[PATCH] ARM: hw_breakpoint: clear DBGVCR out of reset

[PATCH] ARM: hw_breakpoint: clear DBGVCR out of reset

[Will Deacon]

The DBGVCR, used for configuring vector catch debug events, is UNKNOWN
out of reset on ARMv7. When enabling monitor mode, this must be zeroed
to avoid UNPREDICTABLE behaviour.

This patch adds the zeroing code to the debug reset path.

Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/kernel/hw_breakpoint.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 8dbc126..87acc25 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -868,6 +868,13 @@ static void reset_ctrl_regs(void *info)
 		 */
 		asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0));
 		isb();
+
+		/*
+		 * Clear any configured vector-catch events before
+		 * enabling monitor mode.
+		 */
+		asm volatile("mcr p14, 0, %0, c0, c7, 0" : : "r" (0));
+		isb();
 	}
 
 	if (enable_monitor_mode())
-- 
1.7.0.4

[PATCH] ARM: hw_breakpoint: clear DBGVCR out of reset

[Stephen Boyd]

On 4/1/2011 4:24 AM, Will Deacon wrote:
> The DBGVCR, used for configuring vector catch debug events, is UNKNOWN
> out of reset on ARMv7. When enabling monitor mode, this must be zeroed
> to avoid UNPREDICTABLE behaviour.
>
> This patch adds the zeroing code to the debug reset path.
>
> Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
> Signed-off-by: Will Deacon <will.deacon@arm.com>

Please Cc stable as this fix should go to the 37 and 38 stable trees.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

[PATCH] ARM: hw_breakpoint: clear DBGVCR out of reset

[Will Deacon]

Hi Stephen,

On Sun, 2011-04-03 at 08:25 +0100, Stephen Boyd wrote:
> On 4/1/2011 4:24 AM, Will Deacon wrote:
> > The DBGVCR, used for configuring vector catch debug events, is UNKNOWN
> > out of reset on ARMv7. When enabling monitor mode, this must be zeroed
> > to avoid UNPREDICTABLE behaviour.
> >
> > This patch adds the zeroing code to the debug reset path.
> >
> > Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
> > Signed-off-by: Will Deacon <will.deacon@arm.com>
> 
> Please Cc stable as this fix should go to the 37 and 38 stable trees.

Will do. If you could please confirm that it fixes the problems reported
initially then that would be great.

Thanks,

Will

[PATCH] ARM: hw_breakpoint: clear DBGVCR out of reset

[Stepan Moskovchenko]

On 4/3/2011 5:22 AM, Will Deacon wrote:
> Hi Stephen,
>
> On Sun, 2011-04-03 at 08:25 +0100, Stephen Boyd wrote:
>> On 4/1/2011 4:24 AM, Will Deacon wrote:
>>> The DBGVCR, used for configuring vector catch debug events, is UNKNOWN
>>> out of reset on ARMv7. When enabling monitor mode, this must be zeroed
>>> to avoid UNPREDICTABLE behaviour.
>>>
>>> This patch adds the zeroing code to the debug reset path.
>>>
>>> Reported-by: Stepan Moskovchenko<stepanm@codeaurora.org>
>>> Signed-off-by: Will Deacon<will.deacon@arm.com>
>> Please Cc stable as this fix should go to the 37 and 38 stable trees.
> Will do. If you could please confirm that it fixes the problems reported
> initially then that would be great.
>
> Thanks,
>
> Will
>

I confirm that this fixes the problem I was seeing.

Thanks
Steve

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.