Commit | Line | Data |
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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 | { | |
64c7c8f8 NP |
102 | local_irq_enable(); |
103 | ||
1da177e4 | 104 | if (!hlt_counter && boot_cpu_data.hlt_works_ok) { |
64c7c8f8 NP |
105 | clear_thread_flag(TIF_POLLING_NRFLAG); |
106 | smp_mb__after_clear_bit(); | |
107 | while (!need_resched()) { | |
108 | local_irq_disable(); | |
109 | if (!need_resched()) | |
110 | safe_halt(); | |
111 | else | |
112 | local_irq_enable(); | |
113 | } | |
114 | set_thread_flag(TIF_POLLING_NRFLAG); | |
1da177e4 | 115 | } else { |
64c7c8f8 NP |
116 | while (!need_resched()) |
117 | cpu_relax(); | |
1da177e4 LT |
118 | } |
119 | } | |
129f6946 AD |
120 | #ifdef CONFIG_APM_MODULE |
121 | EXPORT_SYMBOL(default_idle); | |
122 | #endif | |
1da177e4 LT |
123 | |
124 | /* | |
125 | * On SMP it's slightly faster (but much more power-consuming!) | |
126 | * to poll the ->work.need_resched flag instead of waiting for the | |
127 | * cross-CPU IPI to arrive. Use this option with caution. | |
128 | */ | |
129 | static void poll_idle (void) | |
130 | { | |
1da177e4 LT |
131 | local_irq_enable(); |
132 | ||
64c7c8f8 NP |
133 | asm volatile( |
134 | "2:" | |
135 | "testl %0, %1;" | |
136 | "rep; nop;" | |
137 | "je 2b;" | |
138 | : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags)); | |
1da177e4 LT |
139 | } |
140 | ||
f3705136 ZM |
141 | #ifdef CONFIG_HOTPLUG_CPU |
142 | #include <asm/nmi.h> | |
143 | /* We don't actually take CPU down, just spin without interrupts. */ | |
144 | static inline void play_dead(void) | |
145 | { | |
e1367daf LS |
146 | /* This must be done before dead CPU ack */ |
147 | cpu_exit_clear(); | |
148 | wbinvd(); | |
149 | mb(); | |
f3705136 ZM |
150 | /* Ack it */ |
151 | __get_cpu_var(cpu_state) = CPU_DEAD; | |
152 | ||
e1367daf LS |
153 | /* |
154 | * With physical CPU hotplug, we should halt the cpu | |
155 | */ | |
f3705136 | 156 | local_irq_disable(); |
e1367daf | 157 | while (1) |
f2ab4461 | 158 | halt(); |
f3705136 ZM |
159 | } |
160 | #else | |
161 | static inline void play_dead(void) | |
162 | { | |
163 | BUG(); | |
164 | } | |
165 | #endif /* CONFIG_HOTPLUG_CPU */ | |
166 | ||
1da177e4 LT |
167 | /* |
168 | * The idle thread. There's no useful work to be | |
169 | * done, so just try to conserve power and have a | |
170 | * low exit latency (ie sit in a loop waiting for | |
171 | * somebody to say that they'd like to reschedule) | |
172 | */ | |
f3705136 | 173 | void cpu_idle(void) |
1da177e4 | 174 | { |
5bfb5d69 | 175 | int cpu = smp_processor_id(); |
f3705136 | 176 | |
64c7c8f8 NP |
177 | set_thread_flag(TIF_POLLING_NRFLAG); |
178 | ||
1da177e4 LT |
179 | /* endless idle loop with no priority at all */ |
180 | while (1) { | |
181 | while (!need_resched()) { | |
182 | void (*idle)(void); | |
183 | ||
184 | if (__get_cpu_var(cpu_idle_state)) | |
185 | __get_cpu_var(cpu_idle_state) = 0; | |
186 | ||
187 | rmb(); | |
188 | idle = pm_idle; | |
189 | ||
190 | if (!idle) | |
191 | idle = default_idle; | |
192 | ||
f3705136 ZM |
193 | if (cpu_is_offline(cpu)) |
194 | play_dead(); | |
195 | ||
1da177e4 LT |
196 | __get_cpu_var(irq_stat).idle_timestamp = jiffies; |
197 | idle(); | |
198 | } | |
5bfb5d69 | 199 | preempt_enable_no_resched(); |
1da177e4 | 200 | schedule(); |
5bfb5d69 | 201 | preempt_disable(); |
1da177e4 LT |
202 | } |
203 | } | |
204 | ||
205 | void cpu_idle_wait(void) | |
206 | { | |
207 | unsigned int cpu, this_cpu = get_cpu(); | |
208 | cpumask_t map; | |
209 | ||
210 | set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); | |
211 | put_cpu(); | |
