MIPS: Implement HAVE_CONTEXT_TRACKING.

This enables support for CONFIG_NO_HZ_FULL.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

 config MIPS
 	bool
 	default y
+	select HAVE_CONTEXT_TRACKING
 	select HAVE_GENERIC_DMA_COHERENT
 	select HAVE_IDE
 	select HAVE_OPROFILE

arch/mips/include/asm/thread_info.h

@@ -109,6 +109,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_RESTORE_SIGMASK	9	/* restore signal mask in do_signal() */
 #define TIF_USEDFPU		16	/* FPU was used by this task this quantum (SMP) */
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
+#define TIF_NOHZ		19	/* in adaptive nohz mode */
 #define TIF_FIXADE		20	/* Fix address errors in software */
 #define TIF_LOGADE		21	/* Log address errors to syslog */
 #define TIF_32BIT_REGS		22	/* also implies 16/32 fprs */
@@ -124,6 +125,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SECCOMP		(1<<TIF_SECCOMP)
 #define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)
 #define _TIF_USEDFPU		(1<<TIF_USEDFPU)
+#define _TIF_NOHZ		(1<<TIF_NOHZ)
 #define _TIF_FIXADE		(1<<TIF_FIXADE)
 #define _TIF_LOGADE		(1<<TIF_LOGADE)
 #define _TIF_32BIT_REGS		(1<<TIF_32BIT_REGS)
@@ -131,16 +133,19 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_FPUBOUND		(1<<TIF_FPUBOUND)
 #define _TIF_LOAD_WATCH		(1<<TIF_LOAD_WATCH)
 
-#define _TIF_WORK_SYSCALL_ENTRY	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
+#define _TIF_WORK_SYSCALL_ENTRY	(_TIF_NOHZ | _TIF_SYSCALL_TRACE |	\
+				 _TIF_SYSCALL_AUDIT)
 
 /* work to do in syscall_trace_leave() */
-#define _TIF_WORK_SYSCALL_EXIT	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT)
+#define _TIF_WORK_SYSCALL_EXIT	(_TIF_NOHZ | _TIF_SYSCALL_TRACE |	\
+				 _TIF_SYSCALL_AUDIT)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK		\
 	(_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_NOTIFY_RESUME)
 /* work to do on any return to u-space */
-#define _TIF_ALLWORK_MASK	(_TIF_WORK_MASK | _TIF_WORK_SYSCALL_EXIT)
+#define _TIF_ALLWORK_MASK	(_TIF_NOHZ | _TIF_WORK_MASK |		\
+				 _TIF_WORK_SYSCALL_EXIT)
 
 #endif /* __KERNEL__ */
 

arch/mips/kernel/cpu-bugs64.c

@@ -6,6 +6,7 @@
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  */
+#include <linux/context_tracking.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/ptrace.h>
@@ -171,8 +172,12 @@ static volatile int daddi_ov __cpuinitdata;
 
 asmlinkage void __init do_daddi_ov(struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
 	daddi_ov = 1;
 	regs->cp0_epc += 4;
+	exception_exit(prev_state);
 }
 
 static inline void check_daddi(void)

arch/mips/kernel/ptrace.c

@@ -15,6 +15,7 @@
  * binaries.
  */
 #include <linux/compiler.h>
+#include <linux/context_tracking.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -534,6 +535,8 @@ static inline int audit_arch(void)
  */
 asmlinkage void syscall_trace_enter(struct pt_regs *regs)
 {
+	user_exit();
+
 	/* do the secure computing check first */
 	secure_computing_strict(regs->regs[2]);
 
@@ -570,6 +573,13 @@ asmlinkage void syscall_trace_enter(struct pt_regs *regs)
  */
 asmlinkage void syscall_trace_leave(struct pt_regs *regs)
 {
+        /*
+	 * We may come here right after calling schedule_user()
+	 * or do_notify_resume(), in which case we can be in RCU
+	 * user mode.
+	 */
+	user_exit();
+
 	audit_syscall_exit(regs);
 
 	if (!(current->ptrace & PT_PTRACED))
@@ -592,4 +602,6 @@ asmlinkage void syscall_trace_leave(struct pt_regs *regs)
 		send_sig(current->exit_code, current, 1);
 		current->exit_code = 0;
 	}
+
+	user_enter();
 }

arch/mips/kernel/signal.c

@@ -8,6 +8,7 @@
  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
  */
 #include <linux/cache.h>
+#include <linux/context_tracking.h>
 #include <linux/irqflags.h>
 #include <linux/sched.h>
 #include <linux/mm.h>
@@ -573,6 +574,8 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 {
 	local_irq_enable();
 
