arch/x86/kernel/process_64.c

   1 /*
   2  *  Copyright (C) 1995  Linus Torvalds
   3  *
   4  *  Pentium III FXSR, SSE support
   5  *      Gareth Hughes <gareth@valinux.com>, May 2000
   6  *
   7  *  X86-64 port
   8  *      Andi Kleen.
   9  *
  10  *      CPU hotplug support - ashok.raj@intel.com
  11  */
  12
  13 /*
  14  * This file handles the architecture-dependent parts of process handling..
  15  */
  16
  17 #include <linux/cpu.h>
  18 #include <linux/errno.h>
  19 #include <linux/sched.h>
  20 #include <linux/fs.h>
  21 #include <linux/kernel.h>
  22 #include <linux/mm.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>
  36 #include <linux/io.h>
  37 #include <linux/ftrace.h>
  38
  39 #include <asm/pgtable.h>
  40 #include <asm/processor.h>
  41 #include <asm/i387.h>
  42 #include <asm/fpu-internal.h>
  43 #include <asm/mmu_context.h>
  44 #include <asm/prctl.h>
  45 #include <asm/desc.h>
  46 #include <asm/proto.h>
  47 #include <asm/ia32.h>
  48 #include <asm/idle.h>
  49 #include <asm/syscalls.h>
  50 #include <asm/debugreg.h>
  51 #include <asm/switch_to.h>
  52
  53 asmlinkage extern void ret_from_fork(void);
  54
  55 DEFINE_PER_CPU(unsigned long, old_rsp);
  56
  57 /* Prints also some state that isn't saved in the pt_regs */
  58 void __show_regs(struct pt_regs *regs, int all)
  59 {
  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;
  64
  65         printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
  66         printk_address(regs->ip, 1);
  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);
  79
  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));
  85
  86         rdmsrl(MSR_FS_BASE, fs);
  87         rdmsrl(MSR_GS_BASE, gs);
  88         rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
  89
  90         if (!all)
  91                 return;
  92
  93         cr0 = read_cr0();
  94         cr2 = read_cr2();
  95         cr3 = read_cr3();
  96         cr4 = read_cr4();
  97
  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,
 101                         es, cr0);
 102         printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3,
 103                         cr4);
 104
 105         get_debugreg(d0, 0);
 106         get_debugreg(d1, 1);
 107         get_debugreg(d2, 2);
 108         get_debugreg(d3, 3);
 109         get_debugreg(d6, 6);
 110         get_debugreg(d7, 7);
 111
 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))
 115                 return;
 116
 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);
 119
 120 }
 121
 122 void release_thread(struct task_struct *dead_task)
 123 {
 124         if (dead_task->mm) {
 125                 if (dead_task->mm->context.size) {
 126                         pr_warn("WARNING: dead process %s still has LDT? <%p/%d>\n",
 127                                 dead_task->comm,
 128                                 dead_task->mm->context.ldt,
 129                                 dead_task->mm->context.size);
 130                         BUG();
 131                 }
 132         }
 133 }
 134
 135 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
 136 {
 137         struct user_desc ud = {
 138                 .base_addr = addr,
 139                 .limit = 0xfffff,
 140                 .seg_32bit = 1,
 141                 .limit_in_pages = 1,
 142                 .useable = 1,
 143         };
 144         struct desc_struct *desc = t->thread.tls_array;
 145         desc += tls;
 146         fill_ldt(desc, &ud);
 147 }
 148
 149 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
 150 {
 151         return get_desc_base(&t->thread.tls_array[tls]);
 152 }
 153
 154 int copy_thread(unsigned long clone_flags, unsigned long sp,
 155                 unsigned long arg, struct task_struct *p)
 156 {
 157         int err;
 158         struct pt_regs *childregs;
 159         struct task_struct *me = current;
 160
 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->fpu_counter = 0;
 167         p->thread.io_bitmap_ptr = NULL;
 168
 169         savesegment(gs, p->thread.gsindex);
 170         p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs;
 171         savesegment(fs, p->thread.fsindex);
 172         p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
 173         savesegment(es, p->thread.es);
 174         savesegment(ds, p->thread.ds);
 175         memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 176
 177         if (unlikely(p->flags & PF_KTHREAD)) {
 178                 /* kernel thread */
 179                 memset(childregs, 0, sizeof(struct pt_regs));
 180                 childregs->sp = (unsigned long)childregs;
 181                 childregs->ss = __KERNEL_DS;
 182                 childregs->bx = sp; /* function */
 183                 childregs->bp = arg;
 184                 childregs->orig_ax = -1;
 185                 childregs->cs = __KERNEL_CS | get_kernel_rpl();
 186                 childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_FIXED;
 187                 return 0;
 188         }
 189         *childregs = *current_pt_regs();
 190
 191         childregs->ax = 0;
 192         if (sp)
 193                 childregs->sp = sp;
 194
 195         err = -ENOMEM;
 196         memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 197
 198         if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
 199                 p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
 200                                                   IO_BITMAP_BYTES, GFP_KERNEL);
 201                 if (!p->thread.io_bitmap_ptr) {
 202                         p->thread.io_bitmap_max = 0;
 203                         return -ENOMEM;
 204                 }
 205                 set_tsk_thread_flag(p, TIF_IO_BITMAP);
 206         }
 207
 208         /*
 209          * Set a new TLS for the child thread?
