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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> | |
1da177e4 LT |
31 | #include <linux/utsname.h> |
32 | #include <linux/delay.h> | |
33 | #include <linux/reboot.h> | |
34 | #include <linux/init.h> | |
35 | #include <linux/mc146818rtc.h> | |
36 | #include <linux/module.h> | |
37 | #include <linux/kallsyms.h> | |
38 | #include <linux/ptrace.h> | |
39 | #include <linux/random.h> | |
40 | ||
41 | #include <asm/uaccess.h> | |
42 | #include <asm/pgtable.h> | |
43 | #include <asm/system.h> | |
44 | #include <asm/io.h> | |
45 | #include <asm/ldt.h> | |
46 | #include <asm/processor.h> | |
47 | #include <asm/i387.h> | |
1da177e4 | 48 | #include <asm/desc.h> |
64ca9004 | 49 | #include <asm/vm86.h> |
1da177e4 LT |
50 | #ifdef CONFIG_MATH_EMULATION |
51 | #include <asm/math_emu.h> | |
52 | #endif | |
53 | ||
1da177e4 LT |
54 | #include <linux/err.h> |
55 | ||
f3705136 ZM |
56 | #include <asm/tlbflush.h> |
57 | #include <asm/cpu.h> | |
58 | ||
1da177e4 LT |
59 | asmlinkage void ret_from_fork(void) __asm__("ret_from_fork"); |
60 | ||
61 | static int hlt_counter; | |
62 | ||
63 | unsigned long boot_option_idle_override = 0; | |
64 | EXPORT_SYMBOL(boot_option_idle_override); | |
65 | ||
66 | /* | |
67 | * Return saved PC of a blocked thread. | |
68 | */ | |
69 | unsigned long thread_saved_pc(struct task_struct *tsk) | |
70 | { | |
71 | return ((unsigned long *)tsk->thread.esp)[3]; | |
72 | } | |
73 | ||
74 | /* | |
75 | * Powermanagement idle function, if any.. | |
76 | */ | |
77 | void (*pm_idle)(void); | |
129f6946 | 78 | EXPORT_SYMBOL(pm_idle); |
1da177e4 LT |
79 | static DEFINE_PER_CPU(unsigned int, cpu_idle_state); |
80 | ||
81 | void disable_hlt(void) | |
82 | { | |
83 | hlt_counter++; | |
84 | } | |
85 | ||
86 | EXPORT_SYMBOL(disable_hlt); | |
87 | ||
88 | void enable_hlt(void) | |
89 | { | |
90 | hlt_counter--; | |
91 | } | |
92 | ||
93 | EXPORT_SYMBOL(enable_hlt); | |
94 | ||
95 | /* | |
96 | * We use this if we don't have any better | |
97 | * idle routine.. | |
98 | */ | |
99 | void default_idle(void) | |
100 | { | |
64c7c8f8 NP |
101 | local_irq_enable(); |
102 | ||
1da177e4 | 103 | if (!hlt_counter && boot_cpu_data.hlt_works_ok) { |
495ab9c0 | 104 | current_thread_info()->status &= ~TS_POLLING; |
64c7c8f8 NP |
105 | smp_mb__after_clear_bit(); |
106 | while (!need_resched()) { | |
107 | local_irq_disable(); | |
108 | if (!need_resched()) | |
109 | safe_halt(); | |
110 | else | |
111 | local_irq_enable(); | |
112 | } | |
495ab9c0 | 113 | current_thread_info()->status |= TS_POLLING; |
1da177e4 | 114 | } else { |
64c7c8f8 NP |
115 | while (!need_resched()) |
116 | cpu_relax(); | |
1da177e4 LT |
117 | } |
118 | } | |
129f6946 AD |
119 | #ifdef CONFIG_APM_MODULE |
120 | EXPORT_SYMBOL(default_idle); | |
121 | #endif | |
1da177e4 LT |
122 | |
123 | /* | |
124 | * On SMP it's slightly faster (but much more power-consuming!) | |
125 | * to poll the ->work.need_resched flag instead of waiting for the | |
126 | * cross-CPU IPI to arrive. Use this option with caution. | |
127 | */ | |
128 | static void poll_idle (void) | |
129 | { | |
1da177e4 LT |
130 | local_irq_enable(); |
131 | ||
64c7c8f8 NP |
132 | asm volatile( |
133 | "2:" | |
134 | "testl %0, %1;" | |
135 | "rep; nop;" | |
136 | "je 2b;" | |
137 | : : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags)); | |
1da177e4 LT |
138 | } |
139 | ||
f3705136 ZM |
140 | #ifdef CONFIG_HOTPLUG_CPU |
141 | #include <asm/nmi.h> | |
142 | /* We don't actually take CPU down, just spin without interrupts. */ | |
143 | static inline void play_dead(void) | |
144 | { | |
e1367daf LS |
145 | /* This must be done before dead CPU ack */ |
146 | cpu_exit_clear(); | |
147 | wbinvd(); | |
148 | mb(); | |
f3705136 ZM |
149 | /* Ack it */ |
150 | __get_cpu_var(cpu_state) = CPU_DEAD; | |
