CoreSight September 2026

coresight@lists.linaro.org

6 participants
39 discussions

[PATCH v2] perf test: Record kcore for the CoreSight callchain test

by Leo Yan

The CoreSight callchain test traces both userspace and kernel execution and checks the callchain across a syscall. Add --kcore to perf record to save the running kernel image alongside the trace data so perf script can use it to decode the kernel trace. If kcore is not available, the test will be skipped. Add a Fixes tag so the change can be backported to stable kernels and improve the test reliability. Fixes: ca0e19074bd6 ("perf test: Add Arm CoreSight callchain test") Reviewed-by: James Clark <james.clark(a)linaro.org> Signed-off-by: Leo Yan <leo.yan(a)arm.com> --- Changes in v2: - Add check /proc/kcore and skip test if absent. Signed-off-by: Leo Yan <leo.yan(a)arm.com> --- tools/perf/tests/shell/coresight/callchain.sh | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/tools/perf/tests/shell/coresight/callchain.sh b/tools/perf/tests/shell/coresight/callchain.sh index 13cca7dc11184002e3ddc058c0d0ffa1c458c483..43ad90bc30345efdd40ba4649ceeb435a1781a4b 100755 --- a/tools/perf/tests/shell/coresight/callchain.sh +++ b/tools/perf/tests/shell/coresight/callchain.sh @@ -30,6 +30,11 @@ skip_if_system_is_not_ready() return 2 } + [ -e /proc/kcore ] || { + echo "[Skip] /proc/kcore is not available" >&2 + return 2 + } + return 0 } @@ -43,7 +48,7 @@ record_trace() mkfifo "$cf" "$af" - perf record -o "$data" -e cs_etm// --per-thread -D -1 --control fifo:"$cf","$af" -- \ + perf record --kcore -o "$data" -e cs_etm// --per-thread -D -1 --control fifo:"$cf","$af" -- \ perf test --record-ctl fifo:"$cf","$af" -w callchain >/dev/null 2>&1 && # It is safe to use 'i3i' with a three-instruction interval, since the --- base-commit: 0ae6fc78c5ce0dfd18d8712a50f0fd4602eff103 change-id: 20260928-perf_cs_etm_callchain_test_add_kcore-f96e891f91c5 Best regards, -- Leo Yan <leo.yan(a)arm.com>

1 month, 2 weeks

[PATCH 0/3] perf: Suppress redundant ITRACE start records for Arm SPE and CoreSight

by Leo Yan

Thanks to Tamas Petz for noticing that Arm CoreSight perf data can contain many PERF_RECORD_ITRACE_START records. PERF_RECORD_ITRACE_START provides the decoder with the initial thread context when that information is absent from the trace stream. Once tracing has started, Arm SPE and CoreSight decoders track subsequent context changes using context packets or recorded sched_switch events. Have both drivers call perf_event_itrace_started() after successfully starting event. This prevents perf core from emitting redundant PERF_RECORD_ITRACE_START records when an event is scheduled in again. Since the Arm SPE and CoreSight drivers can be built as modules, export perf_event_itrace_started() before using it in those drivers. This series was verified with Arm CoreSight using the commands below. The perf data contains 100 sched_switch events but only one PERF_RECORD_ITRACE_START record: taskset -c 2 perf record -e cs_etm//u -e sched:sched_switch -- \ taskset -c 2 bash -c 'while true; do sleep 0.01; done' ^C perf script -D 2>&1 | grep -c sched_switch 100 perf script -D 2>&1 | grep -c PERF_RECORD_ITRACE_START 1 Signed-off-by: Leo Yan <leo.yan(a)arm.com> --- Leo Yan (3): perf/core: Export perf_event_itrace_started() perf: arm_spe: Suppress redundant ITRACE start records coresight: perf: Suppress ITRACE start records drivers/hwtracing/coresight/coresight-etm-perf.c | 2 ++ drivers/perf/arm_spe_pmu.c | 2 ++ kernel/events/core.c | 1 + 3 files changed, 5 insertions(+) --- base-commit: 786262be6048deab760f68c8acc2c85607165894 change-id: 20260901-perf_suppress_itrace_start_records-42faf45e9ce9 Best regards, -- Leo Yan <leo.yan(a)arm.com>

