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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/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 | */ | |
50 | void __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 | if (cpu_wait) | |
67 | (*cpu_wait)(); | |
68 | } | |
69 | #ifdef CONFIG_HOTPLUG_CPU | |
70 | if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) && | |
71 | (system_state == SYSTEM_RUNNING || | |
72 | system_state == SYSTEM_BOOTING)) | |
73 | play_dead(); | |
74 | #endif | |
75 | tick_nohz_restart_sched_tick(); | |
76 | preempt_enable_no_resched(); | |
77 | schedule(); | |
78 | preempt_disable(); | |
79 | } | |
80 | } | |
81 | ||
82 | asmlinkage void ret_from_fork(void); | |
83 | ||
84 | void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) | |
85 | { | |
86 | unsigned long status; | |
87 | ||
88 | /* New thread loses kernel privileges. */ | |
89 | status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); | |
90 | #ifdef CONFIG_64BIT | |
91 | status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; | |
92 | #endif | |
93 | status |= KU_USER; | |
94 | regs->cp0_status = status; | |
95 | clear_used_math(); | |
96 | clear_fpu_owner(); | |
97 | if (cpu_has_dsp) | |
98 | __init_dsp(); | |
99 | regs->cp0_epc = pc; | |
100 | regs->regs[29] = sp; | |
101 | current_thread_info()->addr_limit = USER_DS; | |
102 | } | |
103 | ||
104 | void exit_thread(void) | |
105 | { | |
106 | } | |
107 | ||
108 | void flush_thread(void) | |
109 | { | |
110 | } | |
111 | ||
112 | int copy_thread(unsigned long clone_flags, unsigned long usp, | |
113 | unsigned long unused, struct task_struct *p, struct pt_regs *regs) | |
114 | { | |
115 | struct thread_info *ti = task_thread_info(p); | |
116 | struct pt_regs *childregs; | |
117 | unsigned long childksp; | |
118 | p->set_child_tid = p->clear_child_tid = NULL; | |
119 | ||
120 | childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; | |
121 | ||
122 | preempt_disable(); | |
123 | ||
124 | if (is_fpu_owner()) | |
125 | save_fp(p); | |
126 | ||
127 | if (cpu_has_dsp) | |
128 | save_dsp(p); | |
129 | ||
130 | preempt_enable(); | |
131 | ||
132 | /* set up new TSS. */ | |
133 | childregs = (struct pt_regs *) childksp - 1; | |
134 | /* Put the stack after the struct pt_regs. */ | |
135 | childksp = (unsigned long) childregs; | |
136 | *childregs = *regs; | |
137 | childregs->regs[7] = 0; /* Clear error flag */ | |
138 | ||
139 | childregs->regs[2] = 0; /* Child gets zero as return value */ | |
140 | regs->regs[2] = p->pid; | |
141 | ||
142 | if (childregs->cp0_status & ST0_CU0) { | |
143 | childregs->regs[28] = (unsigned long) ti; | |
144 | childregs->regs[29] = childksp; | |
145 | ti->addr_limit = KERNEL_DS; | |
146 | } else { | |
147 | childregs->regs[29] = usp; | |
148 | ti->addr_limit = USER_DS; | |
149 | } | |
150 | p->thread.reg29 = (unsigned long) childregs; | |
151 | p->thread.reg31 = (unsigned long) ret_from_fork; | |
152 | ||
153 | /* | |
154 | * New tasks lose permission to use the fpu. This accelerates context | |
155 | * switching for most programs since they don't use the fpu. | |
156 | */ | |
157 | p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); | |
158 | childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); | |
159 | ||
160 | #ifdef CONFIG_MIPS_MT_SMTC | |
161 | /* | |
