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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/dsemul.h>
34#include <asm/dsp.h>
35#include <asm/fpu.h>
36#include <asm/irq.h>
37#include <asm/msa.h>
38#include <asm/pgtable.h>
39#include <asm/mipsregs.h>
40#include <asm/processor.h>
41#include <asm/reg.h>
42#include <linux/uaccess.h>
43#include <asm/io.h>
44#include <asm/elf.h>
45#include <asm/isadep.h>
46#include <asm/inst.h>
47#include <asm/stacktrace.h>
48#include <asm/irq_regs.h>
49
50#ifdef CONFIG_HOTPLUG_CPU
51void arch_cpu_idle_dead(void)
52{
53 /* What the heck is this check doing ? */
54 if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
55 play_dead();
56}
57#endif
58
59asmlinkage void ret_from_fork(void);
60asmlinkage void ret_from_kernel_thread(void);
61
62void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
63{
64 unsigned long status;
65
66 /* New thread loses kernel privileges. */
67 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
68 status |= KU_USER;
69 regs->cp0_status = status;
70 lose_fpu(0);
71 clear_thread_flag(TIF_MSA_CTX_LIVE);
72 clear_used_math();
73 atomic_set(¤t->thread.bd_emu_frame, BD_EMUFRAME_NONE);
74 init_dsp();
75 regs->cp0_epc = pc;
76 regs->regs[29] = sp;
77}
78
79void exit_thread(struct task_struct *tsk)
80{
81 /*
82 * User threads may have allocated a delay slot emulation frame.
83 * If so, clean up that allocation.
84 */
85 if (!(current->flags & PF_KTHREAD))
86 dsemul_thread_cleanup(tsk);
87}
88
89int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
90{
91 /*
92 * Save any process state which is live in hardware registers to the
93 * parent context prior to duplication. This prevents the new child
94 * state becoming stale if the parent is preempted before copy_thread()
95 * gets a chance to save the parent's live hardware registers to the
96 * child context.
97 */
98 preempt_disable();
99
100 if (is_msa_enabled())
101 save_msa(current);
102 else if (is_fpu_owner())
103 _save_fp(current);
104
105 save_dsp(current);
106
107 preempt_enable();
108
109 *dst = *src;
110 return 0;
111}
112
113/*
114 * Copy architecture-specific thread state
115 */
116int copy_thread(unsigned long clone_flags, unsigned long usp,
117 unsigned long kthread_arg, struct task_struct *p)
118{
119 struct thread_info *ti = task_thread_info(p);
120 struct pt_regs *childregs, *regs = current_pt_regs();
121 unsigned long childksp;
122 p->set_child_tid = p->clear_child_tid = NULL;
123
124 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
125
126 /* set up new TSS. */
127 childregs = (struct pt_regs *) childksp - 1;
128 /* Put the stack after the struct pt_regs. */
129 childksp = (unsigned long) childregs;
130 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
131 if (unlikely(p->flags & PF_KTHREAD)) {
132 /* kernel thread */
133 unsigned long status = p->thread.cp0_status;
134 memset(childregs, 0, sizeof(struct pt_regs));
135 ti->addr_limit = KERNEL_DS;
136 p->thread.reg16 = usp; /* fn */
137 p->thread.reg17 = kthread_arg;
138 p->thread.reg29 = childksp;
139 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
140#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
141 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
142 ((status & (ST0_KUC | ST0_IEC)) << 2);
143#else
144 status |= ST0_EXL;
145#endif
146 childregs->cp0_status = status;
147 return 0;
148 }
149
150 /* user thread */
151 *childregs = *regs;
152 childregs->regs[7] = 0; /* Clear error flag */
153 childregs->regs[2] = 0; /* Child gets zero as return value */
154 if (usp)
155 childregs->regs[29] = usp;
156 ti->addr_limit = USER_DS;
157
158 p->thread.reg29 = (unsigned long) childregs;
159 p->thread.reg31 = (unsigned long) ret_from_fork;
160
161 /*
162 * New tasks lose permission to use the fpu. This accelerates context
163 * switching for most programs since they don't use the fpu.
