CoreSight

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2715 discussions

[PATCH 0/6] perf: cs-etm: HW_ID improvements

by James Clark

The driver might not always be able to write HW_IDs, but we don't need them for unformatted mode anyway, so fix that in commit ("perf cs-etm: Synthesize missing HW_ID mappings for raw trace"). At the same time, give the driver another chance to send them in commit ("coresight: perf: Retry failed HW_ID writes"). The other commits are semi-related improvements and fixes. ("perf: cs-etm: Respect --no-itrace option") makes debugging broken Coresight perf.data files easier. Applies on top of "[PATCH v2 00/14] perf cs-etm: Per-thread mode fixes and snapshot wrap support" Signed-off-by: James Clark <james.clark(a)linaro.org> --- James Clark (5): perf: cs-etm: Don't add global v0 HW_IDs to unformatted queues perf cs-etm: Free partially created queues perf: cs-etm: Respect --no-itrace option perf/core: Return errors from perf_report_aux_output_id() coresight: perf: Retry failed HW_ID writes Leo Yan (1): perf cs-etm: Synthesize missing HW_ID mappings for raw trace drivers/hwtracing/coresight/coresight-etm-perf.c | 52 +++++---- include/linux/perf_event.h | 2 +- kernel/events/core.c | 6 +- tools/perf/util/auxtrace.c | 2 +- tools/perf/util/auxtrace.h | 1 + tools/perf/util/cs-etm.c | 143 ++++++++++++++++------- 6 files changed, 139 insertions(+), 67 deletions(-) --- base-commit: 78148c85297024ffe7a709acb7cc4fc907271176 change-id: 20260706-james-cs-hw_id-output-failure-1d06d042ef96 prerequisite-change-id: 20260605-james-cs-unformatted-per-thread-fix-50e723aa7f0e:v2 prerequisite-patch-id: 1aa32269a3a7dc76840dd8a24cb5a8715507e898 prerequisite-patch-id: ef471f468351462f67efa58a09a3461306ac5a0a prerequisite-patch-id: c78946cf4ec1c7722570865403a3562625bdaa33 prerequisite-patch-id: 0b953eee0252db3c7ba3ef1e3397048a94482ca2 prerequisite-patch-id: 27da72c2f01bcc68205bbcc14d5019369c02cb83 prerequisite-patch-id: 365c6d5f71c754e4c690b5ebed3453565bb5b809 prerequisite-patch-id: 64e9419a41082a2db3daf255baf0fb40efbae5dd prerequisite-patch-id: 1dc2e6ef8e76b369736b4c88560302861b2e4faf prerequisite-patch-id: b7de38ec4d90f5b45d56390a4e5919a1d6439951 prerequisite-patch-id: 3548d5b161cfb8c11a166ca2b3228ca4821f1ca0 prerequisite-patch-id: 97e66600218a2b32e5b21d0abcb6321590f98de9 prerequisite-patch-id: 292282b20bd8ad7d096ee7ffbc55dcfb75455f53 prerequisite-patch-id: c80259b47850ba65c985c85a29c8cf4948463d59 Best regards, -- James Clark <james.clark(a)linaro.org>

1 month, 1 week

Re: [PATCH] dt-bindings: arm: coresight: Allow funnel clocks

by Leo Yan

Hi Rob, On Mon, Sep 21, 2026 at 06:28:33PM -0500, Rob Herring (Arm) wrote: > Some static funnel nodes have APB and AT clocks. Allow one or two > clocks and the apb_pclk and atclk clock-names entries. > > Assisted-by: LLM > Signed-off-by: Rob Herring (Arm) <robh(a)kernel.org> > > --- > .../bindings/arm/arm,coresight-static-funnel.yaml | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/Documentation/devicetree/bindings/arm/arm,coresight-static-funnel.yaml b/Documentation/devicetree/bindings/arm/arm,coresight-static-funnel.yaml > index 9598a3d0a95b..4a3d08f9568c 100644 > --- a/Documentation/devicetree/bindings/arm/arm,coresight-static-funnel.yaml > +++ b/Documentation/devicetree/bindings/arm/arm,coresight-static-funnel.yaml > @@ -30,6 +30,16 @@ properties: > power-domains: > maxItems: 1 > > + clocks: > + minItems: 1 > + maxItems: 2 > + > + clock-names: > + minItems: 1 > + items: > + - const: apb_pclk > + - const: atclk The question is that a static funnel does not need to program any registers, so in theory it should only need atclk as the module's core clock, but not the APB programming clock (apb_pclk). Maybe I did not get this right when I initially enabled the static funnel in hi3660-coresight.dtsi. We should probably remove pclk from the static funnel node. clocks: minItems: 0 maxItems: 1 clock-names: minItems: 0 items: - const: atclk Thanks, Leo

