powerpc/xmon: Clear all breakpoints when xmon is disabled via debugfs (1ff3b404) · Commits · 戴 / test

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>

arch/powerpc/xmon/xmon.c

+24 −0

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

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

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

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