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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/user.h>
 25 #include <linux/init.h>
 26 #include <linux/completion.h>
 27 #include <linux/kallsyms.h>
 28 #include <linux/random.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/pgtable.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 #ifdef CONFIG_HOTPLUG_CPU
 46 void arch_cpu_idle_dead(void)
 47 {
 48         /* What the heck is this check doing ? */
 49         if (!cpu_isset(smp_processor_id(), cpu_callin_map))
 50                 play_dead();
 51 }
 52 #endif
 53 
 54 asmlinkage void ret_from_fork(void);
 55 asmlinkage void ret_from_kernel_thread(void);
 56 
 57 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 58 {
 59         unsigned long status;
 60 
 61         /* New thread loses kernel privileges. */
 62         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
 63 #ifdef CONFIG_64BIT
 64         status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
 65 #endif
 66         status |= KU_USER;
 67         regs->cp0_status = status;
 68         clear_used_math();
 69         clear_fpu_owner();
 70         if (cpu_has_dsp)
 71                 __init_dsp();
 72         regs->cp0_epc = pc;
 73         regs->regs[29] = sp;
 74 }
 75 
 76 void exit_thread(void)
 77 {
 78 }
 79 
 80 void flush_thread(void)
 81 {
 82 }
 83 
 84 int copy_thread(unsigned long clone_flags, unsigned long usp,
 85         unsigned long arg, struct task_struct *p)
 86 {
 87         struct thread_info *ti = task_thread_info(p);
 88         struct pt_regs *childregs, *regs = current_pt_regs();
 89         unsigned long childksp;
 90         p->set_child_tid = p->clear_child_tid = NULL;
 91 
 92         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 93 
 94         preempt_disable();
 95 
 96         if (is_fpu_owner())
 97                 save_fp(p);
 98 
 99         if (cpu_has_dsp)
100                 save_dsp(p);
101 
102         preempt_enable();
103 
104         /* set up new TSS. */
105         childregs = (struct pt_regs *) childksp - 1;
106         /*  Put the stack after the struct pt_regs.  */
107         childksp = (unsigned long) childregs;
108         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
109         if (unlikely(p->flags & PF_KTHREAD)) {
110                 unsigned long status = p->thread.cp0_status;
111                 memset(childregs, 0, sizeof(struct pt_regs));
112                 ti->addr_limit = KERNEL_DS;
113                 p->thread.reg16 = usp; /* fn */
114                 p->thread.reg17 = arg;
115                 p->thread.reg29 = childksp;
116                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
117 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
118                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
119                          ((status & (ST0_KUC | ST0_IEC)) << 2);
120 #else
121                 status |= ST0_EXL;
122 #endif
123                 childregs->cp0_status = status;
124                 return 0;
125         }
126         *childregs = *regs;
127         childregs->regs[7] = 0; /* Clear error flag */
128         childregs->regs[2] = 0; /* Child gets zero as return value */
129         if (usp)
130                 childregs->regs[29] = usp;
131         ti->addr_limit = USER_DS;
132 
133         p->thread.reg29 = (unsigned long) childregs;
134         p->thread.reg31 = (unsigned long) ret_from_fork;
135 
136         /*
137          * New tasks lose permission to use the fpu. This accelerates context
138          * switching for most programs since they don't use the fpu.
139          */
140         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
141 
142 #ifdef CONFIG_MIPS_MT_SMTC
143         /*
144          * SMTC restores TCStatus after Status, and the CU bits
145          * are aliased there.
