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Message-ID: <20210730202010.240095394@fuller.cnet>
Date: Fri, 30 Jul 2021 17:18:28 -0300
From: Marcelo Tosatti <mtosatti@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Nitesh Lal <nilal@...hat.com>,
Nicolas Saenz Julienne <nsaenzju@...hat.com>,
Frederic Weisbecker <frederic@...nel.org>,
Christoph Lameter <cl@...ux.com>,
Juri Lelli <juri.lelli@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Alex Belits <abelits@...its.com>, Peter Xu <peterx@...hat.com>,
Marcelo Tosatti <mtosatti@...hat.com>
Subject: [patch 1/4] add basic task isolation prctl interface
Add basic prctl task isolation interface, which allows
informing the kernel that application is executing
latency sensitive code (where interruptions are undesired).
Interface is described by task_isolation.rst (added by this patch).
Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>
Index: linux-2.6/Documentation/userspace-api/task_isolation.rst
===================================================================
--- /dev/null
+++ linux-2.6/Documentation/userspace-api/task_isolation.rst
@@ -0,0 +1,187 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===============================
+Task isolation prctl interface
+===============================
+
+Certain types of applications benefit from running uninterrupted by
+background OS activities. Realtime systems and high-bandwidth networking
+applications with user-space drivers can fall into the category.
+
+
+To create a OS noise free environment for the application, this
+interface allows userspace to inform the kernel the start and
+end of the latency sensitive application section (with configurable
+system behaviour for that section).
+
+The prctl options are:
+
+
+ - PR_ISOL_FEAT: Retrieve supported features.
+ - PR_ISOL_GET: Retrieve task isolation parameters.
+ - PR_ISOL_SET: Set task isolation parameters.
+ - PR_ISOL_CTRL_GET: Retrieve task isolation state.
+ - PR_ISOL_CTRL_SET: Set task isolation state (enable/disable task isolation).
+
+The isolation parameters and state are not inherited by
+children created by fork(2) and clone(2). The setting is
+preserved across execve(2).
+
+The sequence of steps to enable task isolation are:
+
+1. Retrieve supported task isolation features (PR_ISOL_FEAT).
+
+2. Configure task isolation features (PR_ISOL_SET/PR_ISOL_GET).
+
+3. Activate or deactivate task isolation features
+ (PR_ISOL_CTRL_GET/PR_ISOL_CTRL_SET).
+
+This interface is based on ideas and code from the
+task isolation patchset from Alex Belits:
+https://lwn.net/Articles/816298/
+
+--------------------
+Feature description
+--------------------
+
+ - ``ISOL_F_QUIESCE``
+
+ This feature allows quiescing select kernel activities on
+ return from system calls.
+
+---------------------
+Interface description
+---------------------
+
+**PR_ISOL_FEAT**:
+
+ Returns the supported features and feature
+ capabilities, as a bitmask. Features and its capabilities
+ are defined at include/uapi/linux/task_isolation.h::
+
+ prctl(PR_ISOL_FEAT, feat, arg3, arg4, arg5);
+
+ The 'feat' argument specifies whether to return
+ supported features (if zero), or feature capabilities
+ (if not zero). Possible non-zero values for 'feat' are:
+
+ - ``ISOL_F_QUIESCE``:
+
+ If arg3 is zero, returns a bitmask containing
+ which kernel activities are supported for quiescing.
+
+ If arg3 is ISOL_F_QUIESCE_DEFMASK, returns
+ default_quiesce_mask, a system-wide configurable.
+ See description of default_quiesce_mask below.
+
+**PR_ISOL_GET**:
+
+ Retrieve task isolation feature configuration.
+ The general format is::
+
+ prctl(PR_ISOL_GET, feat, arg3, arg4, arg5);
+
+ Possible values for feat are:
+
+ - ``ISOL_F_QUIESCE``:
+
+ Returns a bitmask containing which kernel
+ activities are enabled for quiescing.
+
+
+**PR_ISOL_SET**:
+
+ Configures task isolation features. The general format is::
+
+ prctl(PR_ISOL_SET, feat, arg3, arg4, arg5);
+
+ The 'feat' argument specifies which feature to configure.
