2 * Copyright (C) 1995 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
10 * CPU hotplug support - ashok.raj@intel.com
14 * This file handles the architecture-dependent parts of process handling..
17 #include <linux/cpu.h>
18 #include <linux/errno.h>
19 #include <linux/sched.h>
21 #include <linux/kernel.h>
23 #include <linux/elfcore.h>
24 #include <linux/smp.h>
25 #include <linux/slab.h>
26 #include <linux/user.h>
27 #include <linux/interrupt.h>
28 #include <linux/delay.h>
29 #include <linux/module.h>
30 #include <linux/ptrace.h>
31 #include <linux/notifier.h>
32 #include <linux/kprobes.h>
33 #include <linux/kdebug.h>
34 #include <linux/prctl.h>
35 #include <linux/uaccess.h>
37 #include <linux/ftrace.h>
39 #include <asm/pgtable.h>
40 #include <asm/processor.h>
42 #include <asm/fpu-internal.h>
43 #include <asm/mmu_context.h>
44 #include <asm/prctl.h>
46 #include <asm/proto.h>
49 #include <asm/syscalls.h>
50 #include <asm/debugreg.h>
51 #include <asm/switch_to.h>
53 asmlinkage extern void ret_from_fork(void);
55 __visible DEFINE_PER_CPU(unsigned long, old_rsp);
57 /* Prints also some state that isn't saved in the pt_regs */
58 void __show_regs(struct pt_regs *regs, int all)
60 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
61 unsigned long d0, d1, d2, d3, d6, d7;
62 unsigned int fsindex, gsindex;
63 unsigned int ds, cs, es;
65 printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
66 printk_address(regs->ip);
67 printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss,
68 regs->sp, regs->flags);
69 printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",
70 regs->ax, regs->bx, regs->cx);
71 printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n",
72 regs->dx, regs->si, regs->di);
73 printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n",
74 regs->bp, regs->r8, regs->r9);
75 printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n",
76 regs->r10, regs->r11, regs->r12);
77 printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n",
78 regs->r13, regs->r14, regs->r15);
80 asm("movl %%ds,%0" : "=r" (ds));
81 asm("movl %%cs,%0" : "=r" (cs));
82 asm("movl %%es,%0" : "=r" (es));
83 asm("movl %%fs,%0" : "=r" (fsindex));
84 asm("movl %%gs,%0" : "=r" (gsindex));
86 rdmsrl(MSR_FS_BASE, fs);
87 rdmsrl(MSR_GS_BASE, gs);
88 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
98 printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
99 fs, fsindex, gs, gsindex, shadowgs);
100 printk(KERN_DEFAULT "CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds,
102 printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3,
112 /* Only print out debug registers if they are in their non-default state. */
113 if ((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) &&
114 (d6 == DR6_RESERVED) && (d7 == 0x400))
117 printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
118 printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
122 void release_thread(struct task_struct *dead_task)
125 if (dead_task->mm->context.size) {
126 pr_warn("WARNING: dead process %s still has LDT? <%p/%d>\n",
128 dead_task->mm->context.ldt,
129 dead_task->mm->context.size);
135 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
137 struct user_desc ud = {
144 struct desc_struct *desc = t->thread.tls_array;
149 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
151 return get_desc_base(&t->thread.tls_array[tls]);
154 int copy_thread(unsigned long clone_flags, unsigned long sp,
155 unsigned long arg, struct task_struct *p)
158 struct pt_regs *childregs;
159 struct task_struct *me = current;
161 p->thread.sp0 = (unsigned long)task_stack_page(p) + THREAD_SIZE;
162 childregs = task_pt_regs(p);
163 p->thread.sp = (unsigned long) childregs;
164 p->thread.usersp = me->thread.usersp;
165 set_tsk_thread_flag(p, TIF_FORK);
166 p->thread.io_bitmap_ptr = NULL;
168 savesegment(gs, p->thread.gsindex);
169 p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs;
170 savesegment(fs, p->thread.fsindex);
171 p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
172 savesegment(es, p->thread.es);
173 savesegment(ds, p->thread.ds);
174 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
176 if (unlikely(p->flags & PF_KTHREAD)) {
178 memset(childregs, 0, sizeof(struct pt_regs));
179 childregs->sp = (unsigned long)childregs;
180 childregs->ss = __KERNEL_DS;
181 childregs->bx = sp; /* function */
183 childregs->orig_ax = -1;
184 childregs->cs = __KERNEL_CS | get_kernel_rpl();
185 childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;
188 *childregs = *current_pt_regs();
195 if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
196 p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
197 IO_BITMAP_BYTES, GFP_KERNEL);
198 if (!p->thread.io_bitmap_ptr) {
199 p->thread.io_bitmap_max = 0;
202 set_tsk_thread_flag(p, TIF_IO_BITMAP);
206 * Set a new TLS for the child thread?
