arch/x86_64/kernel/process.c

   1 /*
   2  *  linux/arch/x86-64/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  *  X86-64 port
  10  *      Andi Kleen.
  11  *
  12  *  $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
  13  */
  14
  15 /*
  16  * This file handles the architecture-dependent parts of process handling..
  17  */
  18
  19 #include <stdarg.h>
  20
  21 #include <linux/errno.h>
  22 #include <linux/sched.h>
  23 #include <linux/kernel.h>
  24 #include <linux/mm.h>
  25 #include <linux/elfcore.h>
  26 #include <linux/smp.h>
  27 #include <linux/slab.h>
  28 #include <linux/user.h>
  29 #include <linux/module.h>
  30 #include <linux/a.out.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/delay.h>
  33 #include <linux/irq.h>
  34 #include <linux/ptrace.h>
  35 #include <linux/utsname.h>
  36 #include <linux/random.h>
  37
  38 #include <asm/uaccess.h>
  39 #include <asm/pgtable.h>
  40 #include <asm/system.h>
  41 #include <asm/io.h>
  42 #include <asm/processor.h>
  43 #include <asm/i387.h>
  44 #include <asm/mmu_context.h>
  45 #include <asm/pda.h>
  46 #include <asm/prctl.h>
  47 #include <asm/kdebug.h>
  48 #include <asm/desc.h>
  49 #include <asm/proto.h>
  50 #include <asm/ia32.h>
  51
  52 asmlinkage extern void ret_from_fork(void);
  53
  54 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
  55
  56 static atomic_t hlt_counter = ATOMIC_INIT(0);
  57
  58 unsigned long boot_option_idle_override = 0;
  59 EXPORT_SYMBOL(boot_option_idle_override);
  60
  61 /*
  62  * Powermanagement idle function, if any..
  63  */
  64 void (*pm_idle)(void);
  65 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
  66
  67 void disable_hlt(void)
  68 {
  69         atomic_inc(&hlt_counter);
  70 }
  71
  72 EXPORT_SYMBOL(disable_hlt);
  73
  74 void enable_hlt(void)
  75 {
  76         atomic_dec(&hlt_counter);
  77 }
  78
  79 EXPORT_SYMBOL(enable_hlt);
  80
  81 /*
  82  * We use this if we don't have any better
  83  * idle routine..
  84  */
  85 void default_idle(void)
  86 {
  87         if (!atomic_read(&hlt_counter)) {
  88                 local_irq_disable();
  89                 if (!need_resched())
  90                         safe_halt();
  91                 else
  92                         local_irq_enable();
  93         }
  94 }
  95
  96 /*
  97  * On SMP it's slightly faster (but much more power-consuming!)
  98  * to poll the ->need_resched flag instead of waiting for the
  99  * cross-CPU IPI to arrive. Use this option with caution.
 100  */
 101 static void poll_idle (void)
 102 {
 103         int oldval;
 104
 105         local_irq_enable();
 106
 107         /*
 108          * Deal with another CPU just having chosen a thread to
 109          * run here:
 110          */
 111         oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
 112
 113         if (!oldval) {
 114                 set_thread_flag(TIF_POLLING_NRFLAG);
 115                 asm volatile(
 116                         "2:"
 117                         "testl %0,%1;"
 118                         "rep; nop;"
 119                         "je 2b;"
 120                         : :
 121                         "i" (_TIF_NEED_RESCHED),
 122                         "m" (current_thread_info()->flags));
 123         } else {
 124                 set_need_resched();
 125         }
 126 }
 127
 128 void cpu_idle_wait(void)
 129 {
 130         unsigned int cpu, this_cpu = get_cpu();
 131         cpumask_t map;
 132
 133         set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
 134         put_cpu();
 135
 136         cpus_clear(map);
 137         for_each_online_cpu(cpu) {
 138                 per_cpu(cpu_idle_state, cpu) = 1;
 139                 cpu_set(cpu, map);
 140         }
 141
 142         __get_cpu_var(cpu_idle_state) = 0;
 143
 144         wmb();
 145         do {
 146                 ssleep(1);
 147                 for_each_online_cpu(cpu) {
 148                         if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
 149                                 cpu_clear(cpu, map);
 150                 }
 151                 cpus_and(map, map, cpu_online_map);
 152         } while (!cpus_empty(map));
 153 }
 154 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 155
 156 /*
 157  * The idle thread. There's no useful work to be
 158  * done, so just try to conserve power and have a
 159  * low exit latency (ie sit in a loop waiting for
 160  * somebody to say that they'd like to reschedule)
 161  */
 162 void cpu_idle (void)
 163 {
 164         /* endless idle loop with no priority at all */
 165         while (1) {
 166                 while (!need_resched()) {
 167                         void (*idle)(void);
 168
 169                         if (__get_cpu_var(cpu_idle_state))
 170                                 __get_cpu_var(cpu_idle_state) = 0;
 171
 172                         rmb();
 173                         idle = pm_idle;
 174                         if (!idle)
 175                                 idle = default_idle;
 176                         idle();
 177                 }
 178
 179                 schedule();
 180         }
 181 }
 182
 183 /*
 184  * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 185  * which can obviate IPI to trigger checking of need_resched.
