2 * Copyright (C) 1995 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
9 * This file handles the architecture-dependent parts of process handling..
14 #include <linux/cpu.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
18 #include <linux/kernel.h>
20 #include <linux/elfcore.h>
21 #include <linux/smp.h>
22 #include <linux/stddef.h>
23 #include <linux/slab.h>
24 #include <linux/vmalloc.h>
25 #include <linux/user.h>
26 #include <linux/interrupt.h>
27 #include <linux/utsname.h>
28 #include <linux/delay.h>
29 #include <linux/reboot.h>
30 #include <linux/init.h>
31 #include <linux/mc146818rtc.h>
32 #include <linux/module.h>
33 #include <linux/kallsyms.h>
34 #include <linux/ptrace.h>
35 #include <linux/random.h>
36 #include <linux/personality.h>
37 #include <linux/tick.h>
38 #include <linux/percpu.h>
39 #include <linux/prctl.h>
40 #include <linux/dmi.h>
41 #include <linux/ftrace.h>
43 #include <asm/uaccess.h>
44 #include <asm/pgtable.h>
45 #include <asm/system.h>
48 #include <asm/processor.h>
51 #ifdef CONFIG_MATH_EMULATION
52 #include <asm/math_emu.h>
55 #include <linux/err.h>
57 #include <asm/tlbflush.h>
59 #include <asm/kdebug.h>
61 #include <asm/syscalls.h>
64 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
66 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
67 EXPORT_PER_CPU_SYMBOL(current_task);
69 DEFINE_PER_CPU(int, cpu_number);
70 EXPORT_PER_CPU_SYMBOL(cpu_number);
73 * Return saved PC of a blocked thread.
75 unsigned long thread_saved_pc(struct task_struct *tsk)
77 return ((unsigned long *)tsk->thread.sp)[3];
81 static inline void play_dead(void)
88 * The idle thread. There's no useful work to be
89 * done, so just try to conserve power and have a
90 * low exit latency (ie sit in a loop waiting for
91 * somebody to say that they'd like to reschedule)
95 int cpu = smp_processor_id();
97 current_thread_info()->status |= TS_POLLING;
99 /* endless idle loop with no priority at all */
101 tick_nohz_stop_sched_tick(1);
102 while (!need_resched()) {
107 if (rcu_pending(cpu))
108 rcu_check_callbacks(cpu, 0);
110 if (cpu_is_offline(cpu))
114 __get_cpu_var(irq_stat).idle_timestamp = jiffies;
115 /* Don't trace irqs off for idle */
116 stop_critical_timings();
118 start_critical_timings();
120 tick_nohz_restart_sched_tick();
121 preempt_enable_no_resched();
127 void __show_regs(struct pt_regs *regs, int all)
129 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
130 unsigned long d0, d1, d2, d3, d6, d7;
132 unsigned short ss, gs;
135 if (user_mode_vm(regs)) {
137 ss = regs->ss & 0xffff;
140 sp = (unsigned long) (®s->sp);
147 board = dmi_get_system_info(DMI_PRODUCT_NAME);
150 printk("Pid: %d, comm: %s %s (%s %.*s) %s\n",
151 task_pid_nr(current), current->comm,
152 print_tainted(), init_utsname()->release,
153 (int)strcspn(init_utsname()->version, " "),
154 init_utsname()->version, board);
156 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
157 (u16)regs->cs, regs->ip, regs->flags,
159 print_symbol("EIP is at %s\n", regs->ip);
161 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
162 regs->ax, regs->bx, regs->cx, regs->dx);
163 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
164 regs->si, regs->di, regs->bp, sp);
165 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
166 (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss);
174 cr4 = read_cr4_safe();
175 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
182 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
187 printk("DR6: %08lx DR7: %08lx\n",
191 void show_regs(struct pt_regs *regs)
193 __show_regs(regs, 1);
194 show_trace(NULL, regs, ®s->sp, regs->bp);
198 * This gets run with %bx containing the
199 * function to call, and %dx containing
202 extern void kernel_thread_helper(void);
205 * Create a kernel thread
207 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
211 memset(®s, 0, sizeof(regs));
213 regs.bx = (unsigned long) fn;
214 regs.dx = (unsigned long) arg;
218 regs.fs = __KERNEL_PERCPU;
220 regs.ip = (unsigned long) kernel_thread_helper;
221 regs.cs = __KERNEL_CS | get_kernel_rpl();
222 regs.flags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
224 /* Ok, create the new process.. */
225 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
227 EXPORT_SYMBOL(kernel_thread);
230 * Free current thread data structures etc..