208 if (clone_flags & CLONE_SETTLS) {
209 #ifdef CONFIG_IA32_EMULATION
210 if (test_thread_flag(TIF_IA32))
211 err = do_set_thread_area(p, -1,
212 (struct user_desc __user *)childregs->si, 0);
215 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
221 if (err && p->thread.io_bitmap_ptr) {
222 kfree(p->thread.io_bitmap_ptr);
223 p->thread.io_bitmap_max = 0;
230 start_thread_common(struct pt_regs *regs, unsigned long new_ip,
231 unsigned long new_sp,
232 unsigned int _cs, unsigned int _ss, unsigned int _ds)
235 loadsegment(es, _ds);
236 loadsegment(ds, _ds);
238 current->thread.usersp = new_sp;
241 this_cpu_write(old_rsp, new_sp);
244 regs->flags = X86_EFLAGS_IF;
248 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
250 start_thread_common(regs, new_ip, new_sp,
251 __USER_CS, __USER_DS, 0);
254 #ifdef CONFIG_IA32_EMULATION
255 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp)
257 start_thread_common(regs, new_ip, new_sp,
258 test_thread_flag(TIF_X32)
259 ? __USER_CS : __USER32_CS,
260 __USER_DS, __USER_DS);
265 * switch_to(x,y) should switch tasks from x to y.
267 * This could still be optimized:
268 * - fold all the options into a flag word and test it with a single test.
269 * - could test fs/gs bitsliced
271 * Kprobes not supported here. Set the probe on schedule instead.
272 * Function graph tracer not supported too.
274 __visible __notrace_funcgraph struct task_struct *
275 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
277 struct thread_struct *prev = &prev_p->thread;
278 struct thread_struct *next = &next_p->thread;
279 int cpu = smp_processor_id();
280 struct tss_struct *tss = &per_cpu(init_tss, cpu);
281 unsigned fsindex, gsindex;
284 fpu = switch_fpu_prepare(prev_p, next_p, cpu);
286 /* Reload esp0 and ss1. */
289 /* We must save %fs and %gs before load_TLS() because
290 * %fs and %gs may be cleared by load_TLS().
292 * (e.g. xen_load_tls())
294 savesegment(fs, fsindex);
295 savesegment(gs, gsindex);
298 * Load TLS before restoring any segments so that segment loads
299 * reference the correct GDT entries.
304 * Leave lazy mode, flushing any hypercalls made here. This
305 * must be done after loading TLS entries in the GDT but before
306 * loading segments that might reference them, and and it must
307 * be done before math_state_restore, so the TS bit is up to
310 arch_end_context_switch(next_p);
314 * Reading them only returns the selectors, but writing them (if
315 * nonzero) loads the full descriptor from the GDT or LDT. The
316 * LDT for next is loaded in switch_mm, and the GDT is loaded
319 * We therefore need to write new values to the segment
320 * registers on every context switch unless both the new and old
323 * Note that we don't need to do anything for CS and SS, as
324 * those are saved and restored as part of pt_regs.
326 savesegment(es, prev->es);
327 if (unlikely(next->es | prev->es))
328 loadsegment(es, next->es);
330 savesegment(ds, prev->ds);
331 if (unlikely(next->ds | prev->ds))
332 loadsegment(ds, next->ds);
337 * These are even more complicated than FS and GS: they have
338 * 64-bit bases are that controlled by arch_prctl. Those bases
339 * only differ from the values in the GDT or LDT if the selector
342 * Loading the segment register resets the hidden base part of
343 * the register to 0 or the value from the GDT / LDT. If the
344 * next base address zero, writing 0 to the segment register is
345 * much faster than using wrmsr to explicitly zero the base.
347 * The thread_struct.fs and thread_struct.gs values are 0
348 * if the fs and gs bases respectively are not overridden
349 * from the values implied by fsindex and gsindex. They
350 * are nonzero, and store the nonzero base addresses, if
351 * the bases are overridden.
353 * (fs != 0 && fsindex != 0) || (gs != 0 && gsindex != 0) should
356 * Therefore we need to reload the segment registers if either
357 * the old or new selector is nonzero, and we need to override
358 * the base address if next thread expects it to be overridden.
360 * This code is unnecessarily slow in the case where the old and
361 * new indexes are zero and the new base is nonzero -- it will
362 * unnecessarily write 0 to the selector before writing the new
365 * Note: This all depends on arch_prctl being the only way that
366 * user code can override the segment base. Once wrfsbase and
367 * wrgsbase are enabled, most of this code will need to change.
369 if (unlikely(fsindex | next->fsindex | prev->fs)) {
370 loadsegment(fs, next->fsindex);
373 * If user code wrote a nonzero value to FS, then it also
374 * cleared the overridden base address.
376 * XXX: if user code wrote 0 to FS and cleared the base
377 * address itself, we won't notice and we'll incorrectly
378 * restore the prior base address next time we reschdule
385 wrmsrl(MSR_FS_BASE, next->fs);
386 prev->fsindex = fsindex;
388 if (unlikely(gsindex | next->gsindex | prev->gs)) {
389 load_gs_index(next->gsindex);
391 /* This works (and fails) the same way as fsindex above. */
396 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
397 prev->gsindex = gsindex;
399 switch_fpu_finish(next_p, fpu);
402 * Switch the PDA and FPU contexts.
