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Commit ed6b676c authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
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[PATCH] x86_64: Switch to the interrupt stack when running a softirq in local_bh_enable() 



This avoids some potential stack overflows with very deep softirq callchains.
i386 does this too.

TOADD CFI annotation

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 3829ee6b

arch/x86_64/kernel/entry.S

+12 −0
Original line number Diff line number Diff line
@@ -918,3 +918,15 @@ ENTRY(machine_check) 
ENTRY(call_debug)

       zeroentry do_call_debug



ENTRY(call_softirq)

	movq %gs:pda_irqstackptr,%rax

	pushq %r15

	movq %rsp,%r15

	incl %gs:pda_irqcount

	cmove %rax,%rsp

	call __do_softirq

	movq %r15,%rsp

	decl %gs:pda_irqcount

	popq %r15

	ret

arch/x86_64/kernel/irq.c

+19 −0
Original line number Diff line number Diff line
@@ -135,3 +135,22 @@ void fixup_irqs(cpumask_t map) 
	local_irq_disable();

}

#endif



extern void call_softirq(void);



asmlinkage void do_softirq(void)

{

 	__u32 pending;

 	unsigned long flags;



 	if (in_interrupt())

 		return;



 	local_irq_save(flags);

 	pending = local_softirq_pending();

 	/* Switch to interrupt stack */

 	if (pending)

		call_softirq();

 	local_irq_restore(flags);

}

EXPORT_SYMBOL(do_softirq);

include/asm-x86_64/irq.h

+2 −0
Original line number Diff line number Diff line
@@ -57,4 +57,6 @@ int handle_IRQ_event(unsigned int, struct pt_regs *, struct irqaction *); 
extern void fixup_irqs(cpumask_t map);

#endif



#define __ARCH_HAS_DO_SOFTIRQ 1



#endif /* _ASM_IRQ_H */

kernel/softirq.c

+2 −2
Original line number Diff line number Diff line
@@ -86,7 +86,7 @@ asmlinkage void __do_softirq(void) 
	/* Reset the pending bitmask before enabling irqs */

	local_softirq_pending() = 0;



	local_irq_enable();

	//local_irq_enable();



	h = softirq_vec;
@@ -99,7 +99,7 @@ asmlinkage void __do_softirq(void) 
		pending >>= 1;

	} while (pending);



	local_irq_disable();

	//local_irq_disable();



	pending = local_softirq_pending();

	if (pending && --max_restart)