10 files changed, 141 insertions, 52 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 50a1d1f9b6d3..20c49b8450b8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -97,6 +97,7 @@ config X86
         select KTIME_SCALAR if X86_32
         select GENERIC_STRNCPY_FROM_USER
         select GENERIC_STRNLEN_USER
+        select HAVE_RCU_USER_QS if X86_64
 
 config INSTRUCTION_DECODER
         def_bool (KPROBES || PERF_EVENTS || UPROBES)
diff --git a/arch/x86/include/asm/rcu.h b/arch/x86/include/asm/rcu.h
new file mode 100644
index 000000000000..d1ac07a23979
--- /dev/null
+++ b/arch/x86/include/asm/rcu.h
@@ -0,0 +1,32 @@
+#ifndef _ASM_X86_RCU_H
+#define _ASM_X86_RCU_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/rcupdate.h>
+#include <asm/ptrace.h>
+
+static inline void exception_enter(struct pt_regs *regs)
+{
+        rcu_user_exit();
+}
+
+static inline void exception_exit(struct pt_regs *regs)
+{
+#ifdef CONFIG_RCU_USER_QS
+        if (user_mode(regs))
+                rcu_user_enter();
+#endif
+}
+
+#else /* __ASSEMBLY__ */
+
+#ifdef CONFIG_RCU_USER_QS
+# define SCHEDULE_USER call schedule_user
+#else
+# define SCHEDULE_USER call schedule
+#endif
+
+#endif /* !__ASSEMBLY__ */
+
+#endif
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 89f794f007ec..c535d847e3b5 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -89,6 +89,7 @@ struct thread_info {
 #define TIF_NOTSC               16      /* TSC is not accessible in userland */
 #define TIF_IA32                17      /* IA32 compatibility process */
 #define TIF_FORK                18      /* ret_from_fork */
+#define TIF_NOHZ                19      /* in adaptive nohz mode */
 #define TIF_MEMDIE              20      /* is terminating due to OOM killer */
 #define TIF_DEBUG               21      /* uses debug registers */
 #define TIF_IO_BITMAP           22      /* uses I/O bitmap */
@@ -114,6 +115,7 @@ struct thread_info {
 #define _TIF_NOTSC              (1 << TIF_NOTSC)
 #define _TIF_IA32               (1 << TIF_IA32)
 #define _TIF_FORK               (1 << TIF_FORK)
+#define _TIF_NOHZ               (1 << TIF_NOHZ)
 #define _TIF_DEBUG              (1 << TIF_DEBUG)
 #define _TIF_IO_BITMAP          (1 << TIF_IO_BITMAP)
 #define _TIF_FORCED_TF          (1 << TIF_FORCED_TF)
@@ -126,12 +128,13 @@ struct thread_info {
 /* work to do in syscall_trace_enter() */
 #define _TIF_WORK_SYSCALL_ENTRY \
         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT |   \
-         _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT)
+         _TIF_SECCOMP | _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT |     \
+         _TIF_NOHZ)
 
 /* work to do in syscall_trace_leave() */
 #define _TIF_WORK_SYSCALL_EXIT  \
         (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP |    \
-         _TIF_SYSCALL_TRACEPOINT)
+         _TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK                                                  \
@@ -141,7 +144,8 @@ struct thread_info {
 
 /* work to do on any return to user space */
 #define _TIF_ALLWORK_MASK                                               \
-        ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT)
+        ((0x0000FFFF & ~_TIF_SECCOMP) | _TIF_SYSCALL_TRACEPOINT |       \
+        _TIF_NOHZ)
 
 /* Only used for 64 bit */
 #define _TIF_DO_NOTIFY_MASK                                             \
diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
index 39472dd2323f..60c78917190c 100644
--- a/arch/x86/kernel/cpuid.c
+++ b/arch/x86/kernel/cpuid.c
@@ -199,12 +199,14 @@ static int __init cpuid_init(void)
                 goto out_chrdev;
         }
         cpuid_class->devnode = cpuid_devnode;
+        get_online_cpus();
         for_each_online_cpu(i) {
                 err = cpuid_device_create(i);
                 if (err != 0)
                         goto out_class;
         }
         register_hotcpu_notifier(&cpuid_class_cpu_notifier);
+        put_online_cpus();
 
         err = 0;
         goto out;
@@ -214,6 +216,7 @@ out_class:
         for_each_online_cpu(i) {
                 cpuid_device_destroy(i);
         }
+        put_online_cpus();
         class_destroy(cpuid_class);
 out_chrdev:
         __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
@@ -225,11 +228,13 @@ static void __exit cpuid_exit(void)
 {
         int cpu = 0;
 
