From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6AA8C433EF for ; Tue, 15 Mar 2022 19:55:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351534AbiCOT4u (ORCPT ); Tue, 15 Mar 2022 15:56:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351516AbiCOT4o (ORCPT ); Tue, 15 Mar 2022 15:56:44 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 00F5D55BD7 for ; Tue, 15 Mar 2022 12:55:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647374130; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=Gwn64QGuDsJdZxeXUTuYhaHPKQhGEc6DXjrPQtm4DYs=; b=VL8PX+Ei8VTr7sP9FZiaNZHQtT1+Jl5eADZF6pp5fkzFSE4KyMJIDJzqkzAHzW4unLxo9W 0f2yh0xa8ZbJRQ6M+IQKCy5ZvBU3tUfRWZyI4jtOZ3iWn+mKaHux3VOUOtPC++tshEsLfn VVBkgM0/Hv6ImQrewWl/wnfBv2xD85o= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-26-iBOAXlqEPIWfjerKeZa5jw-1; Tue, 15 Mar 2022 15:55:27 -0400 X-MC-Unique: iBOAXlqEPIWfjerKeZa5jw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7D54F803789; Tue, 15 Mar 2022 19:55:26 +0000 (UTC) Received: from fuller.cnet (ovpn-112-3.gru2.redhat.com [10.97.112.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 00876432471; Tue, 15 Mar 2022 19:55:26 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id B473C416D5C1; Tue, 15 Mar 2022 12:33:58 -0300 (-03) Message-ID: <20220315153313.863413290@fedora.localdomain> User-Agent: quilt/0.66 Date: Tue, 15 Mar 2022 12:31:35 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org Cc: Nitesh Lal , Nicolas Saenz Julienne , Frederic Weisbecker , Christoph Lameter , Juri Lelli , Peter Zijlstra , Alex Belits , Peter Xu , Thomas Gleixner , Daniel Bristot de Oliveira , Oscar Shiang , Marcelo Tosatti Subject: [patch v12 03/13] add basic task isolation prctl interface References: <20220315153132.717153751@fedora.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 next patch). Signed-off-by: Marcelo Tosatti --- v11: - Add TIF_TASK_ISOL bit to thread info flags and use it to decide whether to perform task isolation work on return to userspace (Frederic W. Weisbecker) - Fix typo on prctl_task_isoln_cfg_get declaration (Oscar Shiang) v6: - Move oneshot mode enablement to configuration time (Frederic Weisbecker). - Allow more extensions to CFG_SET of ISOL_F_QUIESCE (Frederic Weisbecker). - prctl_task_isolation_activate_get should copy active_mask to address in arg2. v5: - No changes v4: - Switch to structures for parameters when possible (which are more extensible). - Switch to CFG_{S,G}ET naming and drop "internal configuration" prctls (Frederic Weisbecker). v3: - Split in smaller patches (Nitesh Lal). - Misc cleanups (Nitesh Lal). - Clarify nohz_full is not a dependency (Nicolas Saenz). - Incorrect values for prctl definitions (kernel robot). - Save configured state, so applications can activate externally configured task isolation parameters. - Remove "system default" notion (chisol should make it obsolete). v2: - Finer-grained control of quiescing (Frederic Weisbecker / Nicolas Saenz). - Avoid potential regressions by allowing applications to use ISOL_F_QUIESCE_DEFMASK (whose default value is configurable in /sys/). (Nitesh Lal / Nicolas Saenz). include/linux/sched.h | 5 include/linux/task_isolation.h | 91 ++++++++++ include/uapi/linux/prctl.h | 43 +++++ init/init_task.c | 3 kernel/Makefile | 2 kernel/fork.c | 22 ++ kernel/sys.c | 16 + kernel/task_isolation.c | 350 +++++++++++++++++++++++++++++++++++++++++ 8 files changed, 530 insertions(+), 2 deletions(-) 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 @@ -275,4 +275,51 @@ struct prctl_mm_map { #define PR_SET_VMA 0x53564d41 # define PR_SET_VMA_ANON_NAME 