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Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...
[linux-2.6-block.git] / arch / i386 / kernel / process.c
CommitLineData
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		 60asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
61
62static int hlt_counter;
63
64unsigned long boot_option_idle_override = 0;
65EXPORT_SYMBOL(boot_option_idle_override);
66
67/*
68 * Return saved PC of a blocked thread.
69 */
70unsigned 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 */
78void (*pm_idle)(void);
129f6946 79EXPORT_SYMBOL(pm_idle);
1da177e4
LT		 80static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
81
82void disable_hlt(void)
83{
84 hlt_counter++;
85}
86
87EXPORT_SYMBOL(disable_hlt);
88
89void enable_hlt(void)
90{
91 hlt_counter--;
92}
93
94EXPORT_SYMBOL(enable_hlt);
95
96/*
97 * We use this if we don't have any better
98 * idle routine..
99 */
100void 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
113EXPORT_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 */
121static 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. */
151static 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
168static 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 180void cpu_idle(void)
1da177e4 181{
f3705136
ZM		 182 int cpu = raw_smp_processor_id();
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 }
204 schedule();
205 }
206}
207
208void cpu_idle_wait(void)
209{
210 unsigned int cpu, this_cpu = get_cpu();
211 cpumask_t map;
212
213 set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
214 put_cpu();
215
216 cpus_clear(map);
217 for_each_online_cpu(cpu) {
218 per_cpu(cpu_idle_state, cpu) = 1;
219 cpu_set(cpu, map);
220 }
221
222 __get_cpu_var(cpu_idle_state) = 0;
223
224 wmb();
225 do {
226 ssleep(1);
227 for_each_online_cpu(cpu) {
228 if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
229 cpu_clear(cpu, map);
230 }
231 cpus_and(map, map, cpu_online_map);
232 } while (!cpus_empty(map));
233}
234EXPORT_SYMBOL_GPL(cpu_idle_wait);
235
236/*
237 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
238 * which can obviate IPI to trigger checking of need_resched.
239 * We execute MONITOR against need_resched and enter optimized wait state
240 * through MWAIT. Whenever someone changes need_resched, we would be woken
241 * up from MWAIT (without an IPI).
242 */
243static void mwait_idle(void)
244{
245 local_irq_enable();
246
247 if (!need_resched()) {
248 set_thread_flag(TIF_POLLING_NRFLAG);
249 do {
250 __monitor((void *)&current_thread_info()->flags, 0, 0);
251 if (need_resched())
252 break;
253 __mwait(0, 0);
254 } while (!need_resched());
255 clear_thread_flag(TIF_POLLING_NRFLAG);
256 }
257}
258
0bb3184d 259void __devinit select_idle_routine(const struct cpuinfo_x86 *c)
1da177e4
LT		 260{
261 if (cpu_has(c, X86_FEATURE_MWAIT)) {
262 printk("monitor/mwait feature present.\n");
263 /*
264 * Skip, if setup has overridden idle.
265 * One CPU supports mwait => All CPUs supports mwait
266 */
267 if (!pm_idle) {
268 printk("using mwait in idle threads.\n");
269 pm_idle = mwait_idle;
270 }
271 }
272}
273
274static int __init idle_setup (char *str)
275{
276 if (!strncmp(str, "poll", 4)) {
277 printk("using polling idle threads.\n");
278 pm_idle = poll_idle;
279#ifdef CONFIG_X86_SMP
280 if (smp_num_siblings > 1)
281 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
282#endif
283 } else if (!strncmp(str, "halt", 4)) {
284 printk("using halt in idle threads.\n");
285 pm_idle = default_idle;
286 }
287
288 boot_option_idle_override = 1;
289 return 1;
290}
291
292__setup("idle=", idle_setup);
293
294void show_regs(struct pt_regs * regs)
295{
296 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
297
298 printk("\n");
299 printk("Pid: %d, comm: %20s\n", current->pid, current->comm);
300 printk("EIP: %04x:[<%08lx>] CPU: %d\n",0xffff & regs->xcs,regs->eip, smp_processor_id());
301 print_symbol("EIP is at %s\n", regs->eip);
302
717b594a 303 if (user_mode(regs))
1da177e4
LT		 304 printk(" ESP: %04x:%08lx",0xffff & regs->xss,regs->esp);
305 printk(" EFLAGS: %08lx %s (%s)\n",
306 regs->eflags, print_tainted(), system_utsname.release);
307 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
308 regs->eax,regs->ebx,regs->ecx,regs->edx);
309 printk("ESI: %08lx EDI: %08lx EBP: %08lx",
310 regs->esi, regs->edi, regs->ebp);
311 printk(" DS: %04x ES: %04x\n",
312 0xffff & regs->xds,0xffff & regs->xes);
313
4bb0d3ec
ZA		 314 cr0 = read_cr0();
315 cr2 = read_cr2();
316 cr3 = read_cr3();
317 if (current_cpu_data.x86 > 4) {
318 cr4 = read_cr4();
319 }
1da177e4
LT		 320 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", cr0, cr2, cr3, cr4);
321 show_trace(NULL, &regs->esp);
322}
323
324/*
325 * This gets run with %ebx containing the
326 * function to call, and %edx containing
327 * the "args".
