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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/cpu.h>
13#include <linux/errno.h>
14#include <linux/init.h>
15#include <linux/kallsyms.h>
16#include <linux/kernel.h>
17#include <linux/nmi.h>
18#include <linux/personality.h>
19#include <linux/prctl.h>
20#include <linux/random.h>
21#include <linux/sched.h>
22#include <linux/sched/debug.h>
23#include <linux/sched/task_stack.h>
24
25#include <asm/abi.h>
26#include <asm/asm.h>
27#include <asm/dsemul.h>
28#include <asm/dsp.h>
29#include <asm/exec.h>
30#include <asm/fpu.h>
31#include <asm/inst.h>
32#include <asm/irq.h>
33#include <asm/irq_regs.h>
34#include <asm/isadep.h>
35#include <asm/msa.h>
36#include <asm/mips-cps.h>
37#include <asm/mipsregs.h>
38#include <asm/processor.h>
39#include <asm/reg.h>
40#include <asm/stacktrace.h>
41
42#ifdef CONFIG_HOTPLUG_CPU
43void arch_cpu_idle_dead(void)
44{
45 play_dead();
46}
47#endif
48
49asmlinkage void ret_from_fork(void);
50asmlinkage void ret_from_kernel_thread(void);
51
52void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
53{
54 unsigned long status;
55
56 /* New thread loses kernel privileges. */
57 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_CU2|ST0_FR|KU_MASK);
58 status |= KU_USER;
59 regs->cp0_status = status;
60 lose_fpu(0);
61 clear_thread_flag(TIF_MSA_CTX_LIVE);
62 clear_used_math();
63#ifdef CONFIG_MIPS_FP_SUPPORT
64 atomic_set(¤t->thread.bd_emu_frame, BD_EMUFRAME_NONE);
65#endif
66 init_dsp();
67 regs->cp0_epc = pc;
68 regs->regs[29] = sp;
69}
70
71void exit_thread(struct task_struct *tsk)
72{
73 /*
74 * User threads may have allocated a delay slot emulation frame.
75 * If so, clean up that allocation.
76 */
77 if (!(current->flags & PF_KTHREAD))
78 dsemul_thread_cleanup(tsk);
79}
80
81int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
82{
83 /*
84 * Save any process state which is live in hardware registers to the
85 * parent context prior to duplication. This prevents the new child
86 * state becoming stale if the parent is preempted before copy_thread()
87 * gets a chance to save the parent's live hardware registers to the
88 * child context.
89 */
90 preempt_disable();
91
92 if (is_msa_enabled())
93 save_msa(current);
94 else if (is_fpu_owner())
95 _save_fp(current);
96
97 save_dsp(current);
98
99 preempt_enable();
100
101 *dst = *src;
102 return 0;
103}
104
105/*
106 * Copy architecture-specific thread state
107 */
108int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
109{
110 unsigned long clone_flags = args->flags;
111 unsigned long usp = args->stack;
112 unsigned long tls = args->tls;
113 struct thread_info *ti = task_thread_info(p);
114 struct pt_regs *childregs, *regs = current_pt_regs();
115 unsigned long childksp;
116
117 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
118
119 /* set up new TSS. */
120 childregs = (struct pt_regs *) childksp - 1;
121 /* Put the stack after the struct pt_regs. */
122 childksp = (unsigned long) childregs;
123 p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK;
124 if (unlikely(args->fn)) {
125 /* kernel thread */
126 unsigned long status = p->thread.cp0_status;
127 memset(childregs, 0, sizeof(struct pt_regs));
128 p->thread.reg16 = (unsigned long)args->fn;
129 p->thread.reg17 = (unsigned long)args->fn_arg;
130 p->thread.reg29 = childksp;
131 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
132#if defined(CONFIG_CPU_R3000)
133 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
134 ((status & (ST0_KUC | ST0_IEC)) << 2);
135#else
136 status |= ST0_EXL;
137#endif
138 childregs->cp0_status = status;
139 return 0;
140 }
141
142 /* user thread */
143 *childregs = *regs;
144 childregs->regs[7] = 0; /* Clear error flag */
145 childregs->regs[2] = 0; /* Child gets zero as return value */
146 if (usp)
147 childregs->regs[29] = usp;
148
149 p->thread.reg29 = (unsigned long) childregs;
150 p->thread.reg31 = (unsigned long) ret_from_fork;
151
152 /*
153 * New tasks lose permission to use the fpu. This accelerates context
154 * switching for most programs since they don't use the fpu.
