Re: [PATCH v3 08/20] coresight: allow etm4x to be built as a module

[Mike Leach <mike.leach@linaro.org>]

Hi,

That fix sorts the problem on my board.
However, be aware that the etmv4 PM code changes somewhat due to this
patch [1] that is currently on the linux master branch and will appear
in 5.8-rc6, and there are further new coresight patches in Mathieu's
coresight/next and linux-next.

It may be better to rebase onto coresight/next for the next set.

Regards

Mike

[1] 9b6a3f3633a5 coresight: etmv4: Fix CPU power management setup in
probe() function


On Sat, 18 Jul 2020 at 04:25, <tingwei@codeaurora.org> wrote:
>
> Hi Mike,
>
> Thanks for reporting this.  This is a good catch.
>
> I was testing on db845c but I didn't encounter this issue with
> multiple module load/unload test. I guess it's due to timing difference.
> The issue is etm4_cpu_pm_notify() is removed from cpu pm notification
> after last etm4 device is removed. There's racing condition when some
> etm4 device say etm0 is removed but etm4_cpu_pm_notify() is still
> called. I reproduced this issue by manually unbind etm4x device.
>
> The fix is clean etmdrvdata[drvdata->cpu] in etm4_remove() so
> etm4_cpu_pm_notify() is gracefully returned. I've verified this on
> db845c with manually unbind etm4x device test. Do you mind test
> on your db410 as well? I'll put it into v4.
>
> @@ -1542,6 +1543,7 @@ static int __exit etm4_remove(struct amba_device
> *adev)
>
>          etm_perf_symlink(drvdata->csdev, false);
>
> +       etmdrvdata[drvdata->cpu] = NULL;
>          if (--etm4_count == 0) {
>                  etm4_cpu_pm_unregister();
>
>
>
> On 2020-07-18 01:05, Mike Leach wrote:
> > Hi Tingwei,
> >
> > Couldn't see 00/20 cover note for this set, so reporting this here as
> > it relates to etmv4 in part.
> >
> > The following sequence:-
> > (There is a load dependency here of course, if I try to load ETMv4
> > without the coresight core, then I get a lot of missing symbol error
> > messages - I assume this is expected behaviour?)
>
> Coresight_etm4x module depends on coresight module, so it's expected
> behavior.
>
> >
> > root@linaro-developer:/home/linaro/cs-mods# insmod coresight.ko
> > root@linaro-developer:/home/linaro/cs-mods# insmod coresight-etm4x.ko
> >
> > correctly loads the coresight core then ETMv4 module.
> >
> > [ 1208.214674] coresight etm0: CPU0: ETM v4.0 initialized
> > [ 1208.215534] coresight etm1: CPU1: ETM v4.0 initialized
> > [ 1208.221020] coresight etm2: CPU2: ETM v4.0 initialized
> > [ 1208.224757] coresight etm3: CPU3: ETM v4.0 initialized
> >
> > However, if I then unload the ETMv4 module:-
> >
> > root@linaro-developer:/home/linaro/cs-mods# rmmod coresight-etm4x.ko
> >
> > I get a crash:-
> >
> > [ 1215.963689] ------------[ cut here ]------------
> > [ 1215.963741] WARNING: CPU: 3 PID: 0 at
> > drivers/hwtracing/coresight/coresight-etm4x-core.c:1364
> > etm4_cpu_pm_notify+0xad8/0xb48 [coresight_etm4x]
> > [ 1215.967373] Modules linked in: coresight_etm4x(-) coresight [last
> > unloaded: coresight]
> > [ 1215.979960] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G        W
> >   5.8.0-rc5cs-modscs-mods-00020-gc03fe910680d #282
> > [ 1215.987856] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC
> > (DT)
> > [ 1215.998531] pstate: 80000085 (Nzcv daIf -PAN -UAO BTYPE=--)
> > [ 1216.005396] pc : etm4_cpu_pm_notify+0xad8/0xb48 [coresight_etm4x]
> > [ 1216.010687] lr : notifier_call_chain+0x5c/0xa0
> > [ 1216.016926] sp : ffff000009fe7d50
> > [ 1216.021265] x29: ffff000009fe7d50 x28: 0000000000000000
> > [ 1216.024653] x27: 0000011b1d1464b5 x26: 0000000000000001
> > [ 1216.030035] x25: ffff00003c79f888 x24: 0000000000000001
> > [ 1216.035330] x23: 0000000000000000 x22: 0000000000000000