+	user_exit();
+
 	/* deal with pending signal delivery */
 	if (thread_info_flags & _TIF_SIGPENDING)
 		do_signal(regs);
@@ -581,6 +584,8 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
 		clear_thread_flag(TIF_NOTIFY_RESUME);
 		tracehook_notify_resume(regs);
 	}
+
+	user_enter();
 }
 
 #ifdef CONFIG_SMP

arch/mips/kernel/traps.c

@@ -13,6 +13,7 @@
  */
 #include <linux/bug.h>
 #include <linux/compiler.h>
+#include <linux/context_tracking.h>
 #include <linux/kexec.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
@@ -423,7 +424,9 @@ asmlinkage void do_be(struct pt_regs *regs)
 	const struct exception_table_entry *fixup = NULL;
 	int data = regs->cp0_cause & 4;
 	int action = MIPS_BE_FATAL;
+	enum ctx_state prev_state;
 
+	prev_state = exception_enter();
 	/* XXX For now.	 Fixme, this searches the wrong table ...  */
 	if (data && !user_mode(regs))
 		fixup = search_dbe_tables(exception_epc(regs));
@@ -436,11 +439,11 @@ asmlinkage void do_be(struct pt_regs *regs)
 
 	switch (action) {
 	case MIPS_BE_DISCARD:
-		return;
+		goto out;
 	case MIPS_BE_FIXUP:
 		if (fixup) {
 			regs->cp0_epc = fixup->nextinsn;
-			return;
+			goto out;
 		}
 		break;
 	default:
@@ -455,10 +458,13 @@ asmlinkage void do_be(struct pt_regs *regs)
 	       field, regs->cp0_epc, field, regs->regs[31]);
 	if (notify_die(DIE_OOPS, "bus error", regs, 0, regs_to_trapnr(regs), SIGBUS)
 	    == NOTIFY_STOP)
-		return;
+		goto out;
 
 	die_if_kernel("Oops", regs);
 	force_sig(SIGBUS, current);
+
+out:
+	exception_exit(prev_state);
 }
 
 /*
@@ -673,8 +679,10 @@ static int simulate_sync(struct pt_regs *regs, unsigned int opcode)
 
 asmlinkage void do_ov(struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
 	siginfo_t info;
 
+	prev_state = exception_enter();
 	die_if_kernel("Integer overflow", regs);
 
 	info.si_code = FPE_INTOVF;
@@ -682,6 +690,7 @@ asmlinkage void do_ov(struct pt_regs *regs)
 	info.si_errno = 0;
 	info.si_addr = (void __user *) regs->cp0_epc;
 	force_sig_info(SIGFPE, &info, current);
+	exception_exit(prev_state);
 }
 
 int process_fpemu_return(int sig, void __user *fault_addr)
@@ -713,11 +722,13 @@ int process_fpemu_return(int sig, void __user *fault_addr)
  */
 asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 {
+	enum ctx_state prev_state;
 	siginfo_t info = {0};
 
+	prev_state = exception_enter();
 	if (notify_die(DIE_FP, "FP exception", regs, 0, regs_to_trapnr(regs), SIGFPE)
 	    == NOTIFY_STOP)
-		return;
+		goto out;
 	die_if_kernel("FP exception in kernel code", regs);
 
 	if (fcr31 & FPU_CSR_UNI_X) {
@@ -753,7 +764,7 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 		/* If something went wrong, signal */
 		process_fpemu_return(sig, fault_addr);
 
-		return;
+		goto out;
 	} else if (fcr31 & FPU_CSR_INV_X)
 		info.si_code = FPE_FLTINV;
 	else if (fcr31 & FPU_CSR_DIV_X)
@@ -770,6 +781,9 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 	info.si_errno = 0;
 	info.si_addr = (void __user *) regs->cp0_epc;
 	force_sig_info(SIGFPE, &info, current);
+
+out:
+	exception_exit(prev_state);
 }
 
 static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
@@ -835,9 +849,11 @@ static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
 asmlinkage void do_bp(struct pt_regs *regs)
 {
 	unsigned int opcode, bcode;
+	enum ctx_state prev_state;
 	unsigned long epc;
 	u16 instr[2];
 