162 | * SMTC restores TCStatus after Status, and the CU bits | |
163 | * are aliased there. | |
164 | */ | |
165 | childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); | |
166 | #endif | |
167 | clear_tsk_thread_flag(p, TIF_USEDFPU); | |
168 | ||
169 | #ifdef CONFIG_MIPS_MT_FPAFF | |
170 | clear_tsk_thread_flag(p, TIF_FPUBOUND); | |
171 | #endif /* CONFIG_MIPS_MT_FPAFF */ | |
172 | ||
173 | if (clone_flags & CLONE_SETTLS) | |
174 | ti->tp_value = regs->regs[7]; | |
175 | ||
176 | return 0; | |
177 | } | |
178 | ||
179 | /* Fill in the fpu structure for a core dump.. */ | |
180 | int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) | |
181 | { | |
182 | memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); | |
183 | ||
184 | return 1; | |
185 | } | |
186 | ||
187 | void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) | |
188 | { | |
189 | int i; | |
190 | ||
191 | for (i = 0; i < EF_R0; i++) | |
192 | gp[i] = 0; | |
193 | gp[EF_R0] = 0; | |
194 | for (i = 1; i <= 31; i++) | |
195 | gp[EF_R0 + i] = regs->regs[i]; | |
196 | gp[EF_R26] = 0; | |
197 | gp[EF_R27] = 0; | |
198 | gp[EF_LO] = regs->lo; | |
199 | gp[EF_HI] = regs->hi; | |
200 | gp[EF_CP0_EPC] = regs->cp0_epc; | |
201 | gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; | |
202 | gp[EF_CP0_STATUS] = regs->cp0_status; | |
203 | gp[EF_CP0_CAUSE] = regs->cp0_cause; | |
204 | #ifdef EF_UNUSED0 | |
205 | gp[EF_UNUSED0] = 0; | |
206 | #endif | |
207 | } | |
208 | ||
209 | int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) | |
210 | { | |
211 | elf_dump_regs(*regs, task_pt_regs(tsk)); | |
212 | return 1; | |
213 | } | |
214 | ||
215 | int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) | |
216 | { | |
217 | memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); | |
218 | ||
219 | return 1; | |
220 | } | |
221 | ||
222 | /* | |
223 | * Create a kernel thread | |
224 | */ | |
225 | static void __noreturn kernel_thread_helper(void *arg, int (*fn)(void *)) | |
226 | { | |
227 | do_exit(fn(arg)); | |
228 | } | |
229 | ||
230 | long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) | |
231 | { | |
232 | struct pt_regs regs; | |
233 | ||
234 | memset(®s, 0, sizeof(regs)); | |
235 | ||
236 | regs.regs[4] = (unsigned long) arg; | |
237 | regs.regs[5] = (unsigned long) fn; | |
238 | regs.cp0_epc = (unsigned long) kernel_thread_helper; | |
239 | regs.cp0_status = read_c0_status(); | |
240 | #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) | |
241 | regs.cp0_status = (regs.cp0_status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | | |
242 | ((regs.cp0_status & (ST0_KUC | ST0_IEC)) << 2); | |
243 | #else | |
244 | regs.cp0_status |= ST0_EXL; | |
245 | #endif | |
246 | ||
247 | /* Ok, create the new process.. */ | |
248 | return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); | |
249 | } | |
250 | ||
251 | /* | |
252 | * | |
253 | */ | |
254 | struct mips_frame_info { | |
255 | void *func; | |
256 | unsigned long func_size; | |
257 | int frame_size; | |
258 | int pc_offset; | |
259 | }; | |
260 | ||
261 | static inline int is_ra_save_ins(union mips_instruction *ip) | |
262 | { | |
263 | /* sw / sd $ra, offset($sp) */ | |
264 | return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && | |
265 | ip->i_format.rs == 29 && | |
266 | ip->i_format.rt == 31; | |
267 | } | |
268 | ||