 210          */
 211         if (clone_flags & CLONE_SETTLS) {
 212 #ifdef CONFIG_IA32_EMULATION
 213                 if (test_thread_flag(TIF_IA32))
 214                         err = do_set_thread_area(p, -1,
 215                                 (struct user_desc __user *)childregs->si, 0);
 216                 else
 217 #endif
 218                         err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
 219                 if (err)
 220                         goto out;
 221         }
 222         err = 0;
 223 out:
 224         if (err && p->thread.io_bitmap_ptr) {
 225                 kfree(p->thread.io_bitmap_ptr);
 226                 p->thread.io_bitmap_max = 0;
 227         }
 228
 229         return err;
 230 }
 231
 232 static void
 233 start_thread_common(struct pt_regs *regs, unsigned long new_ip,
 234                     unsigned long new_sp,
 235                     unsigned int _cs, unsigned int _ss, unsigned int _ds)
 236 {
 237         loadsegment(fs, 0);
 238         loadsegment(es, _ds);
 239         loadsegment(ds, _ds);
 240         load_gs_index(0);
 241         current->thread.usersp  = new_sp;
 242         regs->ip                = new_ip;
 243         regs->sp                = new_sp;
 244         this_cpu_write(old_rsp, new_sp);
 245         regs->cs                = _cs;
 246         regs->ss                = _ss;
 247         regs->flags             = X86_EFLAGS_IF;
 248 }
 249
 250 void
 251 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
 252 {
 253         start_thread_common(regs, new_ip, new_sp,
 254                             __USER_CS, __USER_DS, 0);
 255 }
 256
 257 #ifdef CONFIG_IA32_EMULATION
 258 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp)
 259 {
 260         start_thread_common(regs, new_ip, new_sp,
 261                             test_thread_flag(TIF_X32)
 262                             ? __USER_CS : __USER32_CS,
 263                             __USER_DS, __USER_DS);
 264 }
 265 #endif
 266
 267 /*
 268  *      switch_to(x,y) should switch tasks from x to y.
 269  *
 270  * This could still be optimized:
 271  * - fold all the options into a flag word and test it with a single test.
 272  * - could test fs/gs bitsliced
 273  *
 274  * Kprobes not supported here. Set the probe on schedule instead.
 275  * Function graph tracer not supported too.
 276  */
 277 __notrace_funcgraph struct task_struct *
 278 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 279 {
 280         struct thread_struct *prev = &prev_p->thread;
 281         struct thread_struct *next = &next_p->thread;
 282         int cpu = smp_processor_id();
 283         struct tss_struct *tss = &per_cpu(init_tss, cpu);
 284         unsigned fsindex, gsindex;
 285         fpu_switch_t fpu;
 286
 287         fpu = switch_fpu_prepare(prev_p, next_p, cpu);
 288
 289         /*
 290          * Reload esp0, LDT and the page table pointer:
 291          */
 292         load_sp0(tss, next);
 293
 294         /*
 295          * Switch DS and ES.
 296          * This won't pick up thread selector changes, but I guess that is ok.
 297          */
 298         savesegment(es, prev->es);
 299         if (unlikely(next->es | prev->es))
 300                 loadsegment(es, next->es);
 301
 302         savesegment(ds, prev->ds);
 303         if (unlikely(next->ds | prev->ds))
 304                 loadsegment(ds, next->ds);
 305
 306
 307         /* We must save %fs and %gs before load_TLS() because
 308          * %fs and %gs may be cleared by load_TLS().