151 | ||
e1367daf LS |
152 | /* |
153 | * With physical CPU hotplug, we should halt the cpu | |
154 | */ | |
f3705136 | 155 | local_irq_disable(); |
e1367daf | 156 | while (1) |
f2ab4461 | 157 | halt(); |
f3705136 ZM |
158 | } |
159 | #else | |
160 | static inline void play_dead(void) | |
161 | { | |
162 | BUG(); | |
163 | } | |
164 | #endif /* CONFIG_HOTPLUG_CPU */ | |
165 | ||
1da177e4 LT |
166 | /* |
167 | * The idle thread. There's no useful work to be | |
168 | * done, so just try to conserve power and have a | |
169 | * low exit latency (ie sit in a loop waiting for | |
170 | * somebody to say that they'd like to reschedule) | |
171 | */ | |
f3705136 | 172 | void cpu_idle(void) |
1da177e4 | 173 | { |
5bfb5d69 | 174 | int cpu = smp_processor_id(); |
f3705136 | 175 | |
495ab9c0 | 176 | current_thread_info()->status |= TS_POLLING; |
64c7c8f8 | 177 | |
1da177e4 LT |
178 | /* endless idle loop with no priority at all */ |
179 | while (1) { | |
180 | while (!need_resched()) { | |
181 | void (*idle)(void); | |
182 | ||
183 | if (__get_cpu_var(cpu_idle_state)) | |
184 | __get_cpu_var(cpu_idle_state) = 0; | |
185 | ||
186 | rmb(); | |
187 | idle = pm_idle; | |
188 | ||
189 | if (!idle) | |
190 | idle = default_idle; | |
191 | ||
f3705136 ZM |
192 | if (cpu_is_offline(cpu)) |
193 | play_dead(); | |
194 | ||
1da177e4 LT |
195 | __get_cpu_var(irq_stat).idle_timestamp = jiffies; |
196 | idle(); | |
197 | } | |
5bfb5d69 | 198 | preempt_enable_no_resched(); |
1da177e4 | 199 | schedule(); |
5bfb5d69 | 200 | preempt_disable(); |
1da177e4 LT |
201 | } |
202 | } | |
203 | ||
204 | void cpu_idle_wait(void) | |
205 | { | |
206 | unsigned int cpu, this_cpu = get_cpu(); | |
207 | cpumask_t map; | |
208 | ||
209 | set_cpus_allowed(current, cpumask_of_cpu(this_cpu)); | |
210 | put_cpu(); | |
211 | ||
212 | cpus_clear(map); | |
213 | for_each_online_cpu(cpu) { | |
214 | per_cpu(cpu_idle_state, cpu) = 1; | |
215 | cpu_set(cpu, map); | |
216 | } | |
217 | ||
218 | __get_cpu_var(cpu_idle_state) = 0; | |
219 | ||
220 | wmb(); | |
221 | do { | |
222 | ssleep(1); | |
223 | for_each_online_cpu(cpu) { | |
224 | if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu)) | |
225 | cpu_clear(cpu, map); | |
226 | } | |
227 | cpus_and(map, map, cpu_online_map); | |
228 | } while (!cpus_empty(map)); | |
229 | } | |
230 | EXPORT_SYMBOL_GPL(cpu_idle_wait); | |
231 | ||
232 | /* | |
233 | * This uses new MONITOR/MWAIT instructions on P4 processors with PNI, | |
234 | * which can obviate IPI to trigger checking of need_resched. | |
235 | * We execute MONITOR against need_resched and enter optimized wait state | |
236 | * through MWAIT. Whenever someone changes need_resched, we would be woken | |
237 | * up from MWAIT (without an IPI). | |
238 | */ | |
239 | static void mwait_idle(void) | |
240 | { | |
241 | local_irq_enable(); | |
242 | ||
64c7c8f8 NP |
243 | while (!need_resched()) { |
244 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
245 | smp_mb(); | |
246 | if (need_resched()) | |
247 | break; | |
248 | __mwait(0, 0); | |
1da177e4 LT |
249 | } |
250 | } | |
251 | ||
0bb3184d | 252 | void __devinit select_idle_routine(const struct cpuinfo_x86 *c) |
1da177e4 LT |
253 | { |
254 | if (cpu_has(c, X86_FEATURE_MWAIT)) { | |
255 | printk("monitor/mwait feature present.\n"); | |
256 | /* | |
257 | * Skip, if setup has overridden idle. | |
258 | * One CPU supports mwait => All CPUs supports mwait | |
259 | */ | |
260 | if (!pm_idle) { | |
261 | printk("using mwait in idle threads.\n"); | |
262 | pm_idle = mwait_idle; | |
263 | } | |
264 | } | |
265 | } | |
266 | ||
267 | static int __init idle_setup (char *str) | |
268 | { | |
269 | if (!strncmp(str, "poll", 4)) { | |
270 | printk("using polling idle threads.\n"); | |
271 | pm_idle = poll_idle; | |
272 | #ifdef CONFIG_X86_SMP | |
