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1da177e4 LT |
1 | /* |
2 | * linux/arch/i386/kernel/process.c | |
3 | * | |
4 | * Copyright (C) 1995 Linus Torvalds | |
5 | * | |
6 | * Pentium III FXSR, SSE support | |
7 | * Gareth Hughes <gareth@valinux.com>, May 2000 | |
8 | */ | |
9 | ||
10 | /* | |
11 | * This file handles the architecture-dependent parts of process handling.. | |
12 | */ | |
13 | ||
14 | #include <stdarg.h> | |
15 | ||
f3705136 | 16 | #include <linux/cpu.h> |
1da177e4 LT |
17 | #include <linux/errno.h> |
18 | #include <linux/sched.h> | |
19 | #include <linux/fs.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/mm.h> | |
22 | #include <linux/elfcore.h> | |
23 | #include <linux/smp.h> | |
24 | #include <linux/smp_lock.h> | |
25 | #include <linux/stddef.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/vmalloc.h> | |
28 | #include <linux/user.h> | |
29 | #include <linux/a.out.h> | |
30 | #include <linux/interrupt.h> | |
31 | #include <linux/config.h> | |
32 | #include <linux/utsname.h> | |
33 | #include <linux/delay.h> | |
34 | #include <linux/reboot.h> | |
35 | #include <linux/init.h> | |
36 | #include <linux/mc146818rtc.h> | |
37 | #include <linux/module.h> | |
38 | #include <linux/kallsyms.h> | |
39 | #include <linux/ptrace.h> | |
40 | #include <linux/random.h> | |
b94cce92 | 41 | #include <linux/kprobes.h> |
1da177e4 LT |
42 | |
43 | #include <asm/uaccess.h> | |
44 | #include <asm/pgtable.h> | |
45 | #include <asm/system.h> | |
46 | #include <asm/io.h> | |
47 | #include <asm/ldt.h> | |
48 | #include <asm/processor.h> | |
49 | #include <asm/i387.h> | |
1da177e4 LT |
50 | #include <asm/desc.h> |
51 | #ifdef CONFIG_MATH_EMULATION | |
52 | #include <asm/math_emu.h> | |
53 | #endif | |
54 | ||
1da177e4 LT |
55 | #include <linux/err.h> |
56 | ||
f3705136 ZM |
57 | #include <asm/tlbflush.h> |
58 | #include <asm/cpu.h> | |
59 | ||
1da177e4 LT |
60 | asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); |
61 | ||
62 | static int hlt_counter; | |
63 | ||
64 | unsigned long boot_option_idle_override = 0; | |
65 | EXPORT_SYMBOL(boot_option_idle_override); | |
66 | ||
67 | /* | |
68 | * Return saved PC of a blocked thread. | |
69 | */ | |
70 | unsigned long thread_saved_pc(struct task_struct *tsk) | |
71 | { | |
72 | return ((unsigned long *)tsk->thread.esp)[3]; | |
73 | } | |
74 | ||
75 | /* | |
76 | * Powermanagement idle function, if any.. | |
77 | */ | |
78 | void (*pm_idle)(void); | |
129f6946 | 79 | EXPORT_SYMBOL(pm_idle); |
1da177e4 LT |
80 | static DEFINE_PER_CPU(unsigned int, cpu_idle_state); |
81 | ||
82 | void disable_hlt(void) | |
83 | { | |
84 | hlt_counter++; | |
85 | } | |
86 | ||
87 | EXPORT_SYMBOL(disable_hlt); | |
88 | ||
89 | void enable_hlt(void) | |
90 | { | |
91 | hlt_counter--; | |
92 | } | |
93 | ||
94 | EXPORT_SYMBOL(enable_hlt); | |
95 | ||
96 | /* | |
97 | * We use this if we don't have any better | |
98 | * idle routine.. | |
99 | */ | |
100 | void default_idle(void) | |
101 | { | |
102 | if (!hlt_counter && boot_cpu_data.hlt_works_ok) { | |
103 | local_irq_disable(); | |
104 | if (!need_resched()) | |
105 | safe_halt(); | |
106 | else | |
107 | local_irq_enable(); | |
108 | } else { | |
109 | cpu_relax(); | |
110 | } | |
111 | } | |
129f6946 AD |
112 | #ifdef CONFIG_APM_MODULE |
113 | EXPORT_SYMBOL(default_idle); | |
114 | #endif | |
1da177e4 LT |
115 | |
116 | /* | |
117 | * On SMP it's slightly faster (but much more power-consuming!) | |
118 | * to poll the ->work.need_resched flag instead of waiting for the | |
119 | * cross-CPU IPI to arrive. Use this option with caution. | |
120 | */ | |
121 | static void poll_idle (void) | |
122 | { | |
123 | int oldval; | |
124 | ||
125 | local_irq_enable(); | |
126 | ||
127 | /* | |
128 | * Deal with another CPU just having chosen a thread to | |
129 | * run here: | |
130 | */ | |
131 | oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED); | |
132 | ||
133 | if (!oldval) { | |
134 | set_thread_flag(TIF_POLLING_NRFLAG); | |
135 | asm volatile( | |
136 | "2:" | |
137 | "testl %0, %1;" | |
