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Message-Id: <b05607c3ce0d3ce52de1784823ef9f6de324283c.1755096883.git.robin.murphy@arm.com>
Date: Wed, 13 Aug 2025 18:01:05 +0100
From: Robin Murphy <robin.murphy@....com>
To: peterz@...radead.org,
mingo@...hat.com,
will@...nel.org,
mark.rutland@....com,
acme@...nel.org,
namhyung@...nel.org,
alexander.shishkin@...ux.intel.com,
jolsa@...nel.org,
irogers@...gle.com,
adrian.hunter@...el.com,
kan.liang@...ux.intel.com
Cc: linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-alpha@...r.kernel.org,
linux-snps-arc@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org,
imx@...ts.linux.dev,
linux-csky@...r.kernel.org,
loongarch@...ts.linux.dev,
linux-mips@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org,
linux-sh@...r.kernel.org,
sparclinux@...r.kernel.org,
linux-pm@...r.kernel.org,
linux-rockchip@...ts.infradead.org,
dmaengine@...r.kernel.org,
linux-fpga@...r.kernel.org,
amd-gfx@...ts.freedesktop.org,
dri-devel@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org,
intel-xe@...ts.freedesktop.org,
coresight@...ts.linaro.org,
iommu@...ts.linux.dev,
linux-amlogic@...ts.infradead.org,
linux-cxl@...r.kernel.org,
linux-arm-msm@...r.kernel.org,
linux-riscv@...ts.infradead.org
Subject: [PATCH 13/19] perf: Add helper for checking grouped events
Several drivers cannot support groups, but enforce this inconsistently
(including not at all) in their event_init routines. Add a helper so
that such drivers can simply and robustly check for the acceptable
conditions that their event is either standalone, or the first one
being added to a software-only group.
In particular it took a while to see that marvell_cn10k_tad_pmu was
seemingly trying to rely on the empirical behaviour of perf tool
creating group leader events with disabled=1 and subsequent siblings
with disabled=0. Down with this sort of thing!
Signed-off-by: Robin Murphy <robin.murphy@....com>
---
arch/x86/events/amd/ibs.c | 30 ++++++---------------------
drivers/devfreq/event/rockchip-dfi.c | 3 +++
drivers/perf/alibaba_uncore_drw_pmu.c | 11 +---------
drivers/perf/arm_dmc620_pmu.c | 12 +----------
drivers/perf/dwc_pcie_pmu.c | 10 ++-------
drivers/perf/marvell_cn10k_tad_pmu.c | 6 ++----
drivers/perf/marvell_pem_pmu.c | 11 ++--------
include/linux/perf_event.h | 7 +++++++
8 files changed, 24 insertions(+), 66 deletions(-)
diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 112f43b23ebf..95de309fc7d5 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -248,27 +248,6 @@ int forward_event_to_ibs(struct perf_event *event)
return -ENOENT;
}
-/*
- * Grouping of IBS events is not possible since IBS can have only
- * one event active at any point in time.
- */
-static int validate_group(struct perf_event *event)
-{
- struct perf_event *sibling;
-
- if (event->group_leader == event)
- return 0;
-
- if (event->group_leader->pmu == event->pmu)
- return -EINVAL;
-
- for_each_sibling_event(sibling, event->group_leader) {
- if (sibling->pmu == event->pmu)
- return -EINVAL;
- }
- return 0;
-}
-
static bool perf_ibs_ldlat_event(struct perf_ibs *perf_ibs,
struct perf_event *event)
{
@@ -309,9 +288,12 @@ static int perf_ibs_init(struct perf_event *event)
event->attr.exclude_hv))
return -EINVAL;
- ret = validate_group(event);
- if (ret)
- return ret;
+ /*
+ * Grouping of IBS events is not possible since IBS can have only
+ * one event active at any point in time.
+ */
+ if (in_hardware_group(event))
+ return -EINVAL;
if (hwc->sample_period) {
if (config & perf_ibs->cnt_mask)
diff --git a/drivers/devfreq/event/rockchip-dfi.c b/drivers/devfreq/event/rockchip-dfi.c
index 0470d7c175f4..88a9ecbe96ce 100644
--- a/drivers/devfreq/event/rockchip-dfi.c
+++ b/drivers/devfreq/event/rockchip-dfi.c
@@ -413,6 +413,9 @@ static int rockchip_ddr_perf_event_init(struct perf_event *event)
dev_warn(dfi->dev, "Can't provide per-task data!\n");
return -EINVAL;
}
+ /* Disallow groups since we can't start/stop/read multiple counters at once */
+ if (in_hardware_group(event))
+ return -EINVAL;
return 0;
}
diff --git a/drivers/perf/alibaba_uncore_drw_pmu.c b/drivers/perf/alibaba_uncore_drw_pmu.c
index 99a0ef9817e0..0081618741c3 100644
--- a/drivers/perf/alibaba_uncore_drw_pmu.c
+++ b/drivers/perf/alibaba_uncore_drw_pmu.c
@@ -526,7 +526,6 @@ static int ali_drw_pmu_event_init(struct perf_event *event)
{
struct ali_drw_pmu *drw_pmu = to_ali_drw_pmu(event->pmu);
struct hw_perf_event *hwc = &event->hw;
- struct perf_event *sibling;
struct device *dev = drw_pmu->pmu.dev;
if (event->attr.type != event->pmu->type)
@@ -548,19 +547,11 @@ static int ali_drw_pmu_event_init(struct perf_event *event)
return -EOPNOTSUPP;
}
- if (event->group_leader != event &&
- !is_software_event(event->group_leader)) {
+ if (in_hardware_group(event)) {
dev_err(dev, "driveway only allow one event!\n");
return -EINVAL;
}
- for_each_sibling_event(sibling, event->group_leader) {
- if (sibling != event && !is_software_event(sibling)) {
- dev_err(dev, "driveway event not allowed!\n");
- return -EINVAL;
- }
- }
-
/* reset all the pmu counters */
writel(ALI_DRW_PMU_CNT_RST, drw_pmu->cfg_base + ALI_DRW_PMU_CNT_CTRL);
diff --git a/drivers/perf/arm_dmc620_pmu.c b/drivers/perf/arm_dmc620_pmu.c
index 619cf937602f..24308de80246 100644
--- a/drivers/perf/arm_dmc620_pmu.c
+++ b/drivers/perf/arm_dmc620_pmu.c
@@ -513,7 +513,6 @@ static int dmc620_pmu_event_init(struct perf_event *event)
{
struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
struct hw_perf_event *hwc = &event->hw;
- struct perf_event *sibling;
if (event->attr.type != event->pmu->type)
return -ENOENT;
@@ -544,22 +543,13 @@ static int dmc620_pmu_event_init(struct perf_event *event)
hwc->idx = -1;
- if (event->group_leader == event)
- return 0;
-
/*
* We can't atomically disable all HW counters so only one event allowed,
* although software events are acceptable.
