| Message ID | 1460483692-25061-12-git-send-email-mathieu.poirier@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
On 19 April 2016 at 07:42, Suzuki K Poulose <Suzuki.Poulose@arm.com> wrote: > On 12/04/16 18:54, Mathieu Poirier wrote: >> >> The sysFS and Perf access methods can't be allowed to interfere >> with one another. As such introducing guards to access >> functions that prevents moving forward if a TMC is already >> being used. >> >> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> >> --- >> drivers/hwtracing/coresight/coresight-tmc-etf.c | 59 >> +++++++++++++++++++++- >> drivers/hwtracing/coresight/coresight-tmc-etr.c | 67 >> +++++++++++++++++++++++-- >> 2 files changed, 119 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c >> b/drivers/hwtracing/coresight/coresight-tmc-etf.c >> index 9b4cdaed09f5..50d32e8ef4ea 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c >> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c >> @@ -111,7 +111,7 @@ static void tmc_etf_disable_hw(struct tmc_drvdata >> *drvdata) >> CS_LOCK(drvdata->base); >> } >> >> -static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode) >> +static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev, u32 >> mode) >> { >> bool allocated = false; >> char *buf = NULL; >> @@ -189,6 +189,53 @@ out: >> return 0; >> } >> >> +static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, u32 >> mode) >> +{ >> + int ret = 0; >> + u32 val; > > > To be on the safer side, I believe 'val' should be unsigned long, to match > the size of local_t. > >> + unsigned long flags; >> + struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); >> + >> + /* This shouldn't be happening */ >> + WARN_ON(mode != CS_MODE_PERF); > > > I think the above check, and the mode parameter itself is superfluous, given > that this is a static function used internally only for the PERF mode. > Similarly for the _sysfs version. We definitely misunderstood each other then - the only reason I added the checks is after what (I thought) you suggested in the previous revision. > >> + >> + spin_lock_irqsave(&drvdata->spinlock, flags); >> + if (drvdata->reading) { >> + ret = -EINVAL; >> + goto out; >> + } >> + >> + val = local_xchg(&drvdata->mode, mode); > > > We should be using local_cmpxchg() here. Otherwise, we could corrupt the > mode. The newly added (above) check allows us to do that now. There can only be one value coming in (CS_MODE_PERF) and the current type can only be CS_MODE_PERF/DISABLED. > Similarly for the _sysfs version. I though the previous version of your > series > did that. > >> + /* >> + * In Perf mode there can be only one writer per sink. There >> + * is also no need to continue if the ETB/ETR is already operated >> + * from sysFS. >> + */ >> + if (val != CS_MODE_DISABLED) { >> + ret = -EINVAL; >> + goto out; >> + } > > > >> static void tmc_disable_etf_sink(struct coresight_device *csdev) >> { >> u32 val; >> @@ -271,6 +318,7 @@ const struct coresight_ops tmc_etf_cs_ops = { >> >> int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) >> { >> + u32 val; >> enum tmc_mode mode; >> int ret = 0; >> unsigned long flags; >> @@ -289,6 +337,13 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) >> goto out; >> } >> >> + val = local_read(&drvdata->mode); >> + /* Don't interfere if operated from Perf */ >> + if (val == CS_MODE_PERF) { >> + ret = -EINVAL; >> + goto out; >> + } > > > Could we get here when CS_DISABLED ? If not, we could get rid of the check > for CS_MODE_SYSFS below. > >> + >> /* If drvdata::buf is NULL the trace data has been read already */ >> if (drvdata->buf == NULL) { >> ret = -EINVAL; >> @@ -296,7 +351,7 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) >> } >> >> /* Disable the TMC if need be */ >> - if (local_read(&drvdata->mode) == CS_MODE_SYSFS) >> + if (val == CS_MODE_SYSFS) >> tmc_etb_disable_hw(drvdata); > > See above Yes, we can get here when mode is set to CS_MODE_DISABLED. Someone can read the /dev/xyz entry whenever they want, including when a sink hasn't been enabled. Thanks, Mathieu > >> drvdata->reading = true; >> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c >> b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> index de5cf0056802..04fc63d85696 100644 >> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c >> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c >> @@ -87,7 +87,7 @@ static void tmc_etr_disable_hw(struct tmc_drvdata >> *drvdata) >> CS_LOCK(drvdata->base); >> } >> >> -static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode) >> +static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev, u32 >> mode) >> { >> bool allocated = false; >> u32 val; >> @@ -166,6 +166,53 @@ out: >> return 0; >> } >> > >> +static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, u32 >> mode) > > ... > >> static void tmc_disable_etr_sink(struct coresight_device *csdev) > > > Same comments as for the etb side. > > Suzuki > > { >