138 | "rep; nop;" | |
139 | "je 2b;" | |
140 | : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags)); | |
141 | ||
142 | clear_thread_flag(TIF_POLLING_NRFLAG); | |
143 | } else { | |
144 | set_need_resched(); | |
145 | } | |
146 | } | |
147 | ||
f3705136 ZM |
148 | #ifdef CONFIG_HOTPLUG_CPU |
149 | #include <asm/nmi.h> | |
150 | /* We don't actually take CPU down, just spin without interrupts. */ | |
151 | static inline void play_dead(void) | |
152 | { | |
e1367daf LS |
153 | /* This must be done before dead CPU ack */ |
154 | cpu_exit_clear(); | |
155 | wbinvd(); | |
156 | mb(); | |
f3705136 ZM |
157 | /* Ack it */ |
158 | __get_cpu_var(cpu_state) = CPU_DEAD; | |
159 | ||
e1367daf LS |
160 | /* |
161 | * With physical CPU hotplug, we should halt the cpu | |
162 | */ | |
f3705136 | 163 | local_irq_disable(); |
e1367daf | 164 | while (1) |
f2ab4461 | 165 | halt(); |
f3705136 ZM |
166 | } |
167 | #else | |
168 | static inline void play_dead(void) | |
169 | { | |
170 | BUG(); | |
171 | } | |
172 | #endif /* CONFIG_HOTPLUG_CPU */ | |
173 | ||
1da177e4 LT |
174 | /* |
175 | * The idle thread. There's no useful work to be | |
176 | * done, so just try to conserve power and have a | |
177 | * low exit latency (ie sit in a loop waiting for | |
178 | * somebody to say that they'd like to reschedule) | |
179 | */ | |
f3705136 | 180 | void cpu_idle(void) |
1da177e4 | 181 | { |
5bfb5d69 | 182 | int cpu = smp_processor_id(); |
f3705136 | 183 | |
1da177e4 LT |
184 | /* endless idle loop with no priority at all */ |
185 | while (1) { | |
186 | while (!need_resched()) { | |
187 | void (*idle)(void); | |
188 | ||
189 | if (__get_cpu_var(cpu_idle_state)) | |
190 | __get_cpu_var(cpu_idle_state) = 0; | |
191 | ||
192 | rmb(); | |
193 | idle = pm_idle; | |
194 | ||
195 | if (!idle) | |
196 | idle = default_idle; | |
197 | ||
f3705136 ZM |
198 | if (cpu_is_offline(cpu)) |
199 | play_dead(); | |
200 | ||
1da177e4 LT |
201 | __get_cpu_var(irq_stat).idle_timestamp = jiffies; |
202 | idle(); | |
203 | } | |
5bfb5d69 | 204 | preempt_enable_no_resched(); |
1da177e4 | 205 | schedule(); |
5bfb5d69 | 206 | preempt_disable(); |
1da177e4 LT |
207 | } |
208 | } | |
209 | ||
210 | void cpu_idle_wait(void) | |
211 | { | |
212 | unsigned int cpu, this_cpu = get_cpu(); | |
213 | cpumask_t map; | |
214 | ||
215 | set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); | |
216 | put_cpu(); | |
217 | ||
218 | cpus_clear(map); | |
219 | for_each_online_cpu(cpu) { | |
220 | per_cpu(cpu_idle_state, cpu) = 1; | |
221 | cpu_set(cpu, map); | |
222 | } | |
223 | ||
224 | __get_cpu_var(cpu_idle_state) = 0; | |
225 | ||
226 | wmb(); | |
227 | do { | |
228 | ssleep(1); | |
229 | for_each_online_cpu(cpu) { | |
230 | if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu)) | |
231 | cpu_clear(cpu, map); | |
232 | } | |
233 | cpus_and(map, map, cpu_online_map); | |
234 | } while (!cpus_empty(map)); | |
235 | } | |
236 | EXPORT_SYMBOL_GPL(cpu_idle_wait); | |
237 | ||
238 | /* | |
239 | * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, | |
240 | * which can obviate IPI to trigger checking of need_resched. | |
241 | * We execute MONITOR against need_resched and enter optimized wait state | |
242 | * through MWAIT. Whenever someone changes need_resched, we would be woken | |
243 | * up from MWAIT (without an IPI). | |
244 | */ | |
245 | static void mwait_idle(void) | |
246 | { | |
247 | local_irq_enable(); | |
248 | ||
249 | if (!need_resched()) { | |
250 | set_thread_flag(TIF_POLLING_NRFLAG); | |
251 | do { | |
252 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
253 | if (need_resched()) | |
254 | break; | |
255 | __mwait(0, 0); | |
256 | } while (!need_resched()); | |
257 | clear_thread_flag(TIF_POLLING_NRFLAG); | |
258 | } | |
259 | } | |
260 | ||
0bb3184d | 261 | void __devinit select_idle_routine(const struct cpuinfo_x86 *c) |
1da177e4 LT |
262 | { |
263 | if (cpu_has(c, X86_FEATURE_MWAIT)) { | |
264 | printk("monitor/mwait feature present.\n"); | |
265 | /* | |
266 | * Skip, if setup has overridden idle. | |
