process.c 11 KB

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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. */
  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/slab.h>
  21. #include <linux/mman.h>
  22. #include <linux/personality.h>
  23. #include <linux/sys.h>
  24. #include <linux/user.h>
  25. #include <linux/a.out.h>
  26. #include <linux/init.h>
  27. #include <linux/completion.h>
  28. #include <linux/kallsyms.h>
  29. #include <linux/random.h>
  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/system.h>
  37. #include <asm/mipsregs.h>
  38. #include <asm/processor.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. /*
  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. */
  50. void __noreturn cpu_idle(void)
  51. {
  52. /* endless idle loop with no priority at all */
  53. while (1) {
  54. tick_nohz_stop_sched_tick(1);
  55. while (!need_resched()) {
  56. #ifdef CONFIG_SMTC_IDLE_HOOK_DEBUG
  57. extern void smtc_idle_loop_hook(void);
  58. smtc_idle_loop_hook();
  59. #endif
  60. if (cpu_wait)
  61. (*cpu_wait)();
  62. }
  63. tick_nohz_restart_sched_tick();
  64. preempt_enable_no_resched();
  65. schedule();
  66. preempt_disable();
  67. }
  68. }
  69. asmlinkage void ret_from_fork(void);
  70. void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  71. {
  72. unsigned long status;
  73. /* New thread loses kernel privileges. */
  74. status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
  75. #ifdef CONFIG_64BIT
  76. status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
  77. #endif
  78. status |= KU_USER;
  79. regs->cp0_status = status;
  80. clear_used_math();
  81. clear_fpu_owner();
  82. if (cpu_has_dsp)
  83. __init_dsp();
  84. regs->cp0_epc = pc;
  85. regs->regs[29] = sp;
  86. current_thread_info()->addr_limit = USER_DS;
  87. }
  88. void exit_thread(void)
  89. {
  90. }
  91. void flush_thread(void)
  92. {
  93. }
  94. int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
  95. unsigned long unused, struct task_struct *p, struct pt_regs *regs)
  96. {
  97. struct thread_info *ti = task_thread_info(p);
  98. struct pt_regs *childregs;
  99. long childksp;
  100. p->set_child_tid = p->clear_child_tid = NULL;
  101. childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
  102. preempt_disable();
  103. if (is_fpu_owner())
  104. save_fp(p);
  105. if (cpu_has_dsp)
  106. save_dsp(p);
  107. preempt_enable();
  108. /* set up new TSS. */
  109. childregs = (struct pt_regs *) childksp - 1;
  110. *childregs = *regs;
  111. childregs->regs[7] = 0; /* Clear error flag */
  112. childregs->regs[2] = 0; /* Child gets zero as return value */
  113. regs->regs[2] = p->pid;
  114. if (childregs->cp0_status & ST0_CU0) {
  115. childregs->regs[28] = (unsigned long) ti;
  116. childregs->regs[29] = childksp;
  117. ti->addr_limit = KERNEL_DS;
  118. } else {
  119. childregs->regs[29] = usp;
  120. ti->addr_limit = USER_DS;
  121. }
  122. p->thread.reg29 = (unsigned long) childregs;
  123. p->thread.reg31 = (unsigned long) ret_from_fork;
  124. /*
  125. * New tasks lose permission to use the fpu. This accelerates context
  126. * switching for most programs since they don't use the fpu.
  127. */
  128. p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
  129. childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
  130. clear_tsk_thread_flag(p, TIF_USEDFPU);
  131. #ifdef CONFIG_MIPS_MT_FPAFF
  132. clear_tsk_thread_flag(p, TIF_FPUBOUND);
  133. /*
  134. * FPU affinity support is cleaner if we track the
  135. * user-visible CPU affinity from the very beginning.
  136. * The generic cpus_allowed mask will already have
  137. * been copied from the parent before copy_thread
  138. * is invoked.