+ Possible values for feat are:
+
+ - ``ISOL_F_QUIESCE``:
+
+ The 'arg3' argument is a bitmask specifying which
+ kernel activities to quiesce. Possible bit sets are:
+
+ - ``ISOL_F_QUIESCE_VMSTATS``
+
+ VM statistics are maintained in per-CPU counters to
+ improve performance. When a CPU modifies a VM statistic,
+ this modification is kept in the per-CPU counter.
+ Certain activities require a global count, which
+ involves requesting each CPU to flush its local counters
+ to the global VM counters.
+
+ This flush is implemented via a workqueue item, which
+ might schedule a workqueue on isolated CPUs.
+
+ To avoid this interruption, task isolation can be
+ configured to, upon return from system calls, synchronize
+ the per-CPU counters to global counters, thus avoiding
+ the interruption.
+
+ To ensure the application returns to userspace
+ with no modified per-CPU counters, its necessary to
+ use mlockall() in addition to this isolcpus flag.
+
+**PR_ISOL_CTRL_GET**:
+
+ Retrieve task isolation control.
+
+ prctl(PR_ISOL_CTRL_GET, 0, 0, 0, 0);
+
+ Returns which isolation features are active.
+
+**PR_ISOL_CTRL_SET**:
+
+ Activates/deactivates task isolation control.
+
+ prctl(PR_ISOL_CTRL_SET, mask, 0, 0, 0);
+
+ The 'mask' argument specifies which features
+ to activate (bit set) or deactivate (bit clear).
+
+ For ISOL_F_QUIESCE, quiescing of background activities
+ happens on return to userspace from the
+ prctl(PR_ISOL_CTRL_SET) call, and on return from
+ subsequent system calls.
+
+ Quiescing can be adjusted (while active) by
+ prctl(PR_ISOL_SET, ISOL_F_QUIESCE, ...).
+
+--------------------
+Default quiesce mask
+--------------------
+
+Applications can either explicitly specify individual
+background activities that should be quiesced, or
+obtain a system configurable value, which is to be
+configured by the system admin/mgmt system.
+
+/sys/kernel/task_isolation/available_quiesce lists, as
+one string per line, the activities which the kernel
+supports quiescing.
+
+To configure the default quiesce mask, write a comma separated
+list of strings (from available_quiesce) to
+/sys/kernel/task_isolation/default_quiesce.
+
+echo > /sys/kernel/task_isolation/default_quiesce disables
+all quiescing via ISOL_F_QUIESCE_DEFMASK.
+
+Using ISOL_F_QUIESCE_DEFMASK allows for the application to
+take advantage of future quiescing capabilities without
+modification (provided default_quiesce is configured
+accordingly).
+
+See PR_ISOL_FEAT subsection of "Interface description" section
+for more details. samples/task_isolation/task_isolation.c
+contains an example.
+
+Examples
+========
+
+The ``samples/task_isolation/`` directory contains sample
+applications.
+
+
Index: linux-2.6/include/uapi/linux/prctl.h
===================================================================
--- linux-2.6.orig/include/uapi/linux/prctl.h
+++ linux-2.6/include/uapi/linux/prctl.h
@@ -267,4 +267,17 @@ struct prctl_mm_map {
# define PR_SCHED_CORE_SHARE_FROM 3 /* pull core_sched cookie to pid */
# define PR_SCHED_CORE_MAX 4
+/* Task isolation control */
+#define PR_ISOL_FEAT 62
+#define PR_ISOL_GET 63
+#define PR_ISOL_SET 64
+#define PR_ISOL_CTRL_GET 65
+#define PR_ISOL_CTRL_SET 66
+
+# define ISOL_F_QUIESCE (1UL << 0)
+# define ISOL_F_QUIESCE_VMSTATS (1UL << 0)
+
