[v2] core, x86: Add user return notifiers

Message ID	1253342422-13811-1-git-send-email-avi@redhat.com (mailing list archive)
State	New, archived
Headers	show Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n8J6g23m032206 for <patchwork-kvm@patchwork.kernel.org>; Sat, 19 Sep 2009 06:42:02 GMT From: Avi Kivity <avi@redhat.com> To: Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com> Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Marcelo Tosatti <mtosatti@redhat.com> Subject: [PATCH v2] core, x86: Add user return notifiers Date: Sat, 19 Sep 2009 09:40:22 +0300 Message-Id: <1253342422-13811-1-git-send-email-avi@redhat.com> In-Reply-To: <4AB3CDEC.5050902@zytor.com> References: <4AB3CDEC.5050902@zytor.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk

diff --git a/arch/Kconfig b/arch/Kconfig index beea3cc..b1d0757 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -82,6 +82,13 @@ config KRETPROBES def_bool y depends on KPROBES && HAVE_KRETPROBES +config USER_RETURN_NOTIFIER + bool + depends on HAVE_USER_RETURN_NOTIFIER + help + Provide a kernel-internal notification when a cpu is about to + switch to user mode. + config HAVE_IOREMAP_PROT bool @@ -125,4 +132,7 @@ config HAVE_DMA_API_DEBUG config HAVE_DEFAULT_NO_SPIN_MUTEXES bool +config HAVE_USER_RETURN_NOTIFIER + bool + source "kernel/gcov/Kconfig" diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index fc20fdc..ed21d6a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -50,6 +50,7 @@ config X86 select HAVE_KERNEL_BZIP2 select HAVE_KERNEL_LZMA select HAVE_ARCH_KMEMCHECK + select HAVE_USER_RETURN_NOTIFIER config OUTPUT_FORMAT string diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index d27d0a2..375c917 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -83,6 +83,7 @@ struct thread_info { #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ #define TIF_SECCOMP 8 /* secure computing */ #define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */ +#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ #define TIF_NOTSC 16 /* TSC is not accessible in userland */ #define TIF_IA32 17 /* 32bit process */ #define TIF_FORK 18 /* ret_from_fork */ @@ -107,6 +108,7 @@ struct thread_info { #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) #define _TIF_SECCOMP (1 << TIF_SECCOMP) #define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY) +#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) #define _TIF_NOTSC (1 << TIF_NOTSC) #define _TIF_IA32 (1 << TIF_IA32) #define _TIF_FORK (1 << TIF_FORK) @@ -142,13 +144,14 @@ struct thread_info { /* Only used for 64 bit */ #define _TIF_DO_NOTIFY_MASK \ - (_TIF_SIGPENDING|_TIF_MCE_NOTIFY|_TIF_NOTIFY_RESUME) + (_TIF_SIGPENDING | _TIF_MCE_NOTIFY | _TIF_NOTIFY_RESUME | \ + _TIF_USER_RETURN_NOTIFY) /* flags to check in __switch_to() */ #define _TIF_WORK_CTXSW \ (_TIF_IO_BITMAP|_TIF_DEBUGCTLMSR|_TIF_DS_AREA_MSR|_TIF_NOTSC) -#define _TIF_WORK_CTXSW_PREV _TIF_WORK_CTXSW +#define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW|_TIF_DEBUG) #define PREEMPT_ACTIVE 0x10000000 diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 071166a..7ea6972 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -9,6 +9,7 @@ #include <linux/pm.h> #include <linux/clockchips.h> #include <linux/random.h> +#include <linux/user-return-notifier.h> #include <trace/power.h> #include <asm/system.h> #include <asm/apic.h> @@ -227,6 +228,7 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, */ memset(tss->io_bitmap, 0xff, prev->io_bitmap_max); } + propagate_user_return_notify(prev_p, next_p); } int sys_fork(struct pt_regs *regs) diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 81e5823..13aa99c 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -19,6 +19,7 @@ #include <linux/stddef.h> #include <linux/personality.h> #include <linux/uaccess.h> +#include <linux/user-return-notifier.h> #include <asm/processor.h> #include <asm/ucontext.h> @@ -872,6 +873,8 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) if (current->replacement_session_keyring) key_replace_session_keyring(); } + if (thread_info_flags & _TIF_USER_RETURN_NOTIFY) + fire_user_return_notifiers(); #ifdef CONFIG_X86_32 clear_thread_flag(TIF_IRET); diff --git a/include/linux/user-return-notifier.h b/include/linux/user-return-notifier.h new file mode 100644 index 0000000..ef04e2e --- /dev/null +++ b/include/linux/user-return-notifier.h @@ -0,0 +1,42 @@ +#ifndef _LINUX_USER_RETURN_NOTIFIER_H +#define _LINUX_USER_RETURN_NOTIFIER_H + +#ifdef CONFIG_USER_RETURN_NOTIFIER + +#include <linux/list.h> +#include <linux/sched.h> + +struct user_return_notifier { + void (*on_user_return)(struct user_return_notifier *urn); + struct hlist_node link; +}; + + +void user_return_notifier_register(struct user_return_notifier *urn); +void user_return_notifier_unregister(struct user_return_notifier *urn); + +static inline void propagate_user_return_notify(struct task_struct *prev, + struct task_struct *next) +{ + if (test_tsk_thread_flag(prev, TIF_USER_RETURN_NOTIFY)) { + clear_tsk_thread_flag(prev, TIF_USER_RETURN_NOTIFY); + set_tsk_thread_flag(next, TIF_USER_RETURN_NOTIFY); + } +} + +void fire_user_return_notifiers(void); + +#else + +struct user_return_notifier {}; + +static inline propagate_user_return_notify(struct task_struct *prev, + struct task_struct *next) +{ +} + +static inline void fire_user_return_notifiers(void) {} + +#endif + +#endif diff --git a/kernel/Makefile b/kernel/Makefile index 961379c..f6abe84 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -98,6 +98,7 @@ obj-$(CONFIG_RING_BUFFER) += trace/ obj-$(CONFIG_SMP) += sched_cpupri.o obj-$(CONFIG_SLOW_WORK) += slow-work.o obj-$(CONFIG_PERF_COUNTERS) += perf_counter.o +obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y) # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is diff --git a/kernel/user-return-notifier.c b/kernel/user-return-notifier.c new file mode 100644 index 0000000..530ccb8 --- /dev/null +++ b/kernel/user-return-notifier.c @@ -0,0 +1,46 @@ + +#include <linux/user-return-notifier.h> +#include <linux/percpu.h> +#include <linux/sched.h> +#include <linux/module.h> + +static DEFINE_PER_CPU(struct hlist_head, return_notifier_list); + +#define URN_LIST_HEAD per_cpu(return_notifier_list, raw_smp_processor_id()) + +/* + * Request a notification when the current cpu returns to userspace. Must be + * called in atomic context. The notifier will also be called in atomic + * context. + */ +void user_return_notifier_register(struct user_return_notifier *urn) +{ + set_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY); + hlist_add_head(&urn->link, &URN_LIST_HEAD); +} +EXPORT_SYMBOL_GPL(user_return_notifier_register); + +/* + * Removes a registered user return notifier. Must be called from atomic + * context, and from the same cpu registration occured in. + */ +void user_return_notifier_unregister(struct user_return_notifier *urn) +{ + hlist_del(&urn->link); + if (hlist_empty(&URN_LIST_HEAD)) + clear_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY); +} +EXPORT_SYMBOL_GPL(user_return_notifier_unregister); + +/* Calls registered user return notifiers */ +void fire_user_return_notifiers(void) +{ + struct user_return_notifier *urn; + struct hlist_node *tmp1, *tmp2; + struct hlist_head *head; + + head = &get_cpu_var(return_notifier_list); + hlist_for_each_entry_safe(urn, tmp1, tmp2, head, link) + urn->on_user_return(urn); + put_cpu_var(); +}

[v2] core, x86: Add user return notifiers

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