1 month, 2 weeks

[PATCH] perf test: Record kcore for the CoreSight callchain test

by Leo Yan

The CoreSight callchain test traces both userspace and kernel execution and checks the callchain across a syscall. Add --kcore to perf record to save the running kernel image alongside the trace data so perf script can use it to decode the kernel trace. Add a Fixes tag so the change can be backported to stable kernels and improve the test reliability. Fixes: ca0e19074bd6 ("perf test: Add Arm CoreSight callchain test") Signed-off-by: Leo Yan <leo.yan(a)arm.com> --- tools/perf/tests/shell/coresight/callchain.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/tests/shell/coresight/callchain.sh b/tools/perf/tests/shell/coresight/callchain.sh index 13cca7dc1118..b69187f1a37f 100755 --- a/tools/perf/tests/shell/coresight/callchain.sh +++ b/tools/perf/tests/shell/coresight/callchain.sh @@ -43,7 +43,7 @@ record_trace() mkfifo "$cf" "$af" - perf record -o "$data" -e cs_etm// --per-thread -D -1 --control fifo:"$cf","$af" -- \ + perf record --kcore -o "$data" -e cs_etm// --per-thread -D -1 --control fifo:"$cf","$af" -- \ perf test --record-ctl fifo:"$cf","$af" -w callchain >/dev/null 2>&1 && # It is safe to use 'i3i' with a three-instruction interval, since the -- 2.34.1

1 month, 2 weeks

Re: [PATCH] coresight: cti: Add const to con_groups allocation type

by Leo Yan

On Thu, Sep 17, 2026 at 02:14:29PM -0700, Kees Cook wrote: > From: Kees Cook <kees+treewide(a)kernel.org> > ... As there is no general way to > safely add const qualifiers, take the size from the assignment target > instead. No change in allocation size results. > > Build tested ARCH=arm64 allmodconfig with GCC aarch64-linux-gnu 16.1.0: > drivers/hwtracing/coresight/coresight-cti-sysfs.o > > Assisted-by: LLM coccinelle > Signed-off-by: Kees Cook <kees+treewide(a)kernel.org> Reviewed-by: Leo Yan <leo.yan(a)arm.com>

1 month, 2 weeks

Re: [PATCH v2 1/1] coresight: syscfg: fix deadlock on device registration failure

by Leo Yan

On Fri, Sep 25, 2026 at 10:40:22AM +0800, yingchao deng wrote: [...] > > @Yingchao, do you mind to work out a formal patch for this? > Happy to. I'll send the patch. Thanks!