+# define ISOL_F_QUIESCE_DEFMASK (1UL << 0)
+
+
#endif /* _LINUX_PRCTL_H */
Index: linux-2.6/kernel/Makefile
===================================================================
--- linux-2.6.orig/kernel/Makefile
+++ linux-2.6/kernel/Makefile
@@ -132,6 +132,8 @@ obj-$(CONFIG_WATCH_QUEUE) += watch_queue
obj-$(CONFIG_RESOURCE_KUNIT_TEST) += resource_kunit.o
obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o
+obj-$(CONFIG_CPU_ISOLATION) += task_isolation.o
+
CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN)
obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o
KASAN_SANITIZE_stackleak.o := n
Index: linux-2.6/kernel/sys.c
===================================================================
--- linux-2.6.orig/kernel/sys.c
+++ linux-2.6/kernel/sys.c
@@ -58,6 +58,7 @@
#include <linux/sched/coredump.h>
#include <linux/sched/task.h>
#include <linux/sched/cputime.h>
+#include <linux/task_isolation.h>
#include <linux/rcupdate.h>
#include <linux/uidgid.h>
#include <linux/cred.h>
@@ -2567,6 +2568,21 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
error = sched_core_share_pid(arg2, arg3, arg4, arg5);
break;
#endif
+ case PR_ISOL_FEAT:
+ error = prctl_task_isolation_feat(arg2, arg3, arg4, arg5);
+ break;
+ case PR_ISOL_GET:
+ error = prctl_task_isolation_get(arg2, arg3, arg4, arg5);
+ break;
+ case PR_ISOL_SET:
+ error = prctl_task_isolation_set(arg2, arg3, arg4, arg5);
+ break;
+ case PR_ISOL_CTRL_GET:
+ error = prctl_task_isolation_ctrl_get(arg2, arg3, arg4, arg5);
+ break;
+ case PR_ISOL_CTRL_SET:
+ error = prctl_task_isolation_ctrl_set(arg2, arg3, arg4, arg5);
+ break;
default:
error = -EINVAL;
break;
Index: linux-2.6/samples/task_isolation/task_isolation.c
===================================================================
--- /dev/null
+++ linux-2.6/samples/task_isolation/task_isolation.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <sys/mman.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/prctl.h>
+#include <linux/prctl.h>
+
+int main(void)
+{
+ int ret, defmask;
+ void *buf = malloc(4096);
+
+ memset(buf, 1, 4096);
+ ret = mlock(buf, 4096);
+ if (ret) {
+ perror("mlock");
+ return EXIT_FAILURE;
+ }
+
+ ret = prctl(PR_ISOL_FEAT, 0, 0, 0, 0);
+ if (ret == -1) {
+ perror("prctl PR_ISOL_FEAT");
+ return EXIT_FAILURE;
+ }
+ printf("supported features bitmask: 0x%x\n", ret);
+
+ if (!(ret & ISOL_F_QUIESCE)) {
+ printf("quiesce feature unsupported, quitting\n");
+ return EXIT_FAILURE;
+ }
+
+ ret = prctl(PR_ISOL_FEAT, ISOL_F_QUIESCE, 0, 0, 0);
+ if (ret == -1) {
+ perror("prctl PR_ISOL_FEAT (ISOL_F_QUIESCE)");
+ return EXIT_FAILURE;
+ }
+ printf("supported ISOL_F_QUIESCE bits: 0x%x\n", ret);
+
+ ret = prctl(PR_ISOL_FEAT, ISOL_F_QUIESCE, ISOL_F_QUIESCE_DEFMASK,
+ 0, 0);
+ if (ret == -1) {
+ perror("prctl PR_ISOL_FEAT (ISOL_F_QUIESCE, DEFMASK)");
+ return EXIT_FAILURE;
+ }
+
+ defmask = ret;
+ printf("default ISOL_F_QUIESCE bits: 0x%x\n", defmask);
+
+ /*
+ * Application can either set the value from ISOL_F_QUIESCE_DEFMASK,
+ * which is configurable through
+ * /sys/kernel/task_isolation/default_quiesce, or specific values.
+ *
+ * Using ISOL_F_QUIESCE_DEFMASK allows for the application to
+ * take advantage of future quiescing capabilities without
+ * modification (provided default_quiesce is configured
+ * accordingly).