267 | * One CPU supports mwait => All CPUs supports mwait | |
268 | */ | |
269 | if (!pm_idle) { | |
270 | printk("using mwait in idle threads.\n"); | |
271 | pm_idle = mwait_idle; | |
272 | } | |
273 | } | |
274 | } | |
275 | ||
276 | static int __init idle_setup (char *str) | |
277 | { | |
278 | if (!strncmp(str, "poll", 4)) { | |
279 | printk("using polling idle threads.\n"); | |
280 | pm_idle = poll_idle; | |
281 | #ifdef CONFIG_X86_SMP | |
282 | if (smp_num_siblings > 1) | |
283 | printk("WARNING: polling idle and HT enabled, performance may degrade.\n"); | |
284 | #endif | |
285 | } else if (!strncmp(str, "halt", 4)) { | |
286 | printk("using halt in idle threads.\n"); | |
287 | pm_idle = default_idle; | |
288 | } | |
289 | ||
290 | boot_option_idle_override = 1; | |
291 | return 1; | |
292 | } | |
293 | ||
294 | __setup("idle=", idle_setup); | |
295 | ||
296 | void show_regs(struct pt_regs * regs) | |
297 | { | |
298 | unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; | |
299 | ||
300 | printk("\n"); | |
301 | printk("Pid: %d, comm: %20s\n", current->pid, current->comm); | |
302 | printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs->xcs,regs->eip, smp_processor_id()); | |
303 | print_symbol("EIP is at %s\n", regs->eip); | |
304 | ||
717b594a | 305 | if (user_mode(regs)) |
1da177e4 LT |
306 | printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp); |
307 | printk(" EFLAGS: %08lx %s (%s)\n", | |
308 | regs->eflags, print_tainted(), system_utsname.release); | |
309 | printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", | |
310 | regs->eax,regs->ebx,regs->ecx,regs->edx); | |
311 | printk("ESI: %08lx EDI: %08lx EBP: %08lx", | |
312 | regs->esi, regs->edi, regs->ebp); | |
313 | printk(" DS: %04x ES: %04x\n", | |
314 | 0xffff & regs->xds,0xffff & regs->xes); | |
315 | ||
4bb0d3ec ZA |
316 | cr0 = read_cr0(); |
317 | cr2 = read_cr2(); | |
318 | cr3 = read_cr3(); | |
319 | if (current_cpu_data.x86 > 4) { | |
320 | cr4 = read_cr4(); | |
321 | } | |
1da177e4 LT |
322 | printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4); |
323 | show_trace(NULL, ®s->esp); | |
324 | } | |
325 | ||
326 | /* | |
327 | * This gets run with %ebx containing the | |
328 | * function to call, and %edx containing | |
329 | * the "args". | |
330 | */ | |
331 | extern void kernel_thread_helper(void); | |
332 | __asm__(".section .text\n" | |
333 | ".align 4\n" | |
334 | "kernel_thread_helper:\n\t" | |
335 | "movl %edx,%eax\n\t" | |
336 | "pushl %edx\n\t" | |
337 | "call *%ebx\n\t" | |
338 | "pushl %eax\n\t" | |
339 | "call do_exit\n" | |
340 | ".previous"); | |
341 | ||
342 | /* | |
343 | * Create a kernel thread | |
344 | */ | |
345 | int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) | |
346 | { | |
347 | struct pt_regs regs; | |
348 | ||
349 | memset(®s, 0, sizeof(regs)); | |
350 | ||
351 | regs.ebx = (unsigned long) fn; | |
352 | regs.edx = (unsigned long) arg; | |
353 | ||
354 | regs.xds = __USER_DS; | |
355 | regs.xes = __USER_DS; | |
356 | regs.orig_eax = -1; | |
357 | regs.eip = (unsigned long) kernel_thread_helper; | |
358 | regs.xcs = __KERNEL_CS; | |
359 | regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; | |
360 | ||
361 | /* Ok, create the new process.. */ | |
362 | return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); | |
363 | } | |
129f6946 | 364 | EXPORT_SYMBOL(kernel_thread); |
1da177e4 LT |
365 | |
366 | /* | |
367 | * Free current thread data structures etc.. | |
368 | */ | |
369 | void exit_thread(void) | |
370 | { | |
371 | struct task_struct *tsk = current; | |
372 | struct thread_struct *t = &tsk->thread; | |
373 | ||
b94cce92 HN |
374 | /* |
375 | * Remove function-return probe instances associated with this task | |
376 | * and put them back on the free list. Do not insert an exit probe for | |
377 | * this function, it will be disabled by kprobe_flush_task if you do. | |
378 | */ | |
379 | kprobe_flush_task(tsk); | |
380 | ||
1da177e4 LT |
381 | /* The process may have allocated an io port bitmap... nuke it. */ |