232 void exit_thread(void)
234 /* The process may have allocated an io port bitmap... nuke it. */
235 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
236 struct task_struct *tsk = current;
237 struct thread_struct *t = &tsk->thread;
239 struct tss_struct *tss = &per_cpu(init_tss, cpu);
241 kfree(t->io_bitmap_ptr);
242 t->io_bitmap_ptr = NULL;
243 clear_thread_flag(TIF_IO_BITMAP);
245 * Careful, clear this in the TSS too:
247 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
248 t->io_bitmap_max = 0;
249 tss->io_bitmap_owner = NULL;
250 tss->io_bitmap_max = 0;
251 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
255 /* Free any BTS tracers that have not been properly released. */
256 if (unlikely(current->bts)) {
257 ds_release_bts(current->bts);
260 kfree(current->bts_buffer);
261 current->bts_buffer = NULL;
262 current->bts_size = 0;
264 #endif /* CONFIG_X86_DS */
267 void flush_thread(void)
269 struct task_struct *tsk = current;
271 tsk->thread.debugreg0 = 0;
272 tsk->thread.debugreg1 = 0;
273 tsk->thread.debugreg2 = 0;
274 tsk->thread.debugreg3 = 0;
275 tsk->thread.debugreg6 = 0;
276 tsk->thread.debugreg7 = 0;
277 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
278 clear_tsk_thread_flag(tsk, TIF_DEBUG);
280 * Forget coprocessor state..
282 tsk->fpu_counter = 0;
287 void release_thread(struct task_struct *dead_task)
289 BUG_ON(dead_task->mm);
290 release_vm86_irqs(dead_task);
294 * This gets called before we allocate a new thread and copy
295 * the current task into it.
297 void prepare_to_copy(struct task_struct *tsk)
302 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
303 unsigned long unused,
304 struct task_struct * p, struct pt_regs * regs)
306 struct pt_regs * childregs;
307 struct task_struct *tsk;
310 childregs = task_pt_regs(p);
315 p->thread.sp = (unsigned long) childregs;
316 p->thread.sp0 = (unsigned long) (childregs+1);
318 p->thread.ip = (unsigned long) ret_from_fork;
320 savesegment(gs, p->thread.gs);
323 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
324 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
325 IO_BITMAP_BYTES, GFP_KERNEL);
326 if (!p->thread.io_bitmap_ptr) {
327 p->thread.io_bitmap_max = 0;
330 set_tsk_thread_flag(p, TIF_IO_BITMAP);
336 * Set a new TLS for the child thread?
338 if (clone_flags & CLONE_SETTLS)
339 err = do_set_thread_area(p, -1,
340 (struct user_desc __user *)childregs->si, 0);
342 if (err && p->thread.io_bitmap_ptr) {
343 kfree(p->thread.io_bitmap_ptr);
344 p->thread.io_bitmap_max = 0;
350 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
352 __asm__("movl %0, %%gs" :: "r"(0));
355 regs->ds = __USER_DS;
356 regs->es = __USER_DS;
357 regs->ss = __USER_DS;
358 regs->cs = __USER_CS;
362 * Free the old FP and other extended state
364 free_thread_xstate(current);
366 EXPORT_SYMBOL_GPL(start_thread);
368 static void hard_disable_TSC(void)
370 write_cr4(read_cr4() | X86_CR4_TSD);
373 void disable_TSC(void)
376 if (!test_and_set_thread_flag(TIF_NOTSC))
378 * Must flip the CPU state synchronously with
379 * TIF_NOTSC in the current running context.
