CoreSight September 2026

coresight@lists.linaro.org

5 participants
30 discussions

[PATCH v12 00/14] 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: - curr_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 v11 to v12: - rename active_config to curr_config. - rename config to sysfs_config. - remove redundant config argument in etmX_args. - add read-back and copy from curr_config to sysfs_config TRCSEQSTR (seq_state). - add r-b and t-b tags. - Link to v11: https://lore.kernel.org/r/20260915-separate_etm_cfg_v2-v11-0-d2b258d51747@a… from v10 to v11: - 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 (14): coresight: etm4x: read-back TRCSEQSTR at disabling and prohibit modifying seq_state while enabling. coresight: etm4x: prohibit modifying 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: etm4x: rename local config as curr_config referring drvdata->curr_config coresight: etm4x: rename drvdata->config to sysfs_config coresight: etm3x: introduce struct etm_caps coresight: etm3x: rename local config as curr_config referring drvdata->curr_config coresight: etm3x: rename drvdata->config to sysfs_config drivers/hwtracing/coresight/coresight-config.c | 18 +- drivers/hwtracing/coresight/coresight-config.h | 22 + drivers/hwtracing/coresight/coresight-etm.h | 48 +- drivers/hwtracing/coresight/coresight-etm3x-core.c | 196 +++-- .../hwtracing/coresight/coresight-etm3x-sysfs.c | 461 +++++----- drivers/hwtracing/coresight/coresight-etm4x-cfg.c | 14 +- drivers/hwtracing/coresight/coresight-etm4x-core.c | 567 ++++++------ .../hwtracing/coresight/coresight-etm4x-sysfs.c | 961 +++++++++++---------- drivers/hwtracing/coresight/coresight-etm4x.h | 199 +++-- 9 files changed, 1340 insertions(+), 1146 deletions(-) --- base-commit: 9e3604d7369cfc0110100eb1a0acab1865ee2d18 change-id: 20260911-separate_etm_cfg_v2-3518a168cbff Best regards, -- Sincerely, Yeoreum Yun