273 | if (smp_num_siblings > 1) | |
274 | printk("WARNING: polling idle and HT enabled, performance may degrade.\n"); | |
275 | #endif | |
276 | } else if (!strncmp(str, "halt", 4)) { | |
277 | printk("using halt in idle threads.\n"); | |
278 | pm_idle = default_idle; | |
279 | } | |
280 | ||
281 | boot_option_idle_override = 1; | |
282 | return 1; | |
283 | } | |
284 | ||
285 | __setup("idle=", idle_setup); | |
286 | ||
287 | void show_regs(struct pt_regs * regs) | |
288 | { | |
289 | unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; | |
290 | ||
291 | printk("\n"); | |
292 | printk("Pid: %d, comm: %20s\n", current->pid, current->comm); | |
293 | printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs->xcs,regs->eip, smp_processor_id()); | |
294 | print_symbol("EIP is at %s\n", regs->eip); | |
295 | ||
db753bdf | 296 | if (user_mode_vm(regs)) |
1da177e4 | 297 | printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp); |
b53e8f68 CE |
298 | printk(" EFLAGS: %08lx %s (%s %.*s)\n", |
299 | regs->eflags, print_tainted(), system_utsname.release, | |
300 | (int)strcspn(system_utsname.version, " "), | |
301 | system_utsname.version); | |
1da177e4 LT |
302 | printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", |
303 | regs->eax,regs->ebx,regs->ecx,regs->edx); | |
304 | printk("ESI: %08lx EDI: %08lx EBP: %08lx", | |
305 | regs->esi, regs->edi, regs->ebp); | |
306 | printk(" DS: %04x ES: %04x\n", | |
307 | 0xffff & regs->xds,0xffff & regs->xes); | |
308 | ||
4bb0d3ec ZA |
309 | cr0 = read_cr0(); |
310 | cr2 = read_cr2(); | |
311 | cr3 = read_cr3(); | |
ff6e8c0d | 312 | cr4 = read_cr4_safe(); |
1da177e4 | 313 | printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4); |
176a2718 | 314 | show_trace(NULL, regs, ®s->esp); |
1da177e4 LT |
315 | } |
316 | ||
317 | /* | |
318 | * This gets run with %ebx containing the | |
319 | * function to call, and %edx containing | |
320 | * the "args". | |
321 | */ | |
322 | extern void kernel_thread_helper(void); | |
323 | __asm__(".section .text\n" | |
324 | ".align 4\n" | |
325 | "kernel_thread_helper:\n\t" | |
326 | "movl %edx,%eax\n\t" | |
327 | "pushl %edx\n\t" | |
328 | "call *%ebx\n\t" | |
329 | "pushl %eax\n\t" | |
330 | "call do_exit\n" | |
331 | ".previous"); | |
332 | ||
333 | /* | |
334 | * Create a kernel thread | |
335 | */ | |
336 | int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) | |
337 | { | |
338 | struct pt_regs regs; | |
339 | ||
340 | memset(®s, 0, sizeof(regs)); | |
341 | ||
342 | regs.ebx = (unsigned long) fn; | |
343 | regs.edx = (unsigned long) arg; | |
344 | ||
345 | regs.xds = __USER_DS; | |
346 | regs.xes = __USER_DS; | |
347 | regs.orig_eax = -1; | |
348 | regs.eip = (unsigned long) kernel_thread_helper; | |
349 | regs.xcs = __KERNEL_CS; | |
350 | regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2; | |
351 | ||
352 | /* Ok, create the new process.. */ | |
353 | return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); | |
354 | } | |
129f6946 | 355 | EXPORT_SYMBOL(kernel_thread); |
1da177e4 LT |
356 | |
357 | /* | |
358 | * Free current thread data structures etc.. | |
359 | */ | |
360 | void exit_thread(void) | |
361 | { | |
1da177e4 | 362 | /* The process may have allocated an io port bitmap... nuke it. */ |
b3cf2576 SE |
363 | if (unlikely(test_thread_flag(TIF_IO_BITMAP))) { |
364 | struct task_struct *tsk = current; | |
365 | struct thread_struct *t = &tsk->thread; | |
1da177e4 LT |
366 | int cpu = get_cpu(); |
367 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
368 | ||
369 | kfree(t->io_bitmap_ptr); | |
370 | t->io_bitmap_ptr = NULL; | |
b3cf2576 | 371 | clear_thread_flag(TIF_IO_BITMAP); |
1da177e4 LT |
372 | /* |
373 | * Careful, clear this in the TSS too: | |
374 | */ | |
375 | memset(tss->io_bitmap, 0xff, tss->io_bitmap_max); | |
