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 struct task_struct *current_set[NR_CPUS] = {&init_task, };
  50
  51 void (*pm_power_off)(void) = NULL;
  52 EXPORT_SYMBOL(pm_power_off);
  53
  54
  55 #if XTENSA_HAVE_COPROCESSORS
  56
  57 void coprocessor_release_all(struct thread_info *ti)
  58 {
  59         unsigned long cpenable;
  60         int i;
  61
  62         /* Make sure we don't switch tasks during this operation. */
  63
  64         preempt_disable();
  65
  66         /* Walk through all cp owners and release it for the requested one. */
  67
  68         cpenable = ti->cpenable;
  69
  70         for (i = 0; i < XCHAL_CP_MAX; i++) {
  71                 if (coprocessor_owner[i] == ti) {
  72                         coprocessor_owner[i] = 0;
  73                         cpenable &= ~(1 << i);
  74                 }
  75         }
  76
  77         ti->cpenable = cpenable;
  78         coprocessor_clear_cpenable();
  79
  80         preempt_enable();
  81 }
  82
  83 void coprocessor_flush_all(struct thread_info *ti)
  84 {
  85         unsigned long cpenable;
  86         int i;
  87
  88         preempt_disable();
  89
  90         cpenable = ti->cpenable;
  91
  92         for (i = 0; i < XCHAL_CP_MAX; i++) {
  93                 if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
  94                         coprocessor_flush(ti, i);
  95                 cpenable >>= 1;
  96         }
  97
  98         preempt_enable();
  99 }
 100
 101 #endif
 102
 103
 104 /*
 105  * Powermanagement idle function, if any is provided by the platform.
 106  */
 107
 108 void cpu_idle(void)
 109 {
 110         local_irq_enable();
 111
 112         /* endless idle loop with no priority at all */
 113         while (1) {
 114                 while (!need_resched())
 115                         platform_idle();
 116                 preempt_enable_no_resched();
 117                 schedule();
 118                 preempt_disable();
 119         }
 120 }
 121
 122 /*
 123  * This is called when the thread calls exit().
 124  */
 125 void exit_thread(void)
 126 {
 127 #if XTENSA_HAVE_COPROCESSORS
 128         coprocessor_release_all(current_thread_info());
 129 #endif
 130 }
 131
 132 /*
 133  * Flush thread state. This is called when a thread does an execve()
 134  * Note that we flush coprocessor registers for the case execve fails.
 135  */
 136 void flush_thread(void)
 137 {
 138 #if XTENSA_HAVE_COPROCESSORS
 139         struct thread_info *ti = current_thread_info();
 140         coprocessor_flush_all(ti);
 141         coprocessor_release_all(ti);
 142 #endif
 143 }
 144
 145 /*
 146  * This is called before the thread is copied.
 147  */
 148 void prepare_to_copy(struct task_struct *tsk)
 149 {
 150 #if XTENSA_HAVE_COPROCESSORS
 151         coprocessor_flush_all(task_thread_info(tsk));
 152 #endif
 153 }
 154
 155 /*
 156  * Copy thread.
 157  *
 158  * The stack layout for the new thread looks like this:
 159  *
 160  *      +------------------------+ <- sp in childregs (= tos)
 161  *      |       childregs        |
 162  *      +------------------------+ <- thread.sp = sp in dummy-frame
 163  *      |      dummy-frame       |    (saved in dummy-frame spill-area)
 164  *      +------------------------+
 165  *
 166  * We create a dummy frame to return to ret_from_fork:
 167  *   a0 points to ret_from_fork (simulating a call4)
 168  *   sp points to itself (thread.sp)
 169  *   a2, a3 are unused.
 170  *
 171  * Note: This is a pristine frame, so we don't need any spill region on top of
 172  *       childregs.
 173  */
 174
 175 int copy_thread(unsigned long clone_flags, unsigned long usp,
 176                 unsigned long unused,
 177                 struct task_struct * p, struct pt_regs * regs)
 178 {
 179         struct pt_regs *childregs;
 180         struct thread_info *ti;
 181         unsigned long tos;
 182         int user_mode = user_mode(regs);
 183
 184         /* Set up new TSS. */
 185         tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 186         if (user_mode)
 187                 childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
 188         else
 189                 childregs = (struct pt_regs*)tos - 1;
 190
 191         *childregs = *regs;
 192
 193         /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
 194         *((int*)childregs - 3) = (unsigned long)childregs;
 195         *((int*)childregs - 4) = 0;
 196
 197         childregs->areg[1] = tos;
 198         childregs->areg[2] = 0;
 199         p->set_child_tid = p->clear_child_tid = NULL;
 200         p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
 201         p->thread.sp = (unsigned long)childregs;
 202
 203         if (user_mode(regs)) {
 204
 205                 int len = childregs->wmask & ~0xf;
 206                 childregs->areg[1] = usp;
 207                 memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
 208                        &regs->areg[XCHAL_NUM_AREGS - len/4], len);
 209 // FIXME: we need to set THREADPTR in thread_info...