 186  * We execute MONITOR against need_resched and enter optimized wait state
 187  * through MWAIT. Whenever someone changes need_resched, we would be woken
 188  * up from MWAIT (without an IPI).
 189  */
 190 static void mwait_idle(void)
 191 {
 192         local_irq_enable();
 193
 194         if (!need_resched()) {
 195                 set_thread_flag(TIF_POLLING_NRFLAG);
 196                 do {
 197                         __monitor((void *)&current_thread_info()->flags, 0, 0);
 198                         if (need_resched())
 199                                 break;
 200                         __mwait(0, 0);
 201                 } while (!need_resched());
 202                 clear_thread_flag(TIF_POLLING_NRFLAG);
 203         }
 204 }
 205
 206 void __init select_idle_routine(const struct cpuinfo_x86 *c)
 207 {
 208         static int printed;
 209         if (cpu_has(c, X86_FEATURE_MWAIT)) {
 210                 /*
 211                  * Skip, if setup has overridden idle.
 212                  * One CPU supports mwait => All CPUs supports mwait
 213                  */
 214                 if (!pm_idle) {
 215                         if (!printed) {
 216                                 printk("using mwait in idle threads.\n");
 217                                 printed = 1;
 218                         }
 219                         pm_idle = mwait_idle;
 220                 }
 221         }
 222 }
 223
 224 static int __init idle_setup (char *str)
 225 {
 226         if (!strncmp(str, "poll", 4)) {
 227                 printk("using polling idle threads.\n");
 228                 pm_idle = poll_idle;
 229         }
 230
 231         boot_option_idle_override = 1;
 232         return 1;
 233 }
 234
 235 __setup("idle=", idle_setup);
 236
 237 /* Prints also some state that isn't saved in the pt_regs */
 238 void __show_regs(struct pt_regs * regs)
 239 {
 240         unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
 241         unsigned int fsindex,gsindex;
 242         unsigned int ds,cs,es;
 243
 244         printk("\n");
 245         print_modules();
 246         printk("Pid: %d, comm: %.20s %s %s\n",
 247                current->pid, current->comm, print_tainted(), system_utsname.release);
 248         printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
 249         printk_address(regs->rip);
 250         printk("\nRSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss, regs->rsp, regs->eflags);
 251         printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
 252                regs->rax, regs->rbx, regs->rcx);
 253         printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
 254                regs->rdx, regs->rsi, regs->rdi);
 255         printk("RBP: %016lx R08: %016lx R09: %016lx\n",
 256                regs->rbp, regs->r8, regs->r9);
 257         printk("R10: %016lx R11: %016lx R12: %016lx\n",
 258                regs->r10, regs->r11, regs->r12);
 259         printk("R13: %016lx R14: %016lx R15: %016lx\n",
 260                regs->r13, regs->r14, regs->r15);
 261
 262         asm("movl %%ds,%0" : "=r" (ds));
 263         asm("movl %%cs,%0" : "=r" (cs));
 264         asm("movl %%es,%0" : "=r" (es));
 265         asm("movl %%fs,%0" : "=r" (fsindex));
 266         asm("movl %%gs,%0" : "=r" (gsindex));
 267
 268         rdmsrl(MSR_FS_BASE, fs);
 269         rdmsrl(MSR_GS_BASE, gs);
 270         rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
 271
 272         asm("movq %%cr0, %0": "=r" (cr0));
 273         asm("movq %%cr2, %0": "=r" (cr2));
 274         asm("movq %%cr3, %0": "=r" (cr3));
 275         asm("movq %%cr4, %0": "=r" (cr4));
 276
 277         printk("FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
 278                fs,fsindex,gs,gsindex,shadowgs);
 279         printk("CS:  %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0);
 280         printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
 281 }
 282
 283 void show_regs(struct pt_regs *regs)
 284 {
 285         __show_regs(regs);
 286         show_trace(&regs->rsp);
 287 }
 288
 289 /*
 290  * Free current thread data structures etc..