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index 9b4cdaed09f5..50d32e8ef4ea 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -111,7 +111,7 @@ static void tmc_etf_disable_hw(struct tmc_drvdata *drvdata) CS_LOCK(drvdata->base); } -static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode) +static int tmc_enable_etf_sink_sysfs(struct coresight_device *csdev, u32 mode) { bool allocated = false; char *buf = NULL; @@ -189,6 +189,53 @@ out: return 0; } +static int tmc_enable_etf_sink_perf(struct coresight_device *csdev, u32 mode) +{ + int ret = 0; + u32 val; + unsigned long flags; + struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); + + /* This shouldn't be happening */ + WARN_ON(mode != CS_MODE_PERF); + + spin_lock_irqsave(&drvdata->spinlock, flags); + if (drvdata->reading) { + ret = -EINVAL; + goto out; + } + + val = local_xchg(&drvdata->mode, mode); + /* + * In Perf mode there can be only one writer per sink. There + * is also no need to continue if the ETB/ETR is already operated + * from sysFS. + */ + if (val != CS_MODE_DISABLED) { + ret = -EINVAL; + goto out; + } + + tmc_etb_enable_hw(drvdata); +out: + spin_unlock_irqrestore(&drvdata->spinlock, flags); + + return ret; +} + +static int tmc_enable_etf_sink(struct coresight_device *csdev, u32 mode) +{ + switch (mode) { + case CS_MODE_SYSFS: + return tmc_enable_etf_sink_sysfs(csdev, mode); + case CS_MODE_PERF: + return tmc_enable_etf_sink_perf(csdev, mode); + } + + /* We shouldn't be here */ + return -EINVAL; +} + static void tmc_disable_etf_sink(struct coresight_device *csdev) { u32 val; @@ -271,6 +318,7 @@ const struct coresight_ops tmc_etf_cs_ops = { int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) { + u32 val; enum tmc_mode mode; int ret = 0; unsigned long flags; @@ -289,6 +337,13 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) goto out; } + val = local_read(&drvdata->mode); + /* Don't interfere if operated from Perf */ + if (val == CS_MODE_PERF) { + ret = -EINVAL; + goto out; + } + /* If drvdata::buf is NULL the trace data has been read already */ if (drvdata->buf == NULL) { ret = -EINVAL; @@ -296,7 +351,7 @@ int tmc_read_prepare_etb(struct tmc_drvdata *drvdata) } /* Disable the TMC if need be */ - if (local_read(&drvdata->mode) == CS_MODE_SYSFS) + if (val == CS_MODE_SYSFS) tmc_etb_disable_hw(drvdata); drvdata->reading = true; diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index de5cf0056802..04fc63d85696 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -87,7 +87,7 @@ static void tmc_etr_disable_hw(struct tmc_drvdata *drvdata) CS_LOCK(drvdata->base); } -static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode) +static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev, u32 mode) { bool allocated = false; u32 val; @@ -166,6 +166,53 @@ out: return 0; } +static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, u32 mode) +{ + int ret = 0; + u32 val; + unsigned long flags; + struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); + + /* This shouldn't be happening */ + WARN_ON(mode != CS_MODE_PERF); + + spin_lock_irqsave(&drvdata->spinlock, flags); + if (drvdata->reading) { + ret = -EINVAL; + goto out; + } + + val = local_xchg(&drvdata->mode, mode); + /* + * In Perf mode there can be only one writer per sink. There + * is also no need to continue if the ETR is already operated + * from sysFS. + */ + if (val != CS_MODE_DISABLED) { + ret = -EINVAL; + goto out; + } + + tmc_etr_enable_hw(drvdata); +out: + spin_unlock_irqrestore(&drvdata->spinlock, flags); + + return ret; +} + +static int tmc_enable_etr_sink(struct coresight_device *csdev, u32 mode) +{ + switch (mode) { + case CS_MODE_SYSFS: + return tmc_enable_etr_sink_sysfs(csdev, mode); + case CS_MODE_PERF: + return tmc_enable_etr_sink_perf(csdev, mode); + } + + /* We shouldn't be here */ + return -EINVAL; +} + static void tmc_disable_etr_sink(struct coresight_device *csdev) { u32 val; @@ -199,6 +246,8 @@ const struct coresight_ops tmc_etr_cs_ops = { int tmc_read_prepare_etr(struct tmc_drvdata *drvdata) { + int ret = 0; + u32 val; unsigned long flags; /* config types are set a boot time and never change */ @@ -207,20 +256,28 @@ int tmc_read_prepare_etr(struct tmc_drvdata *drvdata) spin_lock_irqsave(&drvdata->spinlock, flags); + val = local_read(&drvdata->mode); + /* Don't interfere if operated from Perf */ + if (val == CS_MODE_PERF) { + ret = -EINVAL; + goto out; + } + /* If drvdata::buf is NULL the trace data has been read already */ if (drvdata->buf == NULL) { - spin_unlock_irqrestore(&drvdata->spinlock, flags); - return -EINVAL; + ret = -EINVAL; + goto out; } /* Disable the TMC if need be */ - if (local_read(&drvdata->mode) == CS_MODE_SYSFS) + if (val == CS_MODE_SYSFS) tmc_etr_disable_hw(drvdata); drvdata->reading = true; +out: spin_unlock_irqrestore(&drvdata->spinlock, flags); - return 0; + return ret; } int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
The sysFS and Perf access methods can't be allowed to interfere with one another. As such introducing guards to access functions that prevents moving forward if a TMC is already being used. Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> --- drivers/hwtracing/coresight/coresight-tmc-etf.c | 59 +++++++++++++++++++++- drivers/hwtracing/coresight/coresight-tmc-etr.c | 67 +++++++++++++++++++++++-- 2 files changed, 119 insertions(+), 7 deletions(-) -- 2.5.0