1 month, 2 weeks

[PATCH v11 0/9] fix several inconsistencies with sysfs configuration in etmX

by Yeoreum Yun

The current ETMx configuration via sysfs can lead to the following inconsistencies: - If a configuration is modified via sysfs while a perf session is active, the running configuration may differ between before a sched-out and after a subsequent sched-in. - If a perf session and sysfs session tries to enable concurrently, configuration from configfs could be corrupted (etm4). - There is chance to corrupt drvdata->config if perf session tries to enabled among handling cscfg_csdev_disable_active_config() in etm4_disable_sysfs() (etm4). To resolve these inconsistencies, the configuration should be separated into: - active_config, which is applied configuration for the current session - config, which stores the settings configured via sysfs. and apply configuration from configfs after taking a mode. Patch History ============= from v10 to 11: - replace direct register read from etm3 sysfs with IPI. - fix issue cntr_val and others field which required to be shown after sysfs session disable. - prohibit the write for some etm3 sysfs while sysfs session is enabled. - drop locktype change in etm3 - Link to v10: https://lore.kernel.org/r/20260911-separate_etm_cfg_v2-v10-0-1b715d95927a@a… from v9 to v10: - rebase to coresight/next - https://lore.kernel.org/all/20260725113645.57519-1-yeoreum.yun@arm.com/ from v8 to v9: - add feat_csdev_lock guard interface. - set feat_csdev->drv_spinlock as NULL for etmv4_drvdata. - https://lore.kernel.org/all/20260629090007.1718746-1-yeoreum.yun@arm.com/ from v7 to v8: - accept @Leo Yan' suggestion to handle error. - small minor fixes following @Suzuki' suggestion. - https://lore.kernel.org/all/20260519154812.254884-1-yeoreum.yun@arm.com/ from v6 to v7: - rebase on coresight/next - add ETM_MAX_SEQ_TRANSITIONS define - remove redundant patch relavent cpu-hotplug as coresight-pm patch merged. - https://lore.kernel.org/all/20260422132203.977549-1-yeoreum.yun@arm.com/ from v5 to v6: - fix missing of calling cscfg_csdev_disable_active_config() - add rb & fixes tags. - add ss_status field in etm4x_drvdata to expose STATUS and PENDING bits. - https://lore.kernel.org/all/20260415165528.3369607-1-yeoreum.yun@arm.com/ from v4 to v5: - add rb-tag. - fix underflow issue for nrseqstate. - fix wrong check in etm4_sspcicrn_present(). - remove redundant fields on etmv4_save_state. - rename caps->ss_status to ss_cmp. - fix wrong location of etm4_release_trace_id. - https://lore.kernel.org/all/20260413142003.3549310-1-yeoreum.yun@arm.com/ from v3 to v4: - change etm_drvdata->spinlock type to raw_spin_lock_t - remove redundant call etmX_enable_hw() with starting_cpu() callsback. - fix missing trace id release. - add missing docs. - https://lore.kernel.org/all/20260412175506.412301-1-yeoreum.yun@arm.com/ from v2 to v3: - fix build error for etm3x. - fix checkpatch warning. - https://lore.kernel.org/all/20260410074310.2693385-1-yeoreum.yun@arm.com/ from v1 to v2 - rebased to v7.0-rc7. - introduce etmX_caps structure to save etmX's capabilities. - remove ss_status from etmv4_config. - modify active_config after taking a mode (perf/sysfs). - https://lore.kernel.org/all/20260317181705.2456271-1-yeoreum.yun@arm.com/ --- Yeoreum Yun (9): coresight: etm4x: prohibit modifying ss_status and cntr_val while session is enabled coresight: etm3x: prohibit modifying cntr_val and reset while session is enabled coresight: etm4x: fix inconsistencies with sysfs configuration coresight: etm3x: fix inconsistencies with sysfs configuration coresight: etm3x: remove redundant cpu online check on etm_enable_sysfs() coresight: etm4x: introduce struct etm4_caps coresight: etm4x: exclude ss_status from drvdata->config coresight: etm4x: remove s_ex_level from config coresight: etm3x: introduce struct etm_caps drivers/hwtracing/coresight/coresight-config.c | 18 +- drivers/hwtracing/coresight/coresight-config.h | 22 ++ drivers/hwtracing/coresight/coresight-etm.h | 46 ++- drivers/hwtracing/coresight/coresight-etm3x-core.c | 126 +++--- .../hwtracing/coresight/coresight-etm3x-sysfs.c | 104 +++-- drivers/hwtracing/coresight/coresight-etm4x-cfg.c | 14 +- drivers/hwtracing/coresight/coresight-etm4x-core.c | 426 +++++++++++---------- .../hwtracing/coresight/coresight-etm4x-sysfs.c | 210 ++++++---- drivers/hwtracing/coresight/coresight-etm4x.h | 196 +++++----- 9 files changed, 676 insertions(+), 486 deletions(-) --- base-commit: 9e3604d7369cfc0110100eb1a0acab1865ee2d18 change-id: 20260911-separate_etm_cfg_v2-3518a168cbff Best regards, -- Sincerely, Yeoreum Yun

1 month, 2 weeks

Re: [PATCH v2 1/1] coresight: syscfg: fix deadlock on device registration failure

by Leo Yan

On Mon, Sep 14, 2026 at 03:49:00PM +0800, Yingchao Deng wrote: > cscfg_create_device() calls put_device() on the error path while holding > cscfg_mutex. If device_register() fails, put_device() drops the last > reference and invokes cscfg_dev_release(), which takes cscfg_mutex again, > deadlocking. > > Module init and exit are serialized by the kernel, so cscfg_mutex is not > needed to protect the allocation and freeing of cscfg_mgr. Remove the > mutex from cscfg_dev_release() and take it only while cscfg_mgr fields > are being accessed. > > Fixes: 199380decc5f ("coresight: configfs: Fix unload of configurations on module exit") > Suggested-by: Leo Yan <leo.yan(a)arm.com> > Signed-off-by: Yingchao Deng <dengyingchao(a)kylinsec.com.cn> For this patch: Reviewed-by: Leo Yan <leo.yan(a)arm.com> Sashiko reported an issue for null pointer dereference if configfs init fails fails [1]. It is good to fix it using a separate patch: @@ -1299,8 +1299,10 @@ int __init cscfg_init(void) /* initialise configfs subsystem */ err = cscfg_configfs_init(cscfg_mgr); - if (err) - goto exit_err; + if (err) { + device_unregister(cscfg_device()); + return err; + } /* preload built-in configurations */ err = cscfg_preload(THIS_MODULE); @Yingchao, do you mind to work out a formal patch for this? Thanks, Leo [1] https://sashiko.dev/#/patchset/6CC680FFAC60931F%2B20260914074900.1711-1-den…