+ */
+ defmask = defmask | ISOL_F_QUIESCE_VMSTATS;
+
+ ret = prctl(PR_ISOL_SET, ISOL_F_QUIESCE, defmask,
+ 0, 0);
+ if (ret == -1) {
+ perror("prctl PR_ISOL_SET");
+ return EXIT_FAILURE;
+ }
+
+ ret = prctl(PR_ISOL_CTRL_SET, ISOL_F_QUIESCE, 0, 0, 0);
+ if (ret == -1) {
+ perror("prctl PR_ISOL_CTRL_SET (ISOL_F_QUIESCE)");
+ return EXIT_FAILURE;
+ }
+
+#define NR_LOOPS 999999999
+#define NR_PRINT 100000000
+ /* busy loop */
+ while (ret < NR_LOOPS) {
+ memset(buf, 0, 4096);
+ ret = ret+1;
+ if (!(ret % NR_PRINT))
+ printf("loops=%d of %d\n", ret, NR_LOOPS);
+ }
+
+ ret = prctl(PR_ISOL_CTRL_SET, 0, 0, 0, 0);
+ if (ret == -1) {
+ perror("prctl PR_ISOL_CTRL_SET (0)");
+ exit(0);
+ }
+
+ return EXIT_SUCCESS;
+}
+
Index: linux-2.6/include/linux/sched.h
===================================================================
--- linux-2.6.orig/include/linux/sched.h
+++ linux-2.6/include/linux/sched.h
@@ -66,6 +66,7 @@ struct sighand_struct;
struct signal_struct;
struct task_delay_info;
struct task_group;
+struct isol_info;
/*
* Task state bitmask. NOTE! These bits are also
@@ -1400,6 +1401,10 @@ struct task_struct {
struct llist_head kretprobe_instances;
#endif
+#ifdef CONFIG_CPU_ISOLATION
+ struct isol_info *isol_info;
+#endif
+
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.
Index: linux-2.6/init/init_task.c
===================================================================
--- linux-2.6.orig/init/init_task.c
+++ linux-2.6/init/init_task.c
@@ -213,6 +213,9 @@ struct task_struct init_task
#ifdef CONFIG_SECCOMP_FILTER
.seccomp = { .filter_count = ATOMIC_INIT(0) },
#endif
+#ifdef CONFIG_CPU_ISOLATION
+ .isol_info = NULL,
+#endif
};
EXPORT_SYMBOL(init_task);
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c
+++ linux-2.6/kernel/fork.c
@@ -97,6 +97,7 @@
#include <linux/scs.h>
#include <linux/io_uring.h>
#include <linux/bpf.h>
+#include <linux/task_isolation.h>
#include <asm/pgalloc.h>
#include <linux/uaccess.h>
@@ -734,6 +735,7 @@ void __put_task_struct(struct task_struc
WARN_ON(refcount_read(&tsk->usage));
WARN_ON(tsk == current);
+ tsk_isol_exit(tsk);
io_uring_free(tsk);
cgroup_free(tsk);
task_numa_free(tsk, true);
@@ -2084,7 +2086,9 @@ static __latent_entropy struct task_stru
#ifdef CONFIG_BPF_SYSCALL
RCU_INIT_POINTER(p->bpf_storage, NULL);
#endif
-
+#ifdef CONFIG_CPU_ISOLATION
+ p->isol_info = NULL;
+#endif
/* Perform scheduler related setup. Assign this task to a CPU. */
retval = sched_fork(clone_flags, p);
if (retval)
Index: linux-2.6/include/linux/task_isolation.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/task_isolation.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __LINUX_TASK_ISOL_H
+#define __LINUX_TASK_ISOL_H
+
+#ifdef CONFIG_CPU_ISOLATION
+
+struct isol_info {
+ /* Which features are active */
+ unsigned long active_mask;
+ /* Quiesce mask */
+ unsigned long quiesce_mask;
+};
+
+extern void __tsk_isol_exit(struct task_struct *tsk);
+
+static inline void tsk_isol_exit(struct task_struct *tsk)
+{
+ if (tsk->isol_info)
+ __tsk_isol_exit(tsk);
+}
+
+
+int prctl_task_isolation_feat(unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5);
+int prctl_task_isolation_get(unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5);
+int prctl_task_isolation_set(unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5);
+int prctl_task_isolation_ctrl_get(unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5);
+int prctl_task_isolation_ctrl_set(unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5);
+
+#else
+
+static inline void tsk_isol_exit(struct task_struct *tsk)
+{
+}
+
+static inline int prctl_task_isolation_feat(unsigned long arg2,
+ unsigned long arg3,
+ unsigned long arg4,
+ unsigned long arg5)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int prctl_task_isolation_get(unsigned long arg2,
+ unsigned long arg3,
+ unsigned long arg4,
+ unsigned long arg5)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int prctl_task_isolation_set(unsigned long arg2,
+ unsigned long arg3,
+ unsigned long arg4,
+ unsigned long arg5)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int prctl_task_isolation_ctrl_get(unsigned long arg2,
+ unsigned long arg3,
+ unsigned long arg4,
+ unsigned long arg5)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int prctl_task_isolation_ctrl_set(unsigned long arg2,
+ unsigned long arg3,
+ unsigned long arg4,
+ unsigned long arg5)
+{
+ return -EOPNOTSUPP;
+}
+
+#endif /* CONFIG_CPU_ISOLATION */
+
+#endif /* __LINUX_TASK_ISOL_H */
Index: linux-2.6/kernel/task_isolation.c
===================================================================
--- /dev/null
+++ linux-2.6/kernel/task_isolation.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Implementation of task isolation.