+	prev_state = exception_enter();
 	if (get_isa16_mode(regs->cp0_epc)) {
 		/* Calculate EPC. */
 		epc = exception_epc(regs);
@@ -852,7 +868,7 @@ asmlinkage void do_bp(struct pt_regs *regs)
 				goto out_sigsegv;
 		    bcode = (instr[0] >> 6) & 0x3f;
 		    do_trap_or_bp(regs, bcode, "Break");
-		    return;
+		    goto out;
 		}
 	} else {
 		if (__get_user(opcode, (unsigned int __user *) exception_epc(regs)))
@@ -876,12 +892,12 @@ asmlinkage void do_bp(struct pt_regs *regs)
 	switch (bcode) {
 	case BRK_KPROBE_BP:
 		if (notify_die(DIE_BREAK, "debug", regs, bcode, regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
-			return;
+			goto out;
 		else
 			break;
 	case BRK_KPROBE_SSTEPBP:
 		if (notify_die(DIE_SSTEPBP, "single_step", regs, bcode, regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
-			return;
+			goto out;
 		else
 			break;
 	default:
@@ -889,18 +905,24 @@ asmlinkage void do_bp(struct pt_regs *regs)
 	}
 
 	do_trap_or_bp(regs, bcode, "Break");
+
+out:
+	exception_exit(prev_state);
 	return;
 
 out_sigsegv:
 	force_sig(SIGSEGV, current);
+	goto out;
 }
 
 asmlinkage void do_tr(struct pt_regs *regs)
 {
 	u32 opcode, tcode = 0;
+	enum ctx_state prev_state;
 	u16 instr[2];
 	unsigned long epc = msk_isa16_mode(exception_epc(regs));
 
+	prev_state = exception_enter();
 	if (get_isa16_mode(regs->cp0_epc)) {
 		if (__get_user(instr[0], (u16 __user *)(epc + 0)) ||
 		    __get_user(instr[1], (u16 __user *)(epc + 2)))
@@ -918,10 +940,14 @@ asmlinkage void do_tr(struct pt_regs *regs)
 	}
 
 	do_trap_or_bp(regs, tcode, "Trap");
+
+out:
+	exception_exit(prev_state);
 	return;
 
 out_sigsegv:
 	force_sig(SIGSEGV, current);
+	goto out;
 }
 
 asmlinkage void do_ri(struct pt_regs *regs)
@@ -929,17 +955,19 @@ asmlinkage void do_ri(struct pt_regs *regs)
 	unsigned int __user *epc = (unsigned int __user *)exception_epc(regs);
 	unsigned long old_epc = regs->cp0_epc;
 	unsigned long old31 = regs->regs[31];
+	enum ctx_state prev_state;
 	unsigned int opcode = 0;
 	int status = -1;
 
+	prev_state = exception_enter();
 	if (notify_die(DIE_RI, "RI Fault", regs, 0, regs_to_trapnr(regs), SIGILL)
 	    == NOTIFY_STOP)
-		return;
+		goto out;
 
 	die_if_kernel("Reserved instruction in kernel code", regs);
 
 	if (unlikely(compute_return_epc(regs) < 0))
-		return;
+		goto out;
 
 	if (get_isa16_mode(regs->cp0_epc)) {
 		unsigned short mmop[2] = { 0 };
@@ -974,6 +1002,9 @@ asmlinkage void do_ri(struct pt_regs *regs)
 		regs->regs[31] = old31;
 		force_sig(status, current);
 	}
+
+out:
+	exception_exit(prev_state);
 }
 
 /*
@@ -1040,6 +1071,7 @@ static int default_cu2_call(struct notifier_block *nfb, unsigned long action,
 
 asmlinkage void do_cpu(struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
 	unsigned int __user *epc;
 	unsigned long old_epc, old31;
 	unsigned int opcode;
@@ -1047,6 +1079,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 	int status;
 	unsigned long __maybe_unused flags;
 
