As recommended by section 4.3.7 ("Synchronization when using system instructions to progrom the trace unit") of ARM IHI 0064H.b, the self-hosted trace analyzer must perform a Context synchronization event between writing to the TRCPRGCTLR and reading the TRCSTATR. Additionally, add an ISB between the each read of TRCSTATR on coresight_timeout() when using system instructions to program the trace unit.
Fixes: 1ab3bb9df5e3 ("coresight: etm4x: Add necessary synchronization for sysreg access") Signed-off-by: Yuanfang Zhang quic_yuanfang@quicinc.com --- drivers/hwtracing/coresight/coresight-core.c | 20 ++++++--- drivers/hwtracing/coresight/coresight-etm4x-core.c | 48 +++++++++++++++++++--- include/linux/coresight.h | 4 ++ 3 files changed, 62 insertions(+), 10 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index ea38ecf26fcbfb383eb40a222788bf5d7976013d..c42aa9fddab9b752361b84deab6b10be045b7104 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1017,18 +1017,20 @@ static void coresight_remove_conns(struct coresight_device *csdev) }
/** - * coresight_timeout - loop until a bit has changed to a specific register - * state. + * coresight_timeout_action - loop until a bit has changed to a specific register + * state, with a callback after every trial. * @csa: coresight device access for the device * @offset: Offset of the register from the base of the device. * @position: the position of the bit of interest. * @value: the value the bit should have. + * @cb: Call back after each trial. * * Return: 0 as soon as the bit has taken the desired state or -EAGAIN if * TIMEOUT_US has elapsed, which ever happens first. */ -int coresight_timeout(struct csdev_access *csa, u32 offset, - int position, int value) +int coresight_timeout_action(struct csdev_access *csa, u32 offset, + int position, int value, + coresight_timeout_cb_t cb) { int i; u32 val; @@ -1044,7 +1046,8 @@ int coresight_timeout(struct csdev_access *csa, u32 offset, if (!(val & BIT(position))) return 0; } - + if (cb) + cb(csa, offset, position, value); /* * Delay is arbitrary - the specification doesn't say how long * we are expected to wait. Extra check required to make sure @@ -1056,6 +1059,13 @@ int coresight_timeout(struct csdev_access *csa, u32 offset,
return -EAGAIN; } +EXPORT_SYMBOL_GPL(coresight_timeout_action); + +int coresight_timeout(struct csdev_access *csa, u32 offset, + int position, int value) +{ + return coresight_timeout_action(csa, offset, position, value, NULL); +} EXPORT_SYMBOL_GPL(coresight_timeout);
u32 coresight_relaxed_read32(struct coresight_device *csdev, u32 offset) diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index dd8c74f893dbdfe1a35d811ef2dc476b81ce07ae..b933cdc4e52fd5ecd16d3ad97cf0d3f1a3fd87e4 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -399,6 +399,29 @@ static void etm4_check_arch_features(struct etmv4_drvdata *drvdata, } #endif /* CONFIG_ETM4X_IMPDEF_FEATURE */
+static void etm4x_sys_ins_barrier(struct csdev_access *csa, u32 offset, int pos, int val) +{ + if (!csa->io_mem) + isb(); +} + +/* + * etm4x_wait_status: Poll for TRCSTATR.<pos> == <val>. While using system + * instruction to access the trace unit, each access must be separated by a + * synchronization barrier. See ARM IHI0064H.b section "4.3.7 Synchronization of + * register updates", for system instructions section, in "Notes": + * + * "In particular, whenever disabling or enabling the trace unit, a poll of + * TRCSTATR needs explicit synchronization between each read of TRCSTATR" + */ +static int etm4x_wait_status(struct csdev_access *csa, int pos, int val) +{ + if (!csa->io_mem) + return coresight_timeout_action(csa, TRCSTATR, pos, val, + etm4x_sys_ins_barrier); + return coresight_timeout(csa, TRCSTATR, pos, val); +} + static int etm4_enable_hw(struct etmv4_drvdata *drvdata) { int i, rc; @@ -430,7 +453,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) isb();