155 */
156 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
157
158 clear_tsk_thread_flag(p, TIF_USEDFPU);
159 clear_tsk_thread_flag(p, TIF_USEDMSA);
160 clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
161
162#ifdef CONFIG_MIPS_MT_FPAFF
163 clear_tsk_thread_flag(p, TIF_FPUBOUND);
164#endif /* CONFIG_MIPS_MT_FPAFF */
165
166#ifdef CONFIG_MIPS_FP_SUPPORT
167 atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
168#endif
169
170 if (clone_flags & CLONE_SETTLS)
171 ti->tp_value = tls;
172
173 return 0;
174}
175
176#ifdef CONFIG_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_jr_ra_ins(union mips_instruction *ip)
193{
194#ifdef CONFIG_CPU_MICROMIPS
195 /*
196 * jr16 ra
197 * jr ra
198 */
199 if (mm_insn_16bit(ip->word >> 16)) {
200 if (ip->mm16_r5_format.opcode == mm_pool16c_op &&
201 ip->mm16_r5_format.rt == mm_jr16_op &&
202 ip->mm16_r5_format.imm == 31)
203 return 1;
204 return 0;
205 }
206
207 if (ip->r_format.opcode == mm_pool32a_op &&
208 ip->r_format.func == mm_pool32axf_op &&
209 ((ip->u_format.uimmediate >> 6) & GENMASK(9, 0)) == mm_jalr_op &&
210 ip->r_format.rt == 31)
211 return 1;
212 return 0;
213#else
214 if (ip->r_format.opcode == spec_op &&
215 ip->r_format.func == jr_op &&
216 ip->r_format.rs == 31)
217 return 1;
218 return 0;
219#endif
220}
221
222static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
223{
224#ifdef CONFIG_CPU_MICROMIPS
225 /*
226 * swsp ra,offset
227 * swm16 reglist,offset(sp)
228 * swm32 reglist,offset(sp)
229 * sw32 ra,offset(sp)
230 * jradiussp - NOT SUPPORTED
231 *
232 * microMIPS is way more fun...
233 */
234 if (mm_insn_16bit(ip->word >> 16)) {
235 switch (ip->mm16_r5_format.opcode) {
236 case mm_swsp16_op:
237 if (ip->mm16_r5_format.rt != 31)
238 return 0;
239
240 *poff = ip->mm16_r5_format.imm;
241 *poff = (*poff << 2) / sizeof(ulong);
242 return 1;
243
244 case mm_pool16c_op:
245 switch (ip->mm16_m_format.func) {
246 case mm_swm16_op:
247 *poff = ip->mm16_m_format.imm;
248 *poff += 1 + ip->mm16_m_format.rlist;
249 *poff = (*poff << 2) / sizeof(ulong);
250 return 1;
251
252 default:
253 return 0;
254 }
255
256 default:
257 return 0;
258 }
259 }
260
261 switch (ip->i_format.opcode) {
262 case mm_sw32_op:
263 if (ip->i_format.rs != 29)
264 return 0;
265 if (ip->i_format.rt != 31)
266 return 0;
267
268 *poff = ip->i_format.simmediate / sizeof(ulong);
269 return 1;
270
271 case mm_pool32b_op:
272 switch (ip->mm_m_format.func) {
273 case mm_swm32_func:
274 if (ip->mm_m_format.rd < 0x10)
275 return 0;
276 if (ip->mm_m_format.base != 29)
277 return 0;
278
279 *poff = ip->mm_m_format.simmediate;
280 *poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
281 *poff /= sizeof(ulong);
282 return 1;
283 default:
284 return 0;
285 }
286
287 default:
288 return 0;
289 }
290#else
291 /* sw / sd $ra, offset($sp) */
292 if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
293 ip->i_format.rs == 29 && ip->i_format.rt == 31) {
294 *poff = ip->i_format.simmediate / sizeof(ulong);
295 return 1;
296 }
297#ifdef CONFIG_CPU_LOONGSON64
298 if ((ip->loongson3_lswc2_format.opcode == swc2_op) &&
299 (ip->loongson3_lswc2_format.ls == 1) &&
300 (ip->loongson3_lswc2_format.fr == 0) &&
301 (ip->loongson3_lswc2_format.base == 29)) {
302 if (ip->loongson3_lswc2_format.rt == 31) {
303 *poff = ip->loongson3_lswc2_format.offset << 1;
304 return 1;
305 }
306 if (ip->loongson3_lswc2_format.rq == 31) {
307 *poff = (ip->loongson3_lswc2_format.offset << 1) + 1;
308 return 1;
309 }
310 }
311#endif
312 return 0;
313#endif
314}
315
316static inline int is_jump_ins(union mips_instruction *ip)
317{
318#ifdef CONFIG_CPU_MICROMIPS
319 /*
320 * jr16,jrc,jalr16,jalr16
321 * jal
322 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
323 * jraddiusp - NOT SUPPORTED
324 *
325 * microMIPS is kind of more fun...
