1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License.  See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
7 * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
8 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
9 * Copyright (C) 2004 Thiemo Seufer
10 * Copyright (C) 2013  Imagination Technologies Ltd.
11 */
12#include <linux/errno.h>
13#include <linux/sched.h>
14#include <linux/tick.h>
15#include <linux/kernel.h>
16#include <linux/mm.h>
17#include <linux/stddef.h>
18#include <linux/unistd.h>
19#include <linux/export.h>
20#include <linux/ptrace.h>
21#include <linux/mman.h>
22#include <linux/personality.h>
23#include <linux/sys.h>
24#include <linux/init.h>
25#include <linux/completion.h>
26#include <linux/kallsyms.h>
27#include <linux/random.h>
28#include <linux/prctl.h>
29
30#include <asm/asm.h>
31#include <asm/bootinfo.h>
32#include <asm/cpu.h>
33#include <asm/dsp.h>
34#include <asm/fpu.h>
35#include <asm/msa.h>
36#include <asm/pgtable.h>
37#include <asm/mipsregs.h>
38#include <asm/processor.h>
39#include <asm/reg.h>
40#include <asm/uaccess.h>
41#include <asm/io.h>
42#include <asm/elf.h>
43#include <asm/isadep.h>
44#include <asm/inst.h>
45#include <asm/stacktrace.h>
46#include <asm/irq_regs.h>
47
48#ifdef CONFIG_HOTPLUG_CPU
49void arch_cpu_idle_dead(void)
50{
51	/* What the heck is this check doing ? */
52	if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
53		play_dead();
54}
55#endif
56
57asmlinkage void ret_from_fork(void);
58asmlinkage void ret_from_kernel_thread(void);
59
60void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
61{
62	unsigned long status;
63
64	/* New thread loses kernel privileges. */
65	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
66	status |= KU_USER;
67	regs->cp0_status = status;
68	clear_used_math();
69	clear_fpu_owner();
70	init_dsp();
71	clear_thread_flag(TIF_USEDMSA);
72	clear_thread_flag(TIF_MSA_CTX_LIVE);
73	disable_msa();
74	regs->cp0_epc = pc;
75	regs->regs[29] = sp;
76}
77
78void exit_thread(void)
79{
80}
81
82void flush_thread(void)
83{
84}
85
86int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
87{
88	/*
89	 * Save any process state which is live in hardware registers to the
90	 * parent context prior to duplication. This prevents the new child
91	 * state becoming stale if the parent is preempted before copy_thread()
92	 * gets a chance to save the parent's live hardware registers to the
93	 * child context.
94	 */
95	preempt_disable();
96
97	if (is_msa_enabled())
98		save_msa(current);
99	else if (is_fpu_owner())
100		_save_fp(current);
101
102	save_dsp(current);
103
104	preempt_enable();
105
106	*dst = *src;
107	return 0;
108}
109
110/*
111 * Copy architecture-specific thread state
112 */
113int copy_thread(unsigned long clone_flags, unsigned long usp,
114	unsigned long kthread_arg, struct task_struct *p)
115{
116	struct thread_info *ti = task_thread_info(p);
117	struct pt_regs *childregs, *regs = current_pt_regs();
118	unsigned long childksp;
119	p->set_child_tid = p->clear_child_tid = NULL;
120
121	childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
122
123	/* set up new TSS. */
124	childregs = (struct pt_regs *) childksp - 1;
125	/*  Put the stack after the struct pt_regs.  */
126	childksp = (unsigned long) childregs;
127	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
128	if (unlikely(p->flags & PF_KTHREAD)) {
129		/* kernel thread */
130		unsigned long status = p->thread.cp0_status;
131		memset(childregs, 0, sizeof(struct pt_regs));
132		ti->addr_limit = KERNEL_DS;
133		p->thread.reg16 = usp; /* fn */
134		p->thread.reg17 = kthread_arg;
135		p->thread.reg29 = childksp;
136		p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
137#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
138		status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
139			 ((status & (ST0_KUC | ST0_IEC)) << 2);
140#else
141		status |= ST0_EXL;
142#endif
143		childregs->cp0_status = status;
144		return 0;
145	}
146
147	/* user thread */
148	*childregs = *regs;
149	childregs->regs[7] = 0; /* Clear error flag */
150	childregs->regs[2] = 0; /* Child gets zero as return value */
151	if (usp)
152		childregs->regs[29] = usp;
153	ti->addr_limit = USER_DS;
154
155	p->thread.reg29 = (unsigned long) childregs;
156	p->thread.reg31 = (unsigned long) ret_from_fork;
157
158	/*
159	 * New tasks lose permission to use the fpu. This accelerates context
160	 * switching for most programs since they don't use the fpu.
