arch/xtensa/kernel/process.c

   1 /*
   2  * arch/xtensa/kernel/process.c
   3  *
   4  * Xtensa Processor version.
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file "COPYING" in the main directory of this archive
   8  * for more details.
   9  *
  10  * Copyright (C) 2001 - 2005 Tensilica Inc.
  11  *
  12  * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
  13  * Chris Zankel <chris@zankel.net>
  14  * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
  15  * Kevin Chea
  16  */
  17
  18 #include <linux/errno.h>
  19 #include <linux/sched.h>
  20 #include <linux/kernel.h>
  21 #include <linux/mm.h>
  22 #include <linux/smp.h>
  23 #include <linux/stddef.h>
  24 #include <linux/unistd.h>
  25 #include <linux/ptrace.h>
  26 #include <linux/slab.h>
  27 #include <linux/elf.h>
  28 #include <linux/init.h>
  29 #include <linux/prctl.h>
  30 #include <linux/init_task.h>
  31 #include <linux/module.h>
  32 #include <linux/mqueue.h>
  33 #include <linux/fs.h>
  34
  35 #include <asm/pgtable.h>
  36 #include <asm/uaccess.h>
  37 #include <asm/system.h>
  38 #include <asm/io.h>
  39 #include <asm/processor.h>
  40 #include <asm/platform.h>
  41 #include <asm/mmu.h>
  42 #include <asm/irq.h>
  43 #include <asm/atomic.h>
  44 #include <asm/asm-offsets.h>
  45 #include <asm/regs.h>
  46
  47 extern void ret_from_fork(void);
  48
  49 static struct fs_struct init_fs = INIT_FS;
  50 static struct files_struct init_files = INIT_FILES;
  51 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
  52 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
  53 struct mm_struct init_mm = INIT_MM(init_mm);
  54 EXPORT_SYMBOL(init_mm);
  55
  56 union thread_union init_thread_union
  57         __attribute__((__section__(".data.init_task"))) =
  58 { INIT_THREAD_INFO(init_task) };
  59
  60 struct task_struct init_task = INIT_TASK(init_task);
  61 EXPORT_SYMBOL(init_task);
  62
  63 struct task_struct *current_set[NR_CPUS] = {&init_task, };
  64
  65 void (*pm_power_off)(void) = NULL;
  66 EXPORT_SYMBOL(pm_power_off);
  67
  68
  69 /*
  70  * Powermanagement idle function, if any is provided by the platform.
  71  */
  72
  73 void cpu_idle(void)
  74 {
  75         local_irq_enable();
  76
  77         /* endless idle loop with no priority at all */
  78         while (1) {
  79                 while (!need_resched())
  80                         platform_idle();
  81                 preempt_enable_no_resched();
  82                 schedule();
  83                 preempt_disable();
  84         }
  85 }
  86
  87 /*
  88  * Free current thread data structures etc..
  89  */
  90
  91 void exit_thread(void)
  92 {
  93 }
  94
  95 void flush_thread(void)
  96 {
  97 }
  98
  99 /*
 100  * Copy thread.
 101  *
 102  * The stack layout for the new thread looks like this:
 103  *
 104  *      +------------------------+ <- sp in childregs (= tos)
 105  *      |       childregs        |
 106  *      +------------------------+ <- thread.sp = sp in dummy-frame
 107  *      |      dummy-frame       |    (saved in dummy-frame spill-area)
 108  *      +------------------------+
 109  *
 110  * We create a dummy frame to return to ret_from_fork:
 111  *   a0 points to ret_from_fork (simulating a call4)
 112  *   sp points to itself (thread.sp)
 113  *   a2, a3 are unused.
 114  *
 115  * Note: This is a pristine frame, so we don't need any spill region on top of
 116  *       childregs.