212 | ||
213 | cpus_clear(map); | |
214 | for_each_online_cpu(cpu) { | |
215 | per_cpu(cpu_idle_state, cpu) = 1; | |
216 | cpu_set(cpu, map); | |
217 | } | |
218 | ||
219 | __get_cpu_var(cpu_idle_state) = 0; | |
220 | ||
221 | wmb(); | |
222 | do { | |
223 | ssleep(1); | |
224 | for_each_online_cpu(cpu) { | |
225 | if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu)) | |
226 | cpu_clear(cpu, map); | |
227 | } | |
228 | cpus_and(map, map, cpu_online_map); | |
229 | } while (!cpus_empty(map)); | |
230 | } | |
231 | EXPORT_SYMBOL_GPL(cpu_idle_wait); | |
232 | ||
233 | /* | |
234 | * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, | |
235 | * which can obviate IPI to trigger checking of need_resched. | |
236 | * We execute MONITOR against need_resched and enter optimized wait state | |
237 | * through MWAIT. Whenever someone changes need_resched, we would be woken | |
238 | * up from MWAIT (without an IPI). | |
239 | */ | |
240 | static void mwait_idle(void) | |
241 | { | |
242 | local_irq_enable(); | |
243 | ||
64c7c8f8 NP |
244 | while (!need_resched()) { |
245 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
246 | smp_mb(); | |
247 | if (need_resched()) | |
248 | break; | |
249 | __mwait(0, 0); | |
1da177e4 LT |
250 | } |
251 | } | |
252 | ||
0bb3184d | 253 | void __devinit select_idle_routine(const struct cpuinfo_x86 *c) |
1da177e4 LT |
254 | { |
255 | if (cpu_has(c, X86_FEATURE_MWAIT)) { | |
256 | printk("monitor/mwait feature present.\n"); | |
257 | /* | |
258 | * Skip, if setup has overridden idle. | |
259 | * One CPU supports mwait => All CPUs supports mwait | |
260 | */ | |
261 | if (!pm_idle) { | |
262 | printk("using mwait in idle threads.\n"); | |
263 | pm_idle = mwait_idle; | |
264 | } | |
265 | } | |
266 | } | |
267 | ||
268 | static int __init idle_setup (char *str) | |
269 | { | |
270 | if (!strncmp(str, "poll", 4)) { | |
271 | printk("using polling idle threads.\n"); | |
272 | pm_idle = poll_idle; | |
273 | #ifdef CONFIG_X86_SMP | |
274 | if (smp_num_siblings > 1) | |
275 | printk("WARNING: polling idle and HT enabled, performance may degrade.\n"); | |
276 | #endif | |
277 | } else if (!strncmp(str, "halt", 4)) { | |
278 | printk("using halt in idle threads.\n"); | |
279 | pm_idle = default_idle; | |
280 | } | |
281 | ||
282 | boot_option_idle_override = 1; | |
283 | return 1; | |
284 | } | |
285 | ||
286 | __setup("idle=", idle_setup); | |
287 | ||
288 | void show_regs(struct pt_regs * regs) | |
289 | { | |
290 | unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; | |
291 | ||
292 | printk("\n"); | |
293 | printk("Pid: %d, comm: %20s\n", current->pid, current->comm); | |
294 | printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs->xcs,regs->eip, smp_processor_id()); | |
295 | print_symbol("EIP is at %s\n", regs->eip); | |
296 | ||
717b594a | 297 | if (user_mode(regs)) |
1da177e4 LT |
298 | printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp); |
299 | printk(" EFLAGS: %08lx %s (%s)\n", | |
300 | regs->eflags, print_tainted(), system_utsname.release); | |
301 | printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", | |
302 | regs->eax,regs->ebx,regs->ecx,regs->edx); | |
303 | printk("ESI: %08lx EDI: %08lx EBP: %08lx", | |
304 | regs->esi, regs->edi, regs->ebp); | |
305 | printk(" DS: %04x ES: %04x\n", | |
306 | 0xffff & regs->xds,0xffff & regs->xes); | |
307 | ||
4bb0d3ec ZA |
308 | cr0 = read_cr0(); |
309 | cr2 = read_cr2(); | |
310 | cr3 = read_cr3(); | |
ff6e8c0d | 311 | cr4 = read_cr4_safe(); |
1da177e4 LT |
312 | printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4); |