2 days, 20 hours

[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

2 days, 20 hours

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…

2 days, 21 hours

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…

3 days, 6 hours

[PATCH v2 00/14] perf cs-etm: Fix bogus branch samples on exceptions

by Leo Yan

CoreSight currently models exception entry by changing the preceding instruction range into a taken branch. This can give an IRQ the source PC of an instruction that already retired and overwrite a real branch immediately before the exception. For an untaken B.LS followed by an IRQ, perf script currently reports: hw int 4000f8 => ffff800080010c80 b.ls #0x400118 ... iret ffff800080012284 => 4000fc eret The hardware trace supplies 0x4000fc as the preferred return address. For an IRQ, this is the architectural resume PC (Arm ARM, R_VBQMV). B.LS has retired, and the saved PC identifies the boundary before the following MOV. Using this PC as the IRQ source reflects the architectural state at exception entry: hw int 4000fc => ffff800080010c80 movz x2, #0x1796 ... iret ffff800080012284 => 4000fc eret The IRQ sample represents the transfer from this architectural execution position to the handler. The series synthesizes exception entries from exception packets, preserving the preceding branch and its outcome. The supporting changes: - Let decoders supply sample.ret_addr so later instruction fetching cannot change thread-stack return addresses. Apply this to Intel PT asynchronous samples as well. - Prepare packet ISA and instruction-size handling and share sample synthesis helpers. Mark untaken branches and break history when instruction memory is unavailable. - Add a thread-stack regression test and four AArch64 CoreSight tests. IRQs and page faults must resume at the entry PC; SVC and emulated MRS must resume four bytes later. Based on the AI search and test on my x86 machine, this matches perf's Intel PT handling of IRQs. Intel PT records the next instruction's IP in the FUP packet, and Perf uses that IP as the interrupt sample's source. This series is verified on Orion6 board with "perf test coresight". Signed-off-by: Leo Yan <leo.yan(a)arm.com> --- Changes in v2: - Rework the fix around exception packets to preserve both exception entries and preceding branches. - Add explicit return addresses and the Intel PT asynchronous-branch fix. - Split out packet/synthesis preparation, record not-taken branches and handle unreadable instruction memory. - Add thread-stack regression coverage and four CoreSight tests. - Link to v1: https://lore.kernel.org/r/20260713-perf_cs_etm_fix_non_taken-v1-0-4561607fc… --- Leo Yan (14): perf sample: Allow decoders to supply branch return addresses perf intel-pt: Preserve return addresses for asynchronous branches perf cs-etm: Break branch history when instruction memory is unavailable perf cs-etm: Centralize packet ISA initialization perf cs-etm: Use the recorded instruction size for A32 and A64 perf cs-etm: Mark branches that were not taken perf cs-etm: Factor out final instruction sample synthesis perf cs-etm: Centralize branch sample synthesis checks perf cs-etm: Classify exception calls using the exception packet perf cs-etm: Synthesize exception entries separately from branches perf tests: Check CoreSight IRQ entry and exit perf tests: Check CoreSight syscall entry and exit perf tests: Check CoreSight abort entry and exit perf tests: Check CoreSight emulated instruction entry and exit tools/perf/tests/Build | 1 + tools/perf/tests/builtin-test.c | 3 + .../perf/tests/shell/coresight/abort_entry_exit.sh | 21 ++ tools/perf/tests/shell/coresight/irq_entry_exit.sh | 37 ++++ .../tests/shell/coresight/syscall_entry_exit.sh | 21 ++ .../perf/tests/shell/coresight/trap_entry_exit.sh | 24 +++ tools/perf/tests/shell/lib/coresight_exception.sh | 165 +++++++++++++++ tools/perf/tests/tests.h | 3 + tools/perf/tests/thread-stack.c | 106 ++++++++++ tools/perf/tests/workloads/Build | 4 + tools/perf/tests/workloads/branch_not_taken_loop.c | 33 +++ tools/perf/tests/workloads/page_fault_loop.c | 37 ++++ tools/perf/util/cs-etm-decoder/cs-etm-decoder.c | 106 +++++++--- tools/perf/util/cs-etm.c | 222 ++++++++++----------- tools/perf/util/cs-etm.h | 2 + tools/perf/util/intel-pt.c | 7 + tools/perf/util/sample.c | 1 + tools/perf/util/sample.h | 5 + tools/perf/util/thread-stack.c | 5 +- 19 files changed, 656 insertions(+), 147 deletions(-) --- base-commit: edd8a9fe2eca009599e013a29c421c7a6b5ad1b9 change-id: 20260713-perf_cs_etm_fix_non_taken-5b4d7f73f41e Best regards, -- Leo Yan <leo.yan(a)arm.com>

3 days, 23 hours

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

4 days, 3 hours

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; > } >

4 days, 4 hours

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

by Mike Leach

Reviewed-by: Mike Leach <mike.leach(a)arm.com> On 9/17/26 22:14, Kees Cook wrote: > From: Kees Cook <kees+treewide(a)kernel.org> > > In preparation for making the devm_kmalloc family of allocators type > aware, we need to make sure that the returned type from the allocation > matches the type of the variable being assigned. (Before, the allocator > would always return "void *", which can be implicitly cast to any > pointer type.) > > The assigned type is "const struct attribute_group **", but the > converted allocation type would be "struct attribute_group **", which is > the same type without the const qualifier. 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> > --- > Cc: Suzuki K Poulose <suzuki.poulose(a)arm.com> > Cc: Mike Leach <mike.leach(a)arm.com> > Cc: James Clark <james.clark(a)linaro.org> > Cc: Leo Yan <leo.yan(a)arm.com> > Cc: Alexander Shishkin <alexander.shishkin(a)linux.intel.com> > Cc: <coresight(a)lists.linaro.org> > Cc: <linux-arm-kernel(a)lists.infradead.org> > --- > drivers/hwtracing/coresight/coresight-cti-sysfs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/hwtracing/coresight/coresight-cti-sysfs.c b/drivers/hwtracing/coresight/coresight-cti-sysfs.c > index 3fe2c916d228..2ed5d8eb1dda 100644 > --- a/drivers/hwtracing/coresight/coresight-cti-sysfs.c > +++ b/drivers/hwtracing/coresight/coresight-cti-sysfs.c > @@ -1132,7 +1132,7 @@ static int cti_create_cons_groups(struct device *dev, struct cti_device *ctidev) > /* nr groups = dynamic + static + NULL terminator */ > nr_groups = ctidev->nr_trig_con + CORESIGHT_CTI_STATIC_GROUPS_MAX; > ctidev->con_groups = devm_kcalloc(dev, nr_groups, > - sizeof(struct attribute_group *), > + sizeof(*ctidev->con_groups), > GFP_KERNEL); > if (!ctidev->con_groups) > return -ENOMEM;

