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TOMOYO Linux Cross Reference
Linux/arch/mips/kernel/process.c

Version: ~ [ linux-5.3-rc8 ] ~ [ linux-5.2.13 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.71 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.142 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.191 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.191 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.73 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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
 51 void 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 
 59 asmlinkage void ret_from_fork(void);
 60 asmlinkage void ret_from_kernel_thread(void);
 61 
 62 void 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(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 74         init_dsp();
 75         regs->cp0_epc = pc;
 76         regs->regs[29] = sp;
 77 }
 78 
 79 void 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 
 89 int 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  */
116 int 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>
185 unsigned long __stack_chk_guard __read_mostly;
186 EXPORT_SYMBOL(__stack_chk_guard);
187 #endif
188 
189 struct 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 
199 static 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 
279 static 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 
316 static 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 
346 static 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... */
409 err:
410         return -1;
411 }
412 
413 static struct mips_frame_info schedule_mfi __read_mostly;
414 
415 #ifdef CONFIG_KALLSYMS
416 static unsigned long get___schedule_addr(void)
417 {
418         return kallsyms_lookup_name("__schedule");
419 }
420 #else
421 static 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 
435 static 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 
465 arch_initcall(frame_info_init);
466 
467 /*
468  * Return saved PC of a blocked thread.
469  */
470 unsigned 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 */
485 unsigned 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 }
554 EXPORT_SYMBOL(unwind_stack_by_address);
555 
556 /* used by show_backtrace() */
557 unsigned 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  */
580 unsigned 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 
602 out:
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  */
610 unsigned 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 
618 static 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 
630 void 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 
642 int 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 
654 static 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 
662 int 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(&current->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 }
734 

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