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ARM: hw_breakpoint: reset control registers in hotplug path

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The ARMv7 debug architecture doesn't make any guarantees about the
contents of debug control registers following a debug logic reset.

This patch ensures that we reset the control registers when a cpu
comes ONLINE (for example, with hotplug) so that when we enable
monitor mode while inserting a breakpoint we won't exhibit random
behaviour.

Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2010-11-24 17:45:49 +00:00
parent ac88e07122
commit 7d99331e47
1 changed files with 15 additions and 1 deletions
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16
arch/arm/kernel/hw_breakpoint.c
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@ -764,7 +764,7 @@ out:
/*
* One-time initialisation.
*/
static void __init reset_ctrl_regs(void *unused)
static void reset_ctrl_regs(void *unused)
{
int i;
@ -799,6 +799,18 @@ static void __init reset_ctrl_regs(void *unused)
}
}
static int __cpuinit dbg_reset_notify(struct notifier_block *self,
unsigned long action, void *cpu)
{
if (action == CPU_ONLINE)
smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1);
return NOTIFY_OK;
}
static struct notifier_block __cpuinitdata dbg_reset_nb = {
.notifier_call = dbg_reset_notify,
};
static int __init arch_hw_breakpoint_init(void)
{
int ret = 0;
@ -846,6 +858,8 @@ static int __init arch_hw_breakpoint_init(void)
hook_ifault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT,
"breakpoint debug exception");
/* Register hotplug notifier. */
register_cpu_notifier(&dbg_reset_nb);
out:
return ret;
}