> > [ 1216.040626] x21: 0000000000000000 x20: 0000000000000000
> > [ 1216.045921] x19: ffff000038396480 x18: 0000000000000000
> > [ 1216.051216] x17: 0000000000000000 x16: 0000000000000000
> > [ 1216.056510] x15: 0000000000000000 x14: ffffffffffffffff
> > [ 1216.061806] x13: ffffffffffffffff x12: 0000000000000000
> > [ 1216.067101] x11: 0000000000000000 x10: 00000000000009b0
> > [ 1216.072396] x9 : ffff000009fe7e70 x8 : ffff000009fd4010
> > [ 1216.077690] x7 : 0000000000000000 x6 : 0000000023c2c562
> > [ 1216.082986] x5 : 00ffffffffffffff x4 : 0000000000000003
> > [ 1216.088281] x3 : ffff000038396880 x2 : ffff800008d8d280
> > [ 1216.093576] x1 : ffff80002b1aa000 x0 : 000000005f454c42
> > [ 1216.098873] Call trace:
> > [ 1216.104178]  etm4_cpu_pm_notify+0xad8/0xb48 [coresight_etm4x]
> > [ 1216.106343]  notifier_call_chain+0x5c/0xa0
> > [ 1216.112242]  __atomic_notifier_call_chain+0x48/0x60
> > [ 1216.116236]  cpu_pm_notify+0x44/0x70
> > [ 1216.121008]  cpu_pm_enter+0x3c/0x80
> > [ 1216.124829]  psci_enter_domain_idle_state+0x38/0xa8
> > [ 1216.128040]  cpuidle_enter_state+0x88/0x478
> > [ 1216.132900]  cpuidle_enter+0x44/0x58
> > [ 1216.137069]  call_cpuidle+0x40/0x70
> > [ 1216.140888]  do_idle+0x1e0/0x248
> > [ 1216.144099]  cpu_startup_entry+0x28/0x98
> > [ 1216.147574]  secondary_start_kernel+0x1a0/0x1f8
> > [ 1216.151476] ---[ end trace 97bcd7b8bdd7f9a7 ]---
> >
> > This happens each time, though the CPU number can change.
> > Test platform is Dragonboard DB410, linux 5.8-rc5 + this patch set.
> >
> > Regards
> >
> > Mike
> >
> >
> > On Fri, 17 Jul 2020 at 06:48, Tingwei Zhang <tingwei@codeaurora.org>
> > wrote:
> >>
> >> From: Kim Phillips <kim.phillips@arm.com>
> >>
> >> Allow to build coresight-etm4x as a module, for ease of development.
> >>
> >> - Kconfig becomes a tristate, to allow =m
> >> - append -core to source file name to allow module to
> >>   be called coresight-etm4x by the Makefile
> >> - add an etm4_remove function, for module unload
> >> - add a MODULE_DEVICE_TABLE for autoloading on boot
> >>
> >> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> >> Cc: Leo Yan <leo.yan@linaro.org>
> >> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> >> Cc: Randy Dunlap <rdunlap@infradead.org>
> >> Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >> Cc: Russell King <linux@armlinux.org.uk>
> >> Signed-off-by: Kim Phillips <kim.phillips@arm.com>
> >> Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
> >> ---
> >>  drivers/hwtracing/coresight/Kconfig           |  5 ++-
> >>  drivers/hwtracing/coresight/Makefile          |  4 +--
> >>  ...resight-etm4x.c => coresight-etm4x-core.c} | 31
> >> ++++++++++++++++++-
> >>  3 files changed, 36 insertions(+), 4 deletions(-)
> >>  rename drivers/hwtracing/coresight/{coresight-etm4x.c =>
> > coresight-etm4x-core.c} (98%)
> >>
> >> diff --git a/drivers/hwtracing/coresight/Kconfig
> > b/drivers/hwtracing/coresight/Kconfig
> >> index 8fd9fd139cf3..d6e107bbd30b 100644
> >> --- a/drivers/hwtracing/coresight/Kconfig
> >> +++ b/drivers/hwtracing/coresight/Kconfig
> >> @@ -78,7 +78,7 @@ config CORESIGHT_SOURCE_ETM3X
> >>           module will be called coresight-etm3x.
> >>
> >>  config CORESIGHT_SOURCE_ETM4X
> >> -       bool "CoreSight Embedded Trace Macrocell 4.x driver"
> >> +       tristate "CoreSight Embedded Trace Macrocell 4.x driver"
> >>         depends on ARM64
> >>         select CORESIGHT_LINKS_AND_SINKS
> >>         select PID_IN_CONTEXTIDR
> >> @@ -88,6 +88,9 @@ config CORESIGHT_SOURCE_ETM4X
> >>           for instruction level tracing. Depending on the implemented
> > version
> >>           data tracing may also be available.
> >>
> >> +         To compile this driver as a module, choose M here: the
> >> +         module will be called coresight-etm4x.
