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Message-ID: <20240206185709.981989497@redhat.com>
Date: Tue, 06 Feb 2024 15:49:17 -0300
From: Marcelo Tosatti <mtosatti@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Daniel Bristot de Oliveira <bristot@...nel.org>,
Juri Lelli <juri.lelli@...hat.com>,
Valentin Schneider <vschneid@...hat.com>,
Frederic Weisbecker <frederic@...nel.org>,
Leonardo Bras <leobras@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Marcelo Tosatti <mtosatti@...hat.com>
Subject: [patch 06/12] perf_event_open: check for block interference CPUs
When creating perf events, return an error rather
than interfering with CPUs tagged as block interference.
Note: this patch is incomplete, installation of perf context
on block interference CPUs via task context is not performed.
Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>
Index: linux-isolation/kernel/events/core.c
===================================================================
--- linux-isolation.orig/kernel/events/core.c
+++ linux-isolation/kernel/events/core.c
@@ -55,6 +55,7 @@
#include <linux/pgtable.h>
#include <linux/buildid.h>
#include <linux/task_work.h>
+#include <linux/sched/isolation.h>
#include "internal.h"
@@ -12435,6 +12436,7 @@ SYSCALL_DEFINE5(perf_event_open,
int err;
int f_flags = O_RDWR;
int cgroup_fd = -1;
+ int idx;
/* for future expandability... */
if (flags & ~PERF_FLAG_ALL)
@@ -12712,6 +12714,26 @@ SYSCALL_DEFINE5(perf_event_open,
goto err_context;
}
+ idx = block_interf_srcu_read_lock();
+ if (!task) {
+ if (move_group) {
+ for_each_sibling_event(sibling, group_leader) {
+ if (block_interf_cpu(sibling->cpu)) {
+ err = -EPERM;
+ goto err_block_interf;
+ }
+ }
+ if (block_interf_cpu(group_leader->cpu)) {
+ err = -EPERM;
+ goto err_block_interf;
+ }
+ }
+ if (block_interf_cpu(event->cpu)) {
+ err = -EPERM;
+ goto err_block_interf;
+ }
+ }
+
/*
* This is the point on no return; we cannot fail hereafter. This is
* where we start modifying current state.
@@ -12775,6 +12797,8 @@ SYSCALL_DEFINE5(perf_event_open,
put_task_struct(task);
}
+ block_interf_srcu_read_unlock(idx);
+
mutex_lock(¤t->perf_event_mutex);
list_add_tail(&event->owner_entry, ¤t->perf_event_list);
mutex_unlock(¤t->perf_event_mutex);
@@ -12789,6 +12813,8 @@ SYSCALL_DEFINE5(perf_event_open,
fd_install(event_fd, event_file);
return event_fd;
+err_block_interf:
+ block_interf_srcu_read_unlock(idx);
err_context:
put_pmu_ctx(event->pmu_ctx);
event->pmu_ctx = NULL; /* _free_event() */
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