404 prev->usersp = this_cpu_read(old_rsp);
405 this_cpu_write(old_rsp, next->usersp);
406 this_cpu_write(current_task, next_p);
409 * If it were not for PREEMPT_ACTIVE we could guarantee that the
410 * preempt_count of all tasks was equal here and this would not be
413 task_thread_info(prev_p)->saved_preempt_count = this_cpu_read(__preempt_count);
414 this_cpu_write(__preempt_count, task_thread_info(next_p)->saved_preempt_count);
416 this_cpu_write(kernel_stack,
417 (unsigned long)task_stack_page(next_p) +
418 THREAD_SIZE - KERNEL_STACK_OFFSET);
421 * Now maybe reload the debug registers and handle I/O bitmaps
423 if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
424 task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
425 __switch_to_xtra(prev_p, next_p, tss);
430 void set_personality_64bit(void)
432 /* inherit personality from parent */
434 /* Make sure to be in 64bit mode */
435 clear_thread_flag(TIF_IA32);
436 clear_thread_flag(TIF_ADDR32);
437 clear_thread_flag(TIF_X32);
439 /* Ensure the corresponding mm is not marked. */
441 current->mm->context.ia32_compat = 0;
443 /* TBD: overwrites user setup. Should have two bits.
444 But 64bit processes have always behaved this way,
445 so it's not too bad. The main problem is just that
446 32bit childs are affected again. */
447 current->personality &= ~READ_IMPLIES_EXEC;
450 void set_personality_ia32(bool x32)
452 /* inherit personality from parent */
454 /* Make sure to be in 32bit mode */
455 set_thread_flag(TIF_ADDR32);
457 /* Mark the associated mm as containing 32-bit tasks. */
459 clear_thread_flag(TIF_IA32);
460 set_thread_flag(TIF_X32);
462 current->mm->context.ia32_compat = TIF_X32;
463 current->personality &= ~READ_IMPLIES_EXEC;
464 /* is_compat_task() uses the presence of the x32
465 syscall bit flag to determine compat status */
466 current_thread_info()->status &= ~TS_COMPAT;
468 set_thread_flag(TIF_IA32);
469 clear_thread_flag(TIF_X32);
471 current->mm->context.ia32_compat = TIF_IA32;
472 current->personality |= force_personality32;
473 /* Prepare the first "return" to user space */
474 current_thread_info()->status |= TS_COMPAT;
477 EXPORT_SYMBOL_GPL(set_personality_ia32);
479 unsigned long get_wchan(struct task_struct *p)
485 if (!p || p == current || p->state == TASK_RUNNING)
487 stack = (unsigned long)task_stack_page(p);
488 if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
490 fp = *(u64 *)(p->thread.sp);
492 if (fp < (unsigned long)stack ||
493 fp >= (unsigned long)stack+THREAD_SIZE)
496 if (!in_sched_functions(ip))
499 } while (count++ < 16);
503 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
506 int doit = task == current;
511 if (addr >= TASK_SIZE_OF(task))
514 /* handle small bases via the GDT because that's faster to
516 if (addr <= 0xffffffff) {
517 set_32bit_tls(task, GS_TLS, addr);
519 load_TLS(&task->thread, cpu);
520 load_gs_index(GS_TLS_SEL);
522 task->thread.gsindex = GS_TLS_SEL;
525 task->thread.gsindex = 0;
526 task->thread.gs = addr;
529 ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, addr);
535 /* Not strictly needed for fs, but do it for symmetry
537 if (addr >= TASK_SIZE_OF(task))
540 /* handle small bases via the GDT because that's faster to
542 if (addr <= 0xffffffff) {
543 set_32bit_tls(task, FS_TLS, addr);
545 load_TLS(&task->thread, cpu);
546 loadsegment(fs, FS_TLS_SEL);
548 task->thread.fsindex = FS_TLS_SEL;
551 task->thread.fsindex = 0;
552 task->thread.fs = addr;
554 /* set the selector to 0 to not confuse
557 ret = wrmsrl_safe(MSR_FS_BASE, addr);
564 if (task->thread.fsindex == FS_TLS_SEL)
565 base = read_32bit_tls(task, FS_TLS);
567 rdmsrl(MSR_FS_BASE, base);
569 base = task->thread.fs;
570 ret = put_user(base, (unsigned long __user *)addr);
576 if (task->thread.gsindex == GS_TLS_SEL)
577 base = read_32bit_tls(task, GS_TLS);
579 savesegment(gs, gsindex);
581 rdmsrl(MSR_KERNEL_GS_BASE, base);
583 base = task->thread.gs;
585 base = task->thread.gs;
586 ret = put_user(base, (unsigned long __user *)addr);
598 long sys_arch_prctl(int code, unsigned long addr)
600 return do_arch_prctl(current, code, addr);
603 unsigned long KSTK_ESP(struct task_struct *task)
605 return (test_tsk_thread_flag(task, TIF_IA32)) ?
606 (task_pt_regs(task)->sp) : ((task)->thread.usersp);