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Commit 76b0f133 authored by Paul Mackerras's avatar Paul Mackerras
Browse files

powerpc, hw_breakpoint: Cooperate better with other single-steppers 



The code we had to clear the MSR_SE bit was not doing anything because
the caller (ultimately single_step_exception() in traps.c) had already
cleared.  Instead of trying to leave MSR_SE set if the TIF_SINGLESTEP
flag is set (which indicates that the process is being single-stepped
by ptrace), we instead return NOTIFY_DONE in that case, which means
the caller will generate a SIGTRAP for the process.

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 574cb248

arch/powerpc/kernel/hw_breakpoint.c

+7 −6
Original line number Original line Diff line number Diff line
@@ -304,15 +304,16 @@ int __kprobes single_step_dabr_instruction(struct die_args *args) 
	if (!bp_info->extraneous_interrupt)

	if (!bp_info->extraneous_interrupt)

		perf_bp_event(bp, regs);

		perf_bp_event(bp, regs);





	set_dabr(bp_info->address | bp_info->type | DABR_TRANSLATION);

	current->thread.last_hit_ubp = NULL;



	/*

	/*

	 * Do not disable MSR_SE if the process was already in

	 * If the process was being single-stepped by ptrace, let the

	 * single-stepping mode.

	 * other single-step actions occur (e.g. generate SIGTRAP).

	 */

	 */

	if (!test_thread_flag(TIF_SINGLESTEP))

	if (test_thread_flag(TIF_SINGLESTEP))

		regs->msr &= ~MSR_SE;

		return NOTIFY_DONE;





	set_dabr(bp_info->address | bp_info->type | DABR_TRANSLATION);

	current->thread.last_hit_ubp = NULL;

	return NOTIFY_STOP;

	return NOTIFY_STOP;

}

}