326 */
327 if (mm_insn_16bit(ip->word >> 16)) {
328 if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
329 (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
330 return 1;
331 return 0;
332 }
333
334 if (ip->j_format.opcode == mm_j32_op)
335 return 1;
336 if (ip->j_format.opcode == mm_jal32_op)
337 return 1;
338 if (ip->r_format.opcode != mm_pool32a_op ||
339 ip->r_format.func != mm_pool32axf_op)
340 return 0;
341 return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
342#else
343 if (ip->j_format.opcode == j_op)
344 return 1;
345 if (ip->j_format.opcode == jal_op)
346 return 1;
347 if (ip->r_format.opcode != spec_op)
348 return 0;
349 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
350#endif
351}
352
353static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size)
354{
355#ifdef CONFIG_CPU_MICROMIPS
356 unsigned short tmp;
357
358 /*
359 * addiusp -imm
360 * addius5 sp,-imm
361 * addiu32 sp,sp,-imm
362 * jradiussp - NOT SUPPORTED
363 *
364 * microMIPS is not more fun...
365 */
366 if (mm_insn_16bit(ip->word >> 16)) {
367 if (ip->mm16_r3_format.opcode == mm_pool16d_op &&
368 ip->mm16_r3_format.simmediate & mm_addiusp_func) {
369 tmp = ip->mm_b0_format.simmediate >> 1;
370 tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100;
371 if ((tmp + 2) < 4) /* 0x0,0x1,0x1fe,0x1ff are special */
372 tmp ^= 0x100;
373 *frame_size = -(signed short)(tmp << 2);
374 return 1;
375 }
376 if (ip->mm16_r5_format.opcode == mm_pool16d_op &&
377 ip->mm16_r5_format.rt == 29) {
378 tmp = ip->mm16_r5_format.imm >> 1;
379 *frame_size = -(signed short)(tmp & 0xf);
380 return 1;
381 }
382 return 0;
383 }
384
385 if (ip->mm_i_format.opcode == mm_addiu32_op &&
386 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29) {
387 *frame_size = -ip->i_format.simmediate;
388 return 1;
389 }
390#else
391 /* addiu/daddiu sp,sp,-imm */
392 if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
393 return 0;
394
395 if (ip->i_format.opcode == addiu_op ||
396 ip->i_format.opcode == daddiu_op) {
397 *frame_size = -ip->i_format.simmediate;
398 return 1;
399 }
400#endif
401 return 0;
402}
403
404static int get_frame_info(struct mips_frame_info *info)
405{
406 bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
407 union mips_instruction insn, *ip, *ip_end;
408 unsigned int last_insn_size = 0;
409 bool saw_jump = false;
410
411 info->pc_offset = -1;
412 info->frame_size = 0;
413
414 ip = (void *)msk_isa16_mode((ulong)info->func);
415 if (!ip)
416 goto err;
417
418 ip_end = (void *)ip + (info->func_size ? info->func_size : 512);
419
420 while (ip < ip_end) {
421 ip = (void *)ip + last_insn_size;
422
423 if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
424 insn.word = ip->halfword[0] << 16;
425 last_insn_size = 2;
426 } else if (is_mmips) {
427 insn.word = ip->halfword[0] << 16 | ip->halfword[1];
428 last_insn_size = 4;
429 } else {
430 insn.word = ip->word;
431 last_insn_size = 4;
432 }
433
434 if (is_jr_ra_ins(ip)) {
435 break;
436 } else if (!info->frame_size) {
437 is_sp_move_ins(&insn, &info->frame_size);
438 continue;
439 } else if (!saw_jump && is_jump_ins(ip)) {
440 /*
441 * If we see a jump instruction, we are finished
442 * with the frame save.
443 *
444 * Some functions can have a shortcut return at
445 * the beginning of the function, so don't start
446 * looking for jump instruction until we see the
447 * frame setup.
448 *
449 * The RA save instruction can get put into the
450 * delay slot of the jump instruction, so look
451 * at the next instruction, too.
452 */
453 saw_jump = true;
454 continue;
455 }
456 if (info->pc_offset == -1 &&
457 is_ra_save_ins(&insn, &info->pc_offset))
458 break;
459 if (saw_jump)
460 break;
461 }
462 if (info->frame_size && info->pc_offset >= 0) /* nested */
463 return 0;
464 if (info->pc_offset < 0) /* leaf */
465 return 1;
466 /* prologue seems bogus... */
467err:
468 return -1;
469}
470
471static struct mips_frame_info schedule_mfi __read_mostly;
472
473#ifdef CONFIG_KALLSYMS
474static unsigned long get___schedule_addr(void)
475{
476 return kallsyms_lookup_name("__schedule");
477}
478#else
479static unsigned long get___schedule_addr(void)
480{
481 union mips_instruction *ip = (void *)schedule;
482 int max_insns = 8;
483 int i;
484
485 for (i = 0; i < max_insns; i++, ip++) {
486 if (ip->j_format.opcode == j_op)
487 return J_TARGET(ip, ip->j_format.target);
488 }
489 return 0;
490}
491#endif
492
493static int __init frame_info_init(void)
494{
495 unsigned long size = 0;
496#ifdef CONFIG_KALLSYMS
497 unsigned long ofs;
498#endif
499 unsigned long addr;
500
501 addr = get___schedule_addr();
502 if (!addr)
503 addr = (unsigned long)schedule;
504
505#ifdef CONFIG_KALLSYMS
506 kallsyms_lookup_size_offset(addr, &size, &ofs);
507#endif
508 schedule_mfi.func = (void *)addr;
509 schedule_mfi.func_size = size;
510
511 get_frame_info(&schedule_mfi);
512
513 /*
514 * Without schedule() frame info, result given by
515 * thread_saved_pc() and __get_wchan() are not reliable.
