CoreSight

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2708 discussions

Re: [PATCH] coresight: fix typos in comments

by Leo Yan

On Fri, Sep 04, 2026 at 04:40:51PM +0530, Hemanth Selam wrote: > Fix typos in comments, reported by scripts/checkpatch.pl using the > misspelling list in scripts/spelling.txt. Only touches comments, no code > changes. > > Assisted-by: Cursor:claude-opus-5 > Signed-off-by: Hemanth Selam <hemanth.selam(a)gmail.com> Reviewed-by: Leo Yan <leo.yan(a)arm.com>

2 months

Re: [PATCH] docs: fix typos in Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x

by Leo Yan

On Fri, Sep 04, 2026 at 09:49:42AM +0530, tspamiitesh(a)gmail.com wrote: [...] > -Description: (RW) Enable/disable tracing on this specific trace entiry. > +Description: (RW) Enable/disable tracing on this specific trace entry. > Enabling a source implies the source has been configured > - properly and a sink has been identidifed for it. The path > + properly and a sink has been indentified for it. The path s/indentified/identified ?

2 months

Re: [PATCH v2] coresight: tnoc: fix trace ID path assignment failure on non-AMBA tnoc

by Leo Yan

On Wed, Sep 02, 2026 at 05:41:43PM +0800, Jie Gan wrote: > For a tnoc device not on the AMBA bus, atid was set to -EOPNOTSUPP. > trace_noc_id() returns this value directly to > coresight_path_assign_trace_id(), which only treats a literal 0 > return as "this device has no ID, keep searching the path" - > any other value is checked against IS_VALID_CS_TRACE_ID() and > rejected. A negative atid therefore made path assignment fail with > -EINVAL instead of falling through to the next device in the path > that could supply a valid trace ID. > > Use 0, the same sentinel coresight_path_assign_trace_id() already > recognizes as "not allocated", instead of -EOPNOTSUPP. > > Fixes: 5799dee92dc2 ("coresight-tnoc: add platform driver to support Interconnect TNOC") > Signed-off-by: Jie Gan <jie.gan(a)oss.qualcomm.com> Reviewed-by: Leo Yan <leo.yan(a)arm.com>

2 months

Re: [PATCH] coresight: fix trace ID search skipping pass-through NoC devices

by Leo Yan

On Wed, Sep 02, 2026 at 04:35:11PM +0800, Jie Gan wrote: [...] > Hi Leo, > > Thanks for the suggestion. You're welcome! > I will fix this in the TNOC driver. I agree that there is no need to use > additional error codes to report the failure. > > I will post the new fix patch after below patch[1] to be applied to avoid > conflict. The patch in the link has no fix tag, but current patch is a simple fix. I'd suggest to give priority this patch - this is friendly for porting to stable kernels. If there have dependency (based on your local test), you could explictly mention the dependency in cover letter and resend the tnoc probe series. Thanks, Leo > [1] https://lore.kernel.org/all/20260710-fix-tracenoc-probe-issue-v6-2-41eb36fe…

2 months

Re: [PATCH] coresight: fix trace ID search skipping pass-through NoC devices

by Leo Yan

Hi Jie, On Mon, Aug 17, 2026 at 04:50:15PM +0800, Jie Gan wrote: [...] > @@ -953,8 +953,12 @@ int coresight_path_assign_trace_id(struct coresight_path *path, > /* Assign a trace ID to the path for the first device that wants to do it */ > trace_id = coresight_get_trace_id(nd->csdev, mode, sink); > > - /* 0 means the device has no ID assignment, so keep searching */ > - if (trace_id == 0) > + /* > + * 0 means the device has no ID assignment, and -EOPNOTSUPP > + * means the device explicitly declines to assign one (e.g. a > + * pass-through NoC) - in both cases keep searching downstream. > + */ > + if (trace_id == 0 || trace_id == -EOPNOTSUPP) > continue; Based on IS_VALID_CS_TRACE_ID(), I see 0 is for no ID assignment, could you improve a bit tnoc.c instead? If so, We don't need to add a new error for the same purpose. ---8<--- diff --git a/drivers/hwtracing/coresight/coresight-tnoc.c b/drivers/hwtracing/coresight/coresight-tnoc.c index 9e8de4323d28..bf221c1e5c48 100644 --- a/drivers/hwtracing/coresight/coresight-tnoc.c +++ b/drivers/hwtracing/coresight/coresight-tnoc.c @@ -51,8 +51,8 @@ static void trace_noc_enable_hw(struct trace_noc_drvdata *drvdata) { u32 val; - /* No valid ATID, simply enable the unit */ - if (drvdata->atid == -EOPNOTSUPP) { + /* 0 means no ID assignment, simply enable the unit */ + if (!drvdata->atid) { writel(TRACE_NOC_CTRL_PORTEN, drvdata->base + TRACE_NOC_CTRL); return; } @@ -130,10 +130,8 @@ static int trace_noc_init_default_data(struct trace_noc_drvdata *drvdata) { int atid; - if (!dev_is_amba(drvdata->dev)) { - drvdata->atid = -EOPNOTSUPP; + if (!dev_is_amba(drvdata->dev)) return 0; - } atid = coresight_trace_id_get_system_id(); if (atid < 0)