  139. */
  140. p->thread.user_cpus_allowed = p->cpus_allowed;
  141. #endif /* CONFIG_MIPS_MT_FPAFF */
  142. if (clone_flags & CLONE_SETTLS)
  143. ti->tp_value = regs->regs[7];
  144. return 0;
  145. }
  146. /* Fill in the fpu structure for a core dump.. */
  147. int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
  148. {
  149. memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
  150. return 1;
  151. }
  152. void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
  153. {
  154. int i;
  155. for (i = 0; i < EF_R0; i++)
  156. gp[i] = 0;
  157. gp[EF_R0] = 0;
  158. for (i = 1; i <= 31; i++)
  159. gp[EF_R0 + i] = regs->regs[i];
  160. gp[EF_R26] = 0;
  161. gp[EF_R27] = 0;
  162. gp[EF_LO] = regs->lo;
  163. gp[EF_HI] = regs->hi;
  164. gp[EF_CP0_EPC] = regs->cp0_epc;
  165. gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
  166. gp[EF_CP0_STATUS] = regs->cp0_status;
  167. gp[EF_CP0_CAUSE] = regs->cp0_cause;
  168. #ifdef EF_UNUSED0
  169. gp[EF_UNUSED0] = 0;
  170. #endif
  171. }
  172. int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
  173. {
  174. elf_dump_regs(*regs, task_pt_regs(tsk));
  175. return 1;
  176. }
  177. int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
  178. {
  179. memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
  180. return 1;
  181. }
  182. /*
  183. * Create a kernel thread
  184. */
  185. static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *))
  186. {
  187. do_exit(fn(arg));
  188. }
  189. long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
  190. {
  191. struct pt_regs regs;
  192. memset(&regs, 0, sizeof(regs));
  193. regs.regs[4] = (unsigned long) arg;
  194. regs.regs[5] = (unsigned long) fn;
  195. regs.cp0_epc = (unsigned long) kernel_thread_helper;
  196. regs.cp0_status = read_c0_status();
  197. #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
  198. regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
  199. ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2);
  200. #else
  201. regs.cp0_status |= ST0_EXL;
  202. #endif
  203. /* Ok, create the new process.. */
  204. return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
  205. }
  206. /*
  207. *
  208. */
  209. struct mips_frame_info {
  210. void *func;
  211. unsigned long func_size;
  212. int frame_size;
  213. int pc_offset;
  214. };
  215. static inline int is_ra_save_ins(union mips_instruction *ip)
  216. {
  217. /* sw / sd $ra, offset($sp) */
  218. return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
  219. ip->i_format.rs == 29 &&
  220. ip->i_format.rt == 31;
  221. }
  222. static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
  223. {
  224. if (ip->j_format.opcode == jal_op)
  225. return 1;
  226. if (ip->r_format.opcode != spec_op)
  227. return 0;
  228. return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
  229. }
  230. static inline int is_sp_move_ins(union mips_instruction *ip)
  231. {
  232. /* addiu/daddiu sp,sp,-imm */
  233. if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
  234. return 0;
  235. if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
  236. return 1;
  237. return 0;
  238. }
  239. static int get_frame_info(struct mips_frame_info *info)
  240. {
  241. union mips_instruction *ip = info->func;
  242. unsigned max_insns = info->func_size / sizeof(union mips_instruction);
  243. unsigned i;
  244. info->pc_offset = -1;
  245. info->frame_size = 0;
  246. if (!ip)
  247. goto err;
  248. if (max_insns == 0)
  249. max_insns = 128U; /* unknown function size */
  250. max_insns = min(128U, max_insns);
  251. for (i = 0; i < max_insns; i++, ip++) {
  252. if (is_jal_jalr_jr_ins(ip))
  253. break;
  254. if (!info->frame_size) {
  255. if (is_sp_move_ins(ip))
  256. info->frame_size = - ip->i_format.simmediate;
  257. continue;
  258. }
  259. if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
  260. info->pc_offset =
  261. ip->i_format.simmediate / sizeof(long);
  262. break;
  263. }
  264. }
  265. if (info->frame_size && info->pc_offset >= 0) /* nested */
  266. return 0;
  267. if (info->pc_offset < 0) /* leaf */
  268. return 1;
  269. /* prologue seems boggus... */
  270. err:
  271. return -1;
  272. }
  273. static struct mips_frame_info schedule_mfi __read_mostly;
  274. static int __init frame_info_init(void)
  275. {
  276. unsigned long size = 0;
  277. #ifdef CONFIG_KALLSYMS
  278. unsigned long ofs;
  279. kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
  280. #endif
  281. schedule_mfi.func = schedule;
  282. schedule_mfi.func_size = size;
  283. get_frame_info(&schedule_mfi);
  284. /*
  285. * Without schedule() frame info, result given by
  286. * thread_saved_pc() and get_wchan() are not reliable.