516 */
517 if (schedule_mfi.pc_offset < 0)
518 printk("Can't analyze schedule() prologue at %p\n", schedule);
519
520 return 0;
521}
522
523arch_initcall(frame_info_init);
524
525/*
526 * Return saved PC of a blocked thread.
527 */
528static unsigned long thread_saved_pc(struct task_struct *tsk)
529{
530 struct thread_struct *t = &tsk->thread;
531
532 /* New born processes are a special case */
533 if (t->reg31 == (unsigned long) ret_from_fork)
534 return t->reg31;
535 if (schedule_mfi.pc_offset < 0)
536 return 0;
537 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
538}
539
540
541#ifdef CONFIG_KALLSYMS
542/* generic stack unwinding function */
543unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
544 unsigned long *sp,
545 unsigned long pc,
546 unsigned long *ra)
547{
548 unsigned long low, high, irq_stack_high;
549 struct mips_frame_info info;
550 unsigned long size, ofs;
551 struct pt_regs *regs;
552 int leaf;
553
554 if (!stack_page)
555 return 0;
556
557 /*
558 * IRQ stacks start at IRQ_STACK_START
559 * task stacks at THREAD_SIZE - 32
560 */
561 low = stack_page;
562 if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
563 high = stack_page + IRQ_STACK_START;
564 irq_stack_high = high;
565 } else {
566 high = stack_page + THREAD_SIZE - 32;
567 irq_stack_high = 0;
568 }
569
570 /*
571 * If we reached the top of the interrupt stack, start unwinding
572 * the interrupted task stack.
573 */
574 if (unlikely(*sp == irq_stack_high)) {
575 unsigned long task_sp = *(unsigned long *)*sp;
576
577 /*
578 * Check that the pointer saved in the IRQ stack head points to
579 * something within the stack of the current task
580 */
581 if (!object_is_on_stack((void *)task_sp))
582 return 0;
583
584 /*
585 * Follow pointer to tasks kernel stack frame where interrupted
586 * state was saved.
587 */
588 regs = (struct pt_regs *)task_sp;
589 pc = regs->cp0_epc;
590 if (!user_mode(regs) && __kernel_text_address(pc)) {
591 *sp = regs->regs[29];
592 *ra = regs->regs[31];
593 return pc;
594 }
595 return 0;
596 }
597 if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
598 return 0;
599 /*
600 * Return ra if an exception occurred at the first instruction
601 */
602 if (unlikely(ofs == 0)) {
603 pc = *ra;
604 *ra = 0;
605 return pc;
606 }
607
608 info.func = (void *)(pc - ofs);
609 info.func_size = ofs; /* analyze from start to ofs */
610 leaf = get_frame_info(&info);
611 if (leaf < 0)
612 return 0;
613
614 if (*sp < low || *sp + info.frame_size > high)
615 return 0;
616
617 if (leaf)
618 /*
619 * For some extreme cases, get_frame_info() can
620 * consider wrongly a nested function as a leaf
621 * one. In that cases avoid to return always the
622 * same value.
623 */
624 pc = pc != *ra ? *ra : 0;
625 else
626 pc = ((unsigned long *)(*sp))[info.pc_offset];
627
628 *sp += info.frame_size;
629 *ra = 0;
630 return __kernel_text_address(pc) ? pc : 0;
631}
632EXPORT_SYMBOL(unwind_stack_by_address);
633
634/* used by show_backtrace() */
635unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
636 unsigned long pc, unsigned long *ra)
637{
638 unsigned long stack_page = 0;
639 int cpu;
640
641 for_each_possible_cpu(cpu) {
642 if (on_irq_stack(cpu, *sp)) {
643 stack_page = (unsigned long)irq_stack[cpu];
644 break;
645 }
646 }
647
648 if (!stack_page)
649 stack_page = (unsigned long)task_stack_page(task);
650
651 return unwind_stack_by_address(stack_page, sp, pc, ra);
652}
653#endif
654
655/*
656 * __get_wchan - a maintenance nightmare^W^Wpain in the ass ...