328 */
329extern void kernel_thread_helper(void);
330__asm__(".section .text\n"
331 ".align 4\n"
332 "kernel_thread_helper:\n\t"
333 "movl %edx,%eax\n\t"
334 "pushl %edx\n\t"
335 "call *%ebx\n\t"
336 "pushl %eax\n\t"
337 "call do_exit\n"
338 ".previous");
339
340/*
341 * Create a kernel thread
342 */
343int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
344{
345 struct pt_regs regs;
346
347 memset(&regs, 0, sizeof(regs));
348
349 regs.ebx = (unsigned long) fn;
350 regs.edx = (unsigned long) arg;
351
352 regs.xds = __USER_DS;
353 regs.xes = __USER_DS;
354 regs.orig_eax = -1;
355 regs.eip = (unsigned long) kernel_thread_helper;
356 regs.xcs = __KERNEL_CS;
357 regs.eflags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
358
359 /* Ok, create the new process.. */
360 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
361}
129f6946 362EXPORT_SYMBOL(kernel_thread);
1da177e4
LT		 363
364/*
365 * Free current thread data structures etc..
366 */
367void exit_thread(void)
368{
369 struct task_struct *tsk = current;
370 struct thread_struct *t = &tsk->thread;
371
b94cce92
HN		 372 /*
373 * Remove function-return probe instances associated with this task
374 * and put them back on the free list. Do not insert an exit probe for
375 * this function, it will be disabled by kprobe_flush_task if you do.
376 */
377 kprobe_flush_task(tsk);
378
1da177e4
LT		 379 /* The process may have allocated an io port bitmap... nuke it. */
380 if (unlikely(NULL != t->io_bitmap_ptr)) {
381 int cpu = get_cpu();
382 struct tss_struct *tss = &per_cpu(init_tss, cpu);
383
384 kfree(t->io_bitmap_ptr);
385 t->io_bitmap_ptr = NULL;
386 /*
387 * Careful, clear this in the TSS too:
388 */
389 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
390 t->io_bitmap_max = 0;
391 tss->io_bitmap_owner = NULL;
392 tss->io_bitmap_max = 0;
393 tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
394 put_cpu();
395 }
396}
397
398void flush_thread(void)
399{
400 struct task_struct *tsk = current;
401
b94cce92
HN		 402 /*
403 * Remove function-return probe instances associated with this task
404 * and put them back on the free list. Do not insert an exit probe for
405 * this function, it will be disabled by kprobe_flush_task if you do.
406 */
407 kprobe_flush_task(tsk);
408
1da177e4
LT		 409 memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8);
410 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
411 /*
412 * Forget coprocessor state..
413 */
414 clear_fpu(tsk);
415 clear_used_math();
416}
417
418void release_thread(struct task_struct *dead_task)
419{
420 if (dead_task->mm) {
421 // temporary debugging check
422 if (dead_task->mm->context.size) {
423 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
424 dead_task->comm,
425 dead_task->mm->context.ldt,
426 dead_task->mm->context.size);
427 BUG();
428 }
429 }
430
431 release_vm86_irqs(dead_task);
432}
433
434/*
435 * This gets called before we allocate a new thread and copy
436 * the current task into it.
437 */
438void prepare_to_copy(struct task_struct *tsk)
439{
440 unlazy_fpu(tsk);
441}
442
443int copy_thread(int nr, unsigned long clone_flags, unsigned long esp,
444 unsigned long unused,
445 struct task_struct * p, struct pt_regs * regs)
446{
447 struct pt_regs * childregs;
448 struct task_struct *tsk;
449 int err;
450
451 childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
5df24082
SS		 452 /*
453 * The below -8 is to reserve 8 bytes on top of the ring0 stack.