146          */
147         childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
148 #endif
149         clear_tsk_thread_flag(p, TIF_USEDFPU);
150 
151 #ifdef CONFIG_MIPS_MT_FPAFF
152         clear_tsk_thread_flag(p, TIF_FPUBOUND);
153 #endif /* CONFIG_MIPS_MT_FPAFF */
154 
155         if (clone_flags & CLONE_SETTLS)
156                 ti->tp_value = regs->regs[7];
157 
158         return 0;
159 }
160 
161 /* Fill in the fpu structure for a core dump.. */
162 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
163 {
164         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
165 
166         return 1;
167 }
168 
169 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
170 {
171         int i;
172 
173         for (i = 0; i < EF_R0; i++)
174                 gp[i] = 0;
175         gp[EF_R0] = 0;
176         for (i = 1; i <= 31; i++)
177                 gp[EF_R0 + i] = regs->regs[i];
178         gp[EF_R26] = 0;
179         gp[EF_R27] = 0;
180         gp[EF_LO] = regs->lo;
181         gp[EF_HI] = regs->hi;
182         gp[EF_CP0_EPC] = regs->cp0_epc;
183         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
184         gp[EF_CP0_STATUS] = regs->cp0_status;
185         gp[EF_CP0_CAUSE] = regs->cp0_cause;
186 #ifdef EF_UNUSED0
187         gp[EF_UNUSED0] = 0;
188 #endif
189 }
190 
191 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
192 {
193         elf_dump_regs(*regs, task_pt_regs(tsk));
194         return 1;
195 }
196 
197 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
198 {
199         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
200 
201         return 1;
202 }
203 
204 #ifdef CONFIG_CC_STACKPROTECTOR
205 #include <linux/stackprotector.h>
206 unsigned long __stack_chk_guard __read_mostly;
207 EXPORT_SYMBOL(__stack_chk_guard);
208 #endif
209 
210 struct mips_frame_info {
211         void            *func;
212         unsigned long   func_size;
213         int             frame_size;
214         int             pc_offset;
215 };
216 
217 #define J_TARGET(pc,target)     \
218                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
219 
220 static inline int is_ra_save_ins(union mips_instruction *ip)
221 {
222 #ifdef CONFIG_CPU_MICROMIPS
223         union mips_instruction mmi;
224 
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->halfword[0])) {
235                 mmi.word = (ip->halfword[0] << 16);
236                 return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
237                          mmi.mm16_r5_format.rt == 31) ||
238                         (mmi.mm16_m_format.opcode == mm_pool16c_op &&
239                          mmi.mm16_m_format.func == mm_swm16_op));
240         }
241         else {
242                 mmi.halfword[0] = ip->halfword[1];
243                 mmi.halfword[1] = ip->halfword[0];
244                 return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
245                          mmi.mm_m_format.rd > 9 &&
246                          mmi.mm_m_format.base == 29 &&
247                          mmi.mm_m_format.func == mm_swm32_func) ||
248                         (mmi.i_format.opcode == mm_sw32_op &&
249                          mmi.i_format.rs == 29 &&
250                          mmi.i_format.rt == 31));
251         }
252 #else
253         /* sw / sd $ra, offset($sp) */
254         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
255                 ip->i_format.rs == 29 &&
256                 ip->i_format.rt == 31;
257 #endif
258 }
259 
260 static inline int is_jump_ins(union mips_instruction *ip)
261 {
262 #ifdef CONFIG_CPU_MICROMIPS
263         /*
264          * jr16,jrc,jalr16,jalr16
265          * jal
266          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
267          * jraddiusp - NOT SUPPORTED
268          *
269          * microMIPS is kind of more fun...
270          */
271         union mips_instruction mmi;
272 
273         mmi.word = (ip->halfword[0] << 16);
274 
275         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
276             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
277             ip->j_format.opcode == mm_jal32_op)
278                 return 1;
279         if (ip->r_format.opcode != mm_pool32a_op ||
280                         ip->r_format.func != mm_pool32axf_op)
281                 return 0;
282         return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
283 #else
284         if (ip->j_format.opcode == j_op)
285                 return 1;
286         if (ip->j_format.opcode == jal_op)
287                 return 1;
288         if (ip->r_format.opcode != spec_op)
289                 return 0;
290         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
291 #endif
292 }
293 
294 static inline int is_sp_move_ins(union mips_instruction *ip)
295 {
296 #ifdef CONFIG_CPU_MICROMIPS
297         /*
298          * addiusp -imm
299          * addius5 sp,-imm
300          * addiu32 sp,sp,-imm
301          * jradiussp - NOT SUPPORTED
302          *
303          * microMIPS is not more fun...