376 | t->io_bitmap_max = 0; | |
377 | tss->io_bitmap_owner = NULL; | |
378 | tss->io_bitmap_max = 0; | |
379 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; | |
380 | put_cpu(); | |
381 | } | |
382 | } | |
383 | ||
384 | void flush_thread(void) | |
385 | { | |
386 | struct task_struct *tsk = current; | |
387 | ||
388 | memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); | |
389 | memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); | |
b3cf2576 | 390 | clear_tsk_thread_flag(tsk, TIF_DEBUG); |
1da177e4 LT |
391 | /* |
392 | * Forget coprocessor state.. | |
393 | */ | |
394 | clear_fpu(tsk); | |
395 | clear_used_math(); | |
396 | } | |
397 | ||
398 | void release_thread(struct task_struct *dead_task) | |
399 | { | |
2684927c | 400 | BUG_ON(dead_task->mm); |
1da177e4 LT |
401 | release_vm86_irqs(dead_task); |
402 | } | |
403 | ||
404 | /* | |
405 | * This gets called before we allocate a new thread and copy | |
406 | * the current task into it. | |
407 | */ | |
408 | void prepare_to_copy(struct task_struct *tsk) | |
409 | { | |
410 | unlazy_fpu(tsk); | |
411 | } | |
412 | ||
413 | int copy_thread(int nr, unsigned long clone_flags, unsigned long esp, | |
414 | unsigned long unused, | |
415 | struct task_struct * p, struct pt_regs * regs) | |
416 | { | |
417 | struct pt_regs * childregs; | |
418 | struct task_struct *tsk; | |
419 | int err; | |
420 | ||
07b047fc | 421 | childregs = task_pt_regs(p); |
f48d9663 AN |
422 | *childregs = *regs; |
423 | childregs->eax = 0; | |
424 | childregs->esp = esp; | |
425 | ||
426 | p->thread.esp = (unsigned long) childregs; | |
427 | p->thread.esp0 = (unsigned long) (childregs+1); | |
1da177e4 LT |
428 | |
429 | p->thread.eip = (unsigned long) ret_from_fork; | |
430 | ||
431 | savesegment(fs,p->thread.fs); | |
432 | savesegment(gs,p->thread.gs); | |
433 | ||
434 | tsk = current; | |
b3cf2576 | 435 | if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) { |
1da177e4 LT |
436 | p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL); |
437 | if (!p->thread.io_bitmap_ptr) { | |
438 | p->thread.io_bitmap_max = 0; | |
439 | return -ENOMEM; | |
440 | } | |
441 | memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr, | |
442 | IO_BITMAP_BYTES); | |
b3cf2576 | 443 | set_tsk_thread_flag(p, TIF_IO_BITMAP); |
1da177e4 LT |
444 | } |
445 | ||
446 | /* | |
447 | * Set a new TLS for the child thread? | |
448 | */ | |
449 | if (clone_flags & CLONE_SETTLS) { | |
450 | struct desc_struct *desc; | |
451 | struct user_desc info; | |
452 | int idx; | |
453 | ||
454 | err = -EFAULT; | |
455 | if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info))) | |
456 | goto out; | |
457 | err = -EINVAL; | |
458 | if (LDT_empty(&info)) | |
459 | goto out; | |
460 | ||
461 | idx = info.entry_number; | |
462 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
463 | goto out; | |
464 | ||
465 | desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; | |
466 | desc->a = LDT_entry_a(&info); | |
467 | desc->b = LDT_entry_b(&info); | |
468 | } | |
469 | ||
470 | err = 0; | |
471 | out: | |
472 | if (err && p->thread.io_bitmap_ptr) { | |
473 | kfree(p->thread.io_bitmap_ptr); | |
474 | p->thread.io_bitmap_max = 0; | |
475 | } | |
476 | return err; | |
477 | } | |
478 | ||
479 | /* | |
480 | * fill in the user structure for a core dump.. | |
481 | */ | |
482 | void dump_thread(struct pt_regs * regs, struct user * dump) | |
483 | { | |
484 | int i; | |
485 | ||
486 | /* changed the size calculations - should hopefully work better. lbt */ | |
487 | dump->magic = CMAGIC; | |
488 | dump->start_code = 0; | |
489 | dump->start_stack = regs->esp & ~(PAGE_SIZE - 1); | |
490 | dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT; | |
491 | dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT; | |
492 | dump->u_dsize -= dump->u_tsize; | |