454 * This is necessary to guarantee that the entire "struct pt_regs"
455 * is accessable even if the CPU haven't stored the SS/ESP registers
456 * on the stack (interrupt gate does not save these registers
457 * when switching to the same priv ring).
458 * Therefore beware: accessing the xss/esp fields of the
459 * "struct pt_regs" is possible, but they may contain the
460 * completely wrong values.
461 */
f48d9663
AN		 462 childregs = (struct pt_regs *) ((unsigned long) childregs - 8);
463 *childregs = *regs;
464 childregs->eax = 0;
465 childregs->esp = esp;
466
467 p->thread.esp = (unsigned long) childregs;
468 p->thread.esp0 = (unsigned long) (childregs+1);
1da177e4
LT		 469
470 p->thread.eip = (unsigned long) ret_from_fork;
471
472 savesegment(fs,p->thread.fs);
473 savesegment(gs,p->thread.gs);
474
475 tsk = current;
476 if (unlikely(NULL != tsk->thread.io_bitmap_ptr)) {
477 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
478 if (!p->thread.io_bitmap_ptr) {
479 p->thread.io_bitmap_max = 0;
480 return -ENOMEM;
481 }
482 memcpy(p->thread.io_bitmap_ptr, tsk->thread.io_bitmap_ptr,
483 IO_BITMAP_BYTES);
484 }
485
486 /*
487 * Set a new TLS for the child thread?
488 */
489 if (clone_flags & CLONE_SETTLS) {
490 struct desc_struct *desc;
491 struct user_desc info;
492 int idx;
493
494 err = -EFAULT;
495 if (copy_from_user(&info, (void __user *)childregs->esi, sizeof(info)))
496 goto out;
497 err = -EINVAL;
498 if (LDT_empty(&info))
499 goto out;
500
501 idx = info.entry_number;
502 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
503 goto out;
504
505 desc = p->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
506 desc->a = LDT_entry_a(&info);
507 desc->b = LDT_entry_b(&info);
508 }
509
510 err = 0;
511 out:
512 if (err && p->thread.io_bitmap_ptr) {
513 kfree(p->thread.io_bitmap_ptr);
514 p->thread.io_bitmap_max = 0;
515 }
516 return err;
517}
518
519/*
520 * fill in the user structure for a core dump..
521 */
522void dump_thread(struct pt_regs * regs, struct user * dump)
523{
524 int i;
525
526/* changed the size calculations - should hopefully work better. lbt */
527 dump->magic = CMAGIC;
528 dump->start_code = 0;
529 dump->start_stack = regs->esp & ~(PAGE_SIZE - 1);
530 dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
531 dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
532 dump->u_dsize -= dump->u_tsize;
533 dump->u_ssize = 0;
534 for (i = 0; i < 8; i++)
535 dump->u_debugreg[i] = current->thread.debugreg[i];
536
537 if (dump->start_stack < TASK_SIZE)
538 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
539
540 dump->regs.ebx = regs->ebx;
541 dump->regs.ecx = regs->ecx;
542 dump->regs.edx = regs->edx;
543 dump->regs.esi = regs->esi;
544 dump->regs.edi = regs->edi;
545 dump->regs.ebp = regs->ebp;
546 dump->regs.eax = regs->eax;
547 dump->regs.ds = regs->xds;
548 dump->regs.es = regs->xes;
549 savesegment(fs,dump->regs.fs);
550 savesegment(gs,dump->regs.gs);
551 dump->regs.orig_eax = regs->orig_eax;
552 dump->regs.eip = regs->eip;
553 dump->regs.cs = regs->xcs;
554 dump->regs.eflags = regs->eflags;
555 dump->regs.esp = regs->esp;
556 dump->regs.ss = regs->xss;
557
558 dump->u_fpvalid = dump_fpu (regs, &dump->i387);
559}
129f6946 560EXPORT_SYMBOL(dump_thread);
1da177e4
LT		 561
562/*
563 * Capture the user space registers if the task is not running (in user space)
564 */
565int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
566{
567 struct pt_regs ptregs;
568
569 ptregs = *(struct pt_regs *)
570 ((unsigned long)tsk->thread_info+THREAD_SIZE - sizeof(ptregs));
571 ptregs.xcs &= 0xffff;
572 ptregs.xds &= 0xffff;
573 ptregs.xes &= 0xffff;
574 ptregs.xss &= 0xffff;
575
576 elf_core_copy_regs(regs, &ptregs);
577
578 return 1;
579}
580
581static inline void
582handle_io_bitmap(struct thread_struct *next, struct tss_struct *tss)
583{
584 if (!next->io_bitmap_ptr) {
585 /*
586 * Disable the bitmap via an invalid offset. We still cache
587 * the previous bitmap owner and the IO bitmap contents:
588 */
589 tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
590 return;
591 }
592 if (likely(next == tss->io_bitmap_owner)) {
593 /*
594 * Previous owner of the bitmap (hence the bitmap content)
595 * matches the next task, we dont have to do anything but
596 * to set a valid offset in the TSS:
597 */
598 tss->io_bitmap_base = IO_BITMAP_OFFSET;
599 return;
600 }
601 /*
602 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
603 * and we let the task to get a GPF in case an I/O instruction
604 * is performed. The handler of the GPF will verify that the
605 * faulting task has a valid I/O bitmap and, it true, does the
606 * real copy and restart the instruction. This will save us
607 * redundant copies when the currently switched task does not
608 * perform any I/O during its timeslice.
