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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>
This commit is contained in:
Vaibhav Jain 2018-03-04 23:01:32 +05:30 committed by Michael Ellerman
parent e1368d0c9e
commit 1ff3b40401
1 changed files with 24 additions and 0 deletions
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24
arch/powerpc/xmon/xmon.c
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@ -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;
}