+	prev_state = exception_enter();
 	die_if_kernel("do_cpu invoked from kernel context!", regs);
 
 	cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;
@@ -1060,7 +1093,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 		status = -1;
 
 		if (unlikely(compute_return_epc(regs) < 0))
-			return;
+			goto out;
 
 		if (get_isa16_mode(regs->cp0_epc)) {
 			unsigned short mmop[2] = { 0 };
@@ -1093,7 +1126,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 			force_sig(status, current);
 		}
 
-		return;
+		goto out;
 
 	case 3:
 		/*
@@ -1131,19 +1164,26 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 				mt_ase_fp_affinity();
 		}
 
-		return;
+		goto out;
 
 	case 2:
 		raw_notifier_call_chain(&cu2_chain, CU2_EXCEPTION, regs);
-		return;
+		goto out;
 	}
 
 	force_sig(SIGILL, current);
+
+out:
+	exception_exit(prev_state);
 }
 
 asmlinkage void do_mdmx(struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
 	force_sig(SIGILL, current);
+	exception_exit(prev_state);
 }
 
 /*
@@ -1151,8 +1191,10 @@ asmlinkage void do_mdmx(struct pt_regs *regs)
  */
 asmlinkage void do_watch(struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
 	u32 cause;
 
+	prev_state = exception_enter();
 	/*
 	 * Clear WP (bit 22) bit of cause register so we don't loop
 	 * forever.
@@ -1174,13 +1216,16 @@ asmlinkage void do_watch(struct pt_regs *regs)
 		mips_clear_watch_registers();
 		local_irq_enable();
 	}
+	exception_exit(prev_state);
 }
 
 asmlinkage void do_mcheck(struct pt_regs *regs)
 {
 	const int field = 2 * sizeof(unsigned long);
 	int multi_match = regs->cp0_status & ST0_TS;
+	enum ctx_state prev_state;
 
+	prev_state = exception_enter();
 	show_regs(regs);
 
 	if (multi_match) {
@@ -1202,6 +1247,7 @@ asmlinkage void do_mcheck(struct pt_regs *regs)
 	panic("Caught Machine Check exception - %scaused by multiple "
 	      "matching entries in the TLB.",
 	      (multi_match) ? "" : "not ");
+	exception_exit(prev_state);
 }
 
 asmlinkage void do_mt(struct pt_regs *regs)

arch/mips/kernel/unaligned.c

@@ -72,6 +72,7 @@
  *	 A store crossing a page boundary might be executed only partially.
  *	 Undo the partial store in this case.
  */
+#include <linux/context_tracking.h>
 #include <linux/mm.h>
 #include <linux/signal.h>
 #include <linux/smp.h>
@@ -1550,9 +1551,11 @@ static void emulate_load_store_MIPS16e(struct pt_regs *regs, void __user * addr)
 }
 asmlinkage void do_ade(struct pt_regs *regs)
 {
+	enum ctx_state prev_state;
 	unsigned int __user *pc;
 	mm_segment_t seg;
 
+	prev_state = exception_enter();
 	perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS,
 			1, regs, regs->cp0_badvaddr);
 	/*
@@ -1628,6 +1631,7 @@ asmlinkage void do_ade(struct pt_regs *regs)
 	/*
 	 * XXX On return from the signal handler we should advance the epc
 	 */
+	exception_exit(prev_state);
 }
 
 #ifdef CONFIG_DEBUG_FS

arch/mips/mm/fault.c

@@ -5,6 +5,7 @@
  *
  * Copyright (C) 1995 - 2000 by Ralf Baechle
  */
+#include <linux/context_tracking.h>
 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/interrupt.h>
@@ -32,8 +33,8 @@
  * and the problem, and then passes it off to one of the appropriate
  * routines.
  */
-asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write,
-			      unsigned long address)
+static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
+	unsigned long address)
 {
 	struct vm_area_struct * vma = NULL;
 	struct task_struct *tsk = current;
@@ -312,3 +313,13 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long writ
 	}
 #endif
 }
+
+asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+	unsigned long write, unsigned long address)
+{
+	enum ctx_state prev_state;
+
+	prev_state = exception_enter();
+	__do_page_fault(regs, write, address);
+	exception_exit(prev_state);
+}