Commit 624db9ea authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86: Select CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK 



Now that all invocations of irq_exit_rcu() happen on the irq stack, turn on
CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK which causes the core code to invoke
__do_softirq() directly without going through do_softirq_own_stack().

That means do_softirq_own_stack() is only invoked from task context which
means it can't be on the irq stack. Remove the conditional from
run_softirq_on_irqstack_cond() and rename the function accordingly.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002513.068033456@linutronix.de
parent 52d743f3

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -187,6 +187,7 @@ config X86 
	select HAVE_HW_BREAKPOINT

	select HAVE_IDE

	select HAVE_IOREMAP_PROT

	select HAVE_IRQ_EXIT_ON_IRQ_STACK	if X86_64

	select HAVE_IRQ_TIME_ACCOUNTING

	select HAVE_KERNEL_BZIP2

	select HAVE_KERNEL_GZIP

arch/x86/include/asm/irq_stack.h

+8 −11
Original line number Diff line number Diff line
@@ -189,19 +189,16 @@ 
	"call %P[__func]				\n"



/*

 * Macro to invoke __do_softirq on the irq stack. Contrary to the above

 * the only check which is necessary is whether the interrupt stack is

 * in use already.

 * Macro to invoke __do_softirq on the irq stack. This is only called from

 * task context when bottom halfs are about to be reenabled and soft

 * interrupts are pending to be processed. The interrupt stack cannot be in

 * use here.

 */

#define run_softirq_on_irqstack_cond()					\

#define run_softirq_on_irqstack()					\

{									\

	if (__this_cpu_read(hardirq_stack_inuse)) {			\

		__do_softirq();						\

	} else {							\

	__this_cpu_write(hardirq_stack_inuse, true);			\

	call_on_irqstack(__do_softirq, ASM_CALL_SOFTIRQ);		\

	__this_cpu_write(hardirq_stack_inuse, false);			\

	}								\

}



#else /* CONFIG_X86_64 */

arch/x86/kernel/irq_64.c

+1 −1
Original line number Diff line number Diff line
@@ -76,5 +76,5 @@ int irq_init_percpu_irqstack(unsigned int cpu) 


void do_softirq_own_stack(void)

{

	run_softirq_on_irqstack_cond();

	run_softirq_on_irqstack();

}