493 | dump->u_ssize = 0; | |
494 | for (i = 0; i < 8; i++) | |
495 | dump->u_debugreg[i] = current->thread.debugreg[i]; | |
496 | ||
497 | if (dump->start_stack < TASK_SIZE) | |
498 | dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT; | |
499 | ||
500 | dump->regs.ebx = regs->ebx; | |
501 | dump->regs.ecx = regs->ecx; | |
502 | dump->regs.edx = regs->edx; | |
503 | dump->regs.esi = regs->esi; | |
504 | dump->regs.edi = regs->edi; | |
505 | dump->regs.ebp = regs->ebp; | |
506 | dump->regs.eax = regs->eax; | |
507 | dump->regs.ds = regs->xds; | |
508 | dump->regs.es = regs->xes; | |
509 | savesegment(fs,dump->regs.fs); | |
510 | savesegment(gs,dump->regs.gs); | |
511 | dump->regs.orig_eax = regs->orig_eax; | |
512 | dump->regs.eip = regs->eip; | |
513 | dump->regs.cs = regs->xcs; | |
514 | dump->regs.eflags = regs->eflags; | |
515 | dump->regs.esp = regs->esp; | |
516 | dump->regs.ss = regs->xss; | |
517 | ||
518 | dump->u_fpvalid = dump_fpu (regs, &dump->i387); | |
519 | } | |
129f6946 | 520 | EXPORT_SYMBOL(dump_thread); |
1da177e4 LT |
521 | |
522 | /* | |
523 | * Capture the user space registers if the task is not running (in user space) | |
524 | */ | |
525 | int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) | |
526 | { | |
07b047fc | 527 | struct pt_regs ptregs = *task_pt_regs(tsk); |
1da177e4 LT |
528 | ptregs.xcs &= 0xffff; |
529 | ptregs.xds &= 0xffff; | |
530 | ptregs.xes &= 0xffff; | |
531 | ptregs.xss &= 0xffff; | |
532 | ||
533 | elf_core_copy_regs(regs, &ptregs); | |
534 | ||
535 | return 1; | |
536 | } | |
537 | ||
b3cf2576 SE |
538 | static noinline void __switch_to_xtra(struct task_struct *next_p, |
539 | struct tss_struct *tss) | |
1da177e4 | 540 | { |
b3cf2576 SE |
541 | struct thread_struct *next; |
542 | ||
543 | next = &next_p->thread; | |
544 | ||
545 | if (test_tsk_thread_flag(next_p, TIF_DEBUG)) { | |
546 | set_debugreg(next->debugreg[0], 0); | |
547 | set_debugreg(next->debugreg[1], 1); | |
548 | set_debugreg(next->debugreg[2], 2); | |
549 | set_debugreg(next->debugreg[3], 3); | |
550 | /* no 4 and 5 */ | |
551 | set_debugreg(next->debugreg[6], 6); | |
552 | set_debugreg(next->debugreg[7], 7); | |
553 | } | |
554 | ||
555 | if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) { | |
1da177e4 LT |
556 | /* |
557 | * Disable the bitmap via an invalid offset. We still cache | |
558 | * the previous bitmap owner and the IO bitmap contents: | |
559 | */ | |
560 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET; | |
561 | return; | |
562 | } | |
b3cf2576 | 563 | |
1da177e4 LT |
564 | if (likely(next == tss->io_bitmap_owner)) { |
565 | /* | |
566 | * Previous owner of the bitmap (hence the bitmap content) | |
567 | * matches the next task, we dont have to do anything but | |
568 | * to set a valid offset in the TSS: | |
569 | */ | |
570 | tss->io_bitmap_base = IO_BITMAP_OFFSET; | |
571 | return; | |
572 | } | |
573 | /* | |
574 | * Lazy TSS's I/O bitmap copy. We set an invalid offset here | |
575 | * and we let the task to get a GPF in case an I/O instruction | |
576 | * is performed. The handler of the GPF will verify that the | |
577 | * faulting task has a valid I/O bitmap and, it true, does the | |
578 | * real copy and restart the instruction. This will save us | |
579 | * redundant copies when the currently switched task does not | |
580 | * perform any I/O during its timeslice. | |
581 | */ | |
582 | tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY; | |
583 | } | |
1da177e4 | 584 | |
ffaa8bd6 AA |
585 | /* |
586 | * This function selects if the context switch from prev to next | |
587 | * has to tweak the TSC disable bit in the cr4. | |
588 | */ | |
589 | static inline void disable_tsc(struct task_struct *prev_p, | |
590 | struct task_struct *next_p) | |
591 | { | |