+        get_online_cpus();
         for_each_online_cpu(cpu)
                 cpuid_device_destroy(cpu);
         class_destroy(cpuid_class);
         __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
         unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);
+        put_online_cpus();
 }
 
 module_init(cpuid_init);
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 69babd8c834f..1a8f3cbb6ee3 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -56,6 +56,7 @@
 #include <asm/ftrace.h>
 #include <asm/percpu.h>
 #include <asm/asm.h>
+#include <asm/rcu.h>
 #include <linux/err.h>
 
 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
@@ -565,7 +566,7 @@ sysret_careful:
         TRACE_IRQS_ON
         ENABLE_INTERRUPTS(CLBR_NONE)
         pushq_cfi %rdi
-        call schedule
+        SCHEDULE_USER
         popq_cfi %rdi
         jmp sysret_check
 
@@ -678,7 +679,7 @@ int_careful:
         TRACE_IRQS_ON
         ENABLE_INTERRUPTS(CLBR_NONE)
         pushq_cfi %rdi
-        call schedule
+        SCHEDULE_USER
         popq_cfi %rdi
         DISABLE_INTERRUPTS(CLBR_NONE)
         TRACE_IRQS_OFF
@@ -974,7 +975,7 @@ retint_careful:
         TRACE_IRQS_ON
         ENABLE_INTERRUPTS(CLBR_NONE)
         pushq_cfi %rdi
-        call  schedule
+        SCHEDULE_USER
         popq_cfi %rdi
         GET_THREAD_INFO(%rcx)
         DISABLE_INTERRUPTS(CLBR_NONE)
@@ -1449,7 +1450,7 @@ paranoid_userspace:
 paranoid_schedule:
         TRACE_IRQS_ON
         ENABLE_INTERRUPTS(CLBR_ANY)
-        call schedule
+        SCHEDULE_USER
         DISABLE_INTERRUPTS(CLBR_ANY)
         TRACE_IRQS_OFF
         jmp paranoid_userspace
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index eb113693f043..a7c5661f8496 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -257,12 +257,14 @@ static int __init msr_init(void)
                 goto out_chrdev;
         }
         msr_class->devnode = msr_devnode;
+        get_online_cpus();
         for_each_online_cpu(i) {
                 err = msr_device_create(i);
                 if (err != 0)
                         goto out_class;
         }
         register_hotcpu_notifier(&msr_class_cpu_notifier);
+        put_online_cpus();
 
         err = 0;
         goto out;
@@ -271,6 +273,7 @@ out_class:
         i = 0;
         for_each_online_cpu(i)
                 msr_device_destroy(i);
+        put_online_cpus();
         class_destroy(msr_class);
 out_chrdev:
         __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
@@ -281,11 +284,13 @@ out:
 static void __exit msr_exit(void)
 {
         int cpu = 0;
+        get_online_cpus();
         for_each_online_cpu(cpu)
                 msr_device_destroy(cpu);
         class_destroy(msr_class);
         __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
         unregister_hotcpu_notifier(&msr_class_cpu_notifier);
+        put_online_cpus();
 }
 
 module_init(msr_init);
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index c4c6a5c2bf0f..9f94f8ec26e4 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -21,6 +21,7 @@
 #include <linux/signal.h>
 #include <linux/perf_event.h>
 #include <linux/hw_breakpoint.h>
+#include <linux/rcupdate.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -1463,6 +1464,8 @@ long syscall_trace_enter(struct pt_regs *regs)
 {
         long ret = 0;
 
+        rcu_user_exit();
+
         /*
          * If we stepped into a sysenter/syscall insn, it trapped in
          * kernel mode; do_debug() cleared TF and set TIF_SINGLESTEP.
@@ -1526,4 +1529,6 @@ void syscall_trace_leave(struct pt_regs *regs)
                         !test_thread_flag(TIF_SYSCALL_EMU);
         if (step || test_thread_flag(TIF_SYSCALL_TRACE))
                 tracehook_report_syscall_exit(regs, step);
+
+        rcu_user_enter();
 }
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index b280908a376e..bca0ab903e57 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -779,6 +779,8 @@ static void do_signal(struct pt_regs *regs)
 void
 do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 {
+        rcu_user_exit();
+
 #ifdef CONFIG_X86_MCE
         /* notify userspace of pending MCEs */
         if (thread_info_flags & _TIF_MCE_NOTIFY)
@@ -804,6 +806,8 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 #ifdef CONFIG_X86_32
         clear_thread_flag(TIF_IRET);
 #endif /* CONFIG_X86_32 */
+
+        rcu_user_enter();
 }
 
