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Linux/arch/mips/kernel/process.c

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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 
 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/msa.h>
 35 #include <asm/pgtable.h>
 36 #include <asm/mipsregs.h>
 37 #include <asm/processor.h>
 38 #include <asm/reg.h>
 39 #include <asm/uaccess.h>
 40 #include <asm/io.h>
 41 #include <asm/elf.h>
 42 #include <asm/isadep.h>
 43 #include <asm/inst.h>
 44 #include <asm/stacktrace.h>
 45 #include <asm/irq_regs.h>
 46 
 47 #ifdef CONFIG_HOTPLUG_CPU
 48 void arch_cpu_idle_dead(void)
 49 {
 50         /* What the heck is this check doing ? */
 51         if (!cpu_isset(smp_processor_id(), cpu_callin_map))
 52                 play_dead();
 53 }
 54 #endif
 55 
 56 asmlinkage void ret_from_fork(void);
 57 asmlinkage void ret_from_kernel_thread(void);
 58 
 59 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 60 {
 61         unsigned long status;
 62 
 63         /* New thread loses kernel privileges. */
 64         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
 65         status |= KU_USER;
 66         regs->cp0_status = status;
 67         clear_used_math();
 68         clear_fpu_owner();
 69         init_dsp();
 70         clear_thread_flag(TIF_USEDMSA);
 71         clear_thread_flag(TIF_MSA_CTX_LIVE);
 72         disable_msa();
 73         regs->cp0_epc = pc;
 74         regs->regs[29] = sp;
 75 }
 76 
 77 void exit_thread(void)
 78 {
 79 }
 80 
 81 void flush_thread(void)
 82 {
 83 }
 84 
 85 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 86 {
 87         /*
 88          * Save any process state which is live in hardware registers to the
 89          * parent context prior to duplication. This prevents the new child
 90          * state becoming stale if the parent is preempted before copy_thread()
 91          * gets a chance to save the parent's live hardware registers to the
 92          * child context.
 93          */
 94         preempt_disable();
 95 
 96         if (is_msa_enabled())
 97                 save_msa(current);
 98         else if (is_fpu_owner())
 99                 _save_fp(current);
100 
101         save_dsp(current);
102 
103         preempt_enable();
104 
105         *dst = *src;
106         return 0;
107 }
108 
109 int copy_thread(unsigned long clone_flags, unsigned long usp,
110         unsigned long arg, struct task_struct *p)
111 {
112         struct thread_info *ti = task_thread_info(p);
113         struct pt_regs *childregs, *regs = current_pt_regs();
114         unsigned long childksp;
115         p->set_child_tid = p->clear_child_tid = NULL;
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);
124         if (unlikely(p->flags & PF_KTHREAD)) {
125                 unsigned long status = p->thread.cp0_status;
126                 memset(childregs, 0, sizeof(struct pt_regs));
127                 ti->addr_limit = KERNEL_DS;
128                 p->thread.reg16 = usp; /* fn */
129                 p->thread.reg17 = arg;
130                 p->thread.reg29 = childksp;
131                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
132 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
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         *childregs = *regs;
142         childregs->regs[7] = 0; /* Clear error flag */
143         childregs->regs[2] = 0; /* Child gets zero as return value */
144         if (usp)
145                 childregs->regs[29] = usp;
146         ti->addr_limit = USER_DS;
147 
148         p->thread.reg29 = (unsigned long) childregs;
149         p->thread.reg31 = (unsigned long) ret_from_fork;
150 
151         /*
152          * New tasks lose permission to use the fpu. This accelerates context
153          * switching for most programs since they don't use the fpu.