657 */
658unsigned long __get_wchan(struct task_struct *task)
659{
660 unsigned long pc = 0;
661#ifdef CONFIG_KALLSYMS
662 unsigned long sp;
663 unsigned long ra = 0;
664#endif
665
666 if (!task_stack_page(task))
667 goto out;
668
669 pc = thread_saved_pc(task);
670
671#ifdef CONFIG_KALLSYMS
672 sp = task->thread.reg29 + schedule_mfi.frame_size;
673
674 while (in_sched_functions(pc))
675 pc = unwind_stack(task, &sp, pc, &ra);
676#endif
677
678out:
679 return pc;
680}
681
682unsigned long mips_stack_top(void)
683{
684 unsigned long top = TASK_SIZE & PAGE_MASK;
685
686 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
687 /* One page for branch delay slot "emulation" */
688 top -= PAGE_SIZE;
689 }
690
691 /* Space for the VDSO, data page & GIC user page */
692 top -= PAGE_ALIGN(current->thread.abi->vdso->size);
693 top -= PAGE_SIZE;
694 top -= mips_gic_present() ? PAGE_SIZE : 0;
695
696 /* Space for cache colour alignment */
697 if (cpu_has_dc_aliases)
698 top -= shm_align_mask + 1;
699
700 /* Space to randomize the VDSO base */
701 if (current->flags & PF_RANDOMIZE)
702 top -= VDSO_RANDOMIZE_SIZE;
703
704 return top;
705}
706
707/*
708 * Don't forget that the stack pointer must be aligned on a 8 bytes
709 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
710 */
711unsigned long arch_align_stack(unsigned long sp)
712{
713 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
714 sp -= get_random_u32_below(PAGE_SIZE);
715
716 return sp & ALMASK;
717}
718
719static struct cpumask backtrace_csd_busy;
720
721static void handle_backtrace(void *info)
722{
723 nmi_cpu_backtrace(get_irq_regs());
724 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
725}
726
727static DEFINE_PER_CPU(call_single_data_t, backtrace_csd) =
728 CSD_INIT(handle_backtrace, NULL);
729
730static void raise_backtrace(cpumask_t *mask)
731{
732 call_single_data_t *csd;
733 int cpu;
734
735 for_each_cpu(cpu, mask) {
736 /*
737 * If we previously sent an IPI to the target CPU & it hasn't
738 * cleared its bit in the busy cpumask then it didn't handle
739 * our previous IPI & it's not safe for us to reuse the
740 * call_single_data_t.
741 */
742 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
743 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
744 cpu);
745 continue;
746 }
747
748 csd = &per_cpu(backtrace_csd, cpu);
749 smp_call_function_single_async(cpu, csd);
750 }
751}
752
753void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
754{
755 nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
756}
757
758int mips_get_process_fp_mode(struct task_struct *task)
759{
760 int value = 0;
761
762 if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
763 value |= PR_FP_MODE_FR;
764 if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
765 value |= PR_FP_MODE_FRE;
766
767 return value;
768}
769
770static long prepare_for_fp_mode_switch(void *unused)
771{
772 /*
773 * This is icky, but we use this to simply ensure that all CPUs have
774 * context switched, regardless of whether they were previously running
775 * kernel or user code. This ensures that no CPU that a mode-switching
776 * program may execute on keeps its FPU enabled (& in the old mode)
777 * throughout the mode switch.
778 */
779 return 0;
780}
781
782int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
783{
784 const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
785 struct task_struct *t;
786 struct cpumask process_cpus;
787 int cpu;
788
789 /* If nothing to change, return right away, successfully. */
790 if (value == mips_get_process_fp_mode(task))
791 return 0;
792
793 /* Only accept a mode change if 64-bit FP enabled for o32. */
794 if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
795 return -EOPNOTSUPP;
796
797 /* And only for o32 tasks. */
798 if (IS_ENABLED(CONFIG_64BIT) && !test_thread_flag(TIF_32BIT_REGS))
799 return -EOPNOTSUPP;
800
801 /* Check the value is valid */
802 if (value & ~known_bits)
803 return -EOPNOTSUPP;
804
805 /* Setting FRE without FR is not supported. */
806 if ((value & (PR_FP_MODE_FR | PR_FP_MODE_FRE)) == PR_FP_MODE_FRE)
807 return -EOPNOTSUPP;
808
809 /* Avoid inadvertently triggering emulation */
810 if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
811 !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
812 return -EOPNOTSUPP;
813 if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
814 return -EOPNOTSUPP;
815
816 /* FR = 0 not supported in MIPS R6 */
817 if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
818 return -EOPNOTSUPP;
819
820 /* Indicate the new FP mode in each thread */
821 for_each_thread(task, t) {
822 /* Update desired FP register width */
823 if (value & PR_FP_MODE_FR) {
824 clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
825 } else {
826 set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
827 clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
828 }
829
830 /* Update desired FP single layout */
831 if (value & PR_FP_MODE_FRE)
832 set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
833 else
834 clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
835 }
836
837 /*
838 * We need to ensure that all threads in the process have switched mode
839 * before returning, in order to allow userland to not worry about
840 * races. We can do this by forcing all CPUs that any thread in the
841 * process may be running on to schedule something else - in this case
842 * prepare_for_fp_mode_switch().