2 months

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

by Leo Yan

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? The question is how "allocating contiguous AUX pages unnecessarily exacerbates memory fragmentation." The relevant information I could find is [1]: "On Android, we collect ETM data periodically on internal user devices for AutoFDO optimization (for both userspace libraries and the kernel). Allocating a large chunk of contiguous AUX pages (4M for each CPU) periodically is almost unbearable. The kernel may need to kill many processes to fulfill the request. It affects user experience even after using PMU." We might have missed chance to clarify how the fragmentation issue occurs in the first place. Let's say, a phone with 8 CPUs, allocating 4MB per CPU requires 32MB in total, which is a relatively small portion of 4GiB or 8GiB of RAM commonly found in phones. Moreover, once contiguous pages are freed, the buddy allocator can coalesce them again into buddy list. It is not obvious to me that PREFER_LARGE directly causes fragmentation. One case where AUX allocation could exacerbate fragmentation is when the system is already fragmented. If a high-order allocation fails and the allocator falls back to smaller-order blocks, those allocations may consume free blocks scattered across different buddy regions and make subsequent high-order allocations more difficult. If this is the main concern, I'd suggest using a smaller AUX buffer (e.g. 1MB or even 512KB) for TRBE/SPE to reduce memory pressure. Snapshot mode '-S' could also be considered, as it allows the buffer to be allocated once and reused for subsequent recordings by signals. OTOH, using only order-0 pages can significantly increase TTW overhead on the trace path and lead to overflows, we observe this causes huge trace discontinuity. In the end, we need to trace-off the fragmentation concern against the trace discontinuity. Thanks, Leo [1] https://lore.kernel.org/lkml/CALJ9ZPNLgEBxOmDim-vztUknEETwdL-Z2gJ8K9s44TiPg…

2 months

Re: [PATCH v4] coresight: coresight.h: add '*' to kernel-doc lines

by Leo Yan

On Sun, Aug 30, 2026 at 08:09:12PM -0700, Randy Dunlap wrote: > kernel-doc reports 2 (kernel-doc) lines in coresight.h that don't have > a beginning '*' in them, so fix these lines. > > Also convert struct coresight_trace_id_map to kernel-doc format to > remove another warning. > > Warning: include/linux/coresight.h:173 bad line: > connected to @src_port. NULL until the device is created > Warning: include/linux/coresight.h:177 bad line: > needs to be filtered. > Warning: include/linux/coresight.h:236 This comment starts with '/**', > but isn't a kernel-doc comment. > > Fixes: ec9903d6cc34 ("coresight: Add support for trace filtering by source") > Fixes: d49c9cf15f89 ("coresight: Rename connection members to make the direction explicit") > Signed-off-by: Randy Dunlap <rdunlap(a)infradead.org> Reviewed-by: Leo Yan <leo.yan(a)arm.com>

2 months

[PATCH v9 00/13] 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. Also, This patch set includes some small fixes: - missing trace id release in etm4x. - underflow issue for nrseqstate. - wrong check in etm4x_sspcicrn_present(). - missing call of cscfg_csdev_disable_active_config() This patch based on coresight tree's next Patch History ============= 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 (13): coresight: etm4x: fix wrong check of etm4x_sspcicrn_present() coresight: etm4x: fix underflow for usage of (nrseqstate - 1) coresight: etm4x: fix leaked trace id coresight: etm4x: fix inconsistencies with sysfs configuration coresight: etm4x: missing cscfg_csdev_disable_active_config() in perf enable 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: etm4x: remove redundant fields in etmv4_save_state coresight: etm3x: introduce struct etm_caps .../hwtracing/coresight/coresight-config.c | 18 +- .../hwtracing/coresight/coresight-config.h | 26 + drivers/hwtracing/coresight/coresight-etm.h | 48 +- .../coresight/coresight-etm3x-core.c | 96 ++-- .../coresight/coresight-etm3x-sysfs.c | 159 +++--- .../hwtracing/coresight/coresight-etm4x-cfg.c | 16 +- .../coresight/coresight-etm4x-core.c | 454 ++++++++++-------- .../coresight/coresight-etm4x-sysfs.c | 204 ++++---- drivers/hwtracing/coresight/coresight-etm4x.h | 204 ++++---- 9 files changed, 682 insertions(+), 543 deletions(-) base-commit: 98495b5a4d77dd22e106f462b76e1093a55b29a7 -- LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}