 291  */
 292 void exit_thread(void)
 293 {
 294         struct task_struct *me = current;
 295         struct thread_struct *t = &me->thread;
 296         if (me->thread.io_bitmap_ptr) {
 297                 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
 298
 299                 kfree(t->io_bitmap_ptr);
 300                 t->io_bitmap_ptr = NULL;
 301                 /*
 302                  * Careful, clear this in the TSS too:
 303                  */
 304                 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
 305                 t->io_bitmap_max = 0;
 306                 put_cpu();
 307         }
 308 }
 309
 310 void flush_thread(void)
 311 {
 312         struct task_struct *tsk = current;
 313         struct thread_info *t = current_thread_info();
 314
 315         if (t->flags & _TIF_ABI_PENDING)
 316                 t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32);
 317
 318         tsk->thread.debugreg0 = 0;
 319         tsk->thread.debugreg1 = 0;
 320         tsk->thread.debugreg2 = 0;
 321         tsk->thread.debugreg3 = 0;
 322         tsk->thread.debugreg6 = 0;
 323         tsk->thread.debugreg7 = 0;
 324         memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 325         /*
 326          * Forget coprocessor state..
 327          */
 328         clear_fpu(tsk);
 329         clear_used_math();
 330 }
 331
 332 void release_thread(struct task_struct *dead_task)
 333 {
 334         if (dead_task->mm) {
 335                 if (dead_task->mm->context.size) {
 336                         printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
 337                                         dead_task->comm,
 338                                         dead_task->mm->context.ldt,
 339                                         dead_task->mm->context.size);
 340                         BUG();
 341                 }
 342         }
 343 }
 344
 345 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 346 {
 347         struct user_desc ud = {
 348                 .base_addr = addr,
 349                 .limit = 0xfffff,
 350                 .seg_32bit = 1,
 351                 .limit_in_pages = 1,
 352                 .useable = 1,
 353         };
 354         struct n_desc_struct *desc = (void *)t->thread.tls_array;
 355         desc += tls;
 356         desc->a = LDT_entry_a(&ud);
 357         desc->b = LDT_entry_b(&ud);
 358 }
 359
 360 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 361 {
 362         struct desc_struct *desc = (void *)t->thread.tls_array;
 363         desc += tls;
 364         return desc->base0 |
 365                 (((u32)desc->base1) << 16) |
 366                 (((u32)desc->base2) << 24);
 367 }
 368
 369 /*
 370  * This gets called before we allocate a new thread and copy
 371  * the current task into it.
 372  */
 373 void prepare_to_copy(struct task_struct *tsk)
 374 {
 375         unlazy_fpu(tsk);
 376 }
 377
 378 int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp,
 379                 unsigned long unused,
 380         struct task_struct * p, struct pt_regs * regs)
 381 {
 382         int err;
 383         struct pt_regs * childregs;
 384         struct task_struct *me = current;
 385
 386         childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
 387
 388         *childregs = *regs;
 389
 390         childregs->rax = 0;
 391         childregs->rsp = rsp;
 392         if (rsp == ~0UL) {
 393                 childregs->rsp = (unsigned long)childregs;
 394         }
 395
 396         p->thread.rsp = (unsigned long) childregs;
 397         p->thread.rsp0 = (unsigned long) (childregs+1);
 398         p->thread.userrsp = me->thread.userrsp;
 399
 400         set_ti_thread_flag(p->thread_info, TIF_FORK);
 401
 402         p->thread.fs = me->thread.fs;
 403         p->thread.gs = me->thread.gs;
 404
 405         asm("movl %%gs,%0" : "=m" (p->thread.gsindex));
 406         asm("movl %%fs,%0" : "=m" (p->thread.fsindex));
 407         asm("movl %%es,%0" : "=m" (p->thread.es));
 408         asm("movl %%ds,%0" : "=m" (p->thread.ds));
 409
 410         if (unlikely(me->thread.io_bitmap_ptr != NULL)) {
 411                 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
 412                 if (!p->thread.io_bitmap_ptr) {
 413                         p->thread.io_bitmap_max = 0;
 414                         return -ENOMEM;
 415                 }
 416                 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr, IO_BITMAP_BYTES);
 417         }
 418
 419         /*
 420          * Set a new TLS for the child thread?