+ *
+ * Authors:
+ * Chris Metcalf <cmetcalf@...lanox.com>
+ * Alex Belits <abelits@...its.com>
+ * Yuri Norov <ynorov@...vell.com>
+ * Marcelo Tosatti <mtosatti@...hat.com>
+ */
+
+#include <linux/sched.h>
+#include <linux/task_isolation.h>
+#include <linux/prctl.h>
+#include <linux/slab.h>
+#include <linux/kobject.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/init.h>
+
+static unsigned long default_quiesce_mask;
+
+static int tsk_isol_alloc_context(struct task_struct *task)
+{
+ struct isol_info *info;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (unlikely(!info))
+ return -ENOMEM;
+
+ task->isol_info = info;
+ return 0;
+}
+
+void __tsk_isol_exit(struct task_struct *tsk)
+{
+ kfree(tsk->isol_info);
+ tsk->isol_info = NULL;
+}
+
+static int prctl_task_isolation_feat_quiesce(unsigned long type)
+{
+ switch (type) {
+ case 0:
+ return ISOL_F_QUIESCE_VMSTATS;
+ case ISOL_F_QUIESCE_DEFMASK:
+ return default_quiesce_mask;
+ default:
+ break;
+ }
+
+ return -EINVAL;
+}
+
+static int task_isolation_get_quiesce(void)
+{
+ if (current->isol_info != NULL)
+ return current->isol_info->quiesce_mask;
+
+ return 0;
+}
+
+static int task_isolation_set_quiesce(unsigned long quiesce_mask)
+{
+ if (quiesce_mask != ISOL_F_QUIESCE_VMSTATS && quiesce_mask != 0)
+ return -EINVAL;
+
+ current->isol_info->quiesce_mask = quiesce_mask;
+ return 0;
+}
+
+int prctl_task_isolation_feat(unsigned long feat, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ switch (feat) {
+ case 0:
+ return ISOL_F_QUIESCE;
+ case ISOL_F_QUIESCE:
+ return prctl_task_isolation_feat_quiesce(arg3);
+ default:
+ break;
+ }
+ return -EINVAL;
+}
+
+int prctl_task_isolation_get(unsigned long feat, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ switch (feat) {
+ case ISOL_F_QUIESCE:
+ return task_isolation_get_quiesce();
+ default:
+ break;
+ }
+ return -EINVAL;
+}
+
+int prctl_task_isolation_set(unsigned long feat, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ int ret;
+ bool err_free_ctx = false;
+
+ if (current->isol_info == NULL)
+ err_free_ctx = true;
+
+ ret = tsk_isol_alloc_context(current);
+ if (ret)
+ return ret;
+
+ switch (feat) {
+ case ISOL_F_QUIESCE:
+ ret = task_isolation_set_quiesce(arg3);
+ if (ret)
+ break;
+ return 0;
+ default:
+ break;
+ }
+
+ if (err_free_ctx)
+ __tsk_isol_exit(current);
+ return -EINVAL;
+}
+
+int prctl_task_isolation_ctrl_set(unsigned long feat, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ if (current->isol_info == NULL)
+ return -EINVAL;
+
+ if (feat != ISOL_F_QUIESCE && feat != 0)
+ return -EINVAL;
+
+ current->isol_info->active_mask = feat;
+ return 0;
+}
+
+int prctl_task_isolation_ctrl_get(unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ if (current->isol_info == NULL)
+ return 0;
+
+ return current->isol_info->active_mask;
+}
+
+struct qoptions {
+ unsigned long mask;
+ char *name;
+};
+
+static struct qoptions qopts[] = {
+ {ISOL_F_QUIESCE_VMSTATS, "vmstat"},
+};
+
+#define QLEN (sizeof(qopts) / sizeof(struct qoptions))
+
+static ssize_t default_quiesce_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ char *p, *s;
+ unsigned long defmask = 0;
+
+ s = (char *)buf;
+ if (count == 1 && strlen(strim(s)) == 0) {
+ default_quiesce_mask = 0;
+ return count;
+ }
+
+ while ((p = strsep(&s, ",")) != NULL) {