164 */
165 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
166
167 clear_tsk_thread_flag(p, TIF_USEDFPU);
168 clear_tsk_thread_flag(p, TIF_USEDMSA);
169 clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
170
171#ifdef CONFIG_MIPS_MT_FPAFF
172 clear_tsk_thread_flag(p, TIF_FPUBOUND);
173#endif /* CONFIG_MIPS_MT_FPAFF */
174
175 atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
176
177 if (clone_flags & CLONE_SETTLS)
178 ti->tp_value = regs->regs[7];
179
180 return 0;
181}
182
183#ifdef CONFIG_CC_STACKPROTECTOR
184#include <linux/stackprotector.h>
185unsigned long __stack_chk_guard __read_mostly;
186EXPORT_SYMBOL(__stack_chk_guard);
187#endif
188
189struct mips_frame_info {
190 void *func;
191 unsigned long func_size;
192 int frame_size;
193 int pc_offset;
194};
195
196#define J_TARGET(pc,target) \
197 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
198
199static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
200{
201#ifdef CONFIG_CPU_MICROMIPS
202 /*
203 * swsp ra,offset
204 * swm16 reglist,offset(sp)
205 * swm32 reglist,offset(sp)
206 * sw32 ra,offset(sp)
207 * jradiussp - NOT SUPPORTED
208 *
209 * microMIPS is way more fun...
210 */
211 if (mm_insn_16bit(ip->halfword[1])) {
212 switch (ip->mm16_r5_format.opcode) {
213 case mm_swsp16_op:
214 if (ip->mm16_r5_format.rt != 31)
215 return 0;
216
217 *poff = ip->mm16_r5_format.simmediate;
218 *poff = (*poff << 2) / sizeof(ulong);
219 return 1;
220
221 case mm_pool16c_op:
222 switch (ip->mm16_m_format.func) {
223 case mm_swm16_op:
224 *poff = ip->mm16_m_format.imm;
225 *poff += 1 + ip->mm16_m_format.rlist;
226 *poff = (*poff << 2) / sizeof(ulong);
227 return 1;
228
229 default:
230 return 0;
231 }
232
233 default:
234 return 0;
235 }
236 }
237
238 switch (ip->i_format.opcode) {
239 case mm_sw32_op:
240 if (ip->i_format.rs != 29)
241 return 0;
242 if (ip->i_format.rt != 31)
243 return 0;
244
245 *poff = ip->i_format.simmediate / sizeof(ulong);
246 return 1;
247
248 case mm_pool32b_op:
249 switch (ip->mm_m_format.func) {
250 case mm_swm32_func:
251 if (ip->mm_m_format.rd < 0x10)
252 return 0;
253 if (ip->mm_m_format.base != 29)
254 return 0;
255
256 *poff = ip->mm_m_format.simmediate;
257 *poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
258 *poff /= sizeof(ulong);
259 return 1;
260 default:
261 return 0;
262 }
263
264 default:
265 return 0;
266 }
267#else
268 /* sw / sd $ra, offset($sp) */
269 if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
270 ip->i_format.rs == 29 && ip->i_format.rt == 31) {
271 *poff = ip->i_format.simmediate / sizeof(ulong);
272 return 1;
273 }
274
275 return 0;
276#endif
277}
278
279static inline int is_jump_ins(union mips_instruction *ip)
280{
281#ifdef CONFIG_CPU_MICROMIPS
282 /*
283 * jr16,jrc,jalr16,jalr16
284 * jal
285 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
286 * jraddiusp - NOT SUPPORTED
287 *
288 * microMIPS is kind of more fun...
289 */
290 if (mm_insn_16bit(ip->halfword[1])) {
291 if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
292 (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
293 return 1;
294 return 0;
295 }
296
297 if (ip->j_format.opcode == mm_j32_op)
298 return 1;
299 if (ip->j_format.opcode == mm_jal32_op)
300 return 1;
301 if (ip->r_format.opcode != mm_pool32a_op ||
302 ip->r_format.func != mm_pool32axf_op)
303 return 0;
304 return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
305#else
306 if (ip->j_format.opcode == j_op)
307 return 1;
308 if (ip->j_format.opcode == jal_op)
309 return 1;
310 if (ip->r_format.opcode != spec_op)
311 return 0;
312 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
313#endif
314}
315
316static inline int is_sp_move_ins(union mips_instruction *ip)
317{
318#ifdef CONFIG_CPU_MICROMIPS
319 /*
320 * addiusp -imm
321 * addius5 sp,-imm
322 * addiu32 sp,sp,-imm
323 * jradiussp - NOT SUPPORTED
324 *
325 * microMIPS is not more fun...