385 static void hard_enable_TSC(void)
387 write_cr4(read_cr4() & ~X86_CR4_TSD);
390 static void enable_TSC(void)
393 if (test_and_clear_thread_flag(TIF_NOTSC))
395 * Must flip the CPU state synchronously with
396 * TIF_NOTSC in the current running context.
402 int get_tsc_mode(unsigned long adr)
406 if (test_thread_flag(TIF_NOTSC))
407 val = PR_TSC_SIGSEGV;
411 return put_user(val, (unsigned int __user *)adr);
414 int set_tsc_mode(unsigned int val)
416 if (val == PR_TSC_SIGSEGV)
418 else if (val == PR_TSC_ENABLE)
427 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
428 struct tss_struct *tss)
430 struct thread_struct *prev, *next;
432 prev = &prev_p->thread;
433 next = &next_p->thread;
435 if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
436 test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
437 ds_switch_to(prev_p, next_p);
438 else if (next->debugctlmsr != prev->debugctlmsr)
439 update_debugctlmsr(next->debugctlmsr);
441 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
442 set_debugreg(next->debugreg0, 0);
443 set_debugreg(next->debugreg1, 1);
444 set_debugreg(next->debugreg2, 2);
445 set_debugreg(next->debugreg3, 3);
447 set_debugreg(next->debugreg6, 6);
448 set_debugreg(next->debugreg7, 7);
451 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
452 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
453 /* prev and next are different */
454 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
460 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
462 * Disable the bitmap via an invalid offset. We still cache
463 * the previous bitmap owner and the IO bitmap contents:
465 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
469 if (likely(next == tss->io_bitmap_owner)) {
471 * Previous owner of the bitmap (hence the bitmap content)
472 * matches the next task, we dont have to do anything but
473 * to set a valid offset in the TSS:
475 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
479 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
480 * and we let the task to get a GPF in case an I/O instruction
481 * is performed. The handler of the GPF will verify that the
482 * faulting task has a valid I/O bitmap and, it true, does the
483 * real copy and restart the instruction. This will save us
484 * redundant copies when the currently switched task does not
485 * perform any I/O during its timeslice.
487 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
491 * switch_to(x,yn) should switch tasks from x to y.
493 * We fsave/fwait so that an exception goes off at the right time
494 * (as a call from the fsave or fwait in effect) rather than to
495 * the wrong process. Lazy FP saving no longer makes any sense
496 * with modern CPU's, and this simplifies a lot of things (SMP
497 * and UP become the same).
499 * NOTE! We used to use the x86 hardware context switching. The
500 * reason for not using it any more becomes apparent when you
501 * try to recover gracefully from saved state that is no longer
502 * valid (stale segment register values in particular). With the
503 * hardware task-switch, there is no way to fix up bad state in
504 * a reasonable manner.
506 * The fact that Intel documents the hardware task-switching to
507 * be slow is a fairly red herring - this code is not noticeably
508 * faster. However, there _is_ some room for improvement here,
509 * so the performance issues may eventually be a valid point.
510 * More important, however, is the fact that this allows us much
513 * The return value (in %ax) will be the "prev" task after
514 * the task-switch, and shows up in ret_from_fork in entry.S,
517 __notrace_funcgraph struct task_struct *
518 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
520 struct thread_struct *prev = &prev_p->thread,
521 *next = &next_p->thread;
522 int cpu = smp_processor_id();
523 struct tss_struct *tss = &per_cpu(init_tss, cpu);
525 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
527 __unlazy_fpu(prev_p);
530 /* we're going to use this soon, after a few expensive things */
531 if (next_p->fpu_counter > 5)
532 prefetch(next->xstate);
540 * Save away %gs. No need to save %fs, as it was saved on the
541 * stack on entry. No need to save %es and %ds, as those are
542 * always kernel segments while inside the kernel. Doing this
543 * before setting the new TLS descriptors avoids the situation
544 * where we temporarily have non-reloadable segments in %fs
545 * and %gs. This could be an issue if the NMI handler ever
546 * used %fs or %gs (it does not today), or if the kernel is
547 * running inside of a hypervisor layer.