313 | show_trace(NULL, ®s->esp); | |
314 | } | |
315 | ||
316 | /* | |
317 | * This gets run with %ebx containing the | |
318 | * function to call, and %edx containing | |
319 | * the "args". | |
320 | */ | |
321 | extern void kernel_thread_helper(void); | |
322 | __asm__(".section .text\n" | |
323 | ".align 4\n" | |
324 | "kernel_thread_helper:\n\t" | |
325 | "movl %edx,%eax\n\t" | |
326 | "pushl %edx\n\t" | |
327 | "call *%ebx\n\t" | |
328 | "pushl %eax\n\t" | |
329 | "call do_exit\n" | |
330 | ".previous"); | |
331 | ||
332 | /* | |
333 | * Create a kernel thread | |
334 | */ | |
335 | int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) | |
336 | { | |
337 | struct pt_regs regs; | |
338 | ||
339 | memset(®s, 0, sizeof(regs)); | |
340 | ||
341 | regs.ebx = (unsigned long) fn; | |
342 | regs.edx = (unsigned long) arg; | |
343 | ||
344 | regs.xds = __USER_DS; | |
345 | regs.xes = __USER_DS; | |
346 | regs.orig_eax = -1; | |
347 | regs.eip = (unsigned long) kernel_thread_helper; | |
348 | regs.xcs = __KERNEL_CS; | |
349 | regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; | |
350 | ||
351 | /* Ok, create the new process.. */ | |
352 | return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); | |
353 | } | |
129f6946 | 354 | EXPORT_SYMBOL(kernel_thread); |
1da177e4 LT |
355 | |
356 | /* | |
357 | * Free current thread data structures etc.. | |
358 | */ | |
359 | void exit_thread(void) | |
360 | { | |
361 | struct task_struct *tsk = current; | |
362 | struct thread_struct *t = &tsk->thread; | |
363 | ||
b94cce92 HN |
364 | /* |
365 | * Remove function-return probe instances associated with this task | |
366 | * and put them back on the free list. Do not insert an exit probe for | |
367 | * this function, it will be disabled by kprobe_flush_task if you do. | |
368 | */ | |
369 | kprobe_flush_task(tsk); | |
370 | ||
1da177e4 LT |
371 | /* The process may have allocated an io port bitmap... nuke it. */ |
372 | if (unlikely(NULL != t->io_bitmap_ptr)) { | |
373 | int cpu = get_cpu(); | |
374 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
375 | ||
376 | kfree(t->io_bitmap_ptr); | |
377 | t->io_bitmap_ptr = NULL; | |
378 | /* | |
379 | * Careful, clear this in the TSS too: | |
380 | */ | |
381 | memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); | |
382 | t->io_bitmap_max = 0; | |
383 | tss->io_bitmap_owner = NULL; | |
384 | tss->io_bitmap_max = 0; | |
385 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; | |
386 | put_cpu(); | |
387 | } | |
388 | } | |
389 | ||
390 | void flush_thread(void) | |
391 | { | |
392 | struct task_struct *tsk = current; | |
393 | ||
394 | memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); | |
395 | memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); | |
396 | /* | |
397 | * Forget coprocessor state.. | |
398 | */ | |
399 | clear_fpu(tsk); | |
400 | clear_used_math(); | |
401 | } | |
402 | ||
403 | void release_thread(struct task_struct *dead_task) | |
404 | { | |
2684927c | 405 | BUG_ON(dead_task->mm); |
1da177e4 LT |
406 | release_vm86_irqs(dead_task); |
407 | } | |
408 | ||
409 | /* | |
410 | * This gets called before we allocate a new thread and copy | |
411 | * the current task into it. | |
412 | */ | |
413 | void prepare_to_copy(struct task_struct *tsk) | |
414 | { | |
415 | unlazy_fpu(tsk); | |
416 | } | |
417 | ||
418 | int copy_thread(int nr, unsigned long clone_flags, unsigned long esp, | |
419 | unsigned long unused, | |
420 | struct task_struct * p, struct pt_regs * regs) | |
421 | { | |
422 | struct pt_regs * childregs; | |
423 | struct task_struct *tsk; | |
424 | int err; | |
425 | ||