 421          */
 422         if (clone_flags & CLONE_SETTLS) {
 423 #ifdef CONFIG_IA32_EMULATION
 424                 if (test_thread_flag(TIF_IA32))
 425                         err = ia32_child_tls(p, childregs);
 426                 else
 427 #endif
 428                         err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
 429                 if (err)
 430                         goto out;
 431         }
 432         err = 0;
 433 out:
 434         if (err && p->thread.io_bitmap_ptr) {
 435                 kfree(p->thread.io_bitmap_ptr);
 436                 p->thread.io_bitmap_max = 0;
 437         }
 438         return err;
 439 }
 440
 441 /*
 442  * This special macro can be used to load a debugging register
 443  */
 444 #define loaddebug(thread,r) set_debug(thread->debugreg ## r, r)
 445
 446 /*
 447  *      switch_to(x,y) should switch tasks from x to y.
 448  *
 449  * This could still be optimized:
 450  * - fold all the options into a flag word and test it with a single test.
 451  * - could test fs/gs bitsliced
 452  */
 453 struct task_struct *__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 454 {
 455         struct thread_struct *prev = &prev_p->thread,
 456                                  *next = &next_p->thread;
 457         int cpu = smp_processor_id();
 458         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 459
 460         unlazy_fpu(prev_p);
 461
 462         /*
 463          * Reload esp0, LDT and the page table pointer:
 464          */
 465         tss->rsp0 = next->rsp0;
 466
 467         /*
 468          * Switch DS and ES.
 469          * This won't pick up thread selector changes, but I guess that is ok.
 470          */
 471         asm volatile("movl %%es,%0" : "=m" (prev->es));
 472         if (unlikely(next->es | prev->es))
 473                 loadsegment(es, next->es);
 474
 475         asm volatile ("movl %%ds,%0" : "=m" (prev->ds));
 476         if (unlikely(next->ds | prev->ds))
 477                 loadsegment(ds, next->ds);
 478
 479         load_TLS(next, cpu);
 480
 481         /*
 482          * Switch FS and GS.
 483          */
 484         {
 485                 unsigned fsindex;
 486                 asm volatile("movl %%fs,%0" : "=r" (fsindex));
 487                 /* segment register != 0 always requires a reload.
 488                    also reload when it has changed.
 489                    when prev process used 64bit base always reload
 490                    to avoid an information leak. */
 491                 if (unlikely(fsindex | next->fsindex | prev->fs)) {
 492                         loadsegment(fs, next->fsindex);
 493                         /* check if the user used a selector != 0
 494                          * if yes clear 64bit base, since overloaded base
 495                          * is always mapped to the Null selector
 496                          */
 497                         if (fsindex)
 498                         prev->fs = 0;
 499                 }
 500                 /* when next process has a 64bit base use it */
 501                 if (next->fs)
 502                         wrmsrl(MSR_FS_BASE, next->fs);
 503                 prev->fsindex = fsindex;
 504         }
 505         {
 506                 unsigned gsindex;
 507                 asm volatile("movl %%gs,%0" : "=r" (gsindex));
 508                 if (unlikely(gsindex | next->gsindex | prev->gs)) {
 509                         load_gs_index(next->gsindex);
 510                         if (gsindex)
 511                         prev->gs = 0;
 512                 }
 513                 if (next->gs)
 514                         wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
 515                 prev->gsindex = gsindex;
 516         }
 517
 518         /*
 519          * Switch the PDA context.