269 | static inline int is_jal_jalr_jr_ins(union mips_instruction *ip) | |
270 | { | |
271 | if (ip->j_format.opcode == jal_op) | |
272 | return 1; | |
273 | if (ip->r_format.opcode != spec_op) | |
274 | return 0; | |
275 | return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; | |
276 | } | |
277 | ||
278 | static inline int is_sp_move_ins(union mips_instruction *ip) | |
279 | { | |
280 | /* addiu/daddiu sp,sp,-imm */ | |
281 | if (ip->i_format.rs != 29 || ip->i_format.rt != 29) | |
282 | return 0; | |
283 | if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) | |
284 | return 1; | |
285 | return 0; | |
286 | } | |
287 | ||
288 | static int get_frame_info(struct mips_frame_info *info) | |
289 | { | |
290 | union mips_instruction *ip = info->func; | |
291 | unsigned max_insns = info->func_size / sizeof(union mips_instruction); | |
292 | unsigned i; | |
293 | ||
294 | info->pc_offset = -1; | |
295 | info->frame_size = 0; | |
296 | ||
297 | if (!ip) | |
298 | goto err; | |
299 | ||
300 | if (max_insns == 0) | |
301 | max_insns = 128U; /* unknown function size */ | |
302 | max_insns = min(128U, max_insns); | |
303 | ||
304 | for (i = 0; i < max_insns; i++, ip++) { | |
305 | ||
306 | if (is_jal_jalr_jr_ins(ip)) | |
307 | break; | |
308 | if (!info->frame_size) { | |
309 | if (is_sp_move_ins(ip)) | |
310 | info->frame_size = - ip->i_format.simmediate; | |
311 | continue; | |
312 | } | |
313 | if (info->pc_offset == -1 && is_ra_save_ins(ip)) { | |
314 | info->pc_offset = | |
315 | ip->i_format.simmediate / sizeof(long); | |
316 | break; | |
317 | } | |
318 | } | |
319 | if (info->frame_size && info->pc_offset >= 0) /* nested */ | |
320 | return 0; | |
321 | if (info->pc_offset < 0) /* leaf */ | |
322 | return 1; | |
323 | /* prologue seems boggus... */ | |
324 | err: | |
325 | return -1; | |
326 | } | |
327 | ||
328 | static struct mips_frame_info schedule_mfi __read_mostly; | |
329 | ||
330 | static int __init frame_info_init(void) | |
331 | { | |
332 | unsigned long size = 0; | |
333 | #ifdef CONFIG_KALLSYMS | |
334 | unsigned long ofs; | |
335 | ||
336 | kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs); | |
337 | #endif | |
338 | schedule_mfi.func = schedule; | |
339 | schedule_mfi.func_size = size; | |
340 | ||
341 | get_frame_info(&schedule_mfi); | |
342 | ||
343 | /* | |
344 | * Without schedule() frame info, result given by | |
345 | * thread_saved_pc() and get_wchan() are not reliable. | |
346 | */ | |
347 | if (schedule_mfi.pc_offset < 0) | |
348 | printk("Can't analyze schedule() prologue at %p\n", schedule); | |
349 | ||
350 | return 0; | |
351 | } | |
352 | ||
353 | arch_initcall(frame_info_init); | |
354 | ||
355 | /* | |
356 | * Return saved PC of a blocked thread. | |
357 | */ | |
358 | unsigned long thread_saved_pc(struct task_struct *tsk) | |
359 | { | |
360 | struct thread_struct *t = &tsk->thread; | |
361 | ||
362 | /* New born processes are a special case */ | |
363 | if (t->reg31 == (unsigned long) ret_from_fork) | |
364 | return t->reg31; | |
365 | if (schedule_mfi.pc_offset < 0) | |
366 | return 0; | |
367 | return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; | |
368 | } | |
369 | ||
370 | ||
371 | #ifdef CONFIG_KALLSYMS | |
372 | /* used by show_backtrace() */ | |
373 | unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, | |
