2 * Derived from "arch/i386/kernel/process.c"
3 * Copyright (C) 1995 Linus Torvalds
5 * Updated and modified by Cort Dougan (cort@cs.nmt.edu) and
6 * Paul Mackerras (paulus@cs.anu.edu.au)
9 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
17 #include <linux/config.h>
18 #include <linux/errno.h>
19 #include <linux/sched.h>
20 #include <linux/kernel.h>
22 #include <linux/smp.h>
23 #include <linux/smp_lock.h>
24 #include <linux/stddef.h>
25 #include <linux/unistd.h>
26 #include <linux/ptrace.h>
27 #include <linux/slab.h>
28 #include <linux/user.h>
29 #include <linux/elf.h>
30 #include <linux/init.h>
31 #include <linux/prctl.h>
32 #include <linux/init_task.h>
33 #include <linux/module.h>
34 #include <linux/kallsyms.h>
35 #include <linux/mqueue.h>
36 #include <linux/hardirq.h>
37 #include <linux/utsname.h>
39 #include <asm/pgtable.h>
40 #include <asm/uaccess.h>
41 #include <asm/system.h>
43 #include <asm/processor.h>
46 #include <asm/machdep.h>
49 #include <asm/firmware.h>
52 extern unsigned long _get_SP(void);
55 struct task_struct *last_task_used_math = NULL;
56 struct task_struct *last_task_used_altivec = NULL;
57 struct task_struct *last_task_used_spe = NULL;
61 * Make sure the floating-point register state in the
62 * the thread_struct is up to date for task tsk.
64 void flush_fp_to_thread(struct task_struct *tsk)
66 if (tsk->thread.regs) {
68 * We need to disable preemption here because if we didn't,
69 * another process could get scheduled after the regs->msr
70 * test but before we have finished saving the FP registers
71 * to the thread_struct. That process could take over the
72 * FPU, and then when we get scheduled again we would store
73 * bogus values for the remaining FP registers.
76 if (tsk->thread.regs->msr & MSR_FP) {
79 * This should only ever be called for current or
80 * for a stopped child process. Since we save away
81 * the FP register state on context switch on SMP,
82 * there is something wrong if a stopped child appears
83 * to still have its FP state in the CPU registers.
85 BUG_ON(tsk != current);
93 void enable_kernel_fp(void)
95 WARN_ON(preemptible());
98 if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
101 giveup_fpu(NULL); /* just enables FP for kernel */
103 giveup_fpu(last_task_used_math);
104 #endif /* CONFIG_SMP */
106 EXPORT_SYMBOL(enable_kernel_fp);
108 int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
110 if (!tsk->thread.regs)
112 flush_fp_to_thread(current);
114 memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));
119 #ifdef CONFIG_ALTIVEC
120 void enable_kernel_altivec(void)
122 WARN_ON(preemptible());
125 if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
126 giveup_altivec(current);
128 giveup_altivec(NULL); /* just enable AltiVec for kernel - force */
130 giveup_altivec(last_task_used_altivec);
131 #endif /* CONFIG_SMP */
133 EXPORT_SYMBOL(enable_kernel_altivec);
136 * Make sure the VMX/Altivec register state in the
137 * the thread_struct is up to date for task tsk.
139 void flush_altivec_to_thread(struct task_struct *tsk)
141 if (tsk->thread.regs) {
143 if (tsk->thread.regs->msr & MSR_VEC) {
145 BUG_ON(tsk != current);
147 giveup_altivec(current);
153 int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
155 flush_altivec_to_thread(current);
156 memcpy(vrregs, ¤t->thread.vr[0], sizeof(*vrregs));
159 #endif /* CONFIG_ALTIVEC */
163 void enable_kernel_spe(void)
165 WARN_ON(preemptible());
168 if (current->thread.regs && (current->thread.regs->msr & MSR_SPE))
171 giveup_spe(NULL); /* just enable SPE for kernel - force */
173 giveup_spe(last_task_used_spe);
174 #endif /* __SMP __ */
176 EXPORT_SYMBOL(enable_kernel_spe);
178 void flush_spe_to_thread(struct task_struct *tsk)
180 if (tsk->thread.regs) {
182 if (tsk->thread.regs->msr & MSR_SPE) {
184 BUG_ON(tsk != current);
192 int dump_spe(struct pt_regs *regs, elf_vrregset_t *evrregs)
194 flush_spe_to_thread(current);
195 /* We copy u32 evr[32] + u64 acc + u32 spefscr -> 35 */
196 memcpy(evrregs, ¤t->thread.evr[0], sizeof(u32) * 35);
199 #endif /* CONFIG_SPE */
203 * If we are doing lazy switching of CPU state (FP, altivec or SPE),
204 * and the current task has some state, discard it.