161	 */
162	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
163
164	clear_tsk_thread_flag(p, TIF_USEDFPU);
165	clear_tsk_thread_flag(p, TIF_USEDMSA);
166	clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
167
168#ifdef CONFIG_MIPS_MT_FPAFF
169	clear_tsk_thread_flag(p, TIF_FPUBOUND);
170#endif /* CONFIG_MIPS_MT_FPAFF */
171
172	if (clone_flags & CLONE_SETTLS)
173		ti->tp_value = regs->regs[7];
174
175	return 0;
176}
177
178#ifdef CONFIG_CC_STACKPROTECTOR
179#include <linux/stackprotector.h>
180unsigned long __stack_chk_guard __read_mostly;
181EXPORT_SYMBOL(__stack_chk_guard);
182#endif
183
184struct mips_frame_info {
185	void		*func;
186	unsigned long	func_size;
187	int		frame_size;
188	int		pc_offset;
189};
190
191#define J_TARGET(pc,target)	\
192		(((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
193
194static inline int is_ra_save_ins(union mips_instruction *ip)
195{
196#ifdef CONFIG_CPU_MICROMIPS
197	union mips_instruction mmi;
198
199	/*
200	 * swsp ra,offset
201	 * swm16 reglist,offset(sp)
202	 * swm32 reglist,offset(sp)
203	 * sw32 ra,offset(sp)
204	 * jradiussp - NOT SUPPORTED
205	 *
206	 * microMIPS is way more fun...
207	 */
208	if (mm_insn_16bit(ip->halfword[0])) {
209		mmi.word = (ip->halfword[0] << 16);
210		return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
211			mmi.mm16_r5_format.rt == 31) ||
212		       (mmi.mm16_m_format.opcode == mm_pool16c_op &&
213			mmi.mm16_m_format.func == mm_swm16_op);
214	}
215	else {
216		mmi.halfword[0] = ip->halfword[1];
217		mmi.halfword[1] = ip->halfword[0];
218		return (mmi.mm_m_format.opcode == mm_pool32b_op &&
219			mmi.mm_m_format.rd > 9 &&
220			mmi.mm_m_format.base == 29 &&
221			mmi.mm_m_format.func == mm_swm32_func) ||
222		       (mmi.i_format.opcode == mm_sw32_op &&
223			mmi.i_format.rs == 29 &&
224			mmi.i_format.rt == 31);
225	}
226#else
227	/* sw / sd $ra, offset($sp) */
228	return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
229		ip->i_format.rs == 29 &&
230		ip->i_format.rt == 31;
231#endif
232}
233
234static inline int is_jump_ins(union mips_instruction *ip)
235{
236#ifdef CONFIG_CPU_MICROMIPS
237	/*
238	 * jr16,jrc,jalr16,jalr16
239	 * jal
240	 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
241	 * jraddiusp - NOT SUPPORTED
242	 *
243	 * microMIPS is kind of more fun...