374 | unsigned long pc, unsigned long *ra) | |
375 | { | |
376 | unsigned long stack_page; | |
377 | struct mips_frame_info info; | |
378 | unsigned long size, ofs; | |
379 | int leaf; | |
380 | extern void ret_from_irq(void); | |
381 | extern void ret_from_exception(void); | |
382 | ||
383 | stack_page = (unsigned long)task_stack_page(task); | |
384 | if (!stack_page) | |
385 | return 0; | |
386 | ||
387 | /* | |
388 | * If we reached the bottom of interrupt context, | |
389 | * return saved pc in pt_regs. | |
390 | */ | |
391 | if (pc == (unsigned long)ret_from_irq || | |
392 | pc == (unsigned long)ret_from_exception) { | |
393 | struct pt_regs *regs; | |
394 | if (*sp >= stack_page && | |
395 | *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { | |
396 | regs = (struct pt_regs *)*sp; | |
397 | pc = regs->cp0_epc; | |
398 | if (__kernel_text_address(pc)) { | |
399 | *sp = regs->regs[29]; | |
400 | *ra = regs->regs[31]; | |
401 | return pc; | |
402 | } | |
403 | } | |
404 | return 0; | |
405 | } | |
406 | if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) | |
407 | return 0; | |
408 | /* | |
409 | * Return ra if an exception occured at the first instruction | |
410 | */ | |
411 | if (unlikely(ofs == 0)) { | |
412 | pc = *ra; | |
413 | *ra = 0; | |
414 | return pc; | |
415 | } | |
416 | ||
417 | info.func = (void *)(pc - ofs); | |
418 | info.func_size = ofs; /* analyze from start to ofs */ | |
419 | leaf = get_frame_info(&info); | |
420 | if (leaf < 0) | |
421 | return 0; | |
422 | ||
423 | if (*sp < stack_page || | |
424 | *sp + info.frame_size > stack_page + THREAD_SIZE - 32) | |
425 | return 0; | |
426 | ||
427 | if (leaf) | |
428 | /* | |
429 | * For some extreme cases, get_frame_info() can | |
430 | * consider wrongly a nested function as a leaf | |
431 | * one. In that cases avoid to return always the | |
432 | * same value. | |
433 | */ | |
434 | pc = pc != *ra ? *ra : 0; | |
435 | else | |
436 | pc = ((unsigned long *)(*sp))[info.pc_offset]; | |
437 | ||
438 | *sp += info.frame_size; | |
439 | *ra = 0; | |
440 | return __kernel_text_address(pc) ? pc : 0; | |
441 | } | |
442 | #endif | |
443 | ||
444 | /* | |
445 | * get_wchan - a maintenance nightmare^W^Wpain in the ass ... | |
446 | */ | |
447 | unsigned long get_wchan(struct task_struct *task) | |
448 | { | |
449 | unsigned long pc = 0; | |
450 | #ifdef CONFIG_KALLSYMS | |
451 | unsigned long sp; | |
452 | unsigned long ra = 0; | |
453 | #endif | |
454 | ||
455 | if (!task || task == current || task->state == TASK_RUNNING) | |
456 | goto out; | |
457 | if (!task_stack_page(task)) | |
458 | goto out; | |
459 | ||
460 | pc = thread_saved_pc(task); | |
461 | ||
462 | #ifdef CONFIG_KALLSYMS | |
463 | sp = task->thread.reg29 + schedule_mfi.frame_size; | |
464 | ||
465 | while (in_sched_functions(pc)) | |
466 | pc = unwind_stack(task, &sp, pc, &ra); | |
467 | #endif | |
468 | ||
469 | out: | |
470 | return pc; | |
471 | } | |
472 | ||
473 | /* | |
474 | * Don't forget that the stack pointer must be aligned on a 8 bytes | |
475 | * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. | |
476 | */ | |
477 | unsigned long arch_align_stack(unsigned long sp) | |
478 | { | |
479 | if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) | |
480 | sp -= get_random_int() & ~PAGE_MASK; | |
481 | ||
482 | return sp & ALMASK; | |
483 | } |