326 */
327 if (mm_insn_16bit(ip->halfword[1])) {
328 return (ip->mm16_r3_format.opcode == mm_pool16d_op &&
329 ip->mm16_r3_format.simmediate && mm_addiusp_func) ||
330 (ip->mm16_r5_format.opcode == mm_pool16d_op &&
331 ip->mm16_r5_format.rt == 29);
332 }
333
334 return ip->mm_i_format.opcode == mm_addiu32_op &&
335 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
336#else
337 /* addiu/daddiu sp,sp,-imm */
338 if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
339 return 0;
340 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
341 return 1;
342#endif
343 return 0;
344}
345
346static int get_frame_info(struct mips_frame_info *info)
347{
348 bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
349 union mips_instruction insn, *ip, *ip_end;
350 const unsigned int max_insns = 128;
351 unsigned int i;
352
353 info->pc_offset = -1;
354 info->frame_size = 0;
355
356 ip = (void *)msk_isa16_mode((ulong)info->func);
357 if (!ip)
358 goto err;
359
360 ip_end = (void *)ip + info->func_size;
361
362 for (i = 0; i < max_insns && ip < ip_end; i++, ip++) {
363 if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
364 insn.halfword[0] = 0;
365 insn.halfword[1] = ip->halfword[0];
366 } else if (is_mmips) {
367 insn.halfword[0] = ip->halfword[1];
368 insn.halfword[1] = ip->halfword[0];
369 } else {
370 insn.word = ip->word;
371 }
372
373 if (is_jump_ins(&insn))
374 break;
375
376 if (!info->frame_size) {
377 if (is_sp_move_ins(&insn))
378 {
379#ifdef CONFIG_CPU_MICROMIPS
380 if (mm_insn_16bit(ip->halfword[0]))
381 {
382 unsigned short tmp;
383
384 if (ip->halfword[0] & mm_addiusp_func)
385 {
386 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
387 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
388 } else {
389 tmp = (ip->halfword[0] >> 1);
390 info->frame_size = -(signed short)(tmp & 0xf);
391 }
392 ip = (void *) &ip->halfword[1];
393 ip--;
394 } else
395#endif
396 info->frame_size = - ip->i_format.simmediate;
397 }
398 continue;
399 }
400 if (info->pc_offset == -1 &&
401 is_ra_save_ins(&insn, &info->pc_offset))
402 break;
403 }
404 if (info->frame_size && info->pc_offset >= 0) /* nested */
405 return 0;
406 if (info->pc_offset < 0) /* leaf */
407 return 1;
408 /* prologue seems bogus... */
409err:
410 return -1;
411}
412
413static struct mips_frame_info schedule_mfi __read_mostly;
414
415#ifdef CONFIG_KALLSYMS
416static unsigned long get___schedule_addr(void)
417{
418 return kallsyms_lookup_name("__schedule");
419}
420#else
421static unsigned long get___schedule_addr(void)
422{
423 union mips_instruction *ip = (void *)schedule;
424 int max_insns = 8;
425 int i;
426
427 for (i = 0; i < max_insns; i++, ip++) {
428 if (ip->j_format.opcode == j_op)
429 return J_TARGET(ip, ip->j_format.target);
430 }
431 return 0;
432}
433#endif
434
435static int __init frame_info_init(void)
436{
437 unsigned long size = 0;
438#ifdef CONFIG_KALLSYMS
439 unsigned long ofs;
440#endif
441 unsigned long addr;
442
443 addr = get___schedule_addr();
444 if (!addr)
445 addr = (unsigned long)schedule;
446
447#ifdef CONFIG_KALLSYMS
448 kallsyms_lookup_size_offset(addr, &size, &ofs);
449#endif
450 schedule_mfi.func = (void *)addr;
451 schedule_mfi.func_size = size;
452
453 get_frame_info(&schedule_mfi);
454
455 /*
456 * Without schedule() frame info, result given by
457 * thread_saved_pc() and get_wchan() are not reliable.
458 */
459 if (schedule_mfi.pc_offset < 0)
460 printk("Can't analyze schedule() prologue at %p\n", schedule);
461
462 return 0;
463}
464
465arch_initcall(frame_info_init);
466
467/*
468 * Return saved PC of a blocked thread.
469 */
470unsigned long thread_saved_pc(struct task_struct *tsk)
471{
472 struct thread_struct *t = &tsk->thread;
473
474 /* New born processes are a special case */
475 if (t->reg31 == (unsigned long) ret_from_fork)
476 return t->reg31;
477 if (schedule_mfi.pc_offset < 0)
478 return 0;
479 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
480}
481
482
483#ifdef CONFIG_KALLSYMS
484/* generic stack unwinding function */
485unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
486 unsigned long *sp,
487 unsigned long pc,
488 unsigned long *ra)
489{
490 struct mips_frame_info info;
491 unsigned long size, ofs;
492 int leaf;
493 extern void ret_from_irq(void);
494 extern void ret_from_exception(void);
495
496 if (!stack_page)
497 return 0;
498
499 /*
500 * If we reached the bottom of interrupt context,
501 * return saved pc in pt_regs.
