return 0;
}
#ifndef CONFIG_PREEMPT_RT
void do_softirq_own_stack(void)
{
struct irq_stack *irqstk;
@ -148,6 +149,7 @@ void do_softirq_own_stack(void)
call_on_stack(__do_softirq, isp);
}
#endif
void __handle_irq(struct irq_desc *desc, struct pt_regs *regs)
{