+ int i;
+ bool found = false;
+
+ if (!*p)
+ continue;
+
+ for (i = 0; i < QLEN; i++) {
+ struct qoptions *opt = &qopts[i];
+
+ if (strncmp(strim(p), opt->name, strlen(opt->name)) == 0) {
+ defmask |= opt->mask;
+ found = true;
+ break;
+ }
+ }
+ if (found == true)
+ continue;
+ return -EINVAL;
+ }
+ default_quiesce_mask = defmask;
+
+ return count;
+}
+
+#define MAXARRLEN 100
+
+static ssize_t default_quiesce_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ int i;
+ char tbuf[MAXARRLEN] = "";
+
+ for (i = 0; i < QLEN; i++) {
+ struct qoptions *opt = &qopts[i];
+
+ if (default_quiesce_mask & opt->mask) {
+ strlcat(tbuf, opt->name, MAXARRLEN);
+ strlcat(tbuf, "\n", MAXARRLEN);
+ }
+ }
+
+ return sprintf(buf, "%s", tbuf);
+}
+
+static struct kobj_attribute default_quiesce_attr =
+ __ATTR_RW(default_quiesce);
+
+static ssize_t available_quiesce_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ int i;
+ char tbuf[MAXARRLEN] = "";
+
+ for (i = 0; i < QLEN; i++) {
+ struct qoptions *opt = &qopts[i];
+
+ strlcat(tbuf, opt->name, MAXARRLEN);
+ strlcat(tbuf, "\n", MAXARRLEN);
+ }
+
+ return sprintf(buf, "%s", tbuf);
+}
+
+static struct kobj_attribute available_quiesce_attr =
+ __ATTR_RO(available_quiesce);
+
+static struct attribute *task_isol_attrs[] = {
+ &available_quiesce_attr.attr,
+ &default_quiesce_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group task_isol_attr_group = {
+ .attrs = task_isol_attrs,
+ .bin_attrs = NULL,
+};
+
+static int __init task_isol_ksysfs_init(void)
+{
+ int ret;
+ struct kobject *task_isol_kobj;
+
+ task_isol_kobj = kobject_create_and_add("task_isolation",
+ kernel_kobj);
+ if (!task_isol_kobj) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ ret = sysfs_create_group(task_isol_kobj, &task_isol_attr_group);
+ if (ret)
+ goto out_task_isol_kobj;
+
+ return 0;
+
+out_task_isol_kobj:
+ kobject_put(task_isol_kobj);
+out:
+ return ret;
+}
+
+arch_initcall(task_isol_ksysfs_init);
Index: linux-2.6/samples/Kconfig
===================================================================
--- linux-2.6.orig/samples/Kconfig
+++ linux-2.6/samples/Kconfig
@@ -223,4 +223,11 @@ config SAMPLE_WATCH_QUEUE
Build example userspace program to use the new mount_notify(),
sb_notify() syscalls and the KEYCTL_WATCH_KEY keyctl() function.
+config SAMPLE_TASK_ISOLATION
+ bool "task isolation sample"
+ depends on CC_CAN_LINK && HEADERS_INSTALL
+ help
+ Build example userspace program to use prctl task isolation
+ interface.
+
endif # SAMPLES
Index: linux-2.6/samples/Makefile
===================================================================
--- linux-2.6.orig/samples/Makefile
+++ linux-2.6/samples/Makefile
@@ -30,3 +30,4 @@ obj-$(CONFIG_SAMPLE_INTEL_MEI) += mei/
subdir-$(CONFIG_SAMPLE_WATCHDOG) += watchdog
subdir-$(CONFIG_SAMPLE_WATCH_QUEUE) += watch_queue
obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak/
+subdir-$(CONFIG_SAMPLE_TASK_ISOLATION) += task_isolation
Index: linux-2.6/samples/task_isolation/Makefile
===================================================================
--- /dev/null
+++ linux-2.6/samples/task_isolation/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+userprogs-always-y += task_isolation
+
+userccflags += -I usr/include
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