2 months, 1 week

Re: [PATCH v2 11/14] perf auxtrace: cs-etm: Capture wrapped snapshots

by James Clark

On 24/08/2026 13:21, Adrian Hunter wrote: > On 21/08/2026 12:49, James Clark wrote: >> snapshot_has_wrapped() isn't implemented for Coresight, so when a wrap >> occurs we only save from offset 0 to current head, modulo buffer size, >> rather than capturing the whole buffer. Coresight drivers currently use >> a monotonic head pointer even in snapshot mode, which gives a lot more >> information for taking snapshots than a wrapped pointer. It means we >> don't need to search for data at the end of the buffer to guess if a >> wrap has occurred, and we can go back to saving partial buffers after a >> wrap by checking if the next size to take is less than the buffer >> size. >> >> The drivers will always be able to generate a monotonic head because >> TRBE has a bytes written counter, so even if we stop generating an AUX >> record on every overflow, we can check if the counter indicated an >> overwrite and offset head by a whole buffer size if it wrapped. This >> forces userspace to read the whole buffer rather than between last and >> current head. ETR and other sinks use software double buffering, so can >> continue as they are. >> >> Add a much simpler 'monotonic_snapshot_head' path for tracers to use, >> and use it for Coresight. >> >> Signed-off-by: James Clark <james.clark(a)linaro.org> >> --- >> tools/perf/arch/arm/util/cs-etm.c | 1 + >> .../perf/tests/shell/coresight/raw_dump_stress.sh | 5 ----- >> tools/perf/util/auxtrace.c | 22 ++++++++++++++++------ >> tools/perf/util/auxtrace.h | 2 ++ >> 4 files changed, 19 insertions(+), 11 deletions(-) >> >> diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c >> index d36b7e41399b..dbf76dd3349e 100644 >> --- a/tools/perf/arch/arm/util/cs-etm.c >> +++ b/tools/perf/arch/arm/util/cs-etm.c >> @@ -918,6 +918,7 @@ struct auxtrace_record *cs_etm_record_init(int *err) >> ptr->itr.info_fill = cs_etm_info_fill; >> ptr->itr.snapshot_start = cs_etm_snapshot_start; >> ptr->itr.snapshot_finish = cs_etm_snapshot_finish; >> + ptr->itr.monotonic_snapshot_head = true; >> ptr->itr.reference = cs_etm_reference; >> ptr->itr.free = cs_etm_recording_free; >> ptr->itr.read_finish = auxtrace_record__read_finish; >> diff --git a/tools/perf/tests/shell/coresight/raw_dump_stress.sh b/tools/perf/tests/shell/coresight/raw_dump_stress.sh >> index bea70d825596..c9459ded4cbe 100755 >> --- a/tools/perf/tests/shell/coresight/raw_dump_stress.sh >> +++ b/tools/perf/tests/shell/coresight/raw_dump_stress.sh >> @@ -48,11 +48,6 @@ read -r size offset last_idx <<< "$(awk ' >> # everything was dumped. Allow 48 bytes difference to cover 3 frames: current >> # frame length, a partial frame and a final empty one, all of which aren't >> # dumped. >> -# >> -# TODO: for a single snapshot, offset should always be zero. However, we >> -# currently output AUX records in snapshot mode when we shouldn't, which >> -# increments the offset. Allow for that until it's fixed so we can test raw >> -# dumping. >> decode_size=$((1 + last_idx - offset)) >> if [ "$decode_size" -gt "$((size - 48))" ] && [ "$decode_size" -le "$((size))" ]; then >> echo "PASS: AUXTRACE buffer length matches dumped packet index" >> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c >> index 8ca872e6d465..e3c770b46e94 100644 >> --- a/tools/perf/util/auxtrace.c >> +++ b/tools/perf/util/auxtrace.c >> @@ -2051,9 +2051,9 @@ static int __auxtrace_mmap__read(struct mmap *map, >> bool snapshot, size_t snapshot_size) >> { >> struct auxtrace_mmap *mm = &map->auxtrace_mmap; >> - u64 head, old = mm->prev, offset, ref; >> + u64 head, old = mm->prev, offset, ref, size; >> unsigned char *data = mm->base; >> - size_t size, head_off, old_off, len1, len2, padding; >> + size_t head_off, old_off, len1, len2, padding; >> union perf_event ev; >> void *data1, *data2; >> int kernel_is_64_bit = perf_env__kernel_is_64_bit(env); >> @@ -2061,10 +2061,20 @@ static int __auxtrace_mmap__read(struct mmap *map, >> >> head = auxtrace_mmap__read_head(mm, kernel_is_64_bit); >> >> - if (snapshot && itr->snapshot_has_wrapped) { >> - err = auxtrace_find_snapshot(itr, mm->idx, mm, data, &head, &old); >> - if (err) >> - return err; >> + if (snapshot) { >> + if (itr->snapshot_has_wrapped) { >> + err = auxtrace_find_snapshot(itr, mm->idx, mm, data, &head, &old); >> + if (err) >> + return err; >> + } else if (itr->monotonic_snapshot_head) { >> + size = head - old; >> + /* Force a full buffer read if a wrap has occurred */ >> + if (size > mm->len) { >> + pr_debug3("%s: wrap detected, adjusting old from 0x%"PRIx64" to 0x%"PRIx64"\n", >> + __func__, old, head - mm->len); >> + old = head - mm->len; >> + } >> + } > > I feel like this is asking to keep the ->find_snapshot() callback. > i.e. basically the same thing, but add a helper that BTS and SPE > can call directly, like auxtrace_record__default_find_snapshot(). > For PT, add/use auxtrace_record__snapshot_fixup() that does the > common old/head adjustment. > > Then ->monotonic_snapshot_head is not needed. > Hmm yeah I suppose that makes sense. I can give it a go. >> } >> >> if (old == head) >> diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h >> index a9d0c84184c5..971b817d3396 100644 >> --- a/tools/perf/util/auxtrace.h >> +++ b/tools/perf/util/auxtrace.h >> @@ -385,6 +385,7 @@ struct auxtrace_mmap_params { >> * @evlist: selected events list >> * @snapshot_wrapped_len: number of bits in @snapshot_wrapped >> * @snapshot_wrapped: bitmap indicating if each aux buffer has wrapped >> + * @monotonic_snapshot_head: driver doesn't wrap head pointer on overflow >> */ >> struct auxtrace_record { >> int (*recording_options)(struct auxtrace_record *itr, >> @@ -412,6 +413,7 @@ struct auxtrace_record { >> int snapshot_wrapped_len; >> unsigned long *snapshot_wrapped; >> int snapshot_search_bytes; >> + bool monotonic_snapshot_head; >> }; >> >> /** >> >