206 void discard_lazy_cpu_state(void)
209 if (last_task_used_math == current)
210 last_task_used_math = NULL;
211 #ifdef CONFIG_ALTIVEC
212 if (last_task_used_altivec == current)
213 last_task_used_altivec = NULL;
214 #endif /* CONFIG_ALTIVEC */
216 if (last_task_used_spe == current)
217 last_task_used_spe = NULL;
221 #endif /* CONFIG_SMP */
223 #ifdef CONFIG_PPC_MERGE /* XXX for now */
224 int set_dabr(unsigned long dabr)
227 return ppc_md.set_dabr(dabr);
229 mtspr(SPRN_DABR, dabr);
235 DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
236 static DEFINE_PER_CPU(unsigned long, current_dabr);
239 struct task_struct *__switch_to(struct task_struct *prev,
240 struct task_struct *new)
242 struct thread_struct *new_thread, *old_thread;
244 struct task_struct *last;
247 /* avoid complexity of lazy save/restore of fpu
248 * by just saving it every time we switch out if
249 * this task used the fpu during the last quantum.
251 * If it tries to use the fpu again, it'll trap and
252 * reload its fp regs. So we don't have to do a restore
253 * every switch, just a save.
256 if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
258 #ifdef CONFIG_ALTIVEC
260 * If the previous thread used altivec in the last quantum
261 * (thus changing altivec regs) then save them.
262 * We used to check the VRSAVE register but not all apps
263 * set it, so we don't rely on it now (and in fact we need
264 * to save & restore VSCR even if VRSAVE == 0). -- paulus
266 * On SMP we always save/restore altivec regs just to avoid the
267 * complexity of changing processors.
270 if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
271 giveup_altivec(prev);
272 #endif /* CONFIG_ALTIVEC */
275 * If the previous thread used spe in the last quantum
276 * (thus changing spe regs) then save them.
278 * On SMP we always save/restore spe regs just to avoid the
279 * complexity of changing processors.
281 if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
283 #endif /* CONFIG_SPE */
285 #else /* CONFIG_SMP */
286 #ifdef CONFIG_ALTIVEC
287 /* Avoid the trap. On smp this this never happens since
288 * we don't set last_task_used_altivec -- Cort
290 if (new->thread.regs && last_task_used_altivec == new)
291 new->thread.regs->msr |= MSR_VEC;
292 #endif /* CONFIG_ALTIVEC */
294 /* Avoid the trap. On smp this this never happens since
295 * we don't set last_task_used_spe
297 if (new->thread.regs && last_task_used_spe == new)
298 new->thread.regs->msr |= MSR_SPE;
299 #endif /* CONFIG_SPE */
301 #endif /* CONFIG_SMP */
303 #ifdef CONFIG_PPC64 /* for now */
304 if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr)) {
305 set_dabr(new->thread.dabr);
306 __get_cpu_var(current_dabr) = new->thread.dabr;
312 new_thread = &new->thread;
313 old_thread = ¤t->thread;
317 * Collect processor utilization data per process
319 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
320 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
321 long unsigned start_tb, current_tb;
322 start_tb = old_thread->start_tb;
323 cu->current_tb = current_tb = mfspr(SPRN_PURR);
324 old_thread->accum_tb += (current_tb - start_tb);
325 new_thread->start_tb = current_tb;
329 local_irq_save(flags);
331 account_system_vtime(current);
332 account_process_vtime(current);
333 calculate_steal_time();
335 last = _switch(old_thread, new_thread);
337 local_irq_restore(flags);
342 static int instructions_to_print = 16;
345 #define BAD_PC(pc) ((REGION_ID(pc) != KERNEL_REGION_ID) && \
346 (REGION_ID(pc) != VMALLOC_REGION_ID))
348 #define BAD_PC(pc) ((pc) < KERNELBASE)
351 static void show_instructions(struct pt_regs *regs)
354 unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
357 printk("Instruction dump:");
