Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c1bb9a9c authored by Dongdong Deng's avatar Dongdong Deng Committed by Jason Wessel
Browse files

debug_core: disable hw_breakpoints on all cores in kgdb_cpu_enter() 



The slave cpus do not have the hw breakpoints disabled upon entry to
the debug_core and as a result could cause unrecoverable recursive
faults on badly placed breakpoints, or get out of sync with the arch
specific hw breakpoint operations.

This patch addresses the problem by invoking kgdb_disable_hw_debug()
earlier in kgdb_enter_cpu for each cpu that enters the debug core.

The hw breakpoint dis/enable flow should be:

master_debug_cpu   slave_debug_cpu
         \              /
          kgdb_cpu_enter
                |
        kgdb_disable_hw_debug --> uninstall pre-enabled hw_breakpoint
                |
 do add/rm dis/enable operates to hw_breakpoints on master_debug_cpu..
                |
        correct_hw_break --> correct/install the enabled hw_breakpoint
                |
           leave_kgdb

Signed-off-by: default avatarDongdong Deng <dongdong.deng@windriver.com>
Signed-off-by: default avatarJason Wessel <jason.wessel@windriver.com>
parent 91b152aa

kernel/debug/debug_core.c

+5 −2
Original line number Original line Diff line number Diff line
@@ -485,6 +485,9 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs) 
	int error;

	int error;

	int i, cpu;

	int i, cpu;

	int trace_on = 0;

	int trace_on = 0;



	kgdb_disable_hw_debug(ks->linux_regs);



acquirelock:

acquirelock:

	/*

	/*

	 * Interrupts will be restored by the 'trap return' code, except when

	 * Interrupts will be restored by the 'trap return' code, except when
@@ -569,8 +572,6 @@ return_normal: 
	if (dbg_io_ops->pre_exception)

	if (dbg_io_ops->pre_exception)

		dbg_io_ops->pre_exception();

		dbg_io_ops->pre_exception();





	kgdb_disable_hw_debug(ks->linux_regs);



	/*

	/*

	 * Get the passive CPU lock which will hold all the non-primary

	 * Get the passive CPU lock which will hold all the non-primary

	 * CPU in a spin state while the debugger is active

	 * CPU in a spin state while the debugger is active
@@ -661,6 +662,8 @@ kgdb_restore: 
		else

		else

			kgdb_sstep_pid = 0;

			kgdb_sstep_pid = 0;

	}

	}

	if (arch_kgdb_ops.correct_hw_break)

		arch_kgdb_ops.correct_hw_break();

	if (trace_on)

	if (trace_on)

		tracing_on();

		tracing_on();

	/* Free kgdb_active */

	/* Free kgdb_active */