382 | if (unlikely(NULL != t->io_bitmap_ptr)) { | |
383 | int cpu = get_cpu(); | |
384 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
385 | ||
386 | kfree(t->io_bitmap_ptr); | |
387 | t->io_bitmap_ptr = NULL; | |
388 | /* | |
389 | * Careful, clear this in the TSS too: | |
390 | */ | |
391 | memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); | |
392 | t->io_bitmap_max = 0; | |
393 | tss->io_bitmap_owner = NULL; | |
394 | tss->io_bitmap_max = 0; | |
395 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; | |
396 | put_cpu(); | |
397 | } | |
398 | } | |
399 | ||
400 | void flush_thread(void) | |
401 | { | |
402 | struct task_struct *tsk = current; | |
403 | ||
b94cce92 HN |
404 | /* |
405 | * Remove function-return probe instances associated with this task | |
406 | * and put them back on the free list. Do not insert an exit probe for | |
407 | * this function, it will be disabled by kprobe_flush_task if you do. | |
408 | */ | |
409 | kprobe_flush_task(tsk); | |
410 | ||
1da177e4 LT |
411 | memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); |
412 | memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); | |
413 | /* | |
414 | * Forget coprocessor state.. | |
415 | */ | |
416 | clear_fpu(tsk); | |
417 | clear_used_math(); | |
418 | } | |
419 | ||
420 | void release_thread(struct task_struct *dead_task) | |
421 | { | |
422 | if (dead_task->mm) { | |
423 | // temporary debugging check | |
424 | if (dead_task->mm->context.size) { | |
425 | printk("WARNING: dead process %8s still has LDT? <%p/%d>\n", | |
426 | dead_task->comm, | |
427 | dead_task->mm->context.ldt, | |
428 | dead_task->mm->context.size); | |
429 | BUG(); | |
430 | } | |
431 | } | |
432 | ||
433 | release_vm86_irqs(dead_task); | |
434 | } | |
435 | ||
436 | /* | |
437 | * This gets called before we allocate a new thread and copy | |
438 | * the current task into it. | |
439 | */ | |
440 | void prepare_to_copy(struct task_struct *tsk) | |
441 | { | |
442 | unlazy_fpu(tsk); | |
443 | } | |
444 | ||
445 | int copy_thread(int nr, unsigned long clone_flags, unsigned long esp, | |
446 | unsigned long unused, | |
447 | struct task_struct * p, struct pt_regs * regs) | |
448 | { | |
449 | struct pt_regs * childregs; | |
450 | struct task_struct *tsk; | |
451 | int err; | |
452 | ||
453 | childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1; | |
5df24082 SS |
454 | /* |
455 | * The below -8 is to reserve 8 bytes on top of the ring0 stack. | |
456 | * This is necessary to guarantee that the entire "struct pt_regs" | |
457 | * is accessable even if the CPU haven't stored the SS/ESP registers | |
458 | * on the stack (interrupt gate does not save these registers | |
459 | * when switching to the same priv ring). | |
460 | * Therefore beware: accessing the xss/esp fields of the | |
461 | * "struct pt_regs" is possible, but they may contain the | |
462 | * completely wrong values. | |
463 | */ | |
f48d9663 AN |
464 | childregs = (struct pt_regs *) ((unsigned long) childregs - 8); |
465 | *childregs = *regs; | |
466 | childregs->eax = 0; | |
467 | childregs->esp = esp; | |
468 | ||
469 | p->thread.esp = (unsigned long) childregs; | |
470 | p->thread.esp0 = (unsigned long) (childregs+1); | |
1da177e4 LT |
471 | |
472 | p->thread.eip = (unsigned long) ret_from_fork; | |
473 | ||
474 | savesegment(fs,p->thread.fs); | |
475 | savesegment(gs,p->thread.gs); | |
476 | ||
477 | tsk = current; | |
478 | if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) { | |
479 | p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); | |
480 | if (!p->thread.io_bitmap_ptr) { | |
481 | p->thread.io_bitmap_max = 0; | |
482 | return -ENOMEM; | |
483 | } | |
484 | memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr, | |
485 | IO_BITMAP_BYTES); | |
486 | } | |
487 | ||
488 | /* | |
489 | * Set a new TLS for the child thread? | |
490 | */ | |
491 | if (clone_flags & CLONE_SETTLS) { | |
492 | struct desc_struct *desc; | |
493 | struct user_desc info; | |
494 | int idx; | |
495 | ||
496 | err = -EFAULT; | |
