Commit 143c2a89 authored Feb 13, 2019 by Yang Shi Committed by Russell King Feb 26, 2019

ARM: 8839/1: kprobe: make patch_lock a raw_spinlock_t



When running kprobe on -rt kernel, the below bug is caught:

|BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:931
|in_atomic(): 1, irqs_disabled(): 128, pid: 14, name: migration/0
|Preemption disabled at:[<802f2b98>] cpu_stopper_thread+0xc0/0x140
|CPU: 0 PID: 14 Comm: migration/0 Tainted: G O 4.8.3-rt2 #1
|Hardware name: Freescale LS1021A
|[<8025a43c>] (___might_sleep)
|[<80b5b324>] (rt_spin_lock)
|[<80b5c31c>] (__patch_text_real)
|[<80b5c3ac>] (patch_text_stop_machine)
|[<802f2920>] (multi_cpu_stop)

Since patch_text_stop_machine() is called in stop_machine() which
disables IRQ, sleepable lock should be not used in this atomic context,
 so replace patch_lock to raw lock.

Signed-off-by: Yang Shi <yang.shi@linaro.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

parent fc67e6f1

arch/arm/kernel/patch.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -16,7 +16,7 @@ struct patch {
		unsigned int insn;
		};

		static DEFINE_SPINLOCK(patch_lock);
		static DEFINE_RAW_SPINLOCK(patch_lock);

		static void __kprobes patch_map(void addr, int fixmap, unsigned long *flags)
		__acquires(&patch_lock)
		@@ -33,7 +33,7 @@ static void __kprobes patch_map(void addr, int fixmap, unsigned long *flags)
		return addr;

		if (flags)
		spin_lock_irqsave(&patch_lock, *flags);
		raw_spin_lock_irqsave(&patch_lock, *flags);
		else
		__acquire(&patch_lock);

		@@ -48,7 +48,7 @@ static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
		clear_fixmap(fixmap);

		if (flags)
		spin_unlock_irqrestore(&patch_lock, *flags);
		raw_spin_unlock_irqrestore(&patch_lock, *flags);
		else
		__release(&patch_lock);
		}

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