426 | childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1; | |
5df24082 SS |
427 | /* |
428 | * The below -8 is to reserve 8 bytes on top of the ring0 stack. | |
429 | * This is necessary to guarantee that the entire "struct pt_regs" | |
430 | * is accessable even if the CPU haven't stored the SS/ESP registers | |
431 | * on the stack (interrupt gate does not save these registers | |
432 | * when switching to the same priv ring). | |
433 | * Therefore beware: accessing the xss/esp fields of the | |
434 | * "struct pt_regs" is possible, but they may contain the | |
435 | * completely wrong values. | |
436 | */ | |
f48d9663 AN |
437 | childregs = (struct pt_regs *) ((unsigned long) childregs - 8); |
438 | *childregs = *regs; | |
439 | childregs->eax = 0; | |
440 | childregs->esp = esp; | |
441 | ||
442 | p->thread.esp = (unsigned long) childregs; | |
443 | p->thread.esp0 = (unsigned long) (childregs+1); | |
1da177e4 LT |
444 | |
445 | p->thread.eip = (unsigned long) ret_from_fork; | |
446 | ||
447 | savesegment(fs,p->thread.fs); | |
448 | savesegment(gs,p->thread.gs); | |
449 | ||
450 | tsk = current; | |
451 | if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) { | |
452 | p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); | |
453 | if (!p->thread.io_bitmap_ptr) { | |
454 | p->thread.io_bitmap_max = 0; | |
455 | return -ENOMEM; | |
456 | } | |
457 | memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr, | |
458 | IO_BITMAP_BYTES); | |
459 | } | |
460 | ||
461 | /* | |
462 | * Set a new TLS for the child thread? | |
463 | */ | |
464 | if (clone_flags & CLONE_SETTLS) { | |
465 | struct desc_struct *desc; | |
466 | struct user_desc info; | |
467 | int idx; | |
468 | ||
469 | err = -EFAULT; | |
470 | if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info))) | |
471 | goto out; | |
472 | err = -EINVAL; | |
473 | if (LDT_empty(&info)) | |
474 | goto out; | |
475 | ||
476 | idx = info.entry_number; | |
477 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
478 | goto out; | |
479 | ||
480 | desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; | |
481 | desc->a = LDT_entry_a(&info); | |
482 | desc->b = LDT_entry_b(&info); | |
483 | } | |
484 | ||
485 | err = 0; | |
486 | out: | |
487 | if (err && p->thread.io_bitmap_ptr) { | |
488 | kfree(p->thread.io_bitmap_ptr); | |
489 | p->thread.io_bitmap_max = 0; | |
490 | } | |
491 | return err; | |
492 | } | |
493 | ||
494 | /* | |
495 | * fill in the user structure for a core dump.. | |
496 | */ | |
497 | void dump_thread(struct pt_regs * regs, struct user * dump) | |
498 | { | |
499 | int i; | |
500 | ||
501 | /* changed the size calculations - should hopefully work better. lbt */ | |
502 | dump->magic = CMAGIC; | |
503 | dump->start_code = 0; | |
504 | dump->start_stack = regs->esp & ~(PAGE_SIZE - 1); | |
505 | dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT; | |
506 | dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT; | |
507 | dump->u_dsize -= dump->u_tsize; | |
508 | dump->u_ssize = 0; | |
509 | for (i = 0; i < 8; i++) | |
510 | dump->u_debugreg[i] = current->thread.debugreg[i]; | |
511 | ||
512 | if (dump->start_stack < TASK_SIZE) | |
513 | dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT; | |
514 | ||
515 | dump->regs.ebx = regs->ebx; | |
516 | dump->regs.ecx = regs->ecx; | |
517 | dump->regs.edx = regs->edx; | |
518 | dump->regs.esi = regs->esi; | |
519 | dump->regs.edi = regs->edi; | |
520 | dump->regs.ebp = regs->ebp; | |
521 | dump->regs.eax = regs->eax; | |
522 | dump->regs.ds = regs->xds; | |
523 | dump->regs.es = regs->xes; | |
524 | savesegment(fs,dump->regs.fs); | |
