Re: [PATCH v2] coresight: tmc: Don't enable TMC when it's not ready.
From: Mike Leach
Date: Wed Feb 01 2023 - 15:44:01 EST
Hi,
On Fri, 27 Jan 2023 at 23:10, Yabin Cui <yabinc@xxxxxxxxxx> wrote:
>
> If TMC ETR is enabled without being ready, in later use we may
> see AXI bus errors caused by accessing invalid addresses.
>
> Signed-off-by: Yabin Cui <yabinc@xxxxxxxxxx>
> ---
> V1 -> V2: Make change to all TMCs instead of just ETR
>
> .../hwtracing/coresight/coresight-tmc-core.c | 4 +-
> .../hwtracing/coresight/coresight-tmc-etf.c | 43 +++++++++++++++----
> .../hwtracing/coresight/coresight-tmc-etr.c | 18 ++++++--
> drivers/hwtracing/coresight/coresight-tmc.h | 2 +-
> 4 files changed, 53 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> index 07abf28ad725..c106d142e632 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> @@ -31,7 +31,7 @@ DEFINE_CORESIGHT_DEVLIST(etb_devs, "tmc_etb");
> DEFINE_CORESIGHT_DEVLIST(etf_devs, "tmc_etf");
> DEFINE_CORESIGHT_DEVLIST(etr_devs, "tmc_etr");
>
> -void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata)
> +int tmc_wait_for_tmcready(struct tmc_drvdata *drvdata)
> {
> struct coresight_device *csdev = drvdata->csdev;
> struct csdev_access *csa = &csdev->access;
> @@ -40,7 +40,9 @@ void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata)
> if (coresight_timeout(csa, TMC_STS, TMC_STS_TMCREADY_BIT, 1)) {
> dev_err(&csdev->dev,
> "timeout while waiting for TMC to be Ready\n");
> + return -EBUSY;
> }
> + return 0;
> }
>
> void tmc_flush_and_stop(struct tmc_drvdata *drvdata)
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index 4c4cbd1f7258..2840227e9135 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -16,12 +16,19 @@
> static int tmc_set_etf_buffer(struct coresight_device *csdev,
> struct perf_output_handle *handle);
>
> -static void __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> +static int __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> {
> + int rc = 0;
> +
> CS_UNLOCK(drvdata->base);
>
> /* Wait for TMCSReady bit to be set */
> - tmc_wait_for_tmcready(drvdata);
> + rc = tmc_wait_for_tmcready(drvdata);
> + if (rc) {
> + dev_err(&drvdata->csdev->dev, "fails to enable not ready TMC\n");
> + CS_LOCK(drvdata->base);
> + return rc;
> + }
>
> writel_relaxed(TMC_MODE_CIRCULAR_BUFFER, drvdata->base + TMC_MODE);
> writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI |
> @@ -33,6 +40,7 @@ static void __tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> tmc_enable_hw(drvdata);
>
> CS_LOCK(drvdata->base);
> + return rc;
> }
>
> static int tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> @@ -42,8 +50,10 @@ static int tmc_etb_enable_hw(struct tmc_drvdata *drvdata)
> if (rc)
> return rc;
>
> - __tmc_etb_enable_hw(drvdata);
> - return 0;
> + rc = __tmc_etb_enable_hw(drvdata);
> + if (rc)
> + coresight_disclaim_device(drvdata->csdev);
> + return rc;
> }
>
> static void tmc_etb_dump_hw(struct tmc_drvdata *drvdata)
> @@ -91,12 +101,19 @@ static void tmc_etb_disable_hw(struct tmc_drvdata *drvdata)
> coresight_disclaim_device(drvdata->csdev);
> }
>
> -static void __tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> +static int __tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> {
> + int rc = 0;
> +
> CS_UNLOCK(drvdata->base);
>
> /* Wait for TMCSReady bit to be set */
> - tmc_wait_for_tmcready(drvdata);
> + rc = tmc_wait_for_tmcready(drvdata);
> + if (rc) {
> + dev_err(&drvdata->csdev->dev, "fails to enable not ready TMC\n");
> + CS_LOCK(drvdata->base);
> + return rc;
> + }
>
> writel_relaxed(TMC_MODE_HARDWARE_FIFO, drvdata->base + TMC_MODE);
> writel_relaxed(TMC_FFCR_EN_FMT | TMC_FFCR_EN_TI,
> @@ -105,6 +122,7 @@ static void __tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> tmc_enable_hw(drvdata);
>
> CS_LOCK(drvdata->base);
> + return rc;
> }
>
> static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> @@ -114,8 +132,10 @@ static int tmc_etf_enable_hw(struct tmc_drvdata *drvdata)
> if (rc)
> return rc;
>
> - __tmc_etf_enable_hw(drvdata);
> - return 0;
> + rc = __tmc_etf_enable_hw(drvdata);
> + if (rc)
> + coresight_disclaim_device(drvdata->csdev);
> + return rc;
> }
>
> static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata)
> @@ -639,6 +659,7 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
> char *buf = NULL;
> enum tmc_mode mode;
> unsigned long flags;
> + int rc = 0;
>
> /* config types are set a boot time and never change */
> if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
> @@ -664,7 +685,11 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
> * can't be NULL.