  287. */
  288. if (schedule_mfi.pc_offset < 0)
  289. printk("Can't analyze schedule() prologue at %p\n", schedule);
  290. return 0;
  291. }
  292. arch_initcall(frame_info_init);
  293. /*
  294. * Return saved PC of a blocked thread.
  295. */
  296. unsigned long thread_saved_pc(struct task_struct *tsk)
  297. {
  298. struct thread_struct *t = &tsk->thread;
  299. /* New born processes are a special case */
  300. if (t->reg31 == (unsigned long) ret_from_fork)
  301. return t->reg31;
  302. if (schedule_mfi.pc_offset < 0)
  303. return 0;
  304. return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
  305. }
  306. #ifdef CONFIG_KALLSYMS
  307. /* used by show_backtrace() */
  308. unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
  309. unsigned long pc, unsigned long *ra)
  310. {
  311. unsigned long stack_page;
  312. struct mips_frame_info info;
  313. unsigned long size, ofs;
  314. int leaf;
  315. extern void ret_from_irq(void);
  316. extern void ret_from_exception(void);
  317. stack_page = (unsigned long)task_stack_page(task);
  318. if (!stack_page)
  319. return 0;
  320. /*
  321. * If we reached the bottom of interrupt context,
  322. * return saved pc in pt_regs.
  323. */
  324. if (pc == (unsigned long)ret_from_irq ||
  325. pc == (unsigned long)ret_from_exception) {
  326. struct pt_regs *regs;
  327. if (*sp >= stack_page &&
  328. *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
  329. regs = (struct pt_regs *)*sp;
  330. pc = regs->cp0_epc;
  331. if (__kernel_text_address(pc)) {
  332. *sp = regs->regs[29];
  333. *ra = regs->regs[31];
  334. return pc;
  335. }
  336. }
  337. return 0;
  338. }
  339. if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
  340. return 0;
  341. /*
  342. * Return ra if an exception occured at the first instruction
  343. */
  344. if (unlikely(ofs == 0)) {
  345. pc = *ra;
  346. *ra = 0;
  347. return pc;
  348. }
  349. info.func = (void *)(pc - ofs);
  350. info.func_size = ofs; /* analyze from start to ofs */
  351. leaf = get_frame_info(&info);
  352. if (leaf < 0)
  353. return 0;
  354. if (*sp < stack_page ||
  355. *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
  356. return 0;
  357. if (leaf)
  358. /*
  359. * For some extreme cases, get_frame_info() can
  360. * consider wrongly a nested function as a leaf
  361. * one. In that cases avoid to return always the
  362. * same value.
  363. */
  364. pc = pc != *ra ? *ra : 0;
  365. else
  366. pc = ((unsigned long *)(*sp))[info.pc_offset];
  367. *sp += info.frame_size;
  368. *ra = 0;
  369. return __kernel_text_address(pc) ? pc : 0;
  370. }
  371. #endif
  372. /*
  373. * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
  374. */
  375. unsigned long get_wchan(struct task_struct *task)
  376. {
  377. unsigned long pc = 0;
  378. #ifdef CONFIG_KALLSYMS
  379. unsigned long sp;
  380. unsigned long ra = 0;
  381. #endif
  382. if (!task || task == current || task->state == TASK_RUNNING)
  383. goto out;
  384. if (!task_stack_page(task))
  385. goto out;
  386. pc = thread_saved_pc(task);
  387. #ifdef CONFIG_KALLSYMS
  388. sp = task->thread.reg29 + schedule_mfi.frame_size;
  389. while (in_sched_functions(pc))
  390. pc = unwind_stack(task, &sp, pc, &ra);
  391. #endif
  392. out:
  393. return pc;
  394. }
  395. /*
  396. * Don't forget that the stack pointer must be aligned on a 8 bytes
  397. * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
  398. */
  399. unsigned long arch_align_stack(unsigned long sp)
  400. {
  401. if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
  402. sp -= get_random_int() & ~PAGE_MASK;
  403. return sp & ALMASK;
  404. }