843 *
844 * We begin by generating a mask of all CPUs that any thread in the
845 * process may be running on.
846 */
847 cpumask_clear(&process_cpus);
848 for_each_thread(task, t)
849 cpumask_set_cpu(task_cpu(t), &process_cpus);
850
851 /*
852 * Now we schedule prepare_for_fp_mode_switch() on each of those CPUs.
853 *
854 * The CPUs may have rescheduled already since we switched mode or
855 * generated the cpumask, but that doesn't matter. If the task in this
856 * process is scheduled out then our scheduling
857 * prepare_for_fp_mode_switch() will simply be redundant. If it's
858 * scheduled in then it will already have picked up the new FP mode
859 * whilst doing so.
860 */
861 cpus_read_lock();
862 for_each_cpu_and(cpu, &process_cpus, cpu_online_mask)
863 work_on_cpu(cpu, prepare_for_fp_mode_switch, NULL);
864 cpus_read_unlock();
865
866 return 0;
867}
868
869#if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
870void mips_dump_regs32(u32 *uregs, const struct pt_regs *regs)
871{
872 unsigned int i;
873
874 for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) {
875 /* k0/k1 are copied as zero. */
876 if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27)
877 uregs[i] = 0;
878 else
879 uregs[i] = regs->regs[i - MIPS32_EF_R0];
880 }
881
882 uregs[MIPS32_EF_LO] = regs->lo;
883 uregs[MIPS32_EF_HI] = regs->hi;
884 uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc;
885 uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
886 uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status;
887 uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause;
888}
889#endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
890
891#ifdef CONFIG_64BIT
892void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs)
893{
894 unsigned int i;
895
896 for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) {
897 /* k0/k1 are copied as zero. */
898 if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27)
899 uregs[i] = 0;
900 else
901 uregs[i] = regs->regs[i - MIPS64_EF_R0];
902 }
903
904 uregs[MIPS64_EF_LO] = regs->lo;
905 uregs[MIPS64_EF_HI] = regs->hi;
906 uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc;
907 uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
908 uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status;
909 uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause;
910}
911#endif /* CONFIG_64BIT */
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 */
11#include <linux/errno.h>
12#include <linux/module.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/ptrace.h>
20#include <linux/mman.h>
21#include <linux/personality.h>
22#include <linux/sys.h>
23#include <linux/user.h>
24#include <linux/init.h>
25#include <linux/completion.h>
26#include <linux/kallsyms.h>
27#include <linux/random.h>
28
29#include <asm/asm.h>
30#include <asm/bootinfo.h>
31#include <asm/cpu.h>
32#include <asm/dsp.h>
33#include <asm/fpu.h>
34#include <asm/pgtable.h>
35#include <asm/system.h>
36#include <asm/mipsregs.h>
37#include <asm/processor.h>
38#include <asm/uaccess.h>
39#include <asm/io.h>
40#include <asm/elf.h>
41#include <asm/isadep.h>
42#include <asm/inst.h>
43#include <asm/stacktrace.h>
44
45/*
46 * The idle thread. There's no useful work to be done, so just try to conserve
47 * power and have a low exit latency (ie sit in a loop waiting for somebody to
48 * say that they'd like to reschedule)
49 */
50void __noreturn cpu_idle(void)
51{
52 int cpu;
53
54 /* CPU is going idle. */
55 cpu = smp_processor_id();
56
57 /* endless idle loop with no priority at all */
58 while (1) {
59 tick_nohz_stop_sched_tick(1);
60 while (!need_resched() && cpu_online(cpu)) {
61#ifdef CONFIG_MIPS_MT_SMTC
62 extern void smtc_idle_loop_hook(void);
63
64 smtc_idle_loop_hook();
65#endif
66
67 if (cpu_wait) {
68 /* Don't trace irqs off for idle */
69 stop_critical_timings();
70 (*cpu_wait)();
71 start_critical_timings();
72 }
73 }
74#ifdef CONFIG_HOTPLUG_CPU
75 if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) &&
76 (system_state == SYSTEM_RUNNING ||
77 system_state == SYSTEM_BOOTING))
78 play_dead();
79#endif
80 tick_nohz_restart_sched_tick();
81 preempt_enable_no_resched();
82 schedule();
83 preempt_disable();
84 }
85}
86
87asmlinkage void ret_from_fork(void);
88
89void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
90{
91 unsigned long status;
92
93 /* New thread loses kernel privileges. */
94 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
95#ifdef CONFIG_64BIT
96 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
97#endif
98 status |= KU_USER;
99 regs->cp0_status = status;
100 clear_used_math();
101 clear_fpu_owner();
102 if (cpu_has_dsp)
103 __init_dsp();
104 regs->cp0_epc = pc;
105 regs->regs[29] = sp;
106}
107
108void exit_thread(void)
109{
110}
111
112void flush_thread(void)
113{
114}
115
116int copy_thread(unsigned long clone_flags, unsigned long usp,
117 unsigned long unused, struct task_struct *p, struct pt_regs *regs)
118{
119 struct thread_info *ti = task_thread_info(p);
120 struct pt_regs *childregs;
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 preempt_disable();
127
128 if (is_fpu_owner())
129 save_fp(p);
130
131 if (cpu_has_dsp)
132 save_dsp(p);
133
134 preempt_enable();
135
136 /* set up new TSS. */
137 childregs = (struct pt_regs *) childksp - 1;
138 /* Put the stack after the struct pt_regs. */
139 childksp = (unsigned long) childregs;
140 *childregs = *regs;
141 childregs->regs[7] = 0; /* Clear error flag */
142
143 childregs->regs[2] = 0; /* Child gets zero as return value */
144
145 if (childregs->cp0_status & ST0_CU0) {
146 childregs->regs[28] = (unsigned long) ti;
147 childregs->regs[29] = childksp;
148 ti->addr_limit = KERNEL_DS;
149 } else {
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 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
161 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
162
163#ifdef CONFIG_MIPS_MT_SMTC
164 /*
165 * SMTC restores TCStatus after Status, and the CU bits
166 * are aliased there.
