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Message-Id: <20210408103605.1676875-4-elver@google.com>
Date: Thu, 8 Apr 2021 12:35:58 +0200
From: Marco Elver <elver@...gle.com>
To: elver@...gle.com, peterz@...radead.org,
alexander.shishkin@...ux.intel.com, acme@...nel.org,
mingo@...hat.com, jolsa@...hat.com, mark.rutland@....com,
namhyung@...nel.org, tglx@...utronix.de
Cc: glider@...gle.com, viro@...iv.linux.org.uk, arnd@...db.de,
christian@...uner.io, dvyukov@...gle.com, jannh@...gle.com,
axboe@...nel.dk, mascasa@...gle.com, pcc@...gle.com,
irogers@...gle.com, oleg@...hat.com, kasan-dev@...glegroups.com,
linux-arch@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, x86@...nel.org,
linux-kselftest@...r.kernel.org
Subject: [PATCH v4 03/10] perf: Support only inheriting events if cloned with CLONE_THREAD
Adds bit perf_event_attr::inherit_thread, to restricting inheriting
events only if the child was cloned with CLONE_THREAD.
This option supports the case where an event is supposed to be
process-wide only (including subthreads), but should not propagate
beyond the current process's shared environment.
Link: https://lore.kernel.org/lkml/YBvj6eJR%2FDY2TsEB@hirez.programming.kicks-ass.net/
Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Marco Elver <elver@...gle.com>
---
v2:
* Add patch to series.
---
include/linux/perf_event.h | 5 +++--
include/uapi/linux/perf_event.h | 3 ++-
kernel/events/core.c | 21 ++++++++++++++-------
kernel/fork.c | 2 +-
4 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 3d478abf411c..1660039199b2 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -958,7 +958,7 @@ extern void __perf_event_task_sched_in(struct task_struct *prev,
struct task_struct *task);
extern void __perf_event_task_sched_out(struct task_struct *prev,
struct task_struct *next);
-extern int perf_event_init_task(struct task_struct *child);
+extern int perf_event_init_task(struct task_struct *child, u64 clone_flags);
extern void perf_event_exit_task(struct task_struct *child);
extern void perf_event_free_task(struct task_struct *task);
extern void perf_event_delayed_put(struct task_struct *task);
@@ -1449,7 +1449,8 @@ perf_event_task_sched_in(struct task_struct *prev,
static inline void
perf_event_task_sched_out(struct task_struct *prev,
struct task_struct *next) { }
-static inline int perf_event_init_task(struct task_struct *child) { return 0; }
+static inline int perf_event_init_task(struct task_struct *child,
+ u64 clone_flags) { return 0; }
static inline void perf_event_exit_task(struct task_struct *child) { }
static inline void perf_event_free_task(struct task_struct *task) { }
static inline void perf_event_delayed_put(struct task_struct *task) { }
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index ad15e40d7f5d..813efb65fea8 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -389,7 +389,8 @@ struct perf_event_attr {
cgroup : 1, /* include cgroup events */
text_poke : 1, /* include text poke events */
build_id : 1, /* use build id in mmap2 events */
- __reserved_1 : 29;
+ inherit_thread : 1, /* children only inherit if cloned with CLONE_THREAD */
+ __reserved_1 : 28;
union {
__u32 wakeup_events; /* wakeup every n events */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index a9a0a46909af..de2917b3c59e 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -11649,6 +11649,9 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
(attr->sample_type & PERF_SAMPLE_WEIGHT_STRUCT))
return -EINVAL;
+ if (!attr->inherit && attr->inherit_thread)
+ return -EINVAL;
+
out:
return ret;
@@ -12869,12 +12872,13 @@ static int
inherit_task_group(struct perf_event *event, struct task_struct *parent,
struct perf_event_context *parent_ctx,
struct task_struct *child, int ctxn,
- int *inherited_all)
+ u64 clone_flags, int *inherited_all)
{
int ret;
struct perf_event_context *child_ctx;
- if (!event->attr.inherit) {
+ if (!event->attr.inherit ||
+ (event->attr.inherit_thread && !(clone_flags & CLONE_THREAD))) {
*inherited_all = 0;
return 0;
}
@@ -12906,7 +12910,8 @@ inherit_task_group(struct perf_event *event, struct task_struct *parent,
/*
* Initialize the perf_event context in task_struct
*/
-static int perf_event_init_context(struct task_struct *child, int ctxn)
+static int perf_event_init_context(struct task_struct *child, int ctxn,
+ u64 clone_flags)
{
struct perf_event_context *child_ctx, *parent_ctx;
struct perf_event_context *cloned_ctx;
@@ -12946,7 +12951,8 @@ static int perf_event_init_context(struct task_struct *child, int ctxn)
*/
perf_event_groups_for_each(event, &parent_ctx->pinned_groups) {
ret = inherit_task_group(event, parent, parent_ctx,
- child, ctxn, &inherited_all);
+ child, ctxn, clone_flags,
+ &inherited_all);
if (ret)
goto out_unlock;
}
@@ -12962,7 +12968,8 @@ static int perf_event_init_context(struct task_struct *child, int ctxn)
perf_event_groups_for_each(event, &parent_ctx->flexible_groups) {
ret = inherit_task_group(event, parent, parent_ctx,
- child, ctxn, &inherited_all);
+ child, ctxn, clone_flags,
+ &inherited_all);
if (ret)
goto out_unlock;
}
@@ -13004,7 +13011,7 @@ static int perf_event_init_context(struct task_struct *child, int ctxn)
/*
* Initialize the perf_event context in task_struct
*/
-int perf_event_init_task(struct task_struct *child)
+int perf_event_init_task(struct task_struct *child, u64 clone_flags)
{
int ctxn, ret;
@@ -13013,7 +13020,7 @@ int perf_event_init_task(struct task_struct *child)
INIT_LIST_HEAD(&child->perf_event_list);
for_each_task_context_nr(ctxn) {
- ret = perf_event_init_context(child, ctxn);
+ ret = perf_event_init_context(child, ctxn, clone_flags);
if (ret) {
perf_event_free_task(child);
return ret;
diff --git a/kernel/fork.c b/kernel/fork.c
index 426cd0c51f9e..f592c9a0272a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2084,7 +2084,7 @@ static __latent_entropy struct task_struct *copy_process(
if (retval)
goto bad_fork_cleanup_policy;
- retval = perf_event_init_task(p);
+ retval = perf_event_init_task(p, clone_flags);
if (retval)
goto bad_fork_cleanup_policy;
retval = audit_alloc(p);
--
2.31.0.208.g409f899ff0-goog
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