 117  */
 118
 119 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 120                 unsigned long unused,
 121                 struct task_struct * p, struct pt_regs * regs)
 122 {
 123         struct pt_regs *childregs;
 124         unsigned long tos;
 125         int user_mode = user_mode(regs);
 126
 127         /* Set up new TSS. */
 128         tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 129         if (user_mode)
 130                 childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
 131         else
 132                 childregs = (struct pt_regs*)tos - 1;
 133
 134         *childregs = *regs;
 135
 136         /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
 137         *((int*)childregs - 3) = (unsigned long)childregs;
 138         *((int*)childregs - 4) = 0;
 139
 140         childregs->areg[1] = tos;
 141         childregs->areg[2] = 0;
 142         p->set_child_tid = p->clear_child_tid = NULL;
 143         p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
 144         p->thread.sp = (unsigned long)childregs;
 145         if (user_mode(regs)) {
 146
 147                 int len = childregs->wmask & ~0xf;
 148                 childregs->areg[1] = usp;
 149                 memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
 150                        &regs->areg[XCHAL_NUM_AREGS - len/4], len);
 151
 152                 if (clone_flags & CLONE_SETTLS)
 153                         childregs->areg[2] = childregs->areg[6];
 154
 155         } else {
 156                 /* In kernel space, we start a new thread with a new stack. */
 157                 childregs->wmask = 1;
 158         }
 159         return 0;
 160 }
 161
 162
 163 /*
 164  * These bracket the sleeping functions..
 165  */
 166
 167 unsigned long get_wchan(struct task_struct *p)
 168 {
 169         unsigned long sp, pc;
 170         unsigned long stack_page = (unsigned long) task_stack_page(p);
 171         int count = 0;
 172
 173         if (!p || p == current || p->state == TASK_RUNNING)
 174                 return 0;
 175
 176         sp = p->thread.sp;
 177         pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
 178
 179         do {
 180                 if (sp < stack_page + sizeof(struct task_struct) ||
 181                     sp >= (stack_page + THREAD_SIZE) ||
 182                     pc == 0)
 183                         return 0;
 184                 if (!in_sched_functions(pc))
 185                         return pc;
 186
 187                 /* Stack layout: sp-4: ra, sp-3: sp' */
 188
 189                 pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
 190                 sp = *(unsigned long *)sp - 3;
 191         } while (count++ < 16);
 192         return 0;
 193 }
 194
 195 /*
 196  * do_copy_regs() gathers information from 'struct pt_regs' and
 197  * 'current->thread.areg[]' to fill in the xtensa_gregset_t
 198  * structure.
 199  *
 200  * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
 201  * of processor registers.  Besides different ordering,
 202  * xtensa_gregset_t contains non-live register information that
 203  * 'struct pt_regs' does not.  Exception handling (primarily) uses
 204  * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
 205  *
 206  */
 207
 208 void do_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
 209                    struct task_struct *tsk)
 210 {
 211         int i, n, wb_offset;
 212
 213         elfregs->xchal_config_id0 = XCHAL_HW_CONFIGID0;
 214         elfregs->xchal_config_id1 = XCHAL_HW_CONFIGID1;
 215
 216         __asm__ __volatile__ ("rsr  %0, 176\n" : "=a" (i));
 217         elfregs->cpux = i;
 218         __asm__ __volatile__ ("rsr  %0, 208\n" : "=a" (i));
 219         elfregs->cpuy = i;
 220
 221         /* Note:  PS.EXCM is not set while user task is running; its
 222          * being set in regs->ps is for exception handling convenience.
 223          */
 224
 225         elfregs->pc             = regs->pc;
 226         elfregs->ps             = (regs->ps & ~(1 << PS_EXCM_BIT));
 227         elfregs->exccause       = regs->exccause;
 228         elfregs->excvaddr       = regs->excvaddr;
 229         elfregs->windowbase     = regs->windowbase;
 230         elfregs->windowstart    = regs->windowstart;
 231         elfregs->lbeg           = regs->lbeg;
 232         elfregs->lend           = regs->lend;
 233         elfregs->lcount         = regs->lcount;
 234         elfregs->sar            = regs->sar;
 235         elfregs->syscall        = regs->syscall;
 236
 237         /* Copy register file.