592 | struct thread_info *prev, *next; | |
593 | ||
594 | /* | |
595 | * gcc should eliminate the ->thread_info dereference if | |
596 | * has_secure_computing returns 0 at compile time (SECCOMP=n). | |
597 | */ | |
06b425d8 AV |
598 | prev = task_thread_info(prev_p); |
599 | next = task_thread_info(next_p); | |
ffaa8bd6 AA |
600 | |
601 | if (has_secure_computing(prev) || has_secure_computing(next)) { | |
602 | /* slow path here */ | |
603 | if (has_secure_computing(prev) && | |
604 | !has_secure_computing(next)) { | |
605 | write_cr4(read_cr4() & ~X86_CR4_TSD); | |
606 | } else if (!has_secure_computing(prev) && | |
607 | has_secure_computing(next)) | |
608 | write_cr4(read_cr4() | X86_CR4_TSD); | |
609 | } | |
610 | } | |
611 | ||
1da177e4 LT |
612 | /* |
613 | * switch_to(x,yn) should switch tasks from x to y. | |
614 | * | |
615 | * We fsave/fwait so that an exception goes off at the right time | |
616 | * (as a call from the fsave or fwait in effect) rather than to | |
617 | * the wrong process. Lazy FP saving no longer makes any sense | |
618 | * with modern CPU's, and this simplifies a lot of things (SMP | |
619 | * and UP become the same). | |
620 | * | |
621 | * NOTE! We used to use the x86 hardware context switching. The | |
622 | * reason for not using it any more becomes apparent when you | |
623 | * try to recover gracefully from saved state that is no longer | |
624 | * valid (stale segment register values in particular). With the | |
625 | * hardware task-switch, there is no way to fix up bad state in | |
626 | * a reasonable manner. | |
627 | * | |
628 | * The fact that Intel documents the hardware task-switching to | |
629 | * be slow is a fairly red herring - this code is not noticeably | |
630 | * faster. However, there _is_ some room for improvement here, | |
631 | * so the performance issues may eventually be a valid point. | |
632 | * More important, however, is the fact that this allows us much | |
633 | * more flexibility. | |
634 | * | |
635 | * The return value (in %eax) will be the "prev" task after | |
636 | * the task-switch, and shows up in ret_from_fork in entry.S, | |
637 | * for example. | |
638 | */ | |
639 | struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p) | |
640 | { | |
641 | struct thread_struct *prev = &prev_p->thread, | |
642 | *next = &next_p->thread; | |
643 | int cpu = smp_processor_id(); | |
644 | struct tss_struct *tss = &per_cpu(init_tss, cpu); | |
645 | ||
646 | /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ | |
647 | ||
648 | __unlazy_fpu(prev_p); | |
649 | ||
650 | /* | |
e7a2ff59 | 651 | * Reload esp0. |
1da177e4 LT |
652 | */ |
653 | load_esp0(tss, next); | |
654 | ||
655 | /* | |
e7a2ff59 ZA |
656 | * Save away %fs and %gs. No need to save %es and %ds, as |
657 | * those are always kernel segments while inside the kernel. | |
658 | * Doing this before setting the new TLS descriptors avoids | |
659 | * the situation where we temporarily have non-reloadable | |
660 | * segments in %fs and %gs. This could be an issue if the | |
661 | * NMI handler ever used %fs or %gs (it does not today), or | |
662 | * if the kernel is running inside of a hypervisor layer. | |
1da177e4 | 663 | */ |
e7a2ff59 ZA |
664 | savesegment(fs, prev->fs); |
665 | savesegment(gs, prev->gs); | |
1da177e4 LT |
666 | |
667 | /* | |
e7a2ff59 | 668 | * Load the per-thread Thread-Local Storage descriptor. |
1da177e4 | 669 | */ |
e7a2ff59 | 670 | load_TLS(next, cpu); |
1da177e4 LT |
671 | |
672 | /* | |
673 | * Restore %fs and %gs if needed. | |
b339a18b LT |
674 | * |
675 | * Glibc normally makes %fs be zero, and %gs is one of | |
676 | * the TLS segments. | |
1da177e4 | 677 | */ |
b339a18b | 678 | if (unlikely(prev->fs | next->fs)) |
1da177e4 | 679 | loadsegment(fs, next->fs); |
b339a18b LT |
680 | |
681 | if (prev->gs | next->gs) | |