167 */
168 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
169#endif
170 clear_tsk_thread_flag(p, TIF_USEDFPU);
171
172#ifdef CONFIG_MIPS_MT_FPAFF
173 clear_tsk_thread_flag(p, TIF_FPUBOUND);
174#endif /* CONFIG_MIPS_MT_FPAFF */
175
176 if (clone_flags & CLONE_SETTLS)
177 ti->tp_value = regs->regs[7];
178
179 return 0;
180}
181
182/* Fill in the fpu structure for a core dump.. */
183int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
184{
185 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu));
186
187 return 1;
188}
189
190void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
191{
192 int i;
193
194 for (i = 0; i < EF_R0; i++)
195 gp[i] = 0;
196 gp[EF_R0] = 0;
197 for (i = 1; i <= 31; i++)
198 gp[EF_R0 + i] = regs->regs[i];
199 gp[EF_R26] = 0;
200 gp[EF_R27] = 0;
201 gp[EF_LO] = regs->lo;
202 gp[EF_HI] = regs->hi;
203 gp[EF_CP0_EPC] = regs->cp0_epc;
204 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
205 gp[EF_CP0_STATUS] = regs->cp0_status;
206 gp[EF_CP0_CAUSE] = regs->cp0_cause;
207#ifdef EF_UNUSED0
208 gp[EF_UNUSED0] = 0;
209#endif
210}
211
212int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
213{
214 elf_dump_regs(*regs, task_pt_regs(tsk));
215 return 1;
216}
217
218int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
219{
220 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
221
222 return 1;
223}
224
225/*
226 * Create a kernel thread
227 */
228static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *))
229{
230 do_exit(fn(arg));
231}
232
233long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
234{
235 struct pt_regs regs;
236
237 memset(®s, 0, sizeof(regs));
238
239 regs.regs[4] = (unsigned long) arg;
240 regs.regs[5] = (unsigned long) fn;
241 regs.cp0_epc = (unsigned long) kernel_thread_helper;
242 regs.cp0_status = read_c0_status();
243#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
244 regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
245 ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2);
246#else
247 regs.cp0_status |= ST0_EXL;
248#endif
249
250 /* Ok, create the new process.. */
251 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
252}
253
254/*
255 *
256 */
257struct mips_frame_info {
258 void *func;
259 unsigned long func_size;
260 int frame_size;
261 int pc_offset;
262};
263
264static inline int is_ra_save_ins(union mips_instruction *ip)
265{
266 /* sw / sd $ra, offset($sp) */
267 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
268 ip->i_format.rs == 29 &&
269 ip->i_format.rt == 31;
270}
271
272static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
273{
274 if (ip->j_format.opcode == jal_op)
275 return 1;
276 if (ip->r_format.opcode != spec_op)
277 return 0;
278 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
279}
280
281static inline int is_sp_move_ins(union mips_instruction *ip)
282{
283 /* addiu/daddiu sp,sp,-imm */
284 if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
285 return 0;
286 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
287 return 1;
288 return 0;
289}
290
291static int get_frame_info(struct mips_frame_info *info)
292{
293 union mips_instruction *ip = info->func;
294 unsigned max_insns = info->func_size / sizeof(union mips_instruction);
295 unsigned i;
296
297 info->pc_offset = -1;
298 info->frame_size = 0;
299
300 if (!ip)
301 goto err;
302
303 if (max_insns == 0)
304 max_insns = 128U; /* unknown function size */
305 max_insns = min(128U, max_insns);
306
307 for (i = 0; i < max_insns; i++, ip++) {
308
309 if (is_jal_jalr_jr_ins(ip))
310 break;
311 if (!info->frame_size) {
312 if (is_sp_move_ins(ip))
313 info->frame_size = - ip->i_format.simmediate;
314 continue;
315 }
316 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
317 info->pc_offset =
318 ip->i_format.simmediate / sizeof(long);
319 break;
320 }
321 }
322 if (info->frame_size && info->pc_offset >= 0) /* nested */
323 return 0;
324 if (info->pc_offset < 0) /* leaf */
325 return 1;
326 /* prologue seems boggus... */
327err:
328 return -1;
329}
330
331static struct mips_frame_info schedule_mfi __read_mostly;
332
333static int __init frame_info_init(void)
334{
335 unsigned long size = 0;
336#ifdef CONFIG_KALLSYMS
337 unsigned long ofs;
338
339 kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
340#endif
341 schedule_mfi.func = schedule;
342 schedule_mfi.func_size = size;
343
344 get_frame_info(&schedule_mfi);
345
346 /*
347 * Without schedule() frame info, result given by
348 * thread_saved_pc() and get_wchan() are not reliable.