304          */
305         if (mm_insn_16bit(ip->halfword[0])) {
306                 union mips_instruction mmi;
307 
308                 mmi.word = (ip->halfword[0] << 16);
309                 return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
310                          mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
311                         (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
312                          mmi.mm16_r5_format.rt == 29));
313         }
314         return (ip->mm_i_format.opcode == mm_addiu32_op &&
315                  ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
316 #else
317         /* addiu/daddiu sp,sp,-imm */
318         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
319                 return 0;
320         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
321                 return 1;
322 #endif
323         return 0;
324 }
325 
326 static int get_frame_info(struct mips_frame_info *info)
327 {
328 #ifdef CONFIG_CPU_MICROMIPS
329         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
330 #else
331         union mips_instruction *ip = info->func;
332 #endif
333         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
334         unsigned i;
335 
336         info->pc_offset = -1;
337         info->frame_size = 0;
338 
339         if (!ip)
340                 goto err;
341 
342         if (max_insns == 0)
343                 max_insns = 128U;       /* unknown function size */
344         max_insns = min(128U, max_insns);
345 
346         for (i = 0; i < max_insns; i++, ip++) {
347 
348                 if (is_jump_ins(ip))
349                         break;
350                 if (!info->frame_size) {
351                         if (is_sp_move_ins(ip))
352                         {
353 #ifdef CONFIG_CPU_MICROMIPS
354                                 if (mm_insn_16bit(ip->halfword[0]))
355                                 {
356                                         unsigned short tmp;
357 
358                                         if (ip->halfword[0] & mm_addiusp_func)
359                                         {
360                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
361                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
362                                         } else {
363                                                 tmp = (ip->halfword[0] >> 1);
364                                                 info->frame_size = -(signed short)(tmp & 0xf);
365                                         }
366                                         ip = (void *) &ip->halfword[1];
367                                         ip--;
368                                 } else
369 #endif
370                                 info->frame_size = - ip->i_format.simmediate;
371                         }
372                         continue;
373                 }
374                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
375                         info->pc_offset =
376                                 ip->i_format.simmediate / sizeof(long);
377                         break;
378                 }
379         }
380         if (info->frame_size && info->pc_offset >= 0) /* nested */
381                 return 0;
382         if (info->pc_offset < 0) /* leaf */
383                 return 1;
384         /* prologue seems boggus... */
385 err:
386         return -1;
387 }
388 
389 static struct mips_frame_info schedule_mfi __read_mostly;
390 
391 #ifdef CONFIG_KALLSYMS
392 static unsigned long get___schedule_addr(void)
393 {
394         return kallsyms_lookup_name("__schedule");
395 }
396 #else
397 static unsigned long get___schedule_addr(void)
398 {
399         union mips_instruction *ip = (void *)schedule;
400         int max_insns = 8;
401         int i;
402 
403         for (i = 0; i < max_insns; i++, ip++) {
404                 if (ip->j_format.opcode == j_op)
405                         return J_TARGET(ip, ip->j_format.target);
406         }
407         return 0;
408 }
409 #endif
410 
411 static int __init frame_info_init(void)
412 {
413         unsigned long size = 0;
414 #ifdef CONFIG_KALLSYMS
415         unsigned long ofs;
416 #endif
417         unsigned long addr;
418 
419         addr = get___schedule_addr();
420         if (!addr)
421                 addr = (unsigned long)schedule;
422 
423 #ifdef CONFIG_KALLSYMS
424         kallsyms_lookup_size_offset(addr, &size, &ofs);
425 #endif
426         schedule_mfi.func = (void *)addr;
427         schedule_mfi.func_size = size;
428 
429         get_frame_info(&schedule_mfi);
430 
431         /*
432          * Without schedule() frame info, result given by
433          * thread_saved_pc() and get_wchan() are not reliable.
434          */
435         if (schedule_mfi.pc_offset < 0)
436                 printk("Can't analyze schedule() prologue at %p\n", schedule);
437 
438         return 0;
439 }
440 
441 arch_initcall(frame_info_init);
442 
443 /*
444  * Return saved PC of a blocked thread.
