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/elf.h>
  27 #