 520          */
 521         prev->userrsp = read_pda(oldrsp);
 522         write_pda(oldrsp, next->userrsp);
 523         write_pda(pcurrent, next_p);
 524         write_pda(kernelstack, (unsigned long)next_p->thread_info + THREAD_SIZE - PDA_STACKOFFSET);
 525
 526         /*
 527          * Now maybe reload the debug registers
 528          */
 529         if (unlikely(next->debugreg7)) {
 530                 loaddebug(next, 0);
 531                 loaddebug(next, 1);
 532                 loaddebug(next, 2);
 533                 loaddebug(next, 3);
 534                 /* no 4 and 5 */
 535                 loaddebug(next, 6);
 536                 loaddebug(next, 7);
 537         }
 538
 539
 540         /*
 541          * Handle the IO bitmap
 542          */
 543         if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
 544                 if (next->io_bitmap_ptr)
 545                         /*
 546                          * Copy the relevant range of the IO bitmap.
 547                          * Normally this is 128 bytes or less:
 548                          */
 549                         memcpy(tss->io_bitmap, next->io_bitmap_ptr,
 550                                 max(prev->io_bitmap_max, next->io_bitmap_max));
 551                 else {
 552                         /*
 553                          * Clear any possible leftover bits:
 554                          */
 555                         memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
 556                 }
 557         }
 558
 559         return prev_p;
 560 }
 561
 562 /*
 563  * sys_execve() executes a new program.
 564  */
 565 asmlinkage
 566 long sys_execve(char __user *name, char __user * __user *argv,
 567                 char __user * __user *envp, struct pt_regs regs)
 568 {
 569         long error;
 570         char * filename;
 571
 572         filename = getname(name);
 573         error = PTR_ERR(filename);
 574         if (IS_ERR(filename))
 575                 return error;
 576         error = do_execve(filename, argv, envp, &regs);
 577         if (error == 0) {
 578                 task_lock(current);
 579                 current->ptrace &= ~PT_DTRACE;
 580                 task_unlock(current);
 581         }
 582         putname(filename);
 583         return error;
 584 }
 585
 586 void set_personality_64bit(void)
 587 {
 588         /* inherit personality from parent */
 589
 590         /* Make sure to be in 64bit mode */
 591         clear_thread_flag(TIF_IA32);
 592
 593         /* TBD: overwrites user setup. Should have two bits.
 594            But 64bit processes have always behaved this way,
 595            so it's not too bad. The main problem is just that
 596            32bit childs are affected again. */
 597         current->personality &= ~READ_IMPLIES_EXEC;
 598 }
 599
 600 asmlinkage long sys_fork(struct pt_regs *regs)
 601 {
 602         return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
 603 }
 604
 605 asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp, void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
 606 {
 607         if (!newsp)
 608                 newsp = regs->rsp;
 609         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 610 }
 611
 612 /*
 613  * This is trivial, and on the face of it looks like it
 614  * could equally well be done in user mode.
 615  *
 616  * Not so, for quite unobvious reasons - register pressure.
 617  * In user mode vfork() cannot have a stack frame, and if
 618  * done by calling the "clone()" system call directly, you
 619  * do not have enough call-clobbered registers to hold all
 620  * the information you need.