445  */
446 unsigned long thread_saved_pc(struct task_struct *tsk)
447 {
448         struct thread_struct *t = &tsk->thread;
449 
450         /* New born processes are a special case */
451         if (t->reg31 == (unsigned long) ret_from_fork)
452                 return t->reg31;
453         if (schedule_mfi.pc_offset < 0)
454                 return 0;
455         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
456 }
457 
458 
459 #ifdef CONFIG_KALLSYMS
460 /* generic stack unwinding function */
461 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
462                                               unsigned long *sp,
463                                               unsigned long pc,
464                                               unsigned long *ra)
465 {
466         struct mips_frame_info info;
467         unsigned long size, ofs;
468         int leaf;
469         extern void ret_from_irq(void);
470         extern void ret_from_exception(void);
471 
472         if (!stack_page)
473                 return 0;
474 
475         /*
476          * If we reached the bottom of interrupt context,
477          * return saved pc in pt_regs.
478          */
479         if (pc == (unsigned long)ret_from_irq ||
480             pc == (unsigned long)ret_from_exception) {
481                 struct pt_regs *regs;
482                 if (*sp >= stack_page &&
483                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
484                         regs = (struct pt_regs *)*sp;
485                         pc = regs->cp0_epc;
486                         if (__kernel_text_address(pc)) {
487                                 *sp = regs->regs[29];
488                                 *ra = regs->regs[31];
489                                 return pc;
490                         }
491                 }
492                 return 0;
493         }
494         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
495                 return 0;
496         /*
497          * Return ra if an exception occurred at the first instruction
498          */
499         if (unlikely(ofs == 0)) {
500                 pc = *ra;
501                 *ra = 0;
502                 return pc;
503         }
504 
505         info.func = (void *)(pc - ofs);
506         info.func_size = ofs;   /* analyze from start to ofs */
507         leaf = get_frame_info(&info);
508         if (leaf < 0)
509                 return 0;
510 
511         if (*sp < stack_page ||
512             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
513                 return 0;
514 
515         if (leaf)
516                 /*
517                  * For some extreme cases, get_frame_info() can
518                  * consider wrongly a nested function as a leaf
519                  * one. In that cases avoid to return always the
520                  * same value.
521                  */
522                 pc = pc != *ra ? *ra : 0;
523         else
524                 pc = ((unsigned long *)(*sp))[info.pc_offset];
525 
526         *sp += info.frame_size;
527         *ra = 0;
528         return __kernel_text_address(pc) ? pc : 0;
529 }
530 EXPORT_SYMBOL(unwind_stack_by_address);
531 
532 /* used by show_backtrace() */
533 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
534                            unsigned long pc, unsigned long *ra)
535 {
536         unsigned long stack_page = (unsigned long)task_stack_page(task);
537         return unwind_stack_by_address(stack_page, sp, pc, ra);
538 }
539 #endif
540 
541 /*
542  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
543  */
544 unsigned long get_wchan(struct task_struct *task)
545 {
546         unsigned long pc = 0;
547 #ifdef CONFIG_KALLSYMS
548         unsigned long sp;
549         unsigned long ra = 0;
550 #endif
551 
552         if (!task || task == current || task->state == TASK_RUNNING)
553                 goto out;
554         if (!task_stack_page(task))
555                 goto out;
556 
557         pc = thread_saved_pc(task);
558 
559 #ifdef CONFIG_KALLSYMS
560         sp = task->thread.reg29 + schedule_mfi.frame_size;
561 
562         while (in_sched_functions(pc))
563                 pc = unwind_stack(task, &sp, pc, &ra);
564 #endif
565 
566 out:
567         return pc;
568 }
569 
570 /*
571  * Don't forget that the stack pointer must be aligned on a 8 bytes
572  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
573  */
574 unsigned long arch_align_stack(unsigned long sp)
575 {
576         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
577                 sp -= get_random_int() & ~PAGE_MASK;
578 
579         return sp & ALMASK;
580 }
581 

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