 309          *
 310          * (e.g. xen_load_tls())
 311          */
 312         savesegment(fs, fsindex);
 313         savesegment(gs, gsindex);
 314
 315         load_TLS(next, cpu);
 316
 317         /*
 318          * Leave lazy mode, flushing any hypercalls made here.
 319          * This must be done before restoring TLS segments so
 320          * the GDT and LDT are properly updated, and must be
 321          * done before math_state_restore, so the TS bit is up
 322          * to date.
 323          */
 324         arch_end_context_switch(next_p);
 325
 326         /*
 327          * Switch FS and GS.
 328          *
 329          * Segment register != 0 always requires a reload.  Also
 330          * reload when it has changed.  When prev process used 64bit
 331          * base always reload to avoid an information leak.
 332          */
 333         if (unlikely(fsindex | next->fsindex | prev->fs)) {
 334                 loadsegment(fs, next->fsindex);
 335                 /*
 336                  * Check if the user used a selector != 0; if yes
 337                  *  clear 64bit base, since overloaded base is always
 338                  *  mapped to the Null selector
 339                  */
 340                 if (fsindex)
 341                         prev->fs = 0;
 342         }
 343         /* when next process has a 64bit base use it */
 344         if (next->fs)
 345                 wrmsrl(MSR_FS_BASE, next->fs);
 346         prev->fsindex = fsindex;
 347
 348         if (unlikely(gsindex | next->gsindex | prev->gs)) {
 349                 load_gs_index(next->gsindex);
 350                 if (gsindex)
 351                         prev->gs = 0;
 352         }
 353         if (next->gs)
 354                 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
 355         prev->gsindex = gsindex;
 356
 357         switch_fpu_finish(next_p, fpu);
 358
 359         /*
 360          * Switch the PDA and FPU contexts.
 361          */
 362         prev->usersp = this_cpu_read(old_rsp);
 363         this_cpu_write(old_rsp, next->usersp);
 364         this_cpu_write(current_task, next_p);
 365
 366         this_cpu_write(kernel_stack,
 367                   (unsigned long)task_stack_page(next_p) +
 368                   THREAD_SIZE - KERNEL_STACK_OFFSET);
 369
 370         /*
 371          * Now maybe reload the debug registers and handle I/O bitmaps
 372          */
 373         if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
 374                      task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
 375                 __switch_to_xtra(prev_p, next_p, tss);
 376
 377         return prev_p;
 378 }
 379
 380 void set_personality_64bit(void)
 381 {
 382         /* inherit personality from parent */
 383
 384         /* Make sure to be in 64bit mode */
 385         clear_thread_flag(TIF_IA32);
 386         clear_thread_flag(TIF_ADDR32);
 387         clear_thread_flag(TIF_X32);
 388
 389         /* Ensure the corresponding mm is not marked. */
 390         if (current->mm)
 391                 current->mm->context.ia32_compat = 0;
 392
 393         /* TBD: overwrites user setup. Should have two bits.
 394            But 64bit processes have always behaved this way,
 395            so it's not too bad. The main problem is just that
 396            32bit childs are affected again. */
 397         current->personality &= ~READ_IMPLIES_EXEC;
 398 }
 399
 400 void set_personality_ia32(bool x32)
 401 {
 402         /* inherit personality from parent */
 403
 404         /* Make sure to be in 32bit mode */
 405         set_thread_flag(TIF_ADDR32);
 406
 407         /* Mark the associated mm as containing 32-bit tasks. */
 408         if (current->mm)
 409                 current->mm->context.ia32_compat = 1;
 410
 411         if (x32) {
 412                 clear_thread_flag(TIF_IA32);
 413                 set_thread_flag(TIF_X32);
 414                 current->personality &= ~READ_IMPLIES_EXEC;
 415                 /* is_compat_task() uses the presence of the x32
 416                    syscall bit flag to determine compat status */
 417                 current_thread_info()->status &= ~TS_COMPAT;
 418         } else {
 419                 set_thread_flag(TIF_IA32);
 420                 clear_thread_flag(TIF_X32);
 421                 current->personality |= force_personality32;
 422                 /* Prepare the first "return" to user space */
 423                 current_thread_info()->status |= TS_COMPAT;
 424         }
 425 }
 426 EXPORT_SYMBOL_GPL(set_personality_ia32);
 427
 428 unsigned long get_wchan(struct task_struct *p)
 429 {
 430         unsigned long stack;
 431         u64 fp, ip;
 432         int count = 0;
 433
 434         if (!p || p == current || p->state == TASK_RUNNING)
 435                 return 0;
 436         stack = (unsigned long)task_stack_page(p);
 437         if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