609 */
610 tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
611}
1da177e4 612
ffaa8bd6
AA		 613/*
614 * This function selects if the context switch from prev to next
615 * has to tweak the TSC disable bit in the cr4.
616 */
617static inline void disable_tsc(struct task_struct *prev_p,
618 struct task_struct *next_p)
619{
620 struct thread_info *prev, *next;
621
622 /*
623 * gcc should eliminate the ->thread_info dereference if
624 * has_secure_computing returns 0 at compile time (SECCOMP=n).
625 */
626 prev = prev_p->thread_info;
627 next = next_p->thread_info;
628
629 if (has_secure_computing(prev) || has_secure_computing(next)) {
630 /* slow path here */
631 if (has_secure_computing(prev) &&
632 !has_secure_computing(next)) {
633 write_cr4(read_cr4() & ~X86_CR4_TSD);
634 } else if (!has_secure_computing(prev) &&
635 has_secure_computing(next))
636 write_cr4(read_cr4() | X86_CR4_TSD);
637 }
638}
639
1da177e4
LT		 640/*
641 * switch_to(x,yn) should switch tasks from x to y.
642 *
643 * We fsave/fwait so that an exception goes off at the right time
644 * (as a call from the fsave or fwait in effect) rather than to
645 * the wrong process. Lazy FP saving no longer makes any sense
646 * with modern CPU's, and this simplifies a lot of things (SMP
647 * and UP become the same).
648 *
649 * NOTE! We used to use the x86 hardware context switching. The
650 * reason for not using it any more becomes apparent when you
651 * try to recover gracefully from saved state that is no longer
652 * valid (stale segment register values in particular). With the
653 * hardware task-switch, there is no way to fix up bad state in
654 * a reasonable manner.
655 *
656 * The fact that Intel documents the hardware task-switching to
657 * be slow is a fairly red herring - this code is not noticeably
658 * faster. However, there _is_ some room for improvement here,
659 * so the performance issues may eventually be a valid point.
660 * More important, however, is the fact that this allows us much
661 * more flexibility.
662 *
663 * The return value (in %eax) will be the "prev" task after
664 * the task-switch, and shows up in ret_from_fork in entry.S,
665 * for example.
666 */
667struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
668{
669 struct thread_struct *prev = &prev_p->thread,
670 *next = &next_p->thread;
671 int cpu = smp_processor_id();
672 struct tss_struct *tss = &per_cpu(init_tss, cpu);
673
674 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
675
676 __unlazy_fpu(prev_p);
677
678 /*
e7a2ff59 679 * Reload esp0.
1da177e4
LT		 680 */
681 load_esp0(tss, next);
682
683 /*
e7a2ff59
ZA		 684 * Save away %fs and %gs. No need to save %es and %ds, as
685 * those are always kernel segments while inside the kernel.
686 * Doing this before setting the new TLS descriptors avoids
687 * the situation where we temporarily have non-reloadable
688 * segments in %fs and %gs. This could be an issue if the
689 * NMI handler ever used %fs or %gs (it does not today), or
690 * if the kernel is running inside of a hypervisor layer.