154          */
155         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
156 
157         clear_tsk_thread_flag(p, TIF_USEDFPU);
158         clear_tsk_thread_flag(p, TIF_USEDMSA);
159         clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
160 
161 #ifdef CONFIG_MIPS_MT_FPAFF
162         clear_tsk_thread_flag(p, TIF_FPUBOUND);
163 #endif /* CONFIG_MIPS_MT_FPAFF */
164 
165         if (clone_flags & CLONE_SETTLS)
166                 ti->tp_value = regs->regs[7];
167 
168         return 0;
169 }
170 
171 #ifdef CONFIG_CC_STACKPROTECTOR
172 #include <linux/stackprotector.h>
173 unsigned long __stack_chk_guard __read_mostly;
174 EXPORT_SYMBOL(__stack_chk_guard);
175 #endif
176 
177 struct mips_frame_info {
178         void            *func;
179         unsigned long   func_size;
180         int             frame_size;
181         int             pc_offset;
182 };
183 
184 #define J_TARGET(pc,target)     \
185                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
186 
187 static inline int is_ra_save_ins(union mips_instruction *ip)
188 {
189 #ifdef CONFIG_CPU_MICROMIPS
190         union mips_instruction mmi;
191 
192         /*
193          * swsp ra,offset
194          * swm16 reglist,offset(sp)
195          * swm32 reglist,offset(sp)
196          * sw32 ra,offset(sp)
197          * jradiussp - NOT SUPPORTED
198          *
199          * microMIPS is way more fun...
200          */
201         if (mm_insn_16bit(ip->halfword[0])) {
202                 mmi.word = (ip->halfword[0] << 16);
203                 return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
204                         mmi.mm16_r5_format.rt == 31) ||
205                        (mmi.mm16_m_format.opcode == mm_pool16c_op &&
206                         mmi.mm16_m_format.func == mm_swm16_op);
207         }
208         else {
209                 mmi.halfword[0] = ip->halfword[1];
210                 mmi.halfword[1] = ip->halfword[0];
211                 return (mmi.mm_m_format.opcode == mm_pool32b_op &&
212                         mmi.mm_m_format.rd > 9 &&
213                         mmi.mm_m_format.base == 29 &&
214                         mmi.mm_m_format.func == mm_swm32_func) ||
215                        (mmi.i_format.opcode == mm_sw32_op &&
216                         mmi.i_format.rs == 29 &&
217                         mmi.i_format.rt == 31);
218         }
219 #else
220         /* sw / sd $ra, offset($sp) */
221         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
222                 ip->i_format.rs == 29 &&
223                 ip->i_format.rt == 31;
224 #endif
225 }
226 
227 static inline int is_jump_ins(union mips_instruction *ip)
228 {
229 #ifdef CONFIG_CPU_MICROMIPS
230         /*
231          * jr16,jrc,jalr16,jalr16
232          * jal
233          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
234          * jraddiusp - NOT SUPPORTED
235          *
236          * microMIPS is kind of more fun...
237          */
238         union mips_instruction mmi;
239 
240         mmi.word = (ip->halfword[0] << 16);
241 
242         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
243             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
244             ip->j_format.opcode == mm_jal32_op)
245                 return 1;
246         if (ip->r_format.opcode != mm_pool32a_op ||
247                         ip->r_format.func != mm_pool32axf_op)
248                 return 0;
249         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
250 #else
251         if (ip->j_format.opcode == j_op)
252                 return 1;
253         if (ip->j_format.opcode == jal_op)
254                 return 1;
255         if (ip->r_format.opcode != spec_op)
256                 return 0;
257         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
258 #endif
259 }
260 
261 static inline int is_sp_move_ins(union mips_instruction *ip)
262 {
263 #ifdef CONFIG_CPU_MICROMIPS
264         /*
265          * addiusp -imm
266          * addius5 sp,-imm
267          * addiu32 sp,sp,-imm
268          * jradiussp - NOT SUPPORTED
269          *
270          * microMIPS is not more fun...