 438                 return 0;
 439         fp = *(u64 *)(p->thread.sp);
 440         do {
 441                 if (fp < (unsigned long)stack ||
 442                     fp >= (unsigned long)stack+THREAD_SIZE)
 443                         return 0;
 444                 ip = *(u64 *)(fp+8);
 445                 if (!in_sched_functions(ip))
 446                         return ip;
 447                 fp = *(u64 *)fp;
 448         } while (count++ < 16);
 449         return 0;
 450 }
 451
 452 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
 453 {
 454         int ret = 0;
 455         int doit = task == current;
 456         int cpu;
 457
 458         switch (code) {
 459         case ARCH_SET_GS:
 460                 if (addr >= TASK_SIZE_OF(task))
 461                         return -EPERM;
 462                 cpu = get_cpu();
 463                 /* handle small bases via the GDT because that's faster to
 464                    switch. */
 465                 if (addr <= 0xffffffff) {
 466                         set_32bit_tls(task, GS_TLS, addr);
 467                         if (doit) {
 468                                 load_TLS(&task->thread, cpu);
 469                                 load_gs_index(GS_TLS_SEL);
 470                         }
 471                         task->thread.gsindex = GS_TLS_SEL;
 472                         task->thread.gs = 0;
 473                 } else {
 474                         task->thread.gsindex = 0;
 475                         task->thread.gs = addr;
 476                         if (doit) {
 477                                 load_gs_index(0);
 478                                 ret = wrmsrl_safe(MSR_KERNEL_GS_BASE, addr);
 479                         }
 480                 }
 481                 put_cpu();
 482                 break;
 483         case ARCH_SET_FS:
 484                 /* Not strictly needed for fs, but do it for symmetry
 485                    with gs */
 486                 if (addr >= TASK_SIZE_OF(task))
 487                         return -EPERM;
 488                 cpu = get_cpu();
 489                 /* handle small bases via the GDT because that's faster to
 490                    switch. */
 491                 if (addr <= 0xffffffff) {
 492                         set_32bit_tls(task, FS_TLS, addr);
 493                         if (doit) {
 494                                 load_TLS(&task->thread, cpu);
 495                                 loadsegment(fs, FS_TLS_SEL);
 496                         }
 497                         task->thread.fsindex = FS_TLS_SEL;
 498                         task->thread.fs = 0;
 499                 } else {
 500                         task->thread.fsindex = 0;
 501                         task->thread.fs = addr;
 502                         if (doit) {
 503                                 /* set the selector to 0 to not confuse
 504                                    __switch_to */
 505                                 loadsegment(fs, 0);
 506                                 ret = wrmsrl_safe(MSR_FS_BASE, addr);
 507                         }
 508                 }
 509                 put_cpu();
 510                 break;
 511         case ARCH_GET_FS: {
 512                 unsigned long base;
 513                 if (task->thread.fsindex == FS_TLS_SEL)
 514                         base = read_32bit_tls(task, FS_TLS);
 515                 else if (doit)
 516                         rdmsrl(MSR_FS_BASE, base);
 517                 else
 518                         base = task->thread.fs;
 519                 ret = put_user(base, (unsigned long __user *)addr);
 520                 break;
 521         }
 522         case ARCH_GET_GS: {
 523                 unsigned long base;
 524                 unsigned gsindex;
 525                 if (task->thread.gsindex == GS_TLS_SEL)
 526                         base = read_32bit_tls(task, GS_TLS);
 527                 else if (doit) {
 528                         savesegment(gs, gsindex);
 529                         if (gsindex)
 530                                 rdmsrl(MSR_KERNEL_GS_BASE, base);
 531                         else
 532                                 base = task->thread.gs;
 533                 } else
 534                         base = task->thread.gs;
 535                 ret = put_user(base, (unsigned long __user *)addr);
 536                 break;
 537         }
 538
 539         default:
 540                 ret = -EINVAL;
 541                 break;
 542         }
 543
 544         return ret;
 545 }
 546
 547 long sys_arch_prctl(int code, unsigned long addr)
 548 {
 549         return do_arch_prctl(current, code, addr);
 550 }
 551
 552 unsigned long KSTK_ESP(struct task_struct *task)
 553 {
 554         return (test_tsk_thread_flag(task, TIF_IA32)) ?
 555                         (task_pt_regs(task)->sp) : ((task)->thread.usersp);
 556 }