359 for (i = 0; i < instructions_to_print; i++) {
365 if (BAD_PC(pc) || __get_user(instr, (unsigned int *)pc)) {
369 printk("<%08x> ", instr);
371 printk("%08x ", instr);
380 static struct regbit {
393 static void printbits(unsigned long val, struct regbit *bits)
395 const char *sep = "";
398 for (; bits->bit; ++bits)
399 if (val & bits->bit) {
400 printk("%s%s", sep, bits->name);
408 #define REGS_PER_LINE 4
409 #define LAST_VOLATILE 13
412 #define REGS_PER_LINE 8
413 #define LAST_VOLATILE 12
416 void show_regs(struct pt_regs * regs)
420 printk("NIP: "REG" LR: "REG" CTR: "REG"\n",
421 regs->nip, regs->link, regs->ctr);
422 printk("REGS: %p TRAP: %04lx %s (%s)\n",
423 regs, regs->trap, print_tainted(), system_utsname.release);
424 printk("MSR: "REG" ", regs->msr);
425 printbits(regs->msr, msr_bits);
426 printk(" CR: %08lX XER: %08lX\n", regs->ccr, regs->xer);
428 if (trap == 0x300 || trap == 0x600)
429 printk("DAR: "REG", DSISR: "REG"\n", regs->dar, regs->dsisr);
430 printk("TASK = %p[%d] '%s' THREAD: %p",
431 current, current->pid, current->comm, task_thread_info(current));
434 printk(" CPU: %d", smp_processor_id());
435 #endif /* CONFIG_SMP */
437 for (i = 0; i < 32; i++) {
438 if ((i % REGS_PER_LINE) == 0)
439 printk("\n" KERN_INFO "GPR%02d: ", i);
440 printk(REG " ", regs->gpr[i]);
441 if (i == LAST_VOLATILE && !FULL_REGS(regs))
445 #ifdef CONFIG_KALLSYMS
447 * Lookup NIP late so we have the best change of getting the
448 * above info out without failing
450 printk("NIP ["REG"] ", regs->nip);
451 print_symbol("%s\n", regs->nip);
452 printk("LR ["REG"] ", regs->link);
453 print_symbol("%s\n", regs->link);
455 show_stack(current, (unsigned long *) regs->gpr[1]);
456 if (!user_mode(regs))
457 show_instructions(regs);
460 void exit_thread(void)
462 discard_lazy_cpu_state();
465 void flush_thread(void)
468 struct thread_info *t = current_thread_info();
470 if (t->flags & _TIF_ABI_PENDING)
471 t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
474 discard_lazy_cpu_state();
476 #ifdef CONFIG_PPC64 /* for now */
477 if (current->thread.dabr) {
478 current->thread.dabr = 0;
485 release_thread(struct task_struct *t)
490 * This gets called before we allocate a new thread and copy
491 * the current task into it.
493 void prepare_to_copy(struct task_struct *tsk)
495 flush_fp_to_thread(current);
496 flush_altivec_to_thread(current);
497 flush_spe_to_thread(current);
503 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
504 unsigned long unused, struct task_struct *p,
505 struct pt_regs *regs)
507 struct pt_regs *childregs, *kregs;
508 extern void ret_from_fork(void);
509 unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
511 CHECK_FULL_REGS(regs);
513 sp -= sizeof(struct pt_regs);
514 childregs = (struct pt_regs *) sp;
516 if ((childregs->msr & MSR_PR) == 0) {
517 /* for kernel thread, set `current' and stackptr in new task */
518 childregs->gpr[1] = sp + sizeof(struct pt_regs);
520 childregs->gpr[2] = (unsigned long) p;
522 clear_tsk_thread_flag(p, TIF_32BIT);
524 p->thread.regs = NULL; /* no user register state */
526 childregs->gpr[1] = usp;
527 p->thread.regs = childregs;
528 if (clone_flags & CLONE_SETTLS) {
530 if (!test_thread_flag(TIF_32BIT))
531 childregs->gpr[13] = childregs->gpr[6];
534 childregs->gpr[2] = childregs->gpr[6];
537 childregs->gpr[3] = 0; /* Result from fork() */
538 sp -= STACK_FRAME_OVERHEAD;
541 * The way this works is that at some point in the future
542 * some task will call _switch to switch to the new task.
543 * That will pop off the stack frame created below and start
544 * the new task running at ret_from_fork. The new task will
545 * do some house keeping and then return from the fork or clone
546 * system call, using the stack frame created above.