502 */
503 if (pc == (unsigned long)ret_from_irq ||
504 pc == (unsigned long)ret_from_exception) {
505 struct pt_regs *regs;
506 if (*sp >= stack_page &&
507 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
508 regs = (struct pt_regs *)*sp;
509 pc = regs->cp0_epc;
510 if (!user_mode(regs) && __kernel_text_address(pc)) {
511 *sp = regs->regs[29];
512 *ra = regs->regs[31];
513 return pc;
514 }
515 }
516 return 0;
517 }
518 if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
519 return 0;
520 /*
521 * Return ra if an exception occurred at the first instruction
522 */
523 if (unlikely(ofs == 0)) {
524 pc = *ra;
525 *ra = 0;
526 return pc;
527 }
528
529 info.func = (void *)(pc - ofs);
530 info.func_size = ofs; /* analyze from start to ofs */
531 leaf = get_frame_info(&info);
532 if (leaf < 0)
533 return 0;
534
535 if (*sp < stack_page ||
536 *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
537 return 0;
538
539 if (leaf)
540 /*
541 * For some extreme cases, get_frame_info() can
542 * consider wrongly a nested function as a leaf
543 * one. In that cases avoid to return always the
544 * same value.
545 */
546 pc = pc != *ra ? *ra : 0;
547 else
548 pc = ((unsigned long *)(*sp))[info.pc_offset];
549
550 *sp += info.frame_size;
551 *ra = 0;
552 return __kernel_text_address(pc) ? pc : 0;
553}
554EXPORT_SYMBOL(unwind_stack_by_address);
555
556/* used by show_backtrace() */
557unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
558 unsigned long pc, unsigned long *ra)
559{
560 unsigned long stack_page = 0;
561 int cpu;
562
563 for_each_possible_cpu(cpu) {
564 if (on_irq_stack(cpu, *sp)) {
565 stack_page = (unsigned long)irq_stack[cpu];
566 break;
567 }
568 }
569
570 if (!stack_page)
571 stack_page = (unsigned long)task_stack_page(task);
572
573 return unwind_stack_by_address(stack_page, sp, pc, ra);
574}
575#endif
576
577/*
578 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
579 */
580unsigned long get_wchan(struct task_struct *task)
581{
582 unsigned long pc = 0;
583#ifdef CONFIG_KALLSYMS
584 unsigned long sp;
585 unsigned long ra = 0;
586#endif
587
588 if (!task || task == current || task->state == TASK_RUNNING)
589 goto out;
590 if (!task_stack_page(task))
591 goto out;
592
593 pc = thread_saved_pc(task);
594
595#ifdef CONFIG_KALLSYMS
596 sp = task->thread.reg29 + schedule_mfi.frame_size;
597
598 while (in_sched_functions(pc))
599 pc = unwind_stack(task, &sp, pc, &ra);
600#endif
601
602out:
603 return pc;
604}
605
606/*
607 * Don't forget that the stack pointer must be aligned on a 8 bytes
608 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
609 */
610unsigned long arch_align_stack(unsigned long sp)
611{
612 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
613 sp -= get_random_int() & ~PAGE_MASK;
614
615 return sp & ALMASK;
616}
617
618static void arch_dump_stack(void *info)
619{
620 struct pt_regs *regs;
621
622 regs = get_irq_regs();
623
624 if (regs)
625 show_regs(regs);
626
627 dump_stack();
628}
629
630void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
631{
632 long this_cpu = get_cpu();
633
634 if (cpumask_test_cpu(this_cpu, mask) && !exclude_self)
635 dump_stack();
636
637 smp_call_function_many(mask, arch_dump_stack, NULL, 1);
638
639 put_cpu();
640}
641
642int mips_get_process_fp_mode(struct task_struct *task)
643{
644 int value = 0;
645
646 if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
647 value |= PR_FP_MODE_FR;
648 if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
649 value |= PR_FP_MODE_FRE;
650
651 return value;
652}
653
654static void prepare_for_fp_mode_switch(void *info)
655{
656 struct mm_struct *mm = info;
657
658 if (current->mm == mm)
659 lose_fpu(1);
660}
661
662int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
663{
664 const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
665 struct task_struct *t;
666 int max_users;
667
668 /* Check the value is valid */
669 if (value & ~known_bits)
670 return -EOPNOTSUPP;
671
672 /* Avoid inadvertently triggering emulation */
673 if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
674 !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
675 return -EOPNOTSUPP;
676 if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
677 return -EOPNOTSUPP;
678
679 /* FR = 0 not supported in MIPS R6 */
680 if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
681 return -EOPNOTSUPP;
682
683 /* Proceed with the mode switch */
684 preempt_disable();
685
686 /* Save FP & vector context, then disable FPU & MSA */
687 if (task->signal == current->signal)
688 lose_fpu(1);
689
690 /* Prevent any threads from obtaining live FP context */
691 atomic_set(&task->mm->context.fp_mode_switching, 1);
692 smp_mb__after_atomic();
693
694 /*
695 * If there are multiple online CPUs then force any which are running
696 * threads in this process to lose their FPU context, which they can't
697 * regain until fp_mode_switching is cleared later.