> */
> memset(drvdata->buf, 0, drvdata->size);
> - __tmc_etb_enable_hw(drvdata);
> + rc = __tmc_etb_enable_hw(drvdata);
> + if (rc) {
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return rc;
> + }
There is a similar unprepare function in ETR - this should have similar updates.
> } else {
> /*
> * The ETB/ETF is not tracing and the buffer was just read.
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 867ad8bb9b0c..0811cb44588b 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -983,15 +983,21 @@ static void tmc_sync_etr_buf(struct tmc_drvdata *drvdata)
> etr_buf->ops->sync(etr_buf, rrp, rwp);
> }
>
> -static void __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
> +static int __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
> {
> u32 axictl, sts;
> struct etr_buf *etr_buf = drvdata->etr_buf;
> + int rc = 0;
>
> CS_UNLOCK(drvdata->base);
>
> /* Wait for TMCSReady bit to be set */
> - tmc_wait_for_tmcready(drvdata);
> + rc = tmc_wait_for_tmcready(drvdata);
> + if (rc) {
> + dev_err(&drvdata->csdev->dev, "fails to enable not ready TMC\n");
> + CS_LOCK(drvdata->base);
> + return rc;
> + }
>
> writel_relaxed(etr_buf->size / 4, drvdata->base + TMC_RSZ);
> writel_relaxed(TMC_MODE_CIRCULAR_BUFFER, drvdata->base + TMC_MODE);
> @@ -1032,6 +1038,7 @@ static void __tmc_etr_enable_hw(struct tmc_drvdata *drvdata)
> tmc_enable_hw(drvdata);
>
> CS_LOCK(drvdata->base);
> + return rc;
> }
>
> static int tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
> @@ -1060,7 +1067,12 @@ static int tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
> rc = coresight_claim_device(drvdata->csdev);
> if (!rc) {
> drvdata->etr_buf = etr_buf;
> - __tmc_etr_enable_hw(drvdata);
> + rc = __tmc_etr_enable_hw(drvdata);
> + if (rc) {
> + drvdata->etr_buf = NULL;
> + coresight_disclaim_device(drvdata->csdev);
> + tmc_etr_disable_catu(drvdata);
> + }
> }
>
> return rc;
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index 66959557cf39..01c0382a29c0 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -255,7 +255,7 @@ struct tmc_sg_table {
> };
>
> /* Generic functions */
> -void tmc_wait_for_tmcready(struct tmc_drvdata *drvdata);
> +int tmc_wait_for_tmcready(struct tmc_drvdata *drvdata);
> void tmc_flush_and_stop(struct tmc_drvdata *drvdata);
> void tmc_enable_hw(struct tmc_drvdata *drvdata);
> void tmc_disable_hw(struct tmc_drvdata *drvdata);
> --
> 2.39.1.456.gfc5497dd1b-goog
>
The tmc_flush_and_stop() function also calls tmc_wait_for_tmcready().
The etb/etf_prepare_read operations disable the etb /etf before a
read commences. For consistency if this fails due to TMC not being
ready do we also need to fail the read prepare operations?
Regards
Mike
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK