Re: [PATCH] Coresight: ETMv4: Prevent TRCRSCTLR0&1 from being accessed

From: Mathieu Poirier
Date: Thu Aug 27 2015 - 11:05:38 EST


On 26 August 2015 at 22:06, Chunyan Zhang <zhang.chunyan@xxxxxxxxxx> wrote:
> 1. TRCRSCTLRn - Resource Selection Control Registers n=0~1 are reserved,
> we shouldn't access them.
> 2. The max number of 'n' here is defined in TRCIDR4.NUMRSPAIR whoes value
> indicates the number of resource selection *pairs*, and 0 indicates
> one resource selection pair, 1 indicates two pairs, and so on ...
>
> So, the total number of resource selection control registers which we can
> access is (TRCIDR4.NUMRSPAIR * 2)
>
> Signed-off-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
> ---
> drivers/hwtracing/coresight/coresight-etm4x.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> index 1312e99..9425249 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> @@ -136,7 +136,9 @@ static void etm4_enable_hw(void *info)
> writel_relaxed(drvdata->cntr_val[i],
> drvdata->base + TRCCNTVRn(i));
> }
> - for (i = 0; i < drvdata->nr_resource; i++)
> +
> + /* Resource selector pair 0 is always implemented and reserved */
> + for (i = 2; i < (drvdata->nr_resource + 1) * 2; i++)

Instead of repeating "->nr_resource + 1) * 2" every time, please add
"->nr_resource += 1" in etm4_init_arch_data() along with a comment
that explains why.

> writel_relaxed(drvdata->res_ctrl[i],
> drvdata->base + TRCRSCTLRn(i));
>
> @@ -489,8 +491,9 @@ static ssize_t reset_store(struct device *dev,
> drvdata->cntr_val[i] = 0x0;
> }
>
> - drvdata->res_idx = 0x0;
> - for (i = 0; i < drvdata->nr_resource; i++)
> + /* Resource selector pair 0 is always implemented and reserved */
> + drvdata->res_idx = 0x2;
> + for (i = 2; i < (drvdata->nr_resource + 1) * 2; i++)
> drvdata->res_ctrl[i] = 0x0;
>
> for (i = 0; i < drvdata->nr_ss_cmp; i++) {
> @@ -1729,7 +1732,7 @@ static ssize_t res_idx_store(struct device *dev,
> if (kstrtoul(buf, 16, &val))
> return -EINVAL;
> /* Resource selector pair 0 is always implemented and reserved */
> - if ((val == 0) || (val >= drvdata->nr_resource))
> + if (val < 2 || val > (drvdata->nr_resource + 1) * 2)
> return -EINVAL;
>
> /*
> @@ -2498,7 +2501,9 @@ static void etm4_init_default_data(struct etmv4_drvdata *drvdata)
> drvdata->cntr_val[i] = 0x0;
> }
>
> - for (i = 2; i < drvdata->nr_resource * 2; i++)
> + /* Resource selector pair 0 is always implemented and reserved */
> + drvdata->res_idx = 0x2;
> + for (i = 2; i < (drvdata->nr_resource + 1) * 2; i++)
> drvdata->res_ctrl[i] = 0x0;
>
> for (i = 0; i < drvdata->nr_ss_cmp; i++) {
> --
> 1.9.1
>
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