698 */
699 if (num_online_cpus() > 1) {
700 /* No need to send an IPI for the local CPU */
701 max_users = (task->mm == current->mm) ? 1 : 0;
702
703 if (atomic_read(¤t->mm->mm_users) > max_users)
704 smp_call_function(prepare_for_fp_mode_switch,
705 (void *)current->mm, 1);
706 }
707
708 /*
709 * There are now no threads of the process with live FP context, so it
710 * is safe to proceed with the FP mode switch.
711 */
712 for_each_thread(task, t) {
713 /* Update desired FP register width */
714 if (value & PR_FP_MODE_FR) {
715 clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
716 } else {
717 set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
718 clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
719 }
720
721 /* Update desired FP single layout */
722 if (value & PR_FP_MODE_FRE)
723 set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
724 else
725 clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
726 }
727
728 /* Allow threads to use FP again */
729 atomic_set(&task->mm->context.fp_mode_switching, 0);
730 preempt_enable();
731
732 return 0;
733}
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 lose_fpu(0);
69 clear_thread_flag(TIF_MSA_CTX_LIVE);
70 clear_used_math();
71 init_dsp();
72 regs->cp0_epc = pc;
73 regs->regs[29] = sp;
74}
75
76void exit_thread(void)
77{
78}
79
80void flush_thread(void)
81{
82}
83
84int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
85{
86 /*
87 * Save any process state which is live in hardware registers to the
88 * parent context prior to duplication. This prevents the new child
89 * state becoming stale if the parent is preempted before copy_thread()
90 * gets a chance to save the parent's live hardware registers to the
91 * child context.
92 */
93 preempt_disable();
94
95 if (is_msa_enabled())
96 save_msa(current);
97 else if (is_fpu_owner())
98 _save_fp(current);
99
100 save_dsp(current);
101
102 preempt_enable();
103
104 *dst = *src;
105 return 0;
106}
107
108/*
109 * Copy architecture-specific thread state
110 */
111int copy_thread(unsigned long clone_flags, unsigned long usp,
112 unsigned long kthread_arg, struct task_struct *p)
113{
114 struct thread_info *ti = task_thread_info(p);
115 struct pt_regs *childregs, *regs = current_pt_regs();
116 unsigned long childksp;
117 p->set_child_tid = p->clear_child_tid = NULL;
118
119 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
120
121 /* set up new TSS. */
122 childregs = (struct pt_regs *) childksp - 1;
123 /* Put the stack after the struct pt_regs. */
124 childksp = (unsigned long) childregs;
125 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
126 if (unlikely(p->flags & PF_KTHREAD)) {
127 /* kernel thread */
128 unsigned long status = p->thread.cp0_status;
129 memset(childregs, 0, sizeof(struct pt_regs));
130 ti->addr_limit = KERNEL_DS;
131 p->thread.reg16 = usp; /* fn */
132 p->thread.reg17 = kthread_arg;
133 p->thread.reg29 = childksp;
134 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
135#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
136 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
137 ((status & (ST0_KUC | ST0_IEC)) << 2);
138#else
139 status |= ST0_EXL;
140#endif
141 childregs->cp0_status = status;
142 return 0;
143 }
144
145 /* user thread */
146 *childregs = *regs;
147 childregs->regs[7] = 0; /* Clear error flag */
148 childregs->regs[2] = 0; /* Child gets zero as return value */
149 if (usp)
150 childregs->regs[29] = usp;
151 ti->addr_limit = USER_DS;
152
153 p->thread.reg29 = (unsigned long) childregs;
154 p->thread.reg31 = (unsigned long) ret_from_fork;
155
156 /*
157 * New tasks lose permission to use the fpu. This accelerates context
158 * switching for most programs since they don't use the fpu.
