[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: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 0696e02..096d470 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -918,3 +918,15 @@
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
+
diff --git a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c
index cc3fb85..849a20a 100644
--- a/arch/x86_64/kernel/irq.c
+++ b/arch/x86_64/kernel/irq.c
@@ -135,3 +135,22 @@
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);