525 | savesegment(gs,dump->regs.gs); | |
526 | dump->regs.orig_eax = regs->orig_eax; | |
527 | dump->regs.eip = regs->eip; | |
528 | dump->regs.cs = regs->xcs; | |
529 | dump->regs.eflags = regs->eflags; | |
530 | dump->regs.esp = regs->esp; | |
531 | dump->regs.ss = regs->xss; | |
532 | ||
533 | dump->u_fpvalid = dump_fpu (regs, &dump->i387); | |
534 | } | |
129f6946 | 535 | EXPORT_SYMBOL(dump_thread); |
1da177e4 LT |
536 | |
537 | /* | |
538 | * Capture the user space registers if the task is not running (in user space) | |
539 | */ | |
540 | int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) | |
541 | { | |
542 | struct pt_regs ptregs; | |
543 | ||
544 | ptregs = *(struct pt_regs *) | |
557962a9 SS |
545 | ((unsigned long)tsk->thread_info + |
546 | /* see comments in copy_thread() about -8 */ | |
547 | THREAD_SIZE - sizeof(ptregs) - 8); | |
1da177e4 LT |
548 | ptregs.xcs &= 0xffff; |
549 | ptregs.xds &= 0xffff; | |
550 | ptregs.xes &= 0xffff; | |
551 | ptregs.xss &= 0xffff; | |
552 | ||
553 | elf_core_copy_regs(regs, &ptregs); | |
554 | ||
555 | return 1; | |
556 | } | |
557 | ||
558 | static inline void | |
559 | handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss) | |
560 | { | |
561 | if (!next->io_bitmap_ptr) { | |
562 | /* | |
563 | * Disable the bitmap via an invalid offset. We still cache | |
564 | * the previous bitmap owner and the IO bitmap contents: | |
565 | */ | |
566 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; | |
567 | return; | |
568 | } | |
569 | if (likely(next == tss->io_bitmap_owner)) { | |
570 | /* | |
571 | * Previous owner of the bitmap (hence the bitmap content) | |
572 | * matches the next task, we dont have to do anything but | |
573 | * to set a valid offset in the TSS: | |
574 | */ | |
575 | tss->io_bitmap_base = IO_BITMAP_OFFSET; | |
576 | return; | |
577 | } | |
578 | /* | |
579 | * Lazy TSS's I/O bitmap copy. We set an invalid offset here | |
580 | * and we let the task to get a GPF in case an I/O instruction | |
581 | * is performed. The handler of the GPF will verify that the | |
582 | * faulting task has a valid I/O bitmap and, it true, does the | |
583 | * real copy and restart the instruction. This will save us | |
584 | * redundant copies when the currently switched task does not | |
585 | * perform any I/O during its timeslice. | |
586 | */ | |
587 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; | |
588 | } | |
1da177e4 | 589 | |
ffaa8bd6 AA |
590 | /* |
591 | * This function selects if the context switch from prev to next | |
592 | * has to tweak the TSC disable bit in the cr4. | |
593 | */ | |
594 | static inline void disable_tsc(struct task_struct *prev_p, | |
595 | struct task_struct *next_p) | |
596 | { | |
597 | struct thread_info *prev, *next; | |
598 | ||
599 | /* | |
600 | * gcc should eliminate the ->thread_info dereference if | |
601 | * has_secure_computing returns 0 at compile time (SECCOMP=n). | |
602 | */ | |
603 | prev = prev_p->thread_info; | |
604 | next = next_p->thread_info; | |
605 | ||
606 | if (has_secure_computing(prev) || has_secure_computing(next)) { | |
607 | /* slow path here */ | |
608 | if (has_secure_computing(prev) && | |
609 | !has_secure_computing(next)) { | |
610 | write_cr4(read_cr4() & ~X86_CR4_TSD); | |
611 | } else if (!has_secure_computing(prev) && | |
612 | has_secure_computing(next)) | |
613 | write_cr4(read_cr4() | X86_CR4_TSD); | |
614 | } | |
615 | } | |
616 | ||
1da177e4 LT |
617 | /* |
618 | * switch_to(x,yn) should switch tasks from x to y. | |
619 | * | |
620 | * We fsave/fwait so that an exception goes off at the right time | |