1da177e4 691 */
e7a2ff59
ZA		 692 savesegment(fs, prev->fs);
693 savesegment(gs, prev->gs);
1da177e4
LT		 694
695 /*
e7a2ff59 696 * Load the per-thread Thread-Local Storage descriptor.
1da177e4 697 */
e7a2ff59 698 load_TLS(next, cpu);
1da177e4
LT		 699
700 /*
701 * Restore %fs and %gs if needed.
b339a18b
LT		 702 *
703 * Glibc normally makes %fs be zero, and %gs is one of
704 * the TLS segments.
1da177e4 705 */
b339a18b 706 if (unlikely(prev->fs | next->fs))
1da177e4 707 loadsegment(fs, next->fs);
b339a18b
LT		 708
709 if (prev->gs | next->gs)
1da177e4 710 loadsegment(gs, next->gs);
1da177e4 711
a5201129
ZA		 712 /*
713 * Restore IOPL if needed.
714 */
715 if (unlikely(prev->iopl != next->iopl))
716 set_iopl_mask(next->iopl);
717
1da177e4
LT		 718 /*
719 * Now maybe reload the debug registers
720 */
721 if (unlikely(next->debugreg[7])) {
b339a18b
LT		 722 set_debugreg(next->debugreg[0], 0);
723 set_debugreg(next->debugreg[1], 1);
724 set_debugreg(next->debugreg[2], 2);
725 set_debugreg(next->debugreg[3], 3);
1da177e4 726 /* no 4 and 5 */
b339a18b
LT		 727 set_debugreg(next->debugreg[6], 6);
728 set_debugreg(next->debugreg[7], 7);
1da177e4
LT		 729 }
730
731 if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr))
732 handle_io_bitmap(next, tss);
733
ffaa8bd6
AA		 734 disable_tsc(prev_p, next_p);
735
1da177e4
LT		 736 return prev_p;
737}
738
739asmlinkage int sys_fork(struct pt_regs regs)
740{
741 return do_fork(SIGCHLD, regs.esp, &regs, 0, NULL, NULL);
742}
743
744asmlinkage int sys_clone(struct pt_regs regs)
745{
746 unsigned long clone_flags;
747 unsigned long newsp;
748 int __user *parent_tidptr, *child_tidptr;
749
750 clone_flags = regs.ebx;
751 newsp = regs.ecx;
752 parent_tidptr = (int __user *)regs.edx;
753 child_tidptr = (int __user *)regs.edi;
754 if (!newsp)
755 newsp = regs.esp;
756 return do_fork(clone_flags, newsp, &regs, 0, parent_tidptr, child_tidptr);
757}
758
759/*
760 * This is trivial, and on the face of it looks like it
761 * could equally well be done in user mode.
762 *
763 * Not so, for quite unobvious reasons - register pressure.
764 * In user mode vfork() cannot have a stack frame, and if
765 * done by calling the "clone()" system call directly, you
766 * do not have enough call-clobbered registers to hold all
767 * the information you need.
768 */
769asmlinkage int sys_vfork(struct pt_regs regs)
770{
771 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.esp, &regs, 0, NULL, NULL);
772}
773
774/*
775 * sys_execve() executes a new program.
776 */
777asmlinkage int sys_execve(struct pt_regs regs)
778{
779 int error;
780 char * filename;
781
782 filename = getname((char __user *) regs.ebx);
783 error = PTR_ERR(filename);
784 if (IS_ERR(filename))
785 goto out;
786 error = do_execve(filename,
787 (char __user * __user *) regs.ecx,
788 (char __user * __user *) regs.edx,
789 &regs);
790 if (error == 0) {
791 task_lock(current);
792 current->ptrace &= ~PT_DTRACE;
793 task_unlock(current);
794 /* Make sure we don't return using sysenter.. */
795 set_thread_flag(TIF_IRET);
796 }
797 putname(filename);
798out:
799 return error;
800}
801
802#define top_esp (THREAD_SIZE - sizeof(unsigned long))
803#define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
804
805unsigned long get_wchan(struct task_struct *p)
806{
807 unsigned long ebp, esp, eip;
808 unsigned long stack_page;
809 int count = 0;
810 if (!p || p == current || p->state == TASK_RUNNING)
811 return 0;
812 stack_page = (unsigned long)p->thread_info;
813 esp = p->thread.esp;
814 if (!stack_page || esp < stack_page || esp > top_esp+stack_page)
815 return 0;
816 /* include/asm-i386/system.h:switch_to() pushes ebp last. */
817 ebp = *(unsigned long *) esp;
818 do {
819 if (ebp < stack_page || ebp > top_ebp+stack_page)
820 return 0;
821 eip = *(unsigned long *) (ebp+4);
822 if (!in_sched_functions(eip))
823 return eip;
824 ebp = *(unsigned long *) ebp;
825 } while (count++ < 16);
826 return 0;
827}
129f6946 828EXPORT_SYMBOL(get_wchan);
1da177e4
LT		 829
830/*
831 * sys_alloc_thread_area: get a yet unused TLS descriptor index.