271          */
272         if (mm_insn_16bit(ip->halfword[0])) {
273                 union mips_instruction mmi;
274 
275                 mmi.word = (ip->halfword[0] << 16);
276                 return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
277                         mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
278                        (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
279                         mmi.mm16_r5_format.rt == 29);
280         }
281         return ip->mm_i_format.opcode == mm_addiu32_op &&
282                ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
283 #else
284         /* addiu/daddiu sp,sp,-imm */
285         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
286                 return 0;
287         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
288                 return 1;
289 #endif
290         return 0;
291 }
292 
293 static int get_frame_info(struct mips_frame_info *info)
294 {
295 #ifdef CONFIG_CPU_MICROMIPS
296         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
297 #else
298         union mips_instruction *ip = info->func;
299 #endif
300         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
301         unsigned i;
302 
303         info->pc_offset = -1;
304         info->frame_size = 0;
305 
306         if (!ip)
307                 goto err;
308 
309         if (max_insns == 0)
310                 max_insns = 128U;       /* unknown function size */
311         max_insns = min(128U, max_insns);
312 
313         for (i = 0; i < max_insns; i++, ip++) {
314 
315                 if (is_jump_ins(ip))
316                         break;
317                 if (!info->frame_size) {
318                         if (is_sp_move_ins(ip))
319                         {
320 #ifdef CONFIG_CPU_MICROMIPS
321                                 if (mm_insn_16bit(ip->halfword[0]))
322                                 {
323                                         unsigned short tmp;
324 
325                                         if (ip->halfword[0] & mm_addiusp_func)
326                                         {
327                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
328                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
329                                         } else {
330                                                 tmp = (ip->halfword[0] >> 1);
331                                                 info->frame_size = -(signed short)(tmp & 0xf);
332                                         }
333                                         ip = (void *) &ip->halfword[1];
334                                         ip--;
335                                 } else
336 #endif
337                                 info->frame_size = - ip->i_format.simmediate;
338                         }
339                         continue;
340                 }
341                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
342                         info->pc_offset =
343                                 ip->i_format.simmediate / sizeof(long);
344                         break;
345                 }
346         }
347         if (info->frame_size && info->pc_offset >= 0) /* nested */
348                 return 0;
349         if (info->pc_offset < 0) /* leaf */
350                 return 1;
351         /* prologue seems boggus... */
352 err:
353         return -1;
354 }
355 
356 static struct mips_frame_info schedule_mfi __read_mostly;
357 
358 #ifdef CONFIG_KALLSYMS
359 static unsigned long get___schedule_addr(void)
360 {
361         return kallsyms_lookup_name("__schedule");
362 }
363 #else
364 static unsigned long get___schedule_addr(void)
365 {
366         union mips_instruction *ip = (void *)schedule;
367         int max_insns = 8;
368         int i;
369 
370         for (i = 0; i < max_insns; i++, ip++) {
371                 if (ip->j_format.opcode == j_op)
372                         return J_TARGET(ip, ip->j_format.target);
373         }
374         return 0;
375 }
376 #endif
377 
378 static int __init frame_info_init(void)
379 {
380         unsigned long size = 0;
381 #ifdef CONFIG_KALLSYMS
382         unsigned long ofs;
383 #endif
384         unsigned long addr;
385 
386         addr = get___schedule_addr();
387         if (!addr)
388                 addr = (unsigned long)schedule;
389 
390 #ifdef CONFIG_KALLSYMS
391         kallsyms_lookup_size_offset(addr, &size, &ofs);
392 #endif
393         schedule_mfi.func = (void *)addr;
394         schedule_mfi.func_size = size;
395 
396         get_frame_info(&schedule_mfi);
397 
398         /*
399          * Without schedule() frame info, result given by
400          * thread_saved_pc() and get_wchan() are not reliable.
401          */
402         if (schedule_mfi.pc_offset < 0)
403                 printk("Can't analyze schedule() prologue at %p\n", schedule);
404 
405         return 0;
406 }
407 
408 arch_initcall(frame_info_init);
409 
410 /*
411  * Return saved PC of a blocked thread.