 621  */
 622 asmlinkage long sys_vfork(struct pt_regs *regs)
 623 {
 624         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
 625                     NULL, NULL);
 626 }
 627
 628 unsigned long get_wchan(struct task_struct *p)
 629 {
 630         unsigned long stack;
 631         u64 fp,rip;
 632         int count = 0;
 633
 634         if (!p || p == current || p->state==TASK_RUNNING)
 635                 return 0;
 636         stack = (unsigned long)p->thread_info;
 637         if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
 638                 return 0;
 639         fp = *(u64 *)(p->thread.rsp);
 640         do {
 641                 if (fp < (unsigned long)stack || fp > (unsigned long)stack+THREAD_SIZE)
 642                         return 0;
 643                 rip = *(u64 *)(fp+8);
 644                 if (!in_sched_functions(rip))
 645                         return rip;
 646                 fp = *(u64 *)fp;
 647         } while (count++ < 16);
 648         return 0;
 649 }
 650
 651 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 652 {
 653         int ret = 0;
 654         int doit = task == current;
 655         int cpu;
 656
 657         switch (code) {
 658         case ARCH_SET_GS:
 659                 if (addr >= TASK_SIZE)
 660                         return -EPERM;
 661                 cpu = get_cpu();
 662                 /* handle small bases via the GDT because that's faster to
 663                    switch. */
 664                 if (addr <= 0xffffffff) {
 665                         set_32bit_tls(task, GS_TLS, addr);
 666                         if (doit) {
 667                                 load_TLS(&task->thread, cpu);
 668                                 load_gs_index(GS_TLS_SEL);
 669                         }
 670                         task->thread.gsindex = GS_TLS_SEL;
 671                         task->thread.gs = 0;
 672                 } else {
 673                         task->thread.gsindex = 0;
 674                         task->thread.gs = addr;
 675                         if (doit) {
 676                 load_gs_index(0);
 677                 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
 678                         }
 679                 }
 680                 put_cpu();
 681                 break;
 682         case ARCH_SET_FS:
 683                 /* Not strictly needed for fs, but do it for symmetry
 684                    with gs */
 685                 if (addr >= TASK_SIZE)
 686                         return -EPERM;
 687                 cpu = get_cpu();
 688                 /* handle small bases via the GDT because that's faster to
 689                    switch. */
 690                 if (addr <= 0xffffffff) {
 691                         set_32bit_tls(task, FS_TLS, addr);
 692                         if (doit) {
 693                                 load_TLS(&task->thread, cpu);
 694                                 asm volatile("movl %0,%%fs" :: "r" (FS_TLS_SEL));
 695                         }
 696                         task->thread.fsindex = FS_TLS_SEL;
 697                         task->thread.fs = 0;
 698                 } else {
 699                         task->thread.fsindex = 0;
 700                         task->thread.fs = addr;
 701                         if (doit) {
 702                                 /* set the selector to 0 to not confuse
 703                                    __switch_to */
 704                 asm volatile("movl %0,%%fs" :: "r" (0));
 705                 ret = checking_wrmsrl(MSR_FS_BASE, addr);
 706                         }
 707                 }
 708                 put_cpu();
 709                 break;
 710         case ARCH_GET_FS: {
 711                 unsigned long base;
 712                 if (task->thread.fsindex == FS_TLS_SEL)
 713                         base = read_32bit_tls(task, FS_TLS);
 714                 else if (doit) {
 715                         rdmsrl(MSR_FS_BASE, base);
 716                 } else
 717                         base = task->thread.fs;
 718                 ret = put_user(base, (unsigned long __user *)addr);
 719                 break;
 720         }
 721         case ARCH_GET_GS: {
 722                 unsigned long base;
 723                 if (task->thread.gsindex == GS_TLS_SEL)
 724                         base = read_32bit_tls(task, GS_TLS);
 725                 else if (doit) {
 726                         rdmsrl(MSR_KERNEL_GS_BASE, base);
 727                 } else
 728                         base = task->thread.gs;
 729                 ret = put_user(base, (unsigned long __user *)addr);
 730                 break;
 731         }
 732
 733         default:
 734                 ret = -EINVAL;
 735                 break;
 736         }
 737
 738         return ret;
 739 }
 740
 741 long sys_arch_prctl(int code, unsigned long addr)
 742 {
 743         return do_arch_prctl(current, code, addr);
 744 }
 745
 746 /*
 747  * Capture the user space registers if the task is not running (in user space)
 748  */
 749 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 750 {
 751         struct pt_regs *pp, ptregs;
 752
 753         pp = (struct pt_regs *)(tsk->thread.rsp0);
 754         --pp;
 755
 756         ptregs = *pp;
 757         ptregs.cs &= 0xffff;
 758         ptregs.ss &= 0xffff;
 759
 760         elf_core_copy_regs(regs, &ptregs);
 761
 762         return 1;
 763 }
 764
 765 unsigned long arch_align_stack(unsigned long sp)
 766 {
 767         if (randomize_va_space)
 768                 sp -= get_random_int() % 8192;
 769         return sp & ~0xf;
 770 }