0 +#define PR_ISOL_FEAT_GET 63 +#define PR_ISOL_CFG_GET 64 +#define PR_ISOL_CFG_SET 65 + +/* arg2 to CFG_GET/CFG_SET */ +# define I_CFG_FEAT 1 +# define I_CFG_INHERIT 2 + +#define PR_ISOL_ACTIVATE_GET 66 +#define PR_ISOL_ACTIVATE_SET 67 + + +/* Supported features */ +# define ISOL_F_QUIESCE (1UL << 0) + +# define ISOL_F_QUIESCE_MULTIPLE (1UL << 0) +# define ISOL_F_QUIESCE_VMSTATS (1UL << 0) + +struct task_isol_quiesce_extensions { + __u64 flags; + __u64 supported_quiesce_bits; + __u64 pad[6]; +}; + +/* + * This structure provides control over + * inheritance of task isolation across + * clone and fork. + */ +struct task_isol_inherit_control { + __u8 inherit_mask; + __u8 flags; + __u8 pad[6]; +}; + +# define ISOL_INHERIT_CONF (1UL << 0) +# define ISOL_INHERIT_ACTIVE (1UL << 1) + +struct task_isol_quiesce_control { + __u64 flags; + __u64 quiesce_mask; + __u64 quiesce_oneshot_mask; + __u64 pad[5]; +}; + +# define QUIESCE_CONTROL (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_TASK_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 @@ -59,6 +59,7 @@ #include #include #include +#include #include #include #include @@ -2606,6 +2607,21 @@ SYSCALL_DEFINE5(prctl, int, option, unsi case PR_SET_VMA: error = prctl_set_vma(arg2, arg3, arg4, arg5); break; + case PR_ISOL_FEAT_GET: + error = prctl_task_isol_feat_get(arg2, arg3, arg4, arg5); + break; + case PR_ISOL_CFG_GET: + error = prctl_task_isol_cfg_get(arg2, arg3, arg4, arg5); + break; + case PR_ISOL_CFG_SET: + error = prctl_task_isol_cfg_set(arg2, arg3, arg4, arg5); + break; + case PR_ISOL_ACTIVATE_GET: + error = prctl_task_isol_activate_get(arg2, arg3, arg4, arg5); + break; + case PR_ISOL_ACTIVATE_SET: + error = prctl_task_isol_activate_set(arg2, arg3, arg4, arg5); + break; default: error = -EINVAL; break; Index: linux-2.6/include/linux/sched.h =================================================================== --- linux-2.6.orig/include/linux/sched.h +++ linux-2.6/include/linux/sched.h @@ -67,6 +67,7 @@ struct sighand_struct; struct signal_struct; struct task_delay_info; struct task_group; +struct task_isol_info; /* * Task state bitmask. NOTE! These bits are also @@ -1492,6 +1493,10 @@ struct task_struct { struct callback_head l1d_flush_kill; #endif +#ifdef CONFIG_TASK_ISOLATION + struct task_isol_info *task_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 @@ -209,6 +209,9 @@ struct task_struct init_task #ifdef CONFIG_SECCOMP_FILTER .seccomp = { .filter_count = ATOMIC_INIT(0) }, #endif +#ifdef CONFIG_TASK_ISOLATION + .task_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 #include #include +#include #include #include @@ -748,6 +749,7 @@ void __put_task_struct(struct task_struc WARN_ON(refcount_read(&tsk->usage)); WARN_ON(tsk == current); + task_isol_free(tsk); io_uring_free(tsk); cgroup_free(tsk); task_numa_free(tsk, true); @@ -1557,6 +1559,15 @@ out: return error; } +static int copy_task_isol(struct task_struct *tsk) +{ +#ifdef CONFIG_TASK_ISOLATION + if (current->task_isol_info) + return __copy_task_isol(tsk); +#endif + return 0; +} + static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk) { struct sighand_struct *sig; @@ -2129,7 +2140,9 @@ static __latent_entropy struct task_stru RCU_INIT_POINTER(p->bpf_storage, NULL); p->bpf_ctx = NULL; #endif - +#ifdef CONFIG_TASK_ISOLATION + p->task_isol_info = NULL; +#endif /* Perform scheduler related setup. Assign this task to a CPU. */ retval = sched_fork(clone_flags, p); if (retval) @@ -2173,6 +2186,9 @@ static __latent_entropy struct task_stru retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls); if (retval) goto bad_fork_cleanup_io; + retval = copy_task_isol(p); + if (retval) + goto bad_fork_cleanup_thread; stackleak_task_init(p); @@ -2181,7 +2197,7 @@ static __latent_entropy struct task_stru args->set_tid_size); if (IS_ERR(pid)) { retval = PTR_ERR(pid); - goto bad_fork_cleanup_thread; + goto bad_fork_cleanup_task_isol; } } @@ -2410,6 +2426,8 @@ bad_fork_put_pidfd: bad_fork_free_pid: if (pid != &init_struct_pid) free_pid(pid); +bad_fork_cleanup_task_isol: + task_isol_free(p); bad_fork_cleanup_thread: exit_thread(p); bad_fork_cleanup_io: Index: linux-2.6/include/linux/task_isolation.h =================================================================== --- /dev/null +++ linux-2.6/include/linux/task_isolation.h @@ -0,0 +1,91 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef __LINUX_TASK_ISOL_H +#define __LINUX_TASK_ISOL_H + +#ifdef CONFIG_TASK_ISOLATION + +struct task_isol_info { + /* Which features have been configured */ + u64 conf_mask; + /* Which features are active */ + u64 active_mask; + /* Quiesce mask */ + u64 quiesce_mask; + + /* Oneshot mask */ + u64 oneshot_mask; + + u8 inherit_mask; +}; + +extern void __task_isol_free(struct task_struct *tsk); + +static inline void task_isol_free(struct task_struct *tsk) +{ + if (tsk->task_isol_info) + __task_isol_free(tsk); +} + +int prctl_task_isol_feat_get(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5); +int prctl_task_isol_cfg_get(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5); +int prctl_task_isol_cfg_set(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5); +int prctl_task_isol_activate_get(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5); +int prctl_task_isol_activate_set(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5); + +int __copy_task_isol(struct task_struct *tsk); + +#else + +static inline void task_isol_free(struct task_struct *tsk) +{ +} + +static inline int prctl_task_isol_feat_get(unsigned long arg2, + unsigned long arg3, + unsigned long arg4, + unsigned long arg5) +{ + return -EOPNOTSUPP; +} + +static inline int prctl_task_isol_cfg_get(unsigned long arg2, + unsigned long arg3, + unsigned long arg4, + unsigned long arg5) +{ + return -EOPNOTSUPP; +} + +static inline int prctl_task_isol_cfg_set(unsigned long arg2, + unsigned long arg3, + unsigned long arg4, + unsigned long arg5) +{ + return -EOPNOTSUPP; +} + +static inline int prctl_task_isol_activate_get(unsigned long arg2, + unsigned long arg3, + unsigned long arg4, + unsigned long arg5) +{ + return -EOPNOTSUPP; +} + +static inline int prctl_task_isol_activate_set(unsigned long arg2, + unsigned long arg3, + unsigned long arg4, + unsigned long arg5) +{ + return -EOPNOTSUPP; +} + +#endif /* CONFIG_TASK_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 +1,351 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Implementation of task isolation. + * + * Authors: + * Chris Metcalf + * Alex Belits + * Yuri Norov + * Marcelo Tosatti + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +void __task_isol_free(struct task_struct *tsk) +{ + if (!tsk->task_isol_info) + return; + kfree(tsk->task_isol_info); + tsk->task_isol_info = NULL; +} + +static struct task_isol_info *task_isol_alloc_context(void) +{ + struct task_isol_info *info; + + info = kzalloc(sizeof(*info), GFP_KERNEL); + if (unlikely(!info)) + return ERR_PTR(-ENOMEM); + + return info; +} + +int prctl_task_isol_feat_get(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5) +{ + int ret; + void __user *addr = (void __user *) arg3; + + switch (arg2) { + case 0: { + u64 supported_fmask = ISOL_F_QUIESCE; + + ret = 