/* wait for TRCSTATR.IDLE to go up */ - if (coresight_timeout(csa, TRCSTATR, TRCSTATR_IDLE_BIT, 1)) + if (etm4x_wait_status(csa, TRCSTATR_IDLE_BIT, 1)) dev_err(etm_dev, "timeout while waiting for Idle Trace Status\n"); if (drvdata->nr_pe) @@ -523,7 +546,7 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) isb();
/* wait for TRCSTATR.IDLE to go back down to '0' */ - if (coresight_timeout(csa, TRCSTATR, TRCSTATR_IDLE_BIT, 0)) + if (etm4x_wait_status(csa, TRCSTATR_IDLE_BIT, 0)) dev_err(etm_dev, "timeout while waiting for Idle Trace Status\n");
@@ -906,10 +929,25 @@ static void etm4_disable_hw(void *info) tsb_csync(); etm4x_relaxed_write32(csa, control, TRCPRGCTLR);
+ /* + * As recommended by section 4.3.7 ("Synchronization when using system + * instructions to progrom the trace unit") of ARM IHI 0064H.b, the + * self-hosted trace analyzer must perform a Context synchronization + * event between writing to the TRCPRGCTLR and reading the TRCSTATR. + */ + if (!csa->io_mem) + isb(); + /* wait for TRCSTATR.PMSTABLE to go to '1' */ - if (coresight_timeout(csa, TRCSTATR, TRCSTATR_PMSTABLE_BIT, 1)) + if (etm4x_wait_status(csa, TRCSTATR_PMSTABLE_BIT, 1)) dev_err(etm_dev, "timeout while waiting for PM stable Trace Status\n"); + /* + * As recommended by section 4.3.7 (Synchronization of register updates) + * of ARM IHI 0064H.b. + */ + isb(); + /* read the status of the single shot comparators */ for (i = 0; i < drvdata->nr_ss_cmp; i++) { config->ss_status[i] = @@ -1711,7 +1749,7 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata) etm4_os_lock(drvdata);
/* wait for TRCSTATR.PMSTABLE to go up */ - if (coresight_timeout(csa, TRCSTATR, TRCSTATR_PMSTABLE_BIT, 1)) { + if (etm4x_wait_status(csa, TRCSTATR_PMSTABLE_BIT, 1)) { dev_err(etm_dev, "timeout while waiting for PM Stable Status\n"); etm4_os_unlock(drvdata); @@ -1802,7 +1840,7 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata) state->trcpdcr = etm4x_read32(csa, TRCPDCR);
/* wait for TRCSTATR.IDLE to go up */ - if (coresight_timeout(csa, TRCSTATR, TRCSTATR_IDLE_BIT, 1)) { + if (etm4x_wait_status(csa, TRCSTATR_PMSTABLE_BIT, 1)) { dev_err(etm_dev, "timeout while waiting for Idle Trace Status\n"); etm4_os_unlock(drvdata); diff --git a/include/linux/coresight.h b/include/linux/coresight.h index c1334259427850173ccc5872a6ced550a99f8e1c..f106b1025111892e9d44ac643f7409552952d4da 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -639,6 +639,10 @@ extern int coresight_enable_sysfs(struct coresight_device *csdev); extern void coresight_disable_sysfs(struct coresight_device *csdev); extern int coresight_timeout(struct csdev_access *csa, u32 offset, int position, int value); +typedef void (*coresight_timeout_cb_t) (struct csdev_access *, u32, int, int); +extern int coresight_timeout_action(struct csdev_access *csa, u32 offset, + int position, int value, + coresight_timeout_cb_t cb);
extern int coresight_claim_device(struct coresight_device *csdev); extern int coresight_claim_device_unlocked(struct coresight_device *csdev);
--- base-commit: fac04efc5c793dccbd07e2d59af9f90b7fc0dca4 change-id: 20250116-etm_sync-7be51cc6cbcd
Best regards,