Commit 1ff3b404 authored Mar 04, 2018 by Vaibhav Jain Committed by Michael Ellerman Mar 13, 2018

powerpc/xmon: Clear all breakpoints when xmon is disabled via debugfs



Presently when xmon is disabled by debugfs any existing
instruction/data-access breakpoints set are not disabled. This may
lead to kernel oops when those breakpoints are hit as the necessary
debugger hooks aren't installed.

Hence this patch introduces a new function named clear_all_bpt() which
is called when xmon is disabled via debugfs. The function will
unpatch/clear all the trap and ciabr/dab based breakpoints.

Signed-off-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Fix build break when CONFIG_DEBUG_FS=n]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent e1368d0c

arch/powerpc/xmon/xmon.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -3664,11 +3664,35 @@ device_initcall(setup_xmon_sysrq);
		#endif /* CONFIG_MAGIC_SYSRQ */

		#ifdef CONFIG_DEBUG_FS
		static void clear_all_bpt(void)
		{
		int i;

		/* clear/unpatch all breakpoints */
		remove_bpts();
		remove_cpu_bpts();

		/* Disable all breakpoints */
		for (i = 0; i < NBPTS; ++i)
		bpts[i].enabled = 0;

		/* Clear any data or iabr breakpoints */
		if (iabr \|\| dabr.enabled) {
		iabr = NULL;
		dabr.enabled = 0;
		}

		printf("xmon: All breakpoints cleared\n");
		}

		static int xmon_dbgfs_set(void *data, u64 val)
		{
		xmon_on = !!val;
		xmon_init(xmon_on);

		/* make sure all breakpoints removed when disabling */
		if (!xmon_on)
		clear_all_bpt();
		return 0;
		}