832 */
833static int get_free_idx(void)
834{
835 struct thread_struct *t = &current->thread;
836 int idx;
837
838 for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
839 if (desc_empty(t->tls_array + idx))
840 return idx + GDT_ENTRY_TLS_MIN;
841 return -ESRCH;
842}
843
844/*
845 * Set a given TLS descriptor:
846 */
847asmlinkage int sys_set_thread_area(struct user_desc __user *u_info)
848{
849 struct thread_struct *t = &current->thread;
850 struct user_desc info;
851 struct desc_struct *desc;
852 int cpu, idx;
853
854 if (copy_from_user(&info, u_info, sizeof(info)))
855 return -EFAULT;
856 idx = info.entry_number;
857
858 /*
859 * index -1 means the kernel should try to find and
860 * allocate an empty descriptor:
861 */
862 if (idx == -1) {
863 idx = get_free_idx();
864 if (idx < 0)
865 return idx;
866 if (put_user(idx, &u_info->entry_number))
867 return -EFAULT;
868 }
869
870 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
871 return -EINVAL;
872
873 desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN;
874
875 /*
876 * We must not get preempted while modifying the TLS.
877 */
878 cpu = get_cpu();
879
880 if (LDT_empty(&info)) {
881 desc->a = 0;
882 desc->b = 0;
883 } else {
884 desc->a = LDT_entry_a(&info);
885 desc->b = LDT_entry_b(&info);
886 }
887 load_TLS(t, cpu);
888
889 put_cpu();
890
891 return 0;
892}
893
894/*
895 * Get the current Thread-Local Storage area:
896 */
897
898#define GET_BASE(desc) ( \
899 (((desc)->a >> 16) & 0x0000ffff) | \
900 (((desc)->b << 16) & 0x00ff0000) | \
901 ( (desc)->b & 0xff000000) )
902
903#define GET_LIMIT(desc) ( \
904 ((desc)->a & 0x0ffff) | \
905 ((desc)->b & 0xf0000) )
906
907#define GET_32BIT(desc) (((desc)->b >> 22) & 1)
908#define GET_CONTENTS(desc) (((desc)->b >> 10) & 3)
909#define GET_WRITABLE(desc) (((desc)->b >> 9) & 1)
910#define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1)
911#define GET_PRESENT(desc) (((desc)->b >> 15) & 1)
912#define GET_USEABLE(desc) (((desc)->b >> 20) & 1)
913
914asmlinkage int sys_get_thread_area(struct user_desc __user *u_info)
915{
916 struct user_desc info;
917 struct desc_struct *desc;
918 int idx;
919
920 if (get_user(idx, &u_info->entry_number))
921 return -EFAULT;
922 if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
923 return -EINVAL;
924
71ae18ec
B		 925 memset(&info, 0, sizeof(info));
926
1da177e4
LT		 927 desc = current->thread.tls_array + idx - GDT_ENTRY_TLS_MIN;
928
929 info.entry_number = idx;
930 info.base_addr = GET_BASE(desc);
931 info.limit = GET_LIMIT(desc);
932 info.seg_32bit = GET_32BIT(desc);
933 info.contents = GET_CONTENTS(desc);
934 info.read_exec_only = !GET_WRITABLE(desc);
935 info.limit_in_pages = GET_LIMIT_PAGES(desc);
936 info.seg_not_present = !GET_PRESENT(desc);
937 info.useable = GET_USEABLE(desc);
938
939 if (copy_to_user(u_info, &info, sizeof(info)))
940 return -EFAULT;
941 return 0;
942}
943
944unsigned long arch_align_stack(unsigned long sp)
945{
946 if (randomize_va_space)
947 sp -= get_random_int() % 8192;
948 return sp & ~0xf;
949}
Linux 6.x block layer and io_uring tree(s)