412  */
413 unsigned long thread_saved_pc(struct task_struct *tsk)
414 {
415         struct thread_struct *t = &tsk->thread;
416 
417         /* New born processes are a special case */
418         if (t->reg31 == (unsigned long) ret_from_fork)
419                 return t->reg31;
420         if (schedule_mfi.pc_offset < 0)
421                 return 0;
422         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
423 }
424 
425 
426 #ifdef CONFIG_KALLSYMS
427 /* generic stack unwinding function */
428 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
429                                               unsigned long *sp,
430                                               unsigned long pc,
431                                               unsigned long *ra)
432 {
433         struct mips_frame_info info;
434         unsigned long size, ofs;
435         int leaf;
436         extern void ret_from_irq(void);
437         extern void ret_from_exception(void);
438 
439         if (!stack_page)
440                 return 0;
441 
442         /*
443          * If we reached the bottom of interrupt context,
444          * return saved pc in pt_regs.
445          */
446         if (pc == (unsigned long)ret_from_irq ||
447             pc == (unsigned long)ret_from_exception) {
448                 struct pt_regs *regs;
449                 if (*sp >= stack_page &&
450                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
451                         regs = (struct pt_regs *)*sp;
452                         pc = regs->cp0_epc;
453                         if (__kernel_text_address(pc)) {
454                                 *sp = regs->regs[29];
455                                 *ra = regs->regs[31];
456                                 return pc;
457                         }
458                 }
459                 return 0;
460         }
461         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
462                 return 0;
463         /*
464          * Return ra if an exception occurred at the first instruction
465          */
466         if (unlikely(ofs == 0)) {
467                 pc = *ra;
468                 *ra = 0;
469                 return pc;
470         }
471 
472         info.func = (void *)(pc - ofs);
473         info.func_size = ofs;   /* analyze from start to ofs */
474         leaf = get_frame_info(&info);
475         if (leaf < 0)
476                 return 0;
477 
478         if (*sp < stack_page ||
479             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
480                 return 0;
481 
482         if (leaf)
483                 /*
484                  * For some extreme cases, get_frame_info() can
485                  * consider wrongly a nested function as a leaf
486                  * one. In that cases avoid to return always the
487                  * same value.
488                  */
489                 pc = pc != *ra ? *ra : 0;
490         else
491                 pc = ((unsigned long *)(*sp))[info.pc_offset];
492 
493         *sp += info.frame_size;
494         *ra = 0;
495         return __kernel_text_address(pc) ? pc : 0;
496 }
497 EXPORT_SYMBOL(unwind_stack_by_address);
498 
499 /* used by show_backtrace() */
500 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
501                            unsigned long pc, unsigned long *ra)
502 {
503         unsigned long stack_page = (unsigned long)task_stack_page(task);
504         return unwind_stack_by_address(stack_page, sp, pc, ra);
505 }
506 #endif
507 
508 /*
509  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
510  */
511 unsigned long get_wchan(struct task_struct *task)
512 {
513         unsigned long pc = 0;
514 #ifdef CONFIG_KALLSYMS
515         unsigned long sp;
516         unsigned long ra = 0;
517 #endif
518 
519         if (!task || task == current || task->state == TASK_RUNNING)
520                 goto out;
521         if (!task_stack_page(task))
522                 goto out;
523 
524         pc = thread_saved_pc(task);
525 
526 #ifdef CONFIG_KALLSYMS
527         sp = task->thread.reg29 + schedule_mfi.frame_size;
528 
529         while (in_sched_functions(pc))
530                 pc = unwind_stack(task, &sp, pc, &ra);
531 #endif
532 
533 out:
534         return pc;
535 }
536 
537 /*
538  * Don't forget that the stack pointer must be aligned on a 8 bytes
539  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
540  */
541 unsigned long arch_align_stack(unsigned long sp)
542 {
543         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
544                 sp -= get_random_int() & ~PAGE_MASK;
545 
546         return sp & ALMASK;
547 }
548 
549 static void arch_dump_stack(void *info)
550 {
551         struct pt_regs *regs;
552 
553         regs = get_irq_regs();
554 
555         if (regs)
556                 show_regs(regs);
557 
558         dump_stack();
559 }
560 
561 void arch_trigger_all_cpu_backtrace(bool include_self)
562 {
563         smp_call_function(arch_dump_stack, NULL, 1);
564 }
565 

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