4 days, 4 hours

[PATCH v10 0/8] 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 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 (8): coresight: etm4x: fix inconsistencies with sysfs configuration coresight: etm3x: fix inconsistencies with sysfs configuration coresight: etm3x: change drvdata->spinlock type to raw_spin_lock_t 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 | 48 ++- drivers/hwtracing/coresight/coresight-etm3x-core.c | 96 ++--- .../hwtracing/coresight/coresight-etm3x-sysfs.c | 155 ++++---- drivers/hwtracing/coresight/coresight-etm4x-cfg.c | 14 +- drivers/hwtracing/coresight/coresight-etm4x-core.c | 413 +++++++++++---------- .../hwtracing/coresight/coresight-etm4x-sysfs.c | 204 +++++----- drivers/hwtracing/coresight/coresight-etm4x.h | 196 +++++----- 9 files changed, 645 insertions(+), 521 deletions(-) --- base-commit: 9e3604d7369cfc0110100eb1a0acab1865ee2d18 change-id: 20260911-separate_etm_cfg_v2-3518a168cbff Best regards, -- Sincerely, Yeoreum Yun

1 week, 2 days

Re: [PATCH 1/1] coresight: tmc-etr: Sync the trace buffer for the device

by Leo Yan

On Wed, Sep 16, 2026 at 11:04:20AM +0800, Jie Gan wrote: [...] > > From: Min Chen <min.chen(a)siengine.com> > > > > The flat ETR buffer comes from dma_alloc_noncoherent(), which zeroes it > > with CPU stores. The DMA API requires the caller to sync the buffer for > > the device before the device writes into it, but the TMC driver only > > ever syncs for the CPU afterwards. On a non-coherent sink the zero fill > > is therefore still dirty in cache when the ETR starts writing, and its > > write-back lands on top of the trace data. Good catch! I'm curious how you observed the dirty cache lines overwriting trace data in DDR and causing corruption. > Agree, without the sync, the dirty data may overwrites the trace data. > > Add a sync_for_device() buffer operation and call it from > > __tmc_etr_enable_hw() just before the TMC is enabled. I don't think __tmc_etr_enable_hw() is the best place for the sync, as it can be called frequently when an event is enabled, e.g. when a task is scheduled in or migrated between CPUs. We should be able to sync once after dma_alloc_noncoherent() instead. The issue is not limited to buffer init. The driver also injects barrier packets into the bounce buffer, which can race with the sink. Even worse, the barrier packet write may collide with trace data when they share a cache line. I think we should consider writing barrier packets directly into the AUX buffer. This would avoid stale cache data from barrier packet writes and simplify the flow without additional sync operations. Would you mind if I pick up this patch (keeping you as the author) and add a second patch to address the barrier packet issue? That part may need some several rounds refactoring so can have better shape, I think it would be easier to consolidate the fixes on my side. Thanks, Leo P.s. Please CC me on future CoreSight patches. If you're using the mainline ./scripts/get_maintainer.pl, it should add me automatically. I didn't receive this patch directly, which is why I'm replying to Jie's email (also thanks Jie's review).

1 week, 4 days

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CoreSight September 2026