From 796969104cab0d454dbc792ad0d12a4f365a8564 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Mon, 3 Dec 2007 17:22:36 -0500 Subject: ARM kprobes: special hook for the kprobes breakpoint handler The kprobes code is already able to cope with reentrant probes, so its handler must be called outside of the region protected by undef_lock. If ever this lock is released when handlers are called then this commit could be reverted. Signed-off-by: Nicolas Pitre --- arch/arm/kernel/traps.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'arch/arm/kernel/traps.c') diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index 65bb762b2d80..5595fdd75e82 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include @@ -313,6 +314,17 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs) get_user(instr, (u32 __user *)pc); } +#ifdef CONFIG_KPROBES + /* + * It is possible to have recursive kprobes, so we can't call + * the kprobe trap handler with the undef_lock held. + */ + if (instr == KPROBE_BREAKPOINT_INSTRUCTION && !user_mode(regs)) { + kprobe_trap_handler(regs, instr); + return; + } +#endif + spin_lock_irqsave(&undef_lock, flags); list_for_each_entry(hook, &undef_hook, node) { if ((instr & hook->instr_mask) == hook->instr_val && -- cgit v1.2.3-55-g7522