244	 */
245	union mips_instruction mmi;
246
247	mmi.word = (ip->halfword[0] << 16);
248
249	if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
250	    (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
251	    ip->j_format.opcode == mm_jal32_op)
252		return 1;
253	if (ip->r_format.opcode != mm_pool32a_op ||
254			ip->r_format.func != mm_pool32axf_op)
255		return 0;
256	return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
257#else
258	if (ip->j_format.opcode == j_op)
259		return 1;
260	if (ip->j_format.opcode == jal_op)
261		return 1;
262	if (ip->r_format.opcode != spec_op)
263		return 0;
264	return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
265#endif
266}
267
268static inline int is_sp_move_ins(union mips_instruction *ip)
269{
270#ifdef CONFIG_CPU_MICROMIPS
271	/*
272	 * addiusp -imm
273	 * addius5 sp,-imm
274	 * addiu32 sp,sp,-imm
275	 * jradiussp - NOT SUPPORTED
276	 *
277	 * microMIPS is not more fun...
278	 */
279	if (mm_insn_16bit(ip->halfword[0])) {
280		union mips_instruction mmi;
281
282		mmi.word = (ip->halfword[0] << 16);
283		return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
284			mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
285		       (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
286			mmi.mm16_r5_format.rt == 29);
287	}
288	return ip->mm_i_format.opcode == mm_addiu32_op &&
289	       ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
290#else
291	/* addiu/daddiu sp,sp,-imm */
292	if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
293		return 0;
294	if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
295		return 1;
296#endif
297	return 0;
298}
299
300static int get_frame_info(struct mips_frame_info *info)
301{
302#ifdef CONFIG_CPU_MICROMIPS
303	union mips_instruction *ip = (void *) (((char *) info->func) - 1);
304#else
305	union mips_instruction *ip = info->func;
306#endif
307	unsigned max_insns = info->func_size / sizeof(union mips_instruction);
308	unsigned i;
309
310	info->pc_offset = -1;
311	info->frame_size = 0;
312
313	if (!ip)
314		goto err;
315
316	if (max_insns == 0)
317		max_insns = 128U;	/* unknown function size */
318	max_insns = min(128U, max_insns);
319
320	for (i = 0; i < max_insns; i++, ip++) {
321
322		if (is_jump_ins(ip))
323			break;
324		if (!info->frame_size) {
325			if (is_sp_move_ins(ip))
326			{
327#ifdef CONFIG_CPU_MICROMIPS
328				if (mm_insn_16bit(ip->halfword[0]))
329				{
330					unsigned short tmp;
331
332					if (ip->halfword[0] & mm_addiusp_func)
333					{
334						tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
335						info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
336					} else {
337						tmp = (ip->halfword[0] >> 1);
338						info->frame_size = -(signed short)(tmp & 0xf);
339					}
340					ip = (void *) &ip->halfword[1];
341					ip--;
342				} else
343#endif
344				info->frame_size = - ip->i_format.simmediate;
345			}
346			continue;
347		}
348		if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
349			info->pc_offset =
350				ip->i_format.simmediate / sizeof(long);
351			break;
352		}
353	}
354	if (info->frame_size && info->pc_offset >= 0) /* nested */
355		return 0;
356	if (info->pc_offset < 0) /* leaf */
357		return 1;
358	/* prologue seems boggus... */
359err:
360	return -1;
361}
362
363static struct mips_frame_info schedule_mfi __read_mostly;
364
365#ifdef CONFIG_KALLSYMS
366static unsigned long get___schedule_addr(void)
367{
368	return kallsyms_lookup_name("__schedule");
369}
370#else
371static unsigned long get___schedule_addr(void)
372{
373	union mips_instruction *ip = (void *)schedule;
374	int max_insns = 8;
375	int i;
376
377	for (i = 0; i < max_insns; i++, ip++) {
378		if (ip->j_format.opcode == j_op)
379			return J_TARGET(ip, ip->j_format.target);
380	}
381	return 0;
382}
383#endif
384
385static int __init frame_info_init(void)
386{
387	unsigned long size = 0;
388#ifdef CONFIG_KALLSYMS
389	unsigned long ofs;
390#endif
391	unsigned long addr;
392
393	addr = get___schedule_addr();
394	if (!addr)
395		addr = (unsigned long)schedule;
396
397#ifdef CONFIG_KALLSYMS
398	kallsyms_lookup_size_offset(addr, &size, &ofs);
399#endif
400	schedule_mfi.func = (void *)addr;
401	schedule_mfi.func_size = size;
402
403	get_frame_info(&schedule_mfi);
404
405	/*
406	 * Without schedule() frame info, result given by
407	 * thread_saved_pc() and get_wchan() are not reliable.