159 */
160 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
161
162 clear_tsk_thread_flag(p, TIF_USEDFPU);
163 clear_tsk_thread_flag(p, TIF_USEDMSA);
164 clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
165
166#ifdef CONFIG_MIPS_MT_FPAFF
167 clear_tsk_thread_flag(p, TIF_FPUBOUND);
168#endif /* CONFIG_MIPS_MT_FPAFF */
169
170 if (clone_flags & CLONE_SETTLS)
171 ti->tp_value = regs->regs[7];
172
173 return 0;
174}
175
176#ifdef CONFIG_CC_STACKPROTECTOR
177#include <linux/stackprotector.h>
178unsigned long __stack_chk_guard __read_mostly;
179EXPORT_SYMBOL(__stack_chk_guard);
180#endif
181
182struct mips_frame_info {
183 void *func;
184 unsigned long func_size;
185 int frame_size;
186 int pc_offset;
187};
188
189#define J_TARGET(pc,target) \
190 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
191
192static inline int is_ra_save_ins(union mips_instruction *ip)
193{
194#ifdef CONFIG_CPU_MICROMIPS
195 union mips_instruction mmi;
196
197 /*
198 * swsp ra,offset
199 * swm16 reglist,offset(sp)
200 * swm32 reglist,offset(sp)
201 * sw32 ra,offset(sp)
202 * jradiussp - NOT SUPPORTED
203 *
204 * microMIPS is way more fun...
205 */
206 if (mm_insn_16bit(ip->halfword[0])) {
207 mmi.word = (ip->halfword[0] << 16);
208 return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
209 mmi.mm16_r5_format.rt == 31) ||
210 (mmi.mm16_m_format.opcode == mm_pool16c_op &&
211 mmi.mm16_m_format.func == mm_swm16_op);
212 }
213 else {
214 mmi.halfword[0] = ip->halfword[1];
215 mmi.halfword[1] = ip->halfword[0];
216 return (mmi.mm_m_format.opcode == mm_pool32b_op &&
217 mmi.mm_m_format.rd > 9 &&
218 mmi.mm_m_format.base == 29 &&
219 mmi.mm_m_format.func == mm_swm32_func) ||
220 (mmi.i_format.opcode == mm_sw32_op &&
221 mmi.i_format.rs == 29 &&
222 mmi.i_format.rt == 31);
223 }
224#else
225 /* sw / sd $ra, offset($sp) */
226 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
227 ip->i_format.rs == 29 &&
228 ip->i_format.rt == 31;
229#endif
230}
231
232static inline int is_jump_ins(union mips_instruction *ip)
233{
234#ifdef CONFIG_CPU_MICROMIPS
235 /*
236 * jr16,jrc,jalr16,jalr16
237 * jal
238 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
239 * jraddiusp - NOT SUPPORTED
240 *
241 * microMIPS is kind of more fun...
242 */
243 union mips_instruction mmi;
244
245 mmi.word = (ip->halfword[0] << 16);
246
247 if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
248 (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
249 ip->j_format.opcode == mm_jal32_op)
250 return 1;
251 if (ip->r_format.opcode != mm_pool32a_op ||
252 ip->r_format.func != mm_pool32axf_op)
253 return 0;
254 return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
255#else
256 if (ip->j_format.opcode == j_op)
257 return 1;
258 if (ip->j_format.opcode == jal_op)
259 return 1;
260 if (ip->r_format.opcode != spec_op)
261 return 0;
262 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
263#endif
264}
265
266static inline int is_sp_move_ins(union mips_instruction *ip)
267{
268#ifdef CONFIG_CPU_MICROMIPS
269 /*
270 * addiusp -imm
271 * addius5 sp,-imm
272 * addiu32 sp,sp,-imm
273 * jradiussp - NOT SUPPORTED
274 *
275 * microMIPS is not more fun...
276 */
277 if (mm_insn_16bit(ip->halfword[0])) {
278 union mips_instruction mmi;
279
280 mmi.word = (ip->halfword[0] << 16);
281 return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
282 mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
283 (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
284 mmi.mm16_r5_format.rt == 29);
285 }
286 return ip->mm_i_format.opcode == mm_addiu32_op &&
287 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
288#else
289 /* addiu/daddiu sp,sp,-imm */
290 if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
291 return 0;
292 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
293 return 1;
294#endif
295 return 0;
296}
297
298static int get_frame_info(struct mips_frame_info *info)
299{
300#ifdef CONFIG_CPU_MICROMIPS
301 union mips_instruction *ip = (void *) (((char *) info->func) - 1);
302#else
303 union mips_instruction *ip = info->func;
304#endif
305 unsigned max_insns = info->func_size / sizeof(union mips_instruction);
306 unsigned i;
307
308 info->pc_offset = -1;
309 info->frame_size = 0;
310
311 if (!ip)
312 goto err;
313
314 if (max_insns == 0)
315 max_insns = 128U; /* unknown function size */