 238          * The layout looks like this:
 239          *
 240          * |  a0 ... a15  | Z ... Z |  arX ... arY  |
 241          *  current window  unused    saved frames
 242          */
 243
 244         memset (elfregs->ar, 0, sizeof(elfregs->ar));
 245
 246         wb_offset = regs->windowbase * 4;
 247         n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;
 248
 249         for (i = 0; i < n; i++)
 250                 elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];
 251
 252         n = (regs->wmask >> 4) * 4;
 253
 254         for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
 255                 elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];
 256 }
 257
 258 void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
 259 {
 260         do_copy_regs ((xtensa_gregset_t *)elfregs, regs, current);
 261 }
 262
 263
 264 /* The inverse of do_copy_regs().  No error or sanity checking. */
 265
 266 void do_restore_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
 267                       struct task_struct *tsk)
 268 {
 269         int i, n, wb_offset;
 270
 271         /* Note:  PS.EXCM is not set while user task is running; it
 272          * needs to be set in regs->ps is for exception handling convenience.
 273          */
 274
 275         regs->pc                = elfregs->pc;
 276         regs->ps                = (elfregs->ps | (1 << PS_EXCM_BIT));
 277         regs->exccause          = elfregs->exccause;
 278         regs->excvaddr          = elfregs->excvaddr;
 279         regs->windowbase        = elfregs->windowbase;
 280         regs->windowstart       = elfregs->windowstart;
 281         regs->lbeg              = elfregs->lbeg;
 282         regs->lend              = elfregs->lend;
 283         regs->lcount            = elfregs->lcount;
 284         regs->sar               = elfregs->sar;
 285         regs->syscall   = elfregs->syscall;
 286
 287         /* Clear everything. */
 288
 289         memset (regs->areg, 0, sizeof(regs->areg));
 290
 291         /* Copy regs from live window frame. */
 292
 293         wb_offset = regs->windowbase * 4;
 294         n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;
 295
 296         for (i = 0; i < n; i++)
 297                 regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];
 298
 299         n = (regs->wmask >> 4) * 4;
 300
 301         for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
 302                 regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];
 303 }
 304
 305 /*
 306  * do_save_fpregs() gathers information from 'struct pt_regs' and
 307  * 'current->thread' to fill in the elf_fpregset_t structure.
 308  *
 309  * Core files and ptrace use elf_fpregset_t.
 310  */
 311
 312 void do_save_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
 313                      struct task_struct *tsk)
 314 {
 315 #if XCHAL_HAVE_CP
 316
 317         extern unsigned char    _xtensa_reginfo_tables[];
 318         extern unsigned         _xtensa_reginfo_table_size;
 319         int i;
 320         unsigned long flags;
 321
 322         /* Before dumping coprocessor state from memory,
 323          * ensure any live coprocessor contents for this
 324          * task are first saved to memory:
 325          */
 326         local_irq_save(flags);
 327
 328         for (i = 0; i < XCHAL_CP_MAX; i++) {
 329                 if (tsk == coprocessor_info[i].owner) {
 330                         enable_coprocessor(i);
 331                         save_coprocessor_registers(
 332                             tsk->thread.cp_save+coprocessor_info[i].offset,i);
 333                         disable_coprocessor(i);
 334                 }
 335         }
 336
 337         local_irq_restore(flags);
 338
 339         /* Now dump coprocessor & extra state: */
 340         memcpy((unsigned char*)fpregs,
 341                 _xtensa_reginfo_tables, _xtensa_reginfo_table_size);
 342         memcpy((unsigned char*)fpregs + _xtensa_reginfo_table_size,
 343                 tsk->thread.cp_save, XTENSA_CP_EXTRA_SIZE);
 344 #endif
 345 }
 346
 347 /*
 348  * The inverse of do_save_fpregs().
 349  * Copies coprocessor and extra state from fpregs into regs and tsk->thread.