 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b481341c9369..378967578f22 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -55,6 +55,7 @@
 #include <asm/i387.h>
 #include <asm/fpu-internal.h>
 #include <asm/mce.h>
+#include <asm/rcu.h>
 
 #include <asm/mach_traps.h>
 
@@ -180,11 +181,15 @@ vm86_trap:
 #define DO_ERROR(trapnr, signr, str, name)                              \
 dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
 {                                                                       \
-        if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
-                                                        == NOTIFY_STOP) \
+        exception_enter(regs);                                          \
+        if (notify_die(DIE_TRAP, str, regs, error_code,                 \
+                        trapnr, signr) == NOTIFY_STOP) {                \
+                exception_exit(regs);                                   \
                 return;                                                 \
+        }                                                               \
         conditional_sti(regs);                                          \
         do_trap(trapnr, signr, str, regs, error_code, NULL);            \
+        exception_exit(regs);                                           \
 }
 
 #define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)         \
@@ -195,11 +200,15 @@ dotraplinkage void do_##name(struct pt_regs *regs, long error_code)	\
         info.si_errno = 0;                                              \
         info.si_code = sicode;                                          \
         info.si_addr = (void __user *)siaddr;                           \
-        if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
-                                                        == NOTIFY_STOP) \
+        exception_enter(regs);                                          \
+        if (notify_die(DIE_TRAP, str, regs, error_code,                 \
+                        trapnr, signr) == NOTIFY_STOP) {                \
+                exception_exit(regs);                                   \
                 return;                                                 \
+        }                                                               \
         conditional_sti(regs);                                          \
         do_trap(trapnr, signr, str, regs, error_code, &info);           \
+        exception_exit(regs);                                           \
 }
 
 DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV,
@@ -222,12 +231,14 @@ DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check,
 /* Runs on IST stack */
 dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
 {
+        exception_enter(regs);
         if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
-                        X86_TRAP_SS, SIGBUS) == NOTIFY_STOP)
-                return;
-        preempt_conditional_sti(regs);
-        do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
-        preempt_conditional_cli(regs);
+                       X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
+                preempt_conditional_sti(regs);
+                do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
+                preempt_conditional_cli(regs);
+        }
+        exception_exit(regs);
 }
 
 dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
@@ -235,6 +246,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
         static const char str[] = "double fault";
         struct task_struct *tsk = current;
 
+        exception_enter(regs);
         /* Return not checked because double check cannot be ignored */
         notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
 
@@ -255,16 +267,29 @@ do_general_protection(struct pt_regs *regs, long error_code)
 {
         struct task_struct *tsk;
 
+        exception_enter(regs);
         conditional_sti(regs);
 
 #ifdef CONFIG_X86_32
-        if (regs->flags & X86_VM_MASK)
-                goto gp_in_vm86;
+        if (regs->flags & X86_VM_MASK) {
+                local_irq_enable();
+                handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
+                goto exit;
+        }
 #endif
 
         tsk = current;
-        if (!user_mode(regs))
-                goto gp_in_kernel;
+        if (!user_mode(regs)) {
+                if (fixup_exception(regs))
+                        goto exit;
+
+                tsk->thread.error_code = error_code;
+                tsk->thread.trap_nr = X86_TRAP_GP;
+                if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
+                               X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP)
+                        die("general protection fault", regs, error_code);
+                goto exit;
+        }
 
         tsk->thread.error_code = error_code;
         tsk->thread.trap_nr = X86_TRAP_GP;
@@ -279,25 +304,8 @@ do_general_protection(struct pt_regs *regs, long error_code)
         }
 
         force_sig(SIGSEGV, tsk);
-        return;
-
-#ifdef CONFIG_X86_32
-gp_in_vm86:
-        local_irq_enable();
-        handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
-        return;
-#endif
-
-gp_in_kernel:
-        if (fixup_exception(regs))
-                return;
-
-        tsk->thread.error_code = error_code;
-        tsk->thread.trap_nr = X86_TRAP_GP;
-        if (notify_die(DIE_GPF, "general protection fault", regs, error_code,
-                        X86_TRAP_GP, SIGSEGV) == NOTIFY_STOP)
-                return;
-        die("general protection fault", regs, error_code);
+exit:
+        exception_exit(regs);
 }
 
 /* May run on IST stack. */
@@ -312,15 +320,16 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
             ftrace_int3_handler(regs))
                 return;
 #endif
+        exception_enter(regs);
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
         if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
                                 SIGTRAP) == NOTIFY_STOP)
-                return;
+                goto exit;
 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 
         if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
                         SIGTRAP) == NOTIFY_STOP)
-                return;
+                goto exit;
 