548 sp -= sizeof(struct pt_regs);
549 kregs = (struct pt_regs *) sp;
550 sp -= STACK_FRAME_OVERHEAD;
554 if (cpu_has_feature(CPU_FTR_SLB)) {
555 unsigned long sp_vsid = get_kernel_vsid(sp);
556 unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;
558 sp_vsid <<= SLB_VSID_SHIFT;
559 sp_vsid |= SLB_VSID_KERNEL | llp;
560 p->thread.ksp_vsid = sp_vsid;
564 * The PPC64 ABI makes use of a TOC to contain function
565 * pointers. The function (ret_from_except) is actually a pointer
566 * to the TOC entry. The first entry is a pointer to the actual
569 kregs->nip = *((unsigned long *)ret_from_fork);
571 kregs->nip = (unsigned long)ret_from_fork;
572 p->thread.last_syscall = -1;
579 * Set up a thread for executing a new program
581 void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
584 unsigned long load_addr = regs->gpr[2]; /* saved by ELF_PLAT_INIT */
590 * If we exec out of a kernel thread then thread.regs will not be
593 if (!current->thread.regs) {
594 struct pt_regs *regs = task_stack_page(current) + THREAD_SIZE;
595 current->thread.regs = regs - 1;
598 memset(regs->gpr, 0, sizeof(regs->gpr));
608 regs->msr = MSR_USER;
610 if (!test_thread_flag(TIF_32BIT)) {
611 unsigned long entry, toc;
613 /* start is a relocated pointer to the function descriptor for
614 * the elf _start routine. The first entry in the function
615 * descriptor is the entry address of _start and the second
616 * entry is the TOC value we need to use.
618 __get_user(entry, (unsigned long __user *)start);
619 __get_user(toc, (unsigned long __user *)start+1);
621 /* Check whether the e_entry function descriptor entries
622 * need to be relocated before we can use them.
624 if (load_addr != 0) {
630 regs->msr = MSR_USER64;
634 regs->msr = MSR_USER32;
638 discard_lazy_cpu_state();
639 memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
640 current->thread.fpscr.val = 0;
641 #ifdef CONFIG_ALTIVEC
642 memset(current->thread.vr, 0, sizeof(current->thread.vr));
643 memset(¤t->thread.vscr, 0, sizeof(current->thread.vscr));
644 current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
645 current->thread.vrsave = 0;
646 current->thread.used_vr = 0;
647 #endif /* CONFIG_ALTIVEC */
649 memset(current->thread.evr, 0, sizeof(current->thread.evr));
650 current->thread.acc = 0;
651 current->thread.spefscr = 0;
652 current->thread.used_spe = 0;
653 #endif /* CONFIG_SPE */
656 #define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
657 | PR_FP_EXC_RES | PR_FP_EXC_INV)
659 int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
661 struct pt_regs *regs = tsk->thread.regs;
663 /* This is a bit hairy. If we are an SPE enabled processor
664 * (have embedded fp) we store the IEEE exception enable flags in
665 * fpexc_mode. fpexc_mode is also used for setting FP exception
666 * mode (asyn, precise, disabled) for 'Classic' FP. */
667 if (val & PR_FP_EXC_SW_ENABLE) {
669 tsk->thread.fpexc_mode = val &
670 (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
677 /* on a CONFIG_SPE this does not hurt us. The bits that
678 * __pack_fe01 use do not overlap with bits used for
679 * PR_FP_EXC_SW_ENABLE. Additionally, the MSR[FE0,FE1] bits
680 * on CONFIG_SPE implementations are reserved so writing to
681 * them does not change anything */
682 if (val > PR_FP_EXC_PRECISE)
684 tsk->thread.fpexc_mode = __pack_fe01(val);
685 if (regs != NULL && (regs->msr & MSR_FP) != 0)
686 regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
687 | tsk->thread.fpexc_mode;
691 int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
695 if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
697 val = tsk->thread.fpexc_mode;
702 val = __unpack_fe01(tsk->thread.fpexc_mode);
703 return put_user(val, (unsigned int __user *) adr);
706 #define TRUNC_PTR(x) ((typeof(x))(((unsigned long)(x)) & 0xffffffff))
708 int sys_clone(unsigned long clone_flags, unsigned long usp,
709 int __user *parent_tidp, void __user *child_threadptr,
710 int __user *child_tidp, int p6,
711 struct pt_regs *regs)
713 CHECK_FULL_REGS(regs);
715 usp = regs->gpr[1]; /* stack pointer for child */
717 if (test_thread_flag(TIF_32BIT)) {