*/
- if (!is_software_event(event->group_leader))
+ if (in_hardware_group(event))
return -EINVAL;
- for_each_sibling_event(sibling, event->group_leader) {
- if (sibling != event &&
- !is_software_event(sibling))
- return -EINVAL;
- }
-
return 0;
}
diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
index 146ff57813fb..78c522658d84 100644
--- a/drivers/perf/dwc_pcie_pmu.c
+++ b/drivers/perf/dwc_pcie_pmu.c
@@ -353,7 +353,6 @@ static int dwc_pcie_pmu_event_init(struct perf_event *event)
{
struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
- struct perf_event *sibling;
u32 lane;
if (event->attr.type != event->pmu->type)
@@ -367,15 +366,10 @@ static int dwc_pcie_pmu_event_init(struct perf_event *event)
if (event->cpu < 0 || event->attach_state & PERF_ATTACH_TASK)
return -EINVAL;
- if (event->group_leader != event &&
- !is_software_event(event->group_leader))
+ /* Disallow groups since we can't start/stop/read multiple counters at once */
+ if (in_hardware_group(event))
return -EINVAL;
- for_each_sibling_event(sibling, event->group_leader) {
- if (sibling->pmu != event->pmu && !is_software_event(sibling))
- return -EINVAL;
- }
-
if (type < 0 || type >= DWC_PCIE_EVENT_TYPE_MAX)
return -EINVAL;
diff --git a/drivers/perf/marvell_cn10k_tad_pmu.c b/drivers/perf/marvell_cn10k_tad_pmu.c
index 51ccb0befa05..ee6505cb01a7 100644
--- a/drivers/perf/marvell_cn10k_tad_pmu.c
+++ b/drivers/perf/marvell_cn10k_tad_pmu.c
@@ -152,10 +152,8 @@ static int tad_pmu_event_init(struct perf_event *event)
if (event->attr.type != event->pmu->type)
return -ENOENT;
- if (!event->attr.disabled)
- return -EINVAL;
-
- if (event->state != PERF_EVENT_STATE_OFF)
+ /* Disallow groups since we can't start/stop/read multiple counters at once */
+ if (in_hardware_group(event))
return -EINVAL;
event->cpu = tad_pmu->cpu;
diff --git a/drivers/perf/marvell_pem_pmu.c b/drivers/perf/marvell_pem_pmu.c
index 29fbcd1848e4..53a35a5de7f8 100644
--- a/drivers/perf/marvell_pem_pmu.c
+++ b/drivers/perf/marvell_pem_pmu.c
@@ -190,7 +190,6 @@ static int pem_perf_event_init(struct perf_event *event)
{
struct pem_pmu *pmu = to_pem_pmu(event->pmu);
struct hw_perf_event *hwc = &event->hw;
- struct perf_event *sibling;
if (event->attr.type != event->pmu->type)
return -ENOENT;
@@ -206,16 +205,10 @@ static int pem_perf_event_init(struct perf_event *event)
if (event->cpu < 0)
return -EOPNOTSUPP;
- /* We must NOT create groups containing mixed PMUs */
- if (event->group_leader->pmu != event->pmu &&
- !is_software_event(event->group_leader))
+ /* Disallow groups since we can't start/stop/read multiple counters at once */
+ if (in_hardware_group(event))
return -EINVAL;
- for_each_sibling_event(sibling, event->group_leader) {
- if (sibling->pmu != event->pmu &&
- !is_software_event(sibling))
- return -EINVAL;
- }
/*
* Set ownership of event to one CPU, same event can not be observed
* on multiple cpus at same time.
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index ec9d96025683..4d439c24c901 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1556,6 +1556,13 @@ static inline int in_software_context(struct perf_event *event)
return event->pmu_ctx->pmu->task_ctx_nr == perf_sw_context;
}
+/* True if the event has (or would have) any non-software siblings */
+static inline bool in_hardware_group(const struct perf_event *event)
+{
+ return event != event->group_leader &&
+ !in_software_context(event->group_leader);
+}
+
static inline int is_exclusive_pmu(struct pmu *pmu)
{
return pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE;
--
2.39.2.101.g768bb238c484.dirty
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