621 | * (as a call from the fsave or fwait in effect) rather than to | |
622 | * the wrong process. Lazy FP saving no longer makes any sense | |
623 | * with modern CPU's, and this simplifies a lot of things (SMP | |
624 | * and UP become the same). | |
625 | * | |
626 | * NOTE! We used to use the x86 hardware context switching. The | |
627 | * reason for not using it any more becomes apparent when you | |
628 | * try to recover gracefully from saved state that is no longer | |
629 | * valid (stale segment register values in particular). With the | |
630 | * hardware task-switch, there is no way to fix up bad state in | |
631 | * a reasonable manner. | |
632 | * | |
633 | * The fact that Intel documents the hardware task-switching to | |
634 | * be slow is a fairly red herring - this code is not noticeably | |
635 | * faster. However, there _is_ some room for improvement here, | |
636 | * so the performance issues may eventually be a valid point. | |
637 | * More important, however, is the fact that this allows us much | |
638 | * more flexibility. | |
639 | * | |
640 | * The return value (in %eax) will be the "prev" task after | |
641 | * the task-switch, and shows up in ret_from_fork in entry.S, | |
642 | * for example. | |
643 | */ | |
644 | struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) | |
645 | { | |
646 | struct thread_struct *prev = &prev_p->thread, | |
647 | *next = &next_p->thread; | |
648 | int cpu = smp_processor_id(); | |
649 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
650 | ||
651 | /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ | |
652 | ||
653 | __unlazy_fpu(prev_p); | |
654 | ||
655 | /* | |
e7a2ff59 | 656 | * Reload esp0. |
1da177e4 LT |
657 | */ |
658 | load_esp0(tss, next); | |
659 | ||
660 | /* | |
e7a2ff59 ZA |
661 | * Save away %fs and %gs. No need to save %es and %ds, as |
662 | * those are always kernel segments while inside the kernel. | |
663 | * Doing this before setting the new TLS descriptors avoids | |
664 | * the situation where we temporarily have non-reloadable | |
665 | * segments in %fs and %gs. This could be an issue if the | |
666 | * NMI handler ever used %fs or %gs (it does not today), or | |
667 | * if the kernel is running inside of a hypervisor layer. | |
1da177e4 | 668 | */ |
e7a2ff59 ZA |
669 | savesegment(fs, prev->fs); |
670 | savesegment(gs, prev->gs); | |
1da177e4 LT |
671 | |
672 | /* | |
e7a2ff59 | 673 | * Load the per-thread Thread-Local Storage descriptor. |
1da177e4 | 674 | */ |
e7a2ff59 | 675 | load_TLS(next, cpu); |
1da177e4 LT |
676 | |
677 | /* | |
678 | * Restore %fs and %gs if needed. | |
b339a18b LT |
679 | * |
680 | * Glibc normally makes %fs be zero, and %gs is one of | |
681 | * the TLS segments. | |
1da177e4 | 682 | */ |
b339a18b | 683 | if (unlikely(prev->fs | next->fs)) |
1da177e4 | 684 | loadsegment(fs, next->fs); |
b339a18b LT |
685 | |
686 | if (prev->gs | next->gs) | |
1da177e4 | 687 | loadsegment(gs, next->gs); |
1da177e4 | 688 | |
a5201129 ZA |
689 | /* |
690 | * Restore IOPL if needed. | |
691 | */ | |
692 | if (unlikely(prev->iopl != next->iopl)) | |
693 | set_iopl_mask(next->iopl); | |
694 | ||
1da177e4 LT |
695 | /* |
696 | * Now maybe reload the debug registers | |
697 | */ | |
698 | if (unlikely(next->debugreg[7])) { | |
b339a18b LT |
699 | set_debugreg(next->debugreg[0], 0); |
700 | set_debugreg(next->debugreg[1], 1); | |
701 | set_debugreg(next->debugreg[2], 2); | |
702 | set_debugreg(next->debugreg[3], 3); | |
1da177e4 | 703 | /* no 4 and 5 */ |
b339a18b LT |
704 | set_debugreg(next->debugreg[6], 6); |
705 | set_debugreg(next->debugreg[7], 7); | |