497 | if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info))) | |
498 | goto out; | |
499 | err = -EINVAL; | |
500 | if (LDT_empty(&info)) | |
501 | goto out; | |
502 | ||
503 | idx = info.entry_number; | |
504 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
505 | goto out; | |
506 | ||
507 | desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; | |
508 | desc->a = LDT_entry_a(&info); | |
509 | desc->b = LDT_entry_b(&info); | |
510 | } | |
511 | ||
512 | err = 0; | |
513 | out: | |
514 | if (err && p->thread.io_bitmap_ptr) { | |
515 | kfree(p->thread.io_bitmap_ptr); | |
516 | p->thread.io_bitmap_max = 0; | |
517 | } | |
518 | return err; | |
519 | } | |
520 | ||
521 | /* | |
522 | * fill in the user structure for a core dump.. | |
523 | */ | |
524 | void dump_thread(struct pt_regs * regs, struct user * dump) | |
525 | { | |
526 | int i; | |
527 | ||
528 | /* changed the size calculations - should hopefully work better. lbt */ | |
529 | dump->magic = CMAGIC; | |
530 | dump->start_code = 0; | |
531 | dump->start_stack = regs->esp & ~(PAGE_SIZE - 1); | |
532 | dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT; | |
533 | dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT; | |
534 | dump->u_dsize -= dump->u_tsize; | |
535 | dump->u_ssize = 0; | |
536 | for (i = 0; i < 8; i++) | |
537 | dump->u_debugreg[i] = current->thread.debugreg[i]; | |
538 | ||
539 | if (dump->start_stack < TASK_SIZE) | |
540 | dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT; | |
541 | ||
542 | dump->regs.ebx = regs->ebx; | |
543 | dump->regs.ecx = regs->ecx; | |
544 | dump->regs.edx = regs->edx; | |
545 | dump->regs.esi = regs->esi; | |
546 | dump->regs.edi = regs->edi; | |
547 | dump->regs.ebp = regs->ebp; | |
548 | dump->regs.eax = regs->eax; | |
549 | dump->regs.ds = regs->xds; | |
550 | dump->regs.es = regs->xes; | |
551 | savesegment(fs,dump->regs.fs); | |
552 | savesegment(gs,dump->regs.gs); | |
553 | dump->regs.orig_eax = regs->orig_eax; | |
554 | dump->regs.eip = regs->eip; | |
555 | dump->regs.cs = regs->xcs; | |
556 | dump->regs.eflags = regs->eflags; | |
557 | dump->regs.esp = regs->esp; | |
558 | dump->regs.ss = regs->xss; | |
559 | ||
560 | dump->u_fpvalid = dump_fpu (regs, &dump->i387); | |
561 | } | |
129f6946 | 562 | EXPORT_SYMBOL(dump_thread); |
1da177e4 LT |
563 | |
564 | /* | |
565 | * Capture the user space registers if the task is not running (in user space) | |
566 | */ | |
567 | int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) | |
568 | { | |
569 | struct pt_regs ptregs; | |
570 | ||
571 | ptregs = *(struct pt_regs *) | |
572 | ((unsigned long)tsk->thread_info+THREAD_SIZE - sizeof(ptregs)); | |
573 | ptregs.xcs &= 0xffff; | |
574 | ptregs.xds &= 0xffff; | |
575 | ptregs.xes &= 0xffff; | |
576 | ptregs.xss &= 0xffff; | |
577 | ||
578 | elf_core_copy_regs(regs, &ptregs); | |
579 | ||
580 | return 1; | |
581 | } | |
582 | ||
583 | static inline void | |
584 | handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss) | |
585 | { | |
586 | if (!next->io_bitmap_ptr) { | |
587 | /* | |
588 | * Disable the bitmap via an invalid offset. We still cache | |
589 | * the previous bitmap owner and the IO bitmap contents: | |
590 | */ | |
591 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; | |
592 | return; | |
593 | } | |
594 | if (likely(next == tss->io_bitmap_owner)) { | |
595 | /* | |
596 | * Previous owner of the bitmap (hence the bitmap content) | |
597 | * matches the next task, we dont have to do anything but | |
598 | * to set a valid offset in the TSS: | |
599 | */ | |
600 | tss->io_bitmap_base = IO_BITMAP_OFFSET; | |
601 | return; | |
602 | } | |
603 | /* | |
604 | * Lazy TSS's I/O bitmap copy. We set an invalid offset here | |
605 | * and we let the task to get a GPF in case an I/O instruction | |
606 | * is performed. The handler of the GPF will verify that the | |
607 | * faulting task has a valid I/O bitmap and, it true, does the | |
608 | * real copy and restart the instruction. This will save us | |
609 | * redundant copies when the currently switched task does not | |