349 */
350 if (schedule_mfi.pc_offset < 0)
351 printk("Can't analyze schedule() prologue at %p\n", schedule);
352
353 return 0;
354}
355
356arch_initcall(frame_info_init);
357
358/*
359 * Return saved PC of a blocked thread.
360 */
361unsigned long thread_saved_pc(struct task_struct *tsk)
362{
363 struct thread_struct *t = &tsk->thread;
364
365 /* New born processes are a special case */
366 if (t->reg31 == (unsigned long) ret_from_fork)
367 return t->reg31;
368 if (schedule_mfi.pc_offset < 0)
369 return 0;
370 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
371}
372
373
374#ifdef CONFIG_KALLSYMS
375/* generic stack unwinding function */
376unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
377 unsigned long *sp,
378 unsigned long pc,
379 unsigned long *ra)
380{
381 struct mips_frame_info info;
382 unsigned long size, ofs;
383 int leaf;
384 extern void ret_from_irq(void);
385 extern void ret_from_exception(void);
386
387 if (!stack_page)
388 return 0;
389
390 /*
391 * If we reached the bottom of interrupt context,
392 * return saved pc in pt_regs.
393 */
394 if (pc == (unsigned long)ret_from_irq ||
395 pc == (unsigned long)ret_from_exception) {
396 struct pt_regs *regs;
397 if (*sp >= stack_page &&
398 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
399 regs = (struct pt_regs *)*sp;
400 pc = regs->cp0_epc;
401 if (__kernel_text_address(pc)) {
402 *sp = regs->regs[29];
403 *ra = regs->regs[31];
404 return pc;
405 }
406 }
407 return 0;
408 }
409 if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
410 return 0;
411 /*
412 * Return ra if an exception occurred at the first instruction
413 */
414 if (unlikely(ofs == 0)) {
415 pc = *ra;
416 *ra = 0;
417 return pc;
418 }
419
420 info.func = (void *)(pc - ofs);
421 info.func_size = ofs; /* analyze from start to ofs */
422 leaf = get_frame_info(&info);
423 if (leaf < 0)
424 return 0;
425
426 if (*sp < stack_page ||
427 *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
428 return 0;
429
430 if (leaf)
431 /*
432 * For some extreme cases, get_frame_info() can
433 * consider wrongly a nested function as a leaf
434 * one. In that cases avoid to return always the
435 * same value.
436 */
437 pc = pc != *ra ? *ra : 0;
438 else
439 pc = ((unsigned long *)(*sp))[info.pc_offset];
440
441 *sp += info.frame_size;
442 *ra = 0;
443 return __kernel_text_address(pc) ? pc : 0;
444}
445EXPORT_SYMBOL(unwind_stack_by_address);
446
447/* used by show_backtrace() */
448unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
449 unsigned long pc, unsigned long *ra)
450{
451 unsigned long stack_page = (unsigned long)task_stack_page(task);
452 return unwind_stack_by_address(stack_page, sp, pc, ra);
453}
454#endif
455
456/*
457 * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
458 */
459unsigned long get_wchan(struct task_struct *task)
460{
461 unsigned long pc = 0;
462#ifdef CONFIG_KALLSYMS
463 unsigned long sp;
464 unsigned long ra = 0;
465#endif
466
467 if (!task || task == current || task->state == TASK_RUNNING)
468 goto out;
469 if (!task_stack_page(task))
470 goto out;
471
472 pc = thread_saved_pc(task);
473
474#ifdef CONFIG_KALLSYMS
475 sp = task->thread.reg29 + schedule_mfi.frame_size;
476
477 while (in_sched_functions(pc))
478 pc = unwind_stack(task, &sp, pc, &ra);
479#endif
480
481out:
482 return pc;
483}
484
485/*
486 * Don't forget that the stack pointer must be aligned on a 8 bytes
487 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
488 */
489unsigned long arch_align_stack(unsigned long sp)
490{
491 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
492 sp -= get_random_int() & ~PAGE_MASK;
493
494 return sp & ALMASK;
495}