549 savesegment(gs, prev->gs);
552 * Load the per-thread Thread-Local Storage descriptor.
557 * Restore IOPL if needed. In normal use, the flags restore
558 * in the switch assembly will handle this. But if the kernel
559 * is running virtualized at a non-zero CPL, the popf will
560 * not restore flags, so it must be done in a separate step.
562 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
563 set_iopl_mask(next->iopl);
566 * Now maybe handle debug registers and/or IO bitmaps
568 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
569 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
570 __switch_to_xtra(prev_p, next_p, tss);
573 * Leave lazy mode, flushing any hypercalls made here.
574 * This must be done before restoring TLS segments so
575 * the GDT and LDT are properly updated, and must be
576 * done before math_state_restore, so the TS bit is up
579 arch_leave_lazy_cpu_mode();
581 /* If the task has used fpu the last 5 timeslices, just do a full
582 * restore of the math state immediately to avoid the trap; the
583 * chances of needing FPU soon are obviously high now
585 * tsk_used_math() checks prevent calling math_state_restore(),
586 * which can sleep in the case of !tsk_used_math()
588 if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
589 math_state_restore();
592 * Restore %gs if needed (which is common)
594 if (prev->gs | next->gs)
595 loadsegment(gs, next->gs);
597 x86_write_percpu(current_task, next_p);
602 asmlinkage int sys_fork(struct pt_regs regs)
604 return do_fork(SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
607 asmlinkage int sys_clone(struct pt_regs regs)
609 unsigned long clone_flags;
611 int __user *parent_tidptr, *child_tidptr;
613 clone_flags = regs.bx;
615 parent_tidptr = (int __user *)regs.dx;
616 child_tidptr = (int __user *)regs.di;
619 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
623 * This is trivial, and on the face of it looks like it
624 * could equally well be done in user mode.
626 * Not so, for quite unobvious reasons - register pressure.
627 * In user mode vfork() cannot have a stack frame, and if
628 * done by calling the "clone()" system call directly, you
629 * do not have enough call-clobbered registers to hold all
630 * the information you need.
632 asmlinkage int sys_vfork(struct pt_regs regs)
634 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
638 * sys_execve() executes a new program.
640 asmlinkage int sys_execve(struct pt_regs regs)
645 filename = getname((char __user *) regs.bx);
646 error = PTR_ERR(filename);
647 if (IS_ERR(filename))
649 error = do_execve(filename,
650 (char __user * __user *) regs.cx,
651 (char __user * __user *) regs.dx,
654 /* Make sure we don't return using sysenter.. */
655 set_thread_flag(TIF_IRET);
662 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
663 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
665 unsigned long get_wchan(struct task_struct *p)
667 unsigned long bp, sp, ip;
668 unsigned long stack_page;
670 if (!p || p == current || p->state == TASK_RUNNING)
672 stack_page = (unsigned long)task_stack_page(p);
674 if (!stack_page || sp < stack_page || sp > top_esp+stack_page)
676 /* include/asm-i386/system.h:switch_to() pushes bp last. */
677 bp = *(unsigned long *) sp;
679 if (bp < stack_page || bp > top_ebp+stack_page)
681 ip = *(unsigned long *) (bp+4);
682 if (!in_sched_functions(ip))
684 bp = *(unsigned long *) bp;
685 } while (count++ < 16);
689 unsigned long arch_align_stack(unsigned long sp)
691 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
692 sp -= get_random_int() % 8192;
696 unsigned long arch_randomize_brk(struct mm_struct *mm)
698 unsigned long range_end = mm->brk + 0x02000000;
699 return randomize_range(mm->brk, range_end, 0) ? : mm->brk;