1da177e4 | 682 | loadsegment(gs, next->gs); |
1da177e4 | 683 | |
a5201129 ZA |
684 | /* |
685 | * Restore IOPL if needed. | |
686 | */ | |
687 | if (unlikely(prev->iopl != next->iopl)) | |
688 | set_iopl_mask(next->iopl); | |
689 | ||
1da177e4 | 690 | /* |
b3cf2576 | 691 | * Now maybe handle debug registers and/or IO bitmaps |
1da177e4 | 692 | */ |
b3cf2576 SE |
693 | if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW)) |
694 | || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) | |
695 | __switch_to_xtra(next_p, tss); | |
1da177e4 | 696 | |
ffaa8bd6 AA |
697 | disable_tsc(prev_p, next_p); |
698 | ||
1da177e4 LT |
699 | return prev_p; |
700 | } | |
701 | ||
702 | asmlinkage int sys_fork(struct pt_regs regs) | |
703 | { | |
704 | return do_fork(SIGCHLD, regs.esp, ®s, 0, NULL, NULL); | |
705 | } | |
706 | ||
707 | asmlinkage int sys_clone(struct pt_regs regs) | |
708 | { | |
709 | unsigned long clone_flags; | |
710 | unsigned long newsp; | |
711 | int __user *parent_tidptr, *child_tidptr; | |
712 | ||
713 | clone_flags = regs.ebx; | |
714 | newsp = regs.ecx; | |
715 | parent_tidptr = (int __user *)regs.edx; | |
716 | child_tidptr = (int __user *)regs.edi; | |
717 | if (!newsp) | |
718 | newsp = regs.esp; | |
719 | return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr); | |
720 | } | |
721 | ||
722 | /* | |
723 | * This is trivial, and on the face of it looks like it | |
724 | * could equally well be done in user mode. | |
725 | * | |
726 | * Not so, for quite unobvious reasons - register pressure. | |
727 | * In user mode vfork() cannot have a stack frame, and if | |
728 | * done by calling the "clone()" system call directly, you | |
729 | * do not have enough call-clobbered registers to hold all | |
730 | * the information you need. | |
731 | */ | |
732 | asmlinkage int sys_vfork(struct pt_regs regs) | |
733 | { | |
734 | return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, ®s, 0, NULL, NULL); | |
735 | } | |
736 | ||
737 | /* | |
738 | * sys_execve() executes a new program. | |
739 | */ | |
740 | asmlinkage int sys_execve(struct pt_regs regs) | |
741 | { | |
742 | int error; | |
743 | char * filename; | |
744 | ||
745 | filename = getname((char __user *) regs.ebx); | |
746 | error = PTR_ERR(filename); | |
747 | if (IS_ERR(filename)) | |
748 | goto out; | |
749 | error = do_execve(filename, | |
750 | (char __user * __user *) regs.ecx, | |
751 | (char __user * __user *) regs.edx, | |
752 | ®s); | |
753 | if (error == 0) { | |
754 | task_lock(current); | |
755 | current->ptrace &= ~PT_DTRACE; | |
756 | task_unlock(current); | |
757 | /* Make sure we don't return using sysenter.. */ | |
758 | set_thread_flag(TIF_IRET); | |
759 | } | |
760 | putname(filename); | |
761 | out: | |
762 | return error; | |
763 | } | |
764 | ||
765 | #define top_esp (THREAD_SIZE - sizeof(unsigned long)) | |
766 | #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long)) | |
767 | ||
768 | unsigned long get_wchan(struct task_struct *p) | |
769 | { | |
770 | unsigned long ebp, esp, eip; | |
771 | unsigned long stack_page; | |
772 | int count = 0; | |
773 | if (!p || p == current || p->state == TASK_RUNNING) | |
774 | return 0; | |
65e0fdff | 775 | stack_page = (unsigned long)task_stack_page(p); |
1da177e4 LT |
776 | esp = p->thread.esp; |
777 | if (!stack_page || esp < stack_page || esp > top_esp+stack_page) | |
778 | return 0; | |
779 | /* include/asm-i386/system.h:switch_to() pushes ebp last. */ | |
780 | ebp = *(unsigned long *) esp; | |
781 | do { | |
782 | if (ebp < stack_page || ebp > top_ebp+stack_page) | |
783 | return 0; | |
784 | eip = *(unsigned long *) (ebp+4); | |
785 | if (!in_sched_functions(eip)) | |
786 | return eip; | |
787 | ebp = *(unsigned long *) ebp; | |
788 | } while (count++ < 16); | |
789 | return 0; | |
790 | } | |
791 | ||