> >> +
> >>  config CORESIGHT_STM
> >>         tristate "CoreSight System Trace Macrocell driver"
> >>         depends on (ARM && !(CPU_32v3 || CPU_32v4 || CPU_32v4T)) ||
> > ARM64
> >> diff --git a/drivers/hwtracing/coresight/Makefile
> > b/drivers/hwtracing/coresight/Makefile
> >> index d619cfd0abd8..271dc255454f 100644
> >> --- a/drivers/hwtracing/coresight/Makefile
> >> +++ b/drivers/hwtracing/coresight/Makefile
> >> @@ -14,8 +14,8 @@ obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) +=
> > coresight-funnel.o \
> >>  obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o
> >>  coresight-etm3x-y := coresight-etm3x-core.o coresight-etm-cp14.o \
> >>                                         coresight-etm3x-sysfs.o
> >> -obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
> >> -                                       coresight-etm4x-sysfs.o
> >> +obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o
> >> +coresight-etm4x-y := coresight-etm4x-core.o coresight-etm4x-sysfs.o
> >>  obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
> >>  obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
> >>  obj-$(CONFIG_CORESIGHT_CATU) += coresight-catu.o
> >> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c
> > b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> >> similarity index 98%
> >> rename from drivers/hwtracing/coresight/coresight-etm4x.c
> >> rename to drivers/hwtracing/coresight/coresight-etm4x-core.c
> >> index 747afc875f91..b5945f62794c 100644
> >> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> >> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> >> @@ -1536,6 +1536,26 @@ static struct amba_cs_uci_id uci_id_etm4[] = {
> >>         }
> >>  };
> >>
> >> +static int __exit etm4_remove(struct amba_device *adev)
> >> +{
> >> +       struct etmv4_drvdata *drvdata = dev_get_drvdata(&adev->dev);
> >> +
> >> +       etm_perf_symlink(drvdata->csdev, false);
> >> +
> >> +       if (--etm4_count == 0) {
> >> +               etm4_cpu_pm_unregister();
> >> +
> >> +
> > cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
> >> +               if (hp_online)
> >> +                       cpuhp_remove_state_nocalls(hp_online);
> >> +       }
> >> +
> >> +       coresight_unregister(drvdata->csdev);
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +
> >>  static const struct amba_id etm4_ids[] = {
> >>         CS_AMBA_ID(0x000bb95d),                 /* Cortex-A53 */
> >>         CS_AMBA_ID(0x000bb95e),                 /* Cortex-A57 */
> >> @@ -1553,12 +1573,21 @@ static const struct amba_id etm4_ids[] = {
> >>         {},
> >>  };
> >>
> >> +MODULE_DEVICE_TABLE(amba, etm4_ids);
> >> +
> >>  static struct amba_driver etm4x_driver = {
> >>         .drv = {
> >>                 .name   = "coresight-etm4x",
> >> +               .owner  = THIS_MODULE,
> >>                 .suppress_bind_attrs = true,
> >>         },
> >>         .probe          = etm4_probe,
> >> +       .remove         = etm4_remove,
> >>         .id_table       = etm4_ids,
> >>  };
> >> -builtin_amba_driver(etm4x_driver);
> >> +module_amba_driver(etm4x_driver);
> >> +
> >> +MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
> >> +MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
> >> +MODULE_DESCRIPTION("Arm CoreSight Program Flow Trace v4 driver");
> >> +MODULE_LICENSE("GPL v2");
> >> --
> >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
> > Forum,
> >> a Linux Foundation Collaborative Project
> >>
> >>
> >> _______________________________________________
> >> linux-arm-kernel mailing list
> >> linux-arm-kernel@lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel



--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

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