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SubjectRe: [PATCH 1/1] coresight: etm4x: Configure EL2 exception level when kernel is running in HYP
Hi Tomasz,

On Tue, Sep 04, 2018 at 04:20:34PM +0200, Tomasz Nowicki wrote:
> For non-VHE systems host kernel runs at EL1 and jumps to EL2 whenever
> hypervisor code should be executed. In this case ETM4x driver must
> restrict configuration to EL1 when it setups kernel tracing.
> However, there is no separate hypervisor privilege level when VHE
> is enabled, the host kernel runs at EL2.
>
> This patch fixes configuration of TRCACATRn register for VHE systems
> so that ETM_EXLEVEL_NS_HYP bit is used instead of ETM_EXLEVEL_NS_OS
> to on/off kernel tracing. At the same time, it moves common code
> to new helper.
>
> Signed-off-by: Tomasz Nowicki <tnowicki@caviumnetworks.com>
> ---
> drivers/hwtracing/coresight/coresight-etm4x.c | 39 ++++++++++---------
> 1 file changed, 20 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> index f79b0ea85d76..5f495c942f99 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> @@ -28,6 +28,7 @@
> #include <linux/pm_runtime.h>
> #include <asm/sections.h>
> #include <asm/local.h>
> +#include <asm/virt.h>
>
> #include "coresight-etm4x.h"
> #include "coresight-etm-perf.h"
> @@ -606,7 +607,7 @@ static void etm4_set_default_config(struct etmv4_config *config)
> config->vinst_ctrl |= BIT(0);
> }
>
> -static u64 etm4_get_access_type(struct etmv4_config *config)
> +static u64 etm4_get_ns_access_type(struct etmv4_config *config)
> {
> u64 access_type = 0;
>
> @@ -617,17 +618,27 @@ static u64 etm4_get_access_type(struct etmv4_config *config)
> * Bit[13] Exception level 1 - OS
> * Bit[14] Exception level 2 - Hypervisor
> * Bit[15] Never implemented
> - *
> - * Always stay away from hypervisor mode.
> */
> - access_type = ETM_EXLEVEL_NS_HYP;
>

Extra space

> - if (config->mode & ETM_MODE_EXCL_KERN)
> - access_type |= ETM_EXLEVEL_NS_OS;
> + if (!is_kernel_in_hyp_mode()) {
> + /* Stay away from hypervisor mode for non-VHE */
> + access_type = ETM_EXLEVEL_NS_HYP;
> + if (config->mode & ETM_MODE_EXCL_KERN)
> + access_type |= ETM_EXLEVEL_NS_OS;
> + } else if (config->mode & ETM_MODE_EXCL_KERN) {
> + access_type = ETM_EXLEVEL_NS_HYP;
> + }
>
> if (config->mode & ETM_MODE_EXCL_USER)
> access_type |= ETM_EXLEVEL_NS_APP;
>
> + return access_type;
> +}
> +
> +static u64 etm4_get_access_type(struct etmv4_config *config)
> +{
> + u64 access_type = etm4_get_ns_access_type(config);
> +
> /*
> * EXLEVEL_S, bits[11:8], don't trace anything happening
> * in secure state.
> @@ -881,20 +892,10 @@ void etm4_config_trace_mode(struct etmv4_config *config)
>
> addr_acc = config->addr_acc[ETM_DEFAULT_ADDR_COMP];
> /* clear default config */
> - addr_acc &= ~(ETM_EXLEVEL_NS_APP | ETM_EXLEVEL_NS_OS);
> + addr_acc &= ~(ETM_EXLEVEL_NS_APP | ETM_EXLEVEL_NS_OS |
> + ETM_EXLEVEL_NS_HYP);

Indentation problems

>
> - /*
> - * EXLEVEL_NS, bits[15:12]
> - * The Exception levels are:
> - * Bit[12] Exception level 0 - Application
> - * Bit[13] Exception level 1 - OS
> - * Bit[14] Exception level 2 - Hypervisor
> - * Bit[15] Never implemented
> - */
> - if (mode & ETM_MODE_EXCL_KERN)
> - addr_acc |= ETM_EXLEVEL_NS_OS;
> - else
> - addr_acc |= ETM_EXLEVEL_NS_APP;
> + addr_acc |= etm4_get_ns_access_type(config);
>
> config->addr_acc[ETM_DEFAULT_ADDR_COMP] = addr_acc;
> config->addr_acc[ETM_DEFAULT_ADDR_COMP + 1] = addr_acc;

I tested your patch on my side and it didn't break kernel space decoding.

Since it would have taken longer to ask you to respin than to make the changes
myself, I applied your patch with the above modifications.

Thanks,
Mathieu

> --
> 2.17.1
>

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