408	 */
409	if (schedule_mfi.pc_offset < 0)
410		printk("Can't analyze schedule() prologue at %p\n", schedule);
411
412	return 0;
413}
414
415arch_initcall(frame_info_init);
416
417/*
418 * Return saved PC of a blocked thread.
419 */
420unsigned long thread_saved_pc(struct task_struct *tsk)
421{
422	struct thread_struct *t = &tsk->thread;
423
424	/* New born processes are a special case */
425	if (t->reg31 == (unsigned long) ret_from_fork)
426		return t->reg31;
427	if (schedule_mfi.pc_offset < 0)
428		return 0;
429	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
430}
431
432
433#ifdef CONFIG_KALLSYMS
434/* generic stack unwinding function */
435unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
436					      unsigned long *sp,
437					      unsigned long pc,
438					      unsigned long *ra)
439{
440	struct mips_frame_info info;
441	unsigned long size, ofs;
442	int leaf;
443	extern void ret_from_irq(void);
444	extern void ret_from_exception(void);
445
446	if (!stack_page)
447		return 0;
448
449	/*
450	 * If we reached the bottom of interrupt context,
451	 * return saved pc in pt_regs.
452	 */
453	if (pc == (unsigned long)ret_from_irq ||
454	    pc == (unsigned long)ret_from_exception) {
455		struct pt_regs *regs;
456		if (*sp >= stack_page &&
457		    *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
458			regs = (struct pt_regs *)*sp;
459			pc = regs->cp0_epc;
460			if (!user_mode(regs) && __kernel_text_address(pc)) {
461				*sp = regs->regs[29];
462				*ra = regs->regs[31];
463				return pc;
464			}
465		}
466		return 0;
467	}
468	if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
469		return 0;
470	/*
471	 * Return ra if an exception occurred at the first instruction
472	 */
473	if (unlikely(ofs == 0)) {
474		pc = *ra;
475		*ra = 0;
476		return pc;
477	}
478
479	info.func = (void *)(pc - ofs);
480	info.func_size = ofs;	/* analyze from start to ofs */
481	leaf = get_frame_info(&info);
482	if (leaf < 0)
483		return 0;
484
485	if (*sp < stack_page ||
486	    *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
487		return 0;
488
489	if (leaf)
490		/*
491		 * For some extreme cases, get_frame_info() can
492		 * consider wrongly a nested function as a leaf
493		 * one. In that cases avoid to return always the
494		 * same value.