792 | /* | |
793 | * sys_alloc_thread_area: get a yet unused TLS descriptor index. | |
794 | */ | |
795 | static int get_free_idx(void) | |
796 | { | |
797 | struct thread_struct *t = ¤t->thread; | |
798 | int idx; | |
799 | ||
800 | for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++) | |
801 | if (desc_empty(t->tls_array + idx)) | |
802 | return idx + GDT_ENTRY_TLS_MIN; | |
803 | return -ESRCH; | |
804 | } | |
805 | ||
806 | /* | |
807 | * Set a given TLS descriptor: | |
808 | */ | |
809 | asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) | |
810 | { | |
811 | struct thread_struct *t = ¤t->thread; | |
812 | struct user_desc info; | |
813 | struct desc_struct *desc; | |
814 | int cpu, idx; | |
815 | ||
816 | if (copy_from_user(&info, u_info, sizeof(info))) | |
817 | return -EFAULT; | |
818 | idx = info.entry_number; | |
819 | ||
820 | /* | |
821 | * index -1 means the kernel should try to find and | |
822 | * allocate an empty descriptor: | |
823 | */ | |
824 | if (idx == -1) { | |
825 | idx = get_free_idx(); | |
826 | if (idx < 0) | |
827 | return idx; | |
828 | if (put_user(idx, &u_info->entry_number)) | |
829 | return -EFAULT; | |
830 | } | |
831 | ||
832 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
833 | return -EINVAL; | |
834 | ||
835 | desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN; | |
836 | ||
837 | /* | |
838 | * We must not get preempted while modifying the TLS. | |
839 | */ | |
840 | cpu = get_cpu(); | |
841 | ||
842 | if (LDT_empty(&info)) { | |
843 | desc->a = 0; | |
844 | desc->b = 0; | |
845 | } else { | |
846 | desc->a = LDT_entry_a(&info); | |
847 | desc->b = LDT_entry_b(&info); | |
848 | } | |
849 | load_TLS(t, cpu); | |
850 | ||
851 | put_cpu(); | |
852 | ||
853 | return 0; | |
854 | } | |
855 | ||
856 | /* | |
857 | * Get the current Thread-Local Storage area: | |
858 | */ | |
859 | ||
860 | #define GET_BASE(desc) ( \ | |
861 | (((desc)->a >> 16) & 0x0000ffff) | \ | |
862 | (((desc)->b << 16) & 0x00ff0000) | \ | |
863 | ( (desc)->b & 0xff000000) ) | |
864 | ||
865 | #define GET_LIMIT(desc) ( \ | |
866 | ((desc)->a & 0x0ffff) | \ | |
867 | ((desc)->b & 0xf0000) ) | |
868 | ||
869 | #define GET_32BIT(desc) (((desc)->b >> 22) & 1) | |
870 | #define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) | |
871 | #define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) | |
872 | #define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) | |
873 | #define GET_PRESENT(desc) (((desc)->b >> 15) & 1) | |
874 | #define GET_USEABLE(desc) (((desc)->b >> 20) & 1) | |
875 | ||
876 | asmlinkage int sys_get_thread_area(struct user_desc __user *u_info) | |
877 | { | |
878 | struct user_desc info; | |
879 | struct desc_struct *desc; | |
880 | int idx; | |
881 | ||
882 | if (get_user(idx, &u_info->entry_number)) | |
883 | return -EFAULT; | |
884 | if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) | |
885 | return -EINVAL; | |
886 | ||
71ae18ec PBG |
887 | memset(&info, 0, sizeof(info)); |
888 | ||
1da177e4 LT |
889 | desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; |
890 | ||
891 | info.entry_number = idx; | |
892 | info.base_addr = GET_BASE(desc); | |
893 | info.limit = GET_LIMIT(desc); | |
894 | info.seg_32bit = GET_32BIT(desc); | |
895 | info.contents = GET_CONTENTS(desc); | |
896 | info.read_exec_only = !GET_WRITABLE(desc); | |
897 | info.limit_in_pages = GET_LIMIT_PAGES(desc); | |
898 | info.seg_not_present = !GET_PRESENT(desc); | |
899 | info.useable = GET_USEABLE(desc); | |
900 | ||
901 | if (copy_to_user(u_info, &info, sizeof(info))) | |
902 | return -EFAULT; | |
903 | return 0; | |
904 | } | |
905 | ||
906 | unsigned long arch_align_stack(unsigned long sp) | |
907 | { | |
908 | if (randomize_va_space) | |
909 | sp -= get_random_int() % 8192; | |
910 | return sp & ~0xf; | |
911 | } |