 210                 if (clone_flags & CLONE_SETTLS)
 211                         childregs->areg[2] = childregs->areg[6];
 212
 213         } else {
 214                 /* In kernel space, we start a new thread with a new stack. */
 215                 childregs->wmask = 1;
 216         }
 217
 218 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
 219         ti = task_thread_info(p);
 220         ti->cpenable = 0;
 221 #endif
 222
 223         return 0;
 224 }
 225
 226
 227 /*
 228  * These bracket the sleeping functions..
 229  */
 230
 231 unsigned long get_wchan(struct task_struct *p)
 232 {
 233         unsigned long sp, pc;
 234         unsigned long stack_page = (unsigned long) task_stack_page(p);
 235         int count = 0;
 236
 237         if (!p || p == current || p->state == TASK_RUNNING)
 238                 return 0;
 239
 240         sp = p->thread.sp;
 241         pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
 242
 243         do {
 244                 if (sp < stack_page + sizeof(struct task_struct) ||
 245                     sp >= (stack_page + THREAD_SIZE) ||
 246                     pc == 0)
 247                         return 0;
 248                 if (!in_sched_functions(pc))
 249                         return pc;
 250
 251                 /* Stack layout: sp-4: ra, sp-3: sp' */
 252
 253                 pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
 254                 sp = *(unsigned long *)sp - 3;
 255         } while (count++ < 16);
 256         return 0;
 257 }
 258
 259 /*
 260  * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
 261  * of processor registers.  Besides different ordering,
 262  * xtensa_gregset_t contains non-live register information that
 263  * 'struct pt_regs' does not.  Exception handling (primarily) uses
 264  * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
 265  *
 266  */
 267
 268 void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
 269 {
 270         unsigned long wb, ws, wm;
 271         int live, last;
 272
 273         wb = regs->windowbase;
 274         ws = regs->windowstart;
 275         wm = regs->wmask;
 276         ws = ((ws >> wb) | (ws << (WSBITS - wb))) & ((1 << WSBITS) - 1);
 277
 278         /* Don't leak any random bits. */
 279
 280         memset(elfregs, 0, sizeof (elfregs));
 281
 282         /* Note:  PS.EXCM is not set while user task is running; its
 283          * being set in regs->ps is for exception handling convenience.
 284          */
 285
 286         elfregs->pc             = regs->pc;
 287         elfregs->ps             = (regs->ps & ~(1 << PS_EXCM_BIT));
 288         elfregs->lbeg           = regs->lbeg;
 289         elfregs->lend           = regs->lend;
 290         elfregs->lcount         = regs->lcount;
 291         elfregs->sar            = regs->sar;
 292         elfregs->windowstart    = ws;
 293
 294         live = (wm & 2) ? 4 : (wm & 4) ? 8 : (wm & 8) ? 12 : 16;
 295         last = XCHAL_NUM_AREGS - (wm >> 4) * 4;
 296         memcpy(elfregs->a, regs->areg, live * 4);
 297         memcpy(elfregs->a + last, regs->areg + last, (wm >> 4) * 16);
 298 }
 299
 300 int dump_fpu(void)
 301 {
 302         return 0;
 303 }
 304
 305 asmlinkage
 306 long xtensa_clone(unsigned long clone_flags, unsigned long newsp,
 307                   void __user *parent_tid, void *child_tls,
 308                   void __user *child_tid, long a5,
 309                   struct pt_regs *regs)
 310 {
 311         if (!newsp)
 312                 newsp = regs->areg[1];
 313         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 314 }
 315
 316 /*
 317  * xtensa_execve() executes a new program.
 318  */
 319
 320 asmlinkage
 321 long xtensa_execve(char __user *name, char __user * __user *argv,
 322                    char __user * __user *envp,
 323                    long a3, long a4, long a5,
 324                    struct pt_regs *regs)
 325 {
 326         long error;
 327         char * filename;
 328
 329         filename = getname(name);
 330         error = PTR_ERR(filename);
 331         if (IS_ERR(filename))
 332                 goto out;
 333         error = do_execve(filename, argv, envp, regs);
 334         putname(filename);
 335 out:
 336         return error;
 337 }
 338