0; + if (copy_to_user(addr, &supported_fmask, sizeof(u64))) + ret = -EFAULT; + + return ret; + } + case ISOL_F_QUIESCE: { + struct task_isol_quiesce_extensions *q_ext; + + q_ext = kzalloc(sizeof(struct task_isol_quiesce_extensions), + GFP_KERNEL); + if (!q_ext) + return -ENOMEM; + + q_ext->supported_quiesce_bits = ISOL_F_QUIESCE_VMSTATS; + + ret = 0; + if (copy_to_user(addr, q_ext, sizeof(*q_ext))) + ret = -EFAULT; + kfree(q_ext); + return ret; + } + default: + break; + } + return -EINVAL; +} + +static int cfg_inherit_get(unsigned long arg3, unsigned long arg4, + unsigned long arg5) +{ + struct task_isol_inherit_control *i_ctrl; + int ret; + void __user *addr = (void __user *) arg3; + + if (!current->task_isol_info) + return -EINVAL; + + i_ctrl = kzalloc(sizeof(struct task_isol_inherit_control), + GFP_KERNEL); + if (!i_ctrl) + return -ENOMEM; + + i_ctrl->inherit_mask = current->task_isol_info->inherit_mask; + + ret = 0; + if (copy_to_user(addr, i_ctrl, sizeof(*i_ctrl))) + ret = -EFAULT; + kfree(i_ctrl); + + return ret; +} + +static int cfg_feat_get(unsigned long arg3, unsigned long arg4, + unsigned long arg5) +{ + int ret = 0; + + switch (arg3) { + case 0: { + void __user *addr = (void __user *)arg4; + u64 cfg_mask = 0; + + if (current->task_isol_info) + cfg_mask = current->task_isol_info->conf_mask; + + if (copy_to_user(addr, &cfg_mask, sizeof(u64))) + ret = -EFAULT; + + return ret; + } + case ISOL_F_QUIESCE: { + struct task_isol_quiesce_control *i_qctrl; + void __user *addr = (void __user *)arg5; + + if (arg4 != QUIESCE_CONTROL) + return -EINVAL; + + i_qctrl = kzalloc(sizeof(struct task_isol_quiesce_control), + GFP_KERNEL); + if (!i_qctrl) + return -ENOMEM; + + if (current->task_isol_info) + i_qctrl->quiesce_mask = current->task_isol_info->quiesce_mask; + + if (copy_to_user(addr, i_qctrl, sizeof(*i_qctrl))) + ret = -EFAULT; + + kfree(i_qctrl); + return ret; + } + default: + break; + } + return -EINVAL; +} + +int prctl_task_isol_cfg_get(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5) +{ + switch (arg2) { + case I_CFG_FEAT: + return cfg_feat_get(arg3, arg4, arg5); + case I_CFG_INHERIT: + return cfg_inherit_get(arg3, arg4, arg5); + default: + break; + } + return -EINVAL; +} + +static int cfg_inherit_set(unsigned long arg3, unsigned long arg4, + unsigned long arg5) +{ + int ret = 0; + struct task_isol_inherit_control *i_ctrl; + const void __user *addr = (const void __user *)arg3; + + i_ctrl = kzalloc(sizeof(struct task_isol_inherit_control), + GFP_KERNEL); + if (!i_ctrl) + return -ENOMEM; + + ret = -EFAULT; + if (copy_from_user(i_ctrl, addr, sizeof(*i_ctrl))) + goto out_free; + + ret = -EINVAL; + if (i_ctrl->inherit_mask & ~(ISOL_INHERIT_CONF|ISOL_INHERIT_ACTIVE)) + goto out_free; + + if (i_ctrl->inherit_mask & ISOL_INHERIT_ACTIVE) + if (!(i_ctrl->inherit_mask & ISOL_INHERIT_CONF)) + goto out_free; + + if (!current->task_isol_info) { + struct task_isol_info *task_isol_info; + + task_isol_info = task_isol_alloc_context(); + if (IS_ERR(task_isol_info)) { + ret = PTR_ERR(task_isol_info); + goto out_free; + } + current->task_isol_info = task_isol_info; + } + + ret = 0; + current->task_isol_info->inherit_mask = i_ctrl->inherit_mask; + +out_free: + kfree(i_ctrl); + + return ret; +} + +static int cfg_feat_quiesce_set(unsigned long arg4, unsigned long arg5) +{ + struct task_isol_info *info; + struct task_isol_quiesce_control *i_qctrl; + int ret = 0; + const void __user *addr = (const void __user *)arg5; + + if (arg4 != QUIESCE_CONTROL) + return -EINVAL; + + i_qctrl = kzalloc(sizeof(struct task_isol_quiesce_control), + GFP_KERNEL); + if (!i_qctrl) + return -ENOMEM; + + ret = -EFAULT; + if (copy_from_user(i_qctrl, addr, sizeof(*i_qctrl))) + goto out_free; + + ret = -EINVAL; + if (i_qctrl->flags != 0) + goto out_free; + + if (i_qctrl->quiesce_mask != ISOL_F_QUIESCE_VMSTATS && + i_qctrl->quiesce_mask != 0) + goto out_free; + + if ((~i_qctrl->quiesce_mask & i_qctrl->quiesce_oneshot_mask) != 0) + goto out_free; + + /* current->task_isol_info is only allocated/freed from task + * context. + */ + if (!current->task_isol_info) { + info = task_isol_alloc_context(); + if (IS_ERR(info)) { + ret = PTR_ERR(info); + goto out_free; + } + current->task_isol_info = info; + } + + info = current->task_isol_info; + + info->quiesce_mask = i_qctrl->quiesce_mask; + info->oneshot_mask = i_qctrl->quiesce_oneshot_mask; + info->conf_mask |= ISOL_F_QUIESCE; + ret = 0; + +out_free: + kfree(i_qctrl); + + return ret; +} + +int prctl_task_isol_cfg_set(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5) +{ + switch (arg2) { + case I_CFG_FEAT: + switch (arg3) { + case ISOL_F_QUIESCE: + return cfg_feat_quiesce_set(arg4, arg5); + default: + break; + } + break; + case I_CFG_INHERIT: + return cfg_inherit_set(arg3, arg4, arg5); + default: + break; + } + return -EINVAL; +} + +int __copy_task_isol(struct task_struct *tsk) +{ + struct task_isol_info *info, *new_info; + + info = current->task_isol_info; + if (!(info->inherit_mask & (ISOL_INHERIT_CONF|ISOL_INHERIT_ACTIVE))) + return 0; + + new_info = task_isol_alloc_context(); + if (IS_ERR(new_info)) + return PTR_ERR(new_info); + + new_info->inherit_mask = info->inherit_mask; + + if (info->inherit_mask & ISOL_INHERIT_CONF) { + new_info->quiesce_mask = info->quiesce_mask; + new_info->conf_mask = info->conf_mask; + new_info->oneshot_mask = info->oneshot_mask; + } + + if (info->inherit_mask & ISOL_INHERIT_ACTIVE) + new_info->active_mask = info->active_mask; + + tsk->task_isol_info = new_info; + + return 0; +} + +int prctl_task_isol_activate_set(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5) +{ + int ret; + struct task_isol_info *info; + u64 active_mask; + const void __user *addr_mask = (const void __user *)arg2; + + ret = -EFAULT; + if (copy_from_user(&active_mask, addr_mask, sizeof(u64))) + goto out; + + ret = -EINVAL; + if (active_mask != ISOL_F_QUIESCE && active_mask != 0) + return ret; + + info = current->task_isol_info; + if (!info) + return ret; + + info->active_mask = active_mask; + ret = 0; + +out: + return ret; +} + +int prctl_task_isol_activate_get(unsigned long arg2, unsigned long arg3, + unsigned long arg4, unsigned long arg5) +{ + struct task_isol_info *task_isol_info; + void __user *addr_mask = (void __user *)arg2; + + task_isol_info = current->task_isol_info; + if (!task_isol_info) + return -EINVAL; + + if (copy_to_user(addr_mask, &task_isol_info->active_mask, sizeof(u64))) + return -EFAULT; + + return 0; +} Index: linux-2.6/init/Kconfig =================================================================== --- linux-2.6.orig/init/Kconfig +++ linux-2.6/init/Kconfig @@ -675,6 +675,22 @@ config CPU_ISOLATION Say Y if unsure. +config TASK_ISOLATION + bool "Task isolation prctl()" + depends on GENERIC_ENTRY + default n + help + 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 an OS noise free environment for the application, this option + enables the task isolation prctl interface, which allows userspace to + inform the kernel the start and end of the latency sensitive application + section (with configurable system behaviour for that section). + + Say N if unsure. + source "kernel/rcu/Kconfig" config BUILD_BIN2C