495		 */
496		pc = pc != *ra ? *ra : 0;
497	else
498		pc = ((unsigned long *)(*sp))[info.pc_offset];
499
500	*sp += info.frame_size;
501	*ra = 0;
502	return __kernel_text_address(pc) ? pc : 0;
503}
504EXPORT_SYMBOL(unwind_stack_by_address);
505
506/* used by show_backtrace() */
507unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
508			   unsigned long pc, unsigned long *ra)
509{
510	unsigned long stack_page = (unsigned long)task_stack_page(task);
511	return unwind_stack_by_address(stack_page, sp, pc, ra);
512}
513#endif
514
515/*
516 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
517 */
518unsigned long get_wchan(struct task_struct *task)
519{
520	unsigned long pc = 0;
521#ifdef CONFIG_KALLSYMS
522	unsigned long sp;
523	unsigned long ra = 0;
524#endif
525
526	if (!task || task == current || task->state == TASK_RUNNING)
527		goto out;
528	if (!task_stack_page(task))
529		goto out;
530
531	pc = thread_saved_pc(task);
532
533#ifdef CONFIG_KALLSYMS
534	sp = task->thread.reg29 + schedule_mfi.frame_size;
535
536	while (in_sched_functions(pc))
537		pc = unwind_stack(task, &sp, pc, &ra);
538#endif
539
540out:
541	return pc;
542}
543
544/*
545 * Don't forget that the stack pointer must be aligned on a 8 bytes
546 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
547 */
548unsigned long arch_align_stack(unsigned long sp)
549{
550	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
551		sp -= get_random_int() & ~PAGE_MASK;
552
553	return sp & ALMASK;
554}
555
556static void arch_dump_stack(void *info)
557{
558	struct pt_regs *regs;
559
560	regs = get_irq_regs();
561
562	if (regs)
563		show_regs(regs);
564
565	dump_stack();
566}
567
568void arch_trigger_all_cpu_backtrace(bool include_self)
569{
570	smp_call_function(arch_dump_stack, NULL, 1);
571}
572
573int mips_get_process_fp_mode(struct task_struct *task)
574{
575	int value = 0;
576
577	if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
578		value |= PR_FP_MODE_FR;
579	if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
580		value |= PR_FP_MODE_FRE;
581
582	return value;
583}
584
585int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
586{
587	const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
588	unsigned long switch_count;
589	struct task_struct *t;
590
591	/* Check the value is valid */
592	if (value & ~known_bits)
593		return -EOPNOTSUPP;
594
595	/* Avoid inadvertently triggering emulation */
596	if ((value & PR_FP_MODE_FR) && cpu_has_fpu &&
597	    !(current_cpu_data.fpu_id & MIPS_FPIR_F64))
598		return -EOPNOTSUPP;
599	if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre)
600		return -EOPNOTSUPP;
601
602	/* FR = 0 not supported in MIPS R6 */
603	if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
604		return -EOPNOTSUPP;
605
606	/* Proceed with the mode switch */
607	preempt_disable();
608
609	/* Save FP & vector context, then disable FPU & MSA */
610	if (task->signal == current->signal)
611		lose_fpu(1);
612
613	/* Prevent any threads from obtaining live FP context */
614	atomic_set(&task->mm->context.fp_mode_switching, 1);
615	smp_mb__after_atomic();
616
617	/*
618	 * If there are multiple online CPUs then wait until all threads whose
619	 * FP mode is about to change have been context switched. This approach
620	 * allows us to only worry about whether an FP mode switch is in
621	 * progress when FP is first used in a tasks time slice. Pretty much all
622	 * of the mode switch overhead can thus be confined to cases where mode
623	 * switches are actually occuring. That is, to here. However for the
624	 * thread performing the mode switch it may take a while...
625	 */
626	if (num_online_cpus() > 1) {
627		spin_lock_irq(&task->sighand->siglock);
628
629		for_each_thread(task, t) {
630			if (t == current)
631				continue;
632
633			switch_count = t->nvcsw + t->nivcsw;
634
635			do {
636				spin_unlock_irq(&task->sighand->siglock);
637				cond_resched();
638				spin_lock_irq(&task->sighand->siglock);
639			} while ((t->nvcsw + t->nivcsw) == switch_count);
640		}
641
642		spin_unlock_irq(&task->sighand->siglock);
643	}
644
645	/*
646	 * There are now no threads of the process with live FP context, so it
647	 * is safe to proceed with the FP mode switch.
648	 */
649	for_each_thread(task, t) {
650		/* Update desired FP register width */
651		if (value & PR_FP_MODE_FR) {
652			clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
653		} else {
654			set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
655			clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
656		}
657
658		/* Update desired FP single layout */
659		if (value & PR_FP_MODE_FRE)
660			set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
661		else
662			clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
663	}
664
665	/* Allow threads to use FP again */
666	atomic_set(&task->mm->context.fp_mode_switching, 0);
667	preempt_enable();
668
669	return 0;
670}
671