1da177e4 LT |
706 | } |
707 | ||
708 | if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) | |
709 | handle_io_bitmap(next, tss); | |
710 | ||
ffaa8bd6 AA |
711 | disable_tsc(prev_p, next_p); |
712 | ||
1da177e4 LT |
713 | return prev_p; |
714 | } | |
715 | ||
716 | asmlinkage int sys_fork(struct pt_regs regs) | |
717 | { | |
718 | return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL); | |
719 | } | |
720 | ||
721 | asmlinkage int sys_clone(struct pt_regs regs) | |
722 | { | |
723 | unsigned long clone_flags; | |
724 | unsigned long newsp; | |
725 | int __user *parent_tidptr, *child_tidptr; | |
726 | ||
727 | clone_flags = regs.ebx; | |
728 | newsp = regs.ecx; | |
729 | parent_tidptr = (int __user *)regs.edx; | |
730 | child_tidptr = (int __user *)regs.edi; | |
731 | if (!newsp) | |
732 | newsp = regs.esp; | |
733 | return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); | |
734 | } | |
735 | ||
736 | /* | |
737 | * This is trivial, and on the face of it looks like it | |
738 | * could equally well be done in user mode. | |
739 | * | |
740 | * Not so, for quite unobvious reasons - register pressure. | |
741 | * In user mode vfork() cannot have a stack frame, and if | |
742 | * done by calling the "clone()" system call directly, you | |
743 | * do not have enough call-clobbered registers to hold all | |
744 | * the information you need. | |
745 | */ | |
746 | asmlinkage int sys_vfork(struct pt_regs regs) | |
747 | { | |
748 | return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL); | |
749 | } | |
750 | ||
751 | /* | |
752 | * sys_execve() executes a new program. | |
753 | */ | |
754 | asmlinkage int sys_execve(struct pt_regs regs) | |
755 | { | |
756 | int error; | |
757 | char * filename; | |
758 | ||
759 | filename = getname((char __user *) regs.ebx); | |
760 | error = PTR_ERR(filename); | |
761 | if (IS_ERR(filename)) | |
762 | goto out; | |
763 | error = do_execve(filename, | |
764 | (char __user * __user *) regs.ecx, | |
765 | (char __user * __user *) regs.edx, | |
766 | ®s); | |
767 | if (error == 0) { | |
768 | task_lock(current); | |
769 | current->ptrace &= ~PT_DTRACE; | |
770 | task_unlock(current); | |
771 | /* Make sure we don't return using sysenter.. */ | |
772 | set_thread_flag(TIF_IRET); | |
773 | } | |
774 | putname(filename); | |
775 | out: | |
776 | return error; | |
777 | } | |
778 | ||
779 | #define top_esp (THREAD_SIZE - sizeof(unsigned long)) | |
780 | #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) | |
781 | ||
782 | unsigned long get_wchan(struct task_struct *p) | |
783 | { | |
784 | unsigned long ebp, esp, eip; | |
785 | unsigned long stack_page; | |
786 | int count = 0; | |
787 | if (!p || p == current || p->state == TASK_RUNNING) | |
788 | return 0; | |
789 | stack_page = (unsigned long)p->thread_info; | |
790 | esp = p->thread.esp; | |
791 | if (!stack_page || esp < stack_page || esp > top_esp+stack_page) | |
792 | return 0; | |
793 | /* include/asm-i386/system.h:switch_to() pushes ebp last. */ | |
794 | ebp = *(unsigned long *) esp; | |
795 | do { | |
796 | if (ebp < stack_page || ebp > top_ebp+stack_page) | |
797 | return 0; | |
798 | eip = *(unsigned long *) (ebp+4); | |
799 | if (!in_sched_functions(eip)) | |
800 | return eip; | |
801 | ebp = *(unsigned long *) ebp; | |
802 | } while (count++ < 16); | |
803 | return 0; | |
804 | } | |
129f6946 | 805 | EXPORT_SYMBOL(get_wchan); |
1da177e4 LT |
806 | |
807 | /* | |
808 | * sys_alloc_thread_area: get a yet unused TLS descriptor index. | |
809 | */ | |
810 | static int get_free_idx(void) | |
811 | { | |