718 parent_tidp = TRUNC_PTR(parent_tidp);
719 child_tidp = TRUNC_PTR(child_tidp);
722 return do_fork(clone_flags, usp, regs, 0, parent_tidp, child_tidp);
725 int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
726 unsigned long p4, unsigned long p5, unsigned long p6,
727 struct pt_regs *regs)
729 CHECK_FULL_REGS(regs);
730 return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
733 int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
734 unsigned long p4, unsigned long p5, unsigned long p6,
735 struct pt_regs *regs)
737 CHECK_FULL_REGS(regs);
738 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1],
739 regs, 0, NULL, NULL);
742 int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
743 unsigned long a3, unsigned long a4, unsigned long a5,
744 struct pt_regs *regs)
749 filename = getname((char __user *) a0);
750 error = PTR_ERR(filename);
751 if (IS_ERR(filename))
753 flush_fp_to_thread(current);
754 flush_altivec_to_thread(current);
755 flush_spe_to_thread(current);
756 error = do_execve(filename, (char __user * __user *) a1,
757 (char __user * __user *) a2, regs);
760 current->ptrace &= ~PT_DTRACE;
761 task_unlock(current);
768 static int validate_sp(unsigned long sp, struct task_struct *p,
769 unsigned long nbytes)
771 unsigned long stack_page = (unsigned long)task_stack_page(p);
773 if (sp >= stack_page + sizeof(struct thread_struct)
774 && sp <= stack_page + THREAD_SIZE - nbytes)
777 #ifdef CONFIG_IRQSTACKS
778 stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
779 if (sp >= stack_page + sizeof(struct thread_struct)
780 && sp <= stack_page + THREAD_SIZE - nbytes)
783 stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
784 if (sp >= stack_page + sizeof(struct thread_struct)
785 && sp <= stack_page + THREAD_SIZE - nbytes)
793 #define MIN_STACK_FRAME 112 /* same as STACK_FRAME_OVERHEAD, in fact */
794 #define FRAME_LR_SAVE 2
795 #define INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD + 288)
796 #define REGS_MARKER 0x7265677368657265ul
797 #define FRAME_MARKER 12
799 #define MIN_STACK_FRAME 16
800 #define FRAME_LR_SAVE 1
801 #define INT_FRAME_SIZE (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
802 #define REGS_MARKER 0x72656773ul
803 #define FRAME_MARKER 2
806 unsigned long get_wchan(struct task_struct *p)
808 unsigned long ip, sp;
811 if (!p || p == current || p->state == TASK_RUNNING)
815 if (!validate_sp(sp, p, MIN_STACK_FRAME))
819 sp = *(unsigned long *)sp;
820 if (!validate_sp(sp, p, MIN_STACK_FRAME))
823 ip = ((unsigned long *)sp)[FRAME_LR_SAVE];
824 if (!in_sched_functions(ip))
827 } while (count++ < 16);
830 EXPORT_SYMBOL(get_wchan);
832 static int kstack_depth_to_print = 64;
834 void show_stack(struct task_struct *tsk, unsigned long *stack)
836 unsigned long sp, ip, lr, newsp;
840 sp = (unsigned long) stack;
845 asm("mr %0,1" : "=r" (sp));
847 sp = tsk->thread.ksp;
851 printk("Call Trace:\n");
853 if (!validate_sp(sp, tsk, MIN_STACK_FRAME))
856 stack = (unsigned long *) sp;
858 ip = stack[FRAME_LR_SAVE];
859 if (!firstframe || ip != lr) {
860 printk("["REG"] ["REG"] ", sp, ip);
861 print_symbol("%s", ip);
863 printk(" (unreliable)");
869 * See if this is an exception frame.
870 * We look for the "regshere" marker in the current frame.
872 if (validate_sp(sp, tsk, INT_FRAME_SIZE)
873 && stack[FRAME_MARKER] == REGS_MARKER) {
874 struct pt_regs *regs = (struct pt_regs *)
875 (sp + STACK_FRAME_OVERHEAD);
876 printk("--- Exception: %lx", regs->trap);
877 print_symbol(" at %s\n", regs->nip);
879 print_symbol(" LR = %s\n", lr);
884 } while (count++ < kstack_depth_to_print);
887 void dump_stack(void)
889 show_stack(current, NULL);
891 EXPORT_SYMBOL(dump_stack);
894 void ppc64_runlatch_on(void)
898 if (cpu_has_feature(CPU_FTR_CTRL) && !test_thread_flag(TIF_RUNLATCH)) {
901 ctrl = mfspr(SPRN_CTRLF);
902 ctrl |= CTRL_RUNLATCH;
903 mtspr(SPRN_CTRLT, ctrl);
905 set_thread_flag(TIF_RUNLATCH);
909 void ppc64_runlatch_off(void)
913 if (cpu_has_feature(CPU_FTR_CTRL) && test_thread_flag(TIF_RUNLATCH)) {
916 clear_thread_flag(TIF_RUNLATCH);
918 ctrl = mfspr(SPRN_CTRLF);
919 ctrl &= ~CTRL_RUNLATCH;
920 mtspr(SPRN_CTRLT, ctrl);