From: Will Deacon Date: Fri, 21 Sep 2012 16:53:08 +0000 (+0100) Subject: ARM: hw_breakpoint: don't try to clear v6 debug registers during boot X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=7f4050a07be8ce5fad069722326ccd550577a93a;p=deliverable%2Flinux.git ARM: hw_breakpoint: don't try to clear v6 debug registers during boot v6 cores do not provide a way to clear the debug registers without first enabling monitor mode, meaning that we could take spurious debug exceptions. Instead, rely on the registers being in a sane state when we boot as they are defined to be disabled out of reset anyway. Tested-by: Stephen Boyd Signed-off-by: Will Deacon --- diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c index ae6bf80e3a5e..8cd52faeb77e 100644 --- a/arch/arm/kernel/hw_breakpoint.c +++ b/arch/arm/kernel/hw_breakpoint.c @@ -912,8 +912,8 @@ static void reset_ctrl_regs(void *unused) switch (debug_arch) { case ARM_DEBUG_ARCH_V6: case ARM_DEBUG_ARCH_V6_1: - /* ARMv6 cores just need to reset the registers. */ - goto reset_regs; + /* ARMv6 cores clear the registers out of reset. */ + goto out_mdbgen; case ARM_DEBUG_ARCH_V7_ECP14: /* * Ensure sticky power-down is clear (i.e. debug logic is @@ -966,7 +966,6 @@ clear_vcr: return; } -reset_regs: /* * The control/value register pairs are UNKNOWN out of reset so * clear them to avoid spurious debug events. @@ -991,6 +990,7 @@ reset_regs: * Have a crack at enabling monitor mode. We don't actually need * it yet, but reporting an error early is useful if it fails. */ +out_mdbgen: if (enable_monitor_mode()) cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu)); }