610 | * perform any I/O during its timeslice. | |
611 | */ | |
612 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; | |
613 | } | |
1da177e4 | 614 | |
ffaa8bd6 AA |
615 | /* |
616 | * This function selects if the context switch from prev to next | |
617 | * has to tweak the TSC disable bit in the cr4. | |
618 | */ | |
619 | static inline void disable_tsc(struct task_struct *prev_p, | |
620 | struct task_struct *next_p) | |
621 | { | |
622 | struct thread_info *prev, *next; | |
623 | ||
624 | /* | |
625 | * gcc should eliminate the ->thread_info dereference if | |
626 | * has_secure_computing returns 0 at compile time (SECCOMP=n). | |
627 | */ | |
628 | prev = prev_p->thread_info; | |
629 | next = next_p->thread_info; | |
630 | ||
631 | if (has_secure_computing(prev) || has_secure_computing(next)) { | |
632 | /* slow path here */ | |
633 | if (has_secure_computing(prev) && | |
634 | !has_secure_computing(next)) { | |
635 | write_cr4(read_cr4() & ~X86_CR4_TSD); | |
636 | } else if (!has_secure_computing(prev) && | |
637 | has_secure_computing(next)) | |
638 | write_cr4(read_cr4() | X86_CR4_TSD); | |
639 | } | |
640 | } | |
641 | ||
1da177e4 LT |
642 | /* |
643 | * switch_to(x,yn) should switch tasks from x to y. | |
644 | * | |
645 | * We fsave/fwait so that an exception goes off at the right time | |
646 | * (as a call from the fsave or fwait in effect) rather than to | |
647 | * the wrong process. Lazy FP saving no longer makes any sense | |
648 | * with modern CPU's, and this simplifies a lot of things (SMP | |
649 | * and UP become the same). | |
650 | * | |
651 | * NOTE! We used to use the x86 hardware context switching. The | |
652 | * reason for not using it any more becomes apparent when you | |
653 | * try to recover gracefully from saved state that is no longer | |
654 | * valid (stale segment register values in particular). With the | |
655 | * hardware task-switch, there is no way to fix up bad state in | |
656 | * a reasonable manner. | |
657 | * | |
658 | * The fact that Intel documents the hardware task-switching to | |
659 | * be slow is a fairly red herring - this code is not noticeably | |
660 | * faster. However, there _is_ some room for improvement here, | |
661 | * so the performance issues may eventually be a valid point. | |
662 | * More important, however, is the fact that this allows us much | |
663 | * more flexibility. | |
664 | * | |
665 | * The return value (in %eax) will be the "prev" task after | |
666 | * the task-switch, and shows up in ret_from_fork in entry.S, | |
667 | * for example. | |
668 | */ | |
669 | struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) | |
670 | { | |
671 | struct thread_struct *prev = &prev_p->thread, | |
672 | *next = &next_p->thread; | |
673 | int cpu = smp_processor_id(); | |
674 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
675 | ||
676 | /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ | |
677 | ||
678 | __unlazy_fpu(prev_p); | |
679 | ||
680 | /* | |
e7a2ff59 | 681 | * Reload esp0. |
1da177e4 LT |
682 | */ |
683 | load_esp0(tss, next); | |
684 | ||
685 | /* | |
e7a2ff59 ZA |
686 | * Save away %fs and %gs. No need to save %es and %ds, as |
687 | * those are always kernel segments while inside the kernel. | |
688 | * Doing this before setting the new TLS descriptors avoids | |
689 | * the situation where we temporarily have non-reloadable | |
690 | * segments in %fs and %gs. This could be an issue if the | |
691 | * NMI handler ever used %fs or %gs (it does not today), or | |
692 | * if the kernel is running inside of a hypervisor layer. | |
1da177e4 | 693 | */ |
e7a2ff59 ZA |
694 | savesegment(fs, prev->fs); |
695 | savesegment(gs, prev->gs); | |
1da177e4 LT |
696 | |
697 | /* | |
e7a2ff59 | 698 | * Load the per-thread Thread-Local Storage descriptor. |
1da177e4 | 699 | */ |
e7a2ff59 | 700 | load_TLS(next, cpu); |
1da177e4 LT |
701 | |
702 | /* | |
703 | * Restore %fs and %gs if needed. | |
b339a18b LT |
704 | * |
705 | * Glibc normally makes %fs be zero, and %gs is one of | |
706 | * the TLS segments. | |