1 month, 2 weeks

Re: [PATCH v2] coresight: Check runtime PM resume result

by Leo Yan

On Wed, Sep 23, 2026 at 08:18:56PM -0400, Yuho Choi wrote: > @@ -843,7 +843,11 @@ static bool coresight_get_ref(struct coresight_device *csdev) > goto err_module; > > /* Make sure the device is powered on */ > - pm_runtime_get_sync(parent); > + if (pm_runtime_resume_and_get(parent) < 0) { > + module_put(drv->owner); > + goto err_module; > + } > + There is already a patch that does something similar and fixes the same errors across the CoreSight folder. See: https://lore.kernel.org/linux-arm-kernel/20260911-b4-coresight-runtime-pm-f…

1 month, 2 weeks

Re: [PATCH] dt-bindings: arm: Fix CoreSight CTI Kconfig symbol

by Mike Leach

On 9/16/26 20:57, Rob Herring wrote: > On Sat, Aug 22, 2026 at 10:19:12AM +0200, Karl Mehltretter wrote: >> The option exposing CoreSight CTI integration registers is >> CONFIG_CORESIGHT_CTI_INTEGRATION_REGS, not >> CONFIG_CORESIGHT_CTI_INTEGRATION_TEST. > > DT bindings should not be referring to kernel kconfig symbols (or > anything else in the kernel) in the first place. > Agreed - the comment in general is correct but the last sentence in the paragraph should drop the config reference. e.g. "This information might be found by using the CTI Integration Test registers to explore the trigger connections between CTI and other CoreSight components." The coresight/KConfig file itself adequately documents adding this support and the perils therein. Mike > Rob

1 month, 2 weeks

Re: [PATCH v2 1/1] coresight: syscfg: fix deadlock on device registration failure

by Mike Leach

Reviewed-by: Mike Leach <mike.leach(a)arm.com> On 9/14/26 08:49, Yingchao Deng wrote: > cscfg_create_device() calls put_device() on the error path while holding > cscfg_mutex. If device_register() fails, put_device() drops the last > reference and invokes cscfg_dev_release(), which takes cscfg_mutex again, > deadlocking. > > Module init and exit are serialized by the kernel, so cscfg_mutex is not > needed to protect the allocation and freeing of cscfg_mgr. Remove the > mutex from cscfg_dev_release() and take it only while cscfg_mgr fields > are being accessed. > > Fixes: 199380decc5f ("coresight: configfs: Fix unload of configurations on module exit") > Suggested-by: Leo Yan <leo.yan(a)arm.com> > Signed-off-by: Yingchao Deng <dengyingchao(a)kylinsec.com.cn> > --- > drivers/hwtracing/coresight/coresight-syscfg.c | 18 ++++++------------ > 1 file changed, 6 insertions(+), 12 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > index 2bfdd7b45e49..2dd0b29f44e4 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > @@ -1173,27 +1173,21 @@ struct device *cscfg_device(void) > /* Must have a release function or the kernel will complain on module unload */ > static void cscfg_dev_release(struct device *dev) > { > - mutex_lock(&cscfg_mutex); > kfree(cscfg_mgr); > cscfg_mgr = NULL; > - mutex_unlock(&cscfg_mutex); > } > > /* a device is needed to "own" some kernel elements such as sysfs entries. */ > static int cscfg_create_device(void) > { > struct device *dev; > - int err = -ENOMEM; > - > - mutex_lock(&cscfg_mutex); > - if (cscfg_mgr) { > - err = -EINVAL; > - goto create_dev_exit_unlock; > - } > + int err; > > cscfg_mgr = kzalloc_obj(struct cscfg_manager); > if (!cscfg_mgr) > - goto create_dev_exit_unlock; > + return -ENOMEM; > + > + mutex_lock(&cscfg_mutex); > > /* initialise the cscfg_mgr structure */ > INIT_LIST_HEAD(&cscfg_mgr->csdev_desc_list); > @@ -1204,6 +1198,8 @@ static int cscfg_create_device(void) > cscfg_mgr->load_state = CSCFG_NONE; > raw_spin_lock_init(&cscfg_mgr->sysfs_store_lock); > > + mutex_unlock(&cscfg_mutex); > + > /* setup the device */ > dev = cscfg_device(); > dev->release = cscfg_dev_release; > @@ -1213,8 +1209,6 @@ static int cscfg_create_device(void) > if (err) > put_device(dev); > > -create_dev_exit_unlock: > - mutex_unlock(&cscfg_mutex); > return err; > } >

1 month, 2 weeks

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