         /*
          * Let others (NMI) know that the debug stack is in use
@@ -331,6 +340,8 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
         do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL);
         preempt_conditional_cli(regs);
         debug_stack_usage_dec();
+exit:
+        exception_exit(regs);
 }
 
 #ifdef CONFIG_X86_64
@@ -391,6 +402,8 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
         unsigned long dr6;
         int si_code;
 
+        exception_enter(regs);
+
         get_debugreg(dr6, 6);
 
         /* Filter out all the reserved bits which are preset to 1 */
@@ -406,7 +419,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 
         /* Catch kmemcheck conditions first of all! */
         if ((dr6 & DR_STEP) && kmemcheck_trap(regs))
-                return;
+                goto exit;
 
         /* DR6 may or may not be cleared by the CPU */
         set_debugreg(0, 6);
@@ -421,7 +434,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 
         if (notify_die(DIE_DEBUG, "debug", regs, PTR_ERR(&dr6), error_code,
                                                         SIGTRAP) == NOTIFY_STOP)
-                return;
+                goto exit;
 
         /*
          * Let others (NMI) know that the debug stack is in use
@@ -437,7 +450,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
                                         X86_TRAP_DB);
                 preempt_conditional_cli(regs);
                 debug_stack_usage_dec();
-                return;
+                goto exit;
         }
 
         /*
@@ -458,7 +471,8 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
         preempt_conditional_cli(regs);
         debug_stack_usage_dec();
 
-        return;
+exit:
+        exception_exit(regs);
 }
 
 /*
@@ -555,14 +569,17 @@ dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
 #ifdef CONFIG_X86_32
         ignore_fpu_irq = 1;
 #endif
-
+        exception_enter(regs);
         math_error(regs, error_code, X86_TRAP_MF);
+        exception_exit(regs);
 }
 
 dotraplinkage void
 do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 {
+        exception_enter(regs);
         math_error(regs, error_code, X86_TRAP_XF);
+        exception_exit(regs);
 }
 
 dotraplinkage void
@@ -629,6 +646,7 @@ EXPORT_SYMBOL_GPL(math_state_restore);
 dotraplinkage void __kprobes
 do_device_not_available(struct pt_regs *regs, long error_code)
 {
+        exception_enter(regs);
 #ifdef CONFIG_MATH_EMULATION
         if (read_cr0() & X86_CR0_EM) {
                 struct math_emu_info info = { };
@@ -637,6 +655,7 @@ do_device_not_available(struct pt_regs *regs, long error_code)
 
                 info.regs = regs;
                 math_emulate(&info);
+                exception_exit(regs);
                 return;
         }
 #endif
@@ -644,12 +663,15 @@ do_device_not_available(struct pt_regs *regs, long error_code)
 #ifdef CONFIG_X86_32
         conditional_sti(regs);
 #endif
+        exception_exit(regs);
 }
 
 #ifdef CONFIG_X86_32
 dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
 {
         siginfo_t info;
+
+        exception_enter(regs);
         local_irq_enable();
 
         info.si_signo = SIGILL;
@@ -657,10 +679,11 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
         info.si_code = ILL_BADSTK;
         info.si_addr = NULL;
         if (notify_die(DIE_TRAP, "iret exception", regs, error_code,
-                        X86_TRAP_IRET, SIGILL) == NOTIFY_STOP)
-                return;
-        do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
-                &info);
+                        X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {
+                do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
+                        &info);
+        }
+        exception_exit(regs);
 }
 #endif
 
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 76dcd9d8e0bc..7dde46d68a25 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -18,6 +18,7 @@
 #include <asm/pgalloc.h>                /* pgd_*(), ...                 */
 #include <asm/kmemcheck.h>              /* kmemcheck_*(), ...           */
 #include <asm/fixmap.h>                 /* VSYSCALL_START               */
+#include <asm/rcu.h>                    /* exception_enter(), ...       */
 
 /*
  * Page fault error code bits:
@@ -1000,8 +1001,8 @@ static int fault_in_kernel_space(unsigned long address)
  * and the problem, and then passes it off to one of the appropriate
  * routines.
  */
-dotraplinkage void __kprobes
-do_page_fault(struct pt_regs *regs, unsigned long error_code)
+static void __kprobes
+__do_page_fault(struct pt_regs *regs, unsigned long error_code)
 {
         struct vm_area_struct *vma;
         struct task_struct *tsk;
@@ -1209,3 +1210,11 @@ good_area:
 
         up_read(&mm->mmap_sem);
 }
+
+dotraplinkage void __kprobes
+do_page_fault(struct pt_regs *regs, unsigned long error_code)
+{
+        exception_enter(regs);
+        __do_page_fault(regs, error_code);
+        exception_exit(regs);
+}