1da177e4 | 707 | */ |
b339a18b | 708 | if (unlikely(prev->fs | next->fs)) |
1da177e4 | 709 | loadsegment(fs, next->fs); |
b339a18b LT |
710 | |
711 | if (prev->gs | next->gs) | |
1da177e4 | 712 | loadsegment(gs, next->gs); |
1da177e4 | 713 | |
a5201129 ZA |
714 | /* |
715 | * Restore IOPL if needed. | |
716 | */ | |
717 | if (unlikely(prev->iopl != next->iopl)) | |
718 | set_iopl_mask(next->iopl); | |
719 | ||
1da177e4 LT |
720 | /* |
721 | * Now maybe reload the debug registers | |
722 | */ | |
723 | if (unlikely(next->debugreg[7])) { | |
b339a18b LT |
724 | set_debugreg(next->debugreg[0], 0); |
725 | set_debugreg(next->debugreg[1], 1); | |
726 | set_debugreg(next->debugreg[2], 2); | |
727 | set_debugreg(next->debugreg[3], 3); | |
1da177e4 | 728 | /* no 4 and 5 */ |
b339a18b LT |
729 | set_debugreg(next->debugreg[6], 6); |
730 | set_debugreg(next->debugreg[7], 7); | |
1da177e4 LT |
731 | } |
732 | ||
733 | if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) | |
734 | handle_io_bitmap(next, tss); | |
735 | ||
ffaa8bd6 AA |
736 | disable_tsc(prev_p, next_p); |
737 | ||
1da177e4 LT |
738 | return prev_p; |
739 | } | |
740 | ||
741 | asmlinkage int sys_fork(struct pt_regs regs) | |
742 | { | |
743 | return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL); | |
744 | } | |
745 | ||
746 | asmlinkage int sys_clone(struct pt_regs regs) | |
747 | { | |
748 | unsigned long clone_flags; | |
749 | unsigned long newsp; | |
750 | int __user *parent_tidptr, *child_tidptr; | |
751 | ||
752 | clone_flags = regs.ebx; | |
753 | newsp = regs.ecx; | |
754 | parent_tidptr = (int __user *)regs.edx; | |
755 | child_tidptr = (int __user *)regs.edi; | |
756 | if (!newsp) | |
757 | newsp = regs.esp; | |
758 | return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); | |
759 | } | |
760 | ||
761 | /* | |
762 | * This is trivial, and on the face of it looks like it | |
763 | * could equally well be done in user mode. | |
764 | * | |
765 | * Not so, for quite unobvious reasons - register pressure. | |
766 | * In user mode vfork() cannot have a stack frame, and if | |
767 | * done by calling the "clone()" system call directly, you | |
768 | * do not have enough call-clobbered registers to hold all | |
769 | * the information you need. | |
770 | */ | |
771 | asmlinkage int sys_vfork(struct pt_regs regs) | |
772 | { | |
773 | return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL); | |
774 | } | |
775 | ||
776 | /* | |
777 | * sys_execve() executes a new program. | |
778 | */ | |
779 | asmlinkage int sys_execve(struct pt_regs regs) | |
780 | { | |
781 | int error; | |
782 | char * filename; | |
783 | ||
784 | filename = getname((char __user *) regs.ebx); | |
785 | error = PTR_ERR(filename); | |
786 | if (IS_ERR(filename)) | |
787 | goto out; | |
788 | error = do_execve(filename, | |
789 | (char __user * __user *) regs.ecx, | |
790 | (char __user * __user *) regs.edx, | |
791 | ®s); | |
792 | if (error == 0) { | |
793 | task_lock(current); | |
794 | current->ptrace &= ~PT_DTRACE; | |
795 | task_unlock(current); | |
796 | /* Make sure we don't return using sysenter.. */ | |
797 | set_thread_flag(TIF_IRET); | |
798 | } | |
799 | putname(filename); | |
800 | out: | |
801 | return error; | |
802 | } | |
803 | ||
804 | #define top_esp (THREAD_SIZE - sizeof(unsigned long)) | |
805 | #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) | |
806 | ||
807 | unsigned long get_wchan(struct task_struct *p) | |
808 | { | |
809 | unsigned long ebp, esp, eip; | |
810 | unsigned long stack_page; | |
811 | int count = 0; | |
812 | if (!p || p == current || p->state == TASK_RUNNING) | |
813 | return 0; | |
814 | stack_page = (unsigned long)p->thread_info; | |
815 | esp = p->thread.esp; | |
816 | if (!stack_page || esp < stack_page || esp > top_esp+stack_page) | |
817 | return 0; | |
818 | /* include/asm-i386/system.h:switch_to() pushes ebp last. */ | |
819 | ebp = *(unsigned long *) esp; | |
820 | do { | |
821 | if (ebp < stack_page || ebp > top_ebp+stack_page) | |
822 | return 0; | |