812 | struct thread_struct *t = ¤t->thread; | |
813 | int idx; | |
814 | ||
815 | for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) | |
816 | if (desc_empty(t->tls_array + idx)) | |
817 | return idx + GDT_ENTRY_TLS_MIN; | |
818 | return -ESRCH; | |
819 | } | |
820 | ||
821 | /* | |
822 | * Set a given TLS descriptor: | |
823 | */ | |
824 | asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) | |
825 | { | |
826 | struct thread_struct *t = ¤t->thread; | |
827 | struct user_desc info; | |
828 | struct desc_struct *desc; | |
829 | int cpu, idx; | |
830 | ||
831 | if (copy_from_user(&info, u_info, sizeof(info))) | |
832 | return -EFAULT; | |
833 | idx = info.entry_number; | |
834 | ||
835 | /* | |
836 | * index -1 means the kernel should try to find and | |
837 | * allocate an empty descriptor: | |
838 | */ | |
839 | if (idx == -1) { | |
840 | idx = get_free_idx(); | |
841 | if (idx < 0) | |
842 | return idx; | |
843 | if (put_user(idx, &u_info->entry_number)) | |
844 | return -EFAULT; | |
845 | } | |
846 | ||
847 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
848 | return -EINVAL; | |
849 | ||
850 | desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN; | |
851 | ||
852 | /* | |
853 | * We must not get preempted while modifying the TLS. | |
854 | */ | |
855 | cpu = get_cpu(); | |
856 | ||
857 | if (LDT_empty(&info)) { | |
858 | desc->a = 0; | |
859 | desc->b = 0; | |
860 | } else { | |
861 | desc->a = LDT_entry_a(&info); | |
862 | desc->b = LDT_entry_b(&info); | |
863 | } | |
864 | load_TLS(t, cpu); | |
865 | ||
866 | put_cpu(); | |
867 | ||
868 | return 0; | |
869 | } | |
870 | ||
871 | /* | |
872 | * Get the current Thread-Local Storage area: | |
873 | */ | |
874 | ||
875 | #define GET_BASE(desc) ( \ | |
876 | (((desc)->a >> 16) & 0x0000ffff) | \ | |
877 | (((desc)->b << 16) & 0x00ff0000) | \ | |
878 | ( (desc)->b & 0xff000000) ) | |
879 | ||
880 | #define GET_LIMIT(desc) ( \ | |
881 | ((desc)->a & 0x0ffff) | \ | |
882 | ((desc)->b & 0xf0000) ) | |
883 | ||
884 | #define GET_32BIT(desc) (((desc)->b >> 22) & 1) | |
885 | #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) | |
886 | #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) | |
887 | #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) | |
888 | #define GET_PRESENT(desc) (((desc)->b >> 15) & 1) | |
889 | #define GET_USEABLE(desc) (((desc)->b >> 20) & 1) | |
890 | ||
891 | asmlinkage int sys_get_thread_area(struct user_desc __user *u_info) | |
892 | { | |
893 | struct user_desc info; | |
894 | struct desc_struct *desc; | |
895 | int idx; | |
896 | ||
897 | if (get_user(idx, &u_info->entry_number)) | |
898 | return -EFAULT; | |
899 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
900 | return -EINVAL; | |
901 | ||
71ae18ec PBG |
902 | memset(&info, 0, sizeof(info)); |
903 | ||
1da177e4 LT |
904 | desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; |
905 | ||
906 | info.entry_number = idx; | |
907 | info.base_addr = GET_BASE(desc); | |
908 | info.limit = GET_LIMIT(desc); | |
909 | info.seg_32bit = GET_32BIT(desc); | |
910 | info.contents = GET_CONTENTS(desc); | |
911 | info.read_exec_only = !GET_WRITABLE(desc); | |
912 | info.limit_in_pages = GET_LIMIT_PAGES(desc); | |
913 | info.seg_not_present = !GET_PRESENT(desc); | |
914 | info.useable = GET_USEABLE(desc); | |
915 | ||
916 | if (copy_to_user(u_info, &info, sizeof(info))) | |
917 | return -EFAULT; | |
918 | return 0; | |
919 | } | |
920 | ||
921 | unsigned long arch_align_stack(unsigned long sp) | |
922 | { | |
923 | if (randomize_va_space) | |
924 | sp -= get_random_int() % 8192; | |
925 | return sp & ~0xf; | |
926 | } |