1 month, 1 week

Re: [PATCH 2/2] perf: arm_spe: Prefer large AUX mappings

by Leo Yan

Hi Will, On Mon, Aug 10, 2026 at 04:10:48PM +0100, Will Deacon wrote: > On Mon, Aug 10, 2026 at 03:44:42PM +0100, Leo Yan wrote: > > Commit 18049c8cff9c ("perf/aux: Allocate non-contiguous AUX pages by > > default") made the AUX allocator use order-0 pages by default unless a > > PMU explicitly asks for contiguous allocations. > > But that commit specifically calls out SPE as benefitting from > non-contiguous pages: > > "For instance, ARM SPE and TRBE operate with virtual pages, and > Coresight ETR allocates a separate buffer. For these PMUs, > allocating contiguous AUX pages unnecessarily exacerbates memory > fragmentation. This fragmentation can prevent their use on > long-running devices." > > so why doesn't passing PERF_PMU_CAP_AUX_PREFER_LARGE reintroduce the > problems that 18049c8cff9c was trying to solve? How about adding a field to struct pmu to specify a preferred maximum page order for the AUX buffer? The perf core could try that order first and fall back to smaller orders if the allocation fails. For example, the Neoverse V2 TRM documents: L1 Trace Buffer Extension (TRBE) TLB: 1 entry Given the single L1 TRBE TLB entry, the TRBE driver could prefer PMD_ORDER (2 MiB with 4 KiB pages) to reduce TLB pressure. This reflects the hardware characteristic. This could be a trade-off instead of using PERF_PMU_CAP_AUX_PREFER_LARGE, avoiding large contiguous allocations that could reintroduce the Android OOM issue. I did a quick test with this approach and the results look positive. Does this sound like a reasonable direction? I might also need Yabin's judgement from Android side. Thanks, Leo

1 month, 1 week

Re: [PATCH] coresight: syscfg: Fix null pointer dereference when configfs init fails

by Mike Leach

Reviewed-by: Mike Leach <mike.leach(a)arm.com> On 9/28/26 13:35, Yingchao Deng wrote: > If cscfg_configfs_init() fails, cscfg_init() takes the exit_err path: > > cscfg_init() -> cscfg_clear_device() -> cscfg_configfs_release() > -> configfs_unregister_subsystem() > > which tears down a configfs subsystem that was never registered. > configfs_unregister_subsystem() begins with: > > struct dentry *dentry = dget(group->cg_item.ci_dentry); > struct dentry *root = dentry->d_sb->s_root; > > ci_dentry is assigned in configfs_create_dir() only once the subsystem > directory has been created, which never happened here. cscfg_mgr > comes from kzalloc_obj(), so ci_dentry is still NULL, and dget() > hands a NULL dentry back unchanged - the next line dereferences it. > > Handle the failure in cscfg_init() directly: unregister the device and > return the error, releasing the devres-allocated config item type and > cscfg_mgr without touching the subsystem. > > Fixes: a13d5a246aca ("coresight: syscfg: Add initial configfs support") > Suggested-by: Leo Yan <leo.yan(a)arm.com> > Link: https://lore.kernel.org/all/20260924162404.GN200420@e132581.arm.com/ > Signed-off-by: Yingchao Deng <dengyingchao(a)kylinsec.com.cn> > --- > drivers/hwtracing/coresight/coresight-syscfg.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > index 2bfdd7b45e49..00b29d1656c0 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > @@ -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);

1 month, 1 week

[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

1 month, 1 week

[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, 1 week

[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, 1 week

[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, 1 week

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, 1 week

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, 1 week

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