823 | eip = *(unsigned long *) (ebp+4); | |
824 | if (!in_sched_functions(eip)) | |
825 | return eip; | |
826 | ebp = *(unsigned long *) ebp; | |
827 | } while (count++ < 16); | |
828 | return 0; | |
829 | } | |
129f6946 | 830 | EXPORT_SYMBOL(get_wchan); |
1da177e4 LT |
831 | |
832 | /* | |
833 | * sys_alloc_thread_area: get a yet unused TLS descriptor index. | |
834 | */ | |
835 | static int get_free_idx(void) | |
836 | { | |
837 | struct thread_struct *t = ¤t->thread; | |
838 | int idx; | |
839 | ||
840 | for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) | |
841 | if (desc_empty(t->tls_array + idx)) | |
842 | return idx + GDT_ENTRY_TLS_MIN; | |
843 | return -ESRCH; | |
844 | } | |
845 | ||
846 | /* | |
847 | * Set a given TLS descriptor: | |
848 | */ | |
849 | asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) | |
850 | { | |
851 | struct thread_struct *t = ¤t->thread; | |
852 | struct user_desc info; | |
853 | struct desc_struct *desc; | |
854 | int cpu, idx; | |
855 | ||
856 | if (copy_from_user(&info, u_info, sizeof(info))) | |
857 | return -EFAULT; | |
858 | idx = info.entry_number; | |
859 | ||
860 | /* | |
861 | * index -1 means the kernel should try to find and | |
862 | * allocate an empty descriptor: | |
863 | */ | |
864 | if (idx == -1) { | |
865 | idx = get_free_idx(); | |
866 | if (idx < 0) | |
867 | return idx; | |
868 | if (put_user(idx, &u_info->entry_number)) | |
869 | return -EFAULT; | |
870 | } | |
871 | ||
872 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
873 | return -EINVAL; | |
874 | ||
875 | desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN; | |
876 | ||
877 | /* | |
878 | * We must not get preempted while modifying the TLS. | |
879 | */ | |
880 | cpu = get_cpu(); | |
881 | ||
882 | if (LDT_empty(&info)) { | |
883 | desc->a = 0; | |
884 | desc->b = 0; | |
885 | } else { | |
886 | desc->a = LDT_entry_a(&info); | |
887 | desc->b = LDT_entry_b(&info); | |
888 | } | |
889 | load_TLS(t, cpu); | |
890 | ||
891 | put_cpu(); | |
892 | ||
893 | return 0; | |
894 | } | |
895 | ||
896 | /* | |
897 | * Get the current Thread-Local Storage area: | |
898 | */ | |
899 | ||
900 | #define GET_BASE(desc) ( \ | |
901 | (((desc)->a >> 16) & 0x0000ffff) | \ | |
902 | (((desc)->b << 16) & 0x00ff0000) | \ | |
903 | ( (desc)->b & 0xff000000) ) | |
904 | ||
905 | #define GET_LIMIT(desc) ( \ | |
906 | ((desc)->a & 0x0ffff) | \ | |
907 | ((desc)->b & 0xf0000) ) | |
908 | ||
909 | #define GET_32BIT(desc) (((desc)->b >> 22) & 1) | |
910 | #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) | |
911 | #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) | |
912 | #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) | |
913 | #define GET_PRESENT(desc) (((desc)->b >> 15) & 1) | |
914 | #define GET_USEABLE(desc) (((desc)->b >> 20) & 1) | |
915 | ||
916 | asmlinkage int sys_get_thread_area(struct user_desc __user *u_info) | |
917 | { | |
918 | struct user_desc info; | |
919 | struct desc_struct *desc; | |
920 | int idx; | |
921 | ||
922 | if (get_user(idx, &u_info->entry_number)) | |
923 | return -EFAULT; | |
924 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
925 | return -EINVAL; | |
926 | ||
71ae18ec PBG |
927 | memset(&info, 0, sizeof(info)); |
928 | ||
1da177e4 LT |
929 | desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; |
930 | ||
931 | info.entry_number = idx; | |
932 | info.base_addr = GET_BASE(desc); | |
933 | info.limit = GET_LIMIT(desc); | |
934 | info.seg_32bit = GET_32BIT(desc); | |
935 | info.contents = GET_CONTENTS(desc); | |
936 | info.read_exec_only = !GET_WRITABLE(desc); | |
937 | info.limit_in_pages = GET_LIMIT_PAGES(desc); | |
938 | info.seg_not_present = !GET_PRESENT(desc); | |
939 | info.useable = GET_USEABLE(desc); | |
940 | ||
941 | if (copy_to_user(u_info, &info, sizeof(info))) | |
942 | return -EFAULT; | |
943 | return 0; | |
944 | } | |
945 | ||
946 | unsigned long arch_align_stack(unsigned long sp) | |
947 | { | |
948 | if (randomize_va_space) | |
949 | sp -= get_random_int() % 8192; | |
950 | return sp & ~0xf; | |
951 | } |