316 max_insns = min(128U, max_insns);
317
318 for (i = 0; i < max_insns; i++, ip++) {
319
320 if (is_jump_ins(ip))
321 break;
322 if (!info->frame_size) {
323 if (is_sp_move_ins(ip))
324 {
325#ifdef CONFIG_CPU_MICROMIPS
326 if (mm_insn_16bit(ip->halfword[0]))
327 {
328 unsigned short tmp;
329
330 if (ip->halfword[0] & mm_addiusp_func)
331 {
332 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
333 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
334 } else {
335 tmp = (ip->halfword[0] >> 1);
336 info->frame_size = -(signed short)(tmp & 0xf);
337 }
338 ip = (void *) &ip->halfword[1];
339 ip--;
340 } else
341#endif
342 info->frame_size = - ip->i_format.simmediate;
343 }
344 continue;
345 }
346 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
347 info->pc_offset =
348 ip->i_format.simmediate / sizeof(long);
349 break;
350 }
351 }
352 if (info->frame_size && info->pc_offset >= 0) /* nested */
353 return 0;
354 if (info->pc_offset < 0) /* leaf */
355 return 1;
356 /* prologue seems boggus... */
357err:
358 return -1;
359}
360
361static struct mips_frame_info schedule_mfi __read_mostly;
362
363#ifdef CONFIG_KALLSYMS
364static unsigned long get___schedule_addr(void)
365{
366 return kallsyms_lookup_name("__schedule");
367}
368#else
369static unsigned long get___schedule_addr(void)
370{
371 union mips_instruction *ip = (void *)schedule;
372 int max_insns = 8;
373 int i;
374
375 for (i = 0; i < max_insns; i++, ip++) {
376 if (ip->j_format.opcode == j_op)
377 return J_TARGET(ip, ip->j_format.target);
378 }
379 return 0;
380}
381#endif
382
383static int __init frame_info_init(void)
384{
385 unsigned long size = 0;
386#ifdef CONFIG_KALLSYMS
387 unsigned long ofs;
388#endif
389 unsigned long addr;
390
391 addr = get___schedule_addr();
392 if (!addr)
393 addr = (unsigned long)schedule;
394
395#ifdef CONFIG_KALLSYMS
396 kallsyms_lookup_size_offset(addr, &size, &ofs);
397#endif
398 schedule_mfi.func = (void *)addr;
399 schedule_mfi.func_size = size;
400
401 get_frame_info(&schedule_mfi);
402
403 /*
404 * Without schedule() frame info, result given by
405 * thread_saved_pc() and get_wchan() are not reliable.
406 */
407 if (schedule_mfi.pc_offset < 0)
408 printk("Can't analyze schedule() prologue at %p\n", schedule);
409
410 return 0;
411}
412
413arch_initcall(frame_info_init);
414
415/*
416 * Return saved PC of a blocked thread.
417 */
418unsigned long thread_saved_pc(struct task_struct *tsk)
419{
420 struct thread_struct *t = &tsk->thread;
421
422 /* New born processes are a special case */
423 if (t->reg31 == (unsigned long) ret_from_fork)
424 return t->reg31;
425 if (schedule_mfi.pc_offset < 0)
426 return 0;
427 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
428}
429
430
431#ifdef CONFIG_KALLSYMS
432/* generic stack unwinding function */
433unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
434 unsigned long *sp,
435 unsigned long pc,
436 unsigned long *ra)
437{
438 struct mips_frame_info info;
439 unsigned long size, ofs;
440 int leaf;
441 extern void ret_from_irq(void);
442 extern void ret_from_exception(void);
443
444 if (!stack_page)
445 return 0;
446
447 /*
448 * If we reached the bottom of interrupt context,
449 * return saved pc in pt_regs.
450 */
451 if (pc == (unsigned long)ret_from_irq ||
452 pc == (unsigned long)ret_from_exception) {
453 struct pt_regs *regs;
454 if (*sp >= stack_page &&
455 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
456 regs = (struct pt_regs *)*sp;
457 pc = regs->cp0_epc;
458 if (__kernel_text_address(pc)) {
459 *sp = regs->regs[29];
460 *ra = regs->regs[31];
461 return pc;
462 }
463 }
464 return 0;
465 }
466 if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
467 return 0;
468 /*
469 * Return ra if an exception occurred at the first instruction
470 */
471 if (unlikely(ofs == 0)) {
472 pc = *ra;
473 *ra = 0;
474 return pc;
475 }
476
477 info.func = (void *)(pc - ofs);
478 info.func_size = ofs; /* analyze from start to ofs */
479 leaf = get_frame_info(&info);
480 if (leaf < 0)
481 return 0;
482
483 if (*sp < stack_page ||
484 *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
485 return 0;
486
487 if (leaf)
488 /*
489 * For some extreme cases, get_frame_info() can
490 * consider wrongly a nested function as a leaf
491 * one. In that cases avoid to return always the
492 * same value.