2 months, 2 weeks

Re: [PATCH v2 03/14] perf cs-etm: Turn on context packet timestamps in per-thread mode

by James Clark

On 21/08/2026 11:01, sashiko-bot(a)kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [Medium] Unconditionally enabling timestamps in per-thread mode breaks recording out-of-the-box on hardware without timestamp support (e.g., ETMv3 or ETMv4 without TRCIDR0.TSSIZE). > -- > > --- Patch [3]: [PATCH v2 03/14] perf cs-etm: Turn on context packet timestamps in per-thread mode --- > commit 23dc37429523715cdb26c5647b22b1a9dc0c89ab > Author: James Clark <james.clark(a)linaro.org> > > perf cs-etm: Turn on context packet timestamps in per-thread mode > > This enables context packet timestamps in per-thread mode, replacing the > previous unset default. It helps keep samples in order when supporting > multiple per-thread mode threads. > >> diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c >> index acfdb3f53821e..d0486a164a700 100644 >> --- a/tools/perf/arch/arm/util/cs-etm.c >> +++ b/tools/perf/arch/arm/util/cs-etm.c >> @@ -453,13 +453,22 @@ static int cs_etm_recording_options(struct auxtrace_record *itr, > [ ... ] >> if (!perf_cpu_map__is_any_cpu_or_is_empty(cpus)) { >> + /* >> + * Timestamps are required to interleave samples from different >> + * CPUs. >> + */ >> evsel__set_config_if_unset(cs_etm_evsel, "timestamp", 1); >> + /* Context IDs are required to associate trace to a process */ >> evsel__set_config_if_unset(cs_etm_evsel, "contextid", 1); >> + } else { >> + /* >> + * Enable context packet timestamps only (no periodic >> + * timestamps). Even in per-thread mode with a single process we >> + * still need to correlate trace to a specific mmap around >> + * execs, which can be done with just context packet timestamps. >> + */ >> + evsel__set_config_if_unset(cs_etm_evsel, "timestamp", UINT64_MAX); > > [Severity: Medium] > Will unconditionally setting this timestamp break recording out-of-the-box on > hardware without timestamp support, like ETMv3? > > Looking at cs_etm_validate_timestamp(), if the timestamp config is set but > unsupported, it aborts the trace: > > tools/perf/arch/arm/util/cs-etm.c:cs_etm_validate_timestamp() { > if (!val) > return 0; > > if (cs_etm_get_version(cs_etm_pmu, cpu) == CS_ETMV3) { > pr_err("%s: timestamp not supported in ETMv3...\n"); > return -EINVAL; > } > } > > Does this mean users running perf record --per-thread on such hardware will > now get an error by default unless they explicitly pass timestamp=0? > Yes but the behavior is the same in per-CPU mode so this isn't a new issue. It's easily worked around and nobody has ever complained. >> } >> >> /* >

2 months, 2 weeks

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