 350  * Returns 0 on success, non-zero if layout doesn't match.
 351  */
 352
 353 int  do_restore_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
 354                         struct task_struct *tsk)
 355 {
 356 #if XCHAL_HAVE_CP
 357
 358         extern unsigned char    _xtensa_reginfo_tables[];
 359         extern unsigned         _xtensa_reginfo_table_size;
 360         int i;
 361         unsigned long flags;
 362
 363         /* Make sure save area layouts match.
 364          * FIXME:  in the future we could allow restoring from
 365          * a different layout of the same registers, by comparing
 366          * fpregs' table with _xtensa_reginfo_tables and matching
 367          * entries and copying registers one at a time.
 368          * Not too sure yet whether that's very useful.
 369          */
 370
 371         if( memcmp((unsigned char*)fpregs,
 372                 _xtensa_reginfo_tables, _xtensa_reginfo_table_size) ) {
 373             return -1;
 374         }
 375
 376         /* Before restoring coprocessor state from memory,
 377          * ensure any live coprocessor contents for this
 378          * task are first invalidated.
 379          */
 380
 381         local_irq_save(flags);
 382
 383         for (i = 0; i < XCHAL_CP_MAX; i++) {
 384                 if (tsk == coprocessor_info[i].owner) {
 385                         enable_coprocessor(i);
 386                         save_coprocessor_registers(
 387                             tsk->thread.cp_save+coprocessor_info[i].offset,i);
 388                         coprocessor_info[i].owner = 0;
 389                         disable_coprocessor(i);
 390                 }
 391         }
 392
 393         local_irq_restore(flags);
 394
 395         /*  Now restore coprocessor & extra state:  */
 396
 397         memcpy(tsk->thread.cp_save,
 398                 (unsigned char*)fpregs + _xtensa_reginfo_table_size,
 399                 XTENSA_CP_EXTRA_SIZE);
 400 #endif
 401         return 0;
 402 }
 403 /*
 404  * Fill in the CP structure for a core dump for a particular task.
 405  */
 406
 407 int
 408 dump_task_fpu(struct pt_regs *regs, struct task_struct *task, elf_fpregset_t *r)
 409 {
 410         return 0;       /* no coprocessors active on this processor */
 411 }
 412
 413 /*
 414  * Fill in the CP structure for a core dump.
 415  * This includes any FPU coprocessor.
 416  * Here, we dump all coprocessors, and other ("extra") custom state.
 417  *
 418  * This function is called by elf_core_dump() in fs/binfmt_elf.c
 419  * (in which case 'regs' comes from calls to do_coredump, see signals.c).
 420  */
 421 int  dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 422 {
 423         return dump_task_fpu(regs, current, r);
 424 }
 425
 426 asmlinkage
 427 long xtensa_clone(unsigned long clone_flags, unsigned long newsp,
 428                   void __user *parent_tid, void *child_tls,
 429                   void __user *child_tid, long a5,
 430                   struct pt_regs *regs)
 431 {
 432         if (!newsp)
 433                 newsp = regs->areg[1];
 434         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 435 }
 436
 437 /*
 438  *  * xtensa_execve() executes a new program.
 439  *   */
 440
 441 asmlinkage
 442 long xtensa_execve(char __user *name, char __user * __user *argv,
 443                    char __user * __user *envp,
 444                    long a3, long a4, long a5,
 445                    struct pt_regs *regs)
 446 {
 447         long error;
 448         char * filename;
 449
 450         filename = getname(name);
 451         error = PTR_ERR(filename);
 452         if (IS_ERR(filename))
 453                 goto out;
 454         // FIXME: release coprocessor??
 455         error = do_execve(filename, argv, envp, regs);
 456         if (error == 0) {
 457                 task_lock(current);
 458                 current->ptrace &= ~PT_DTRACE;
 459                 task_unlock(current);
 460         }
 461         putname(filename);
 462 out:
 463         return error;
 464 }
 465