493 */
494 pc = pc != *ra ? *ra : 0;
495 else
496 pc = ((unsigned long *)(*sp))[info.pc_offset];
497
498 *sp += info.frame_size;
499 *ra = 0;
500 return __kernel_text_address(pc) ? pc : 0;
501}
502EXPORT_SYMBOL(unwind_stack_by_address);
503
504/* used by show_backtrace() */
505unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
506 unsigned long pc, unsigned long *ra)
507{
508 unsigned long stack_page = (unsigned long)task_stack_page(task);
509 return unwind_stack_by_address(stack_page, sp, pc, ra);
510}
511#endif
512
513/*
514 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
515 */
516unsigned long get_wchan(struct task_struct *task)
517{
518 unsigned long pc = 0;
519#ifdef CONFIG_KALLSYMS
520 unsigned long sp;
521 unsigned long ra = 0;
522#endif
523
524 if (!task || task == current || task->state == TASK_RUNNING)
525 goto out;
526 if (!task_stack_page(task))
527 goto out;
528
529 pc = thread_saved_pc(task);
530
531#ifdef CONFIG_KALLSYMS
532 sp = task->thread.reg29 + schedule_mfi.frame_size;
533
534 while (in_sched_functions(pc))
535 pc = unwind_stack(task, &sp, pc, &ra);
536#endif
537
538out:
539 return pc;
540}
541
542/*
543 * Don't forget that the stack pointer must be aligned on a 8 bytes
544 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
545 */
546unsigned long arch_align_stack(unsigned long sp)
547{
548 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
549 sp -= get_random_int() & ~PAGE_MASK;
550
551 return sp & ALMASK;
552}
553
554static void arch_dump_stack(void *info)
555{
556 struct pt_regs *regs;
557
558 regs = get_irq_regs();
559
560 if (regs)
561 show_regs(regs);
562
563 dump_stack();
564}
565
566void arch_trigger_all_cpu_backtrace(bool include_self)
567{
568 smp_call_function(arch_dump_stack, NULL, 1);
569}
570
571int mips_get_process_fp_mode(struct task_struct *task)
572{
573 int value = 0;
574
575 if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
576 value |= PR_FP_MODE_FR;
577 if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
578 value |= PR_FP_MODE_FRE;
579
580 return value;
581}
582
583int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
584{
585 const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
586 unsigned long switch_count;
587 struct task_struct *t;
588
589 /* Check the value is valid */
590 if (value & ~known_bits)
591 return -EOPNOTSUPP;
592
593 /* Avoid inadvertently triggering emulation */
594 if ((value & PR_FP_MODE_FR) && cpu_has_fpu &&
595 !(current_cpu_data.fpu_id & MIPS_FPIR_F64))
596 return -EOPNOTSUPP;
597 if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre)
598 return -EOPNOTSUPP;
599
600 /* FR = 0 not supported in MIPS R6 */
601 if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
602 return -EOPNOTSUPP;
603
604 /* Save FP & vector context, then disable FPU & MSA */
605 if (task->signal == current->signal)
606 lose_fpu(1);
607
608 /* Prevent any threads from obtaining live FP context */
609 atomic_set(&task->mm->context.fp_mode_switching, 1);
610 smp_mb__after_atomic();
611
612 /*
613 * If there are multiple online CPUs then wait until all threads whose
614 * FP mode is about to change have been context switched. This approach
615 * allows us to only worry about whether an FP mode switch is in
616 * progress when FP is first used in a tasks time slice. Pretty much all
617 * of the mode switch overhead can thus be confined to cases where mode
618 * switches are actually occurring. That is, to here. However for the
619 * thread performing the mode switch it may take a while...
620 */
621 if (num_online_cpus() > 1) {
622 spin_lock_irq(&task->sighand->siglock);
623
624 for_each_thread(task, t) {
625 if (t == current)
626 continue;
627
628 switch_count = t->nvcsw + t->nivcsw;
629
630 do {
631 spin_unlock_irq(&task->sighand->siglock);
632 cond_resched();
633 spin_lock_irq(&task->sighand->siglock);
634 } while ((t->nvcsw + t->nivcsw) == switch_count);
635 }
636
637 spin_unlock_irq(&task->sighand->siglock);
638 }
639
640 /*
641 * There are now no threads of the process with live FP context, so it
642 * is safe to proceed with the FP mode switch.
643 */
644 for_each_thread(task, t) {
645 /* Update desired FP register width */
646 if (value & PR_FP_MODE_FR) {
647 clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
648 } else {
649 set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
650 clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
651 }
652
653 /* Update desired FP single layout */
654 if (value & PR_FP_MODE_FRE)
655 set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
656 else
657 clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
658 }
659
660 /* Allow threads to use FP again */
661 atomic_set(&task->mm->context.fp_mode_switching, 0);
662
663 return 0;
664}