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Commit 5a14fead authored by Anton Vorontsov's avatar Anton Vorontsov Committed by Greg Kroah-Hartman
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kernel/debug: Mask KGDB NMI upon entry 



The new arch callback should manage NMIs that usually cause KGDB to
enter. That is, not all NMIs should be enabled/disabled, but only
those that issue kgdb_handle_exception().

We must mask it as serial-line interrupt can be used as an NMI, so
if the original KGDB-entry cause was say a breakpoint, then every
input to KDB console will cause KGDB to reenter, which we don't want.

Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: default avatarJason Wessel <jason.wessel@windriver.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c5dd553b

include/linux/kgdb.h

+3 −0
Original line number Diff line number Diff line
@@ -240,6 +240,7 @@ extern void kgdb_arch_late(void); 
 * hardware breakpoints.

 * @correct_hw_break: Allow an architecture to specify how to correct the

 * hardware debug registers.

 * @enable_nmi: Manage NMI-triggered entry to KGDB

 */

struct kgdb_arch {

	unsigned char		gdb_bpt_instr[BREAK_INSTR_SIZE];
@@ -252,6 +253,8 @@ struct kgdb_arch { 
	void	(*disable_hw_break)(struct pt_regs *regs);

	void	(*remove_all_hw_break)(void);

	void	(*correct_hw_break)(void);



	void	(*enable_nmi)(bool on);

};



/**

kernel/debug/debug_core.c

+11 −3
Original line number Diff line number Diff line
@@ -672,6 +672,10 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) 
{

	struct kgdb_state kgdb_var;

	struct kgdb_state *ks = &kgdb_var;

	int ret = 0;



	if (arch_kgdb_ops.enable_nmi)

		arch_kgdb_ops.enable_nmi(0);



	ks->cpu			= raw_smp_processor_id();

	ks->ex_vector		= evector;
@@ -681,11 +685,15 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) 
	ks->linux_regs		= regs;



	if (kgdb_reenter_check(ks))

		return 0; /* Ouch, double exception ! */

		goto out; /* Ouch, double exception ! */

	if (kgdb_info[ks->cpu].enter_kgdb != 0)

		return 0;

		goto out;



	return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);

	ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);

out:

	if (arch_kgdb_ops.enable_nmi)

		arch_kgdb_ops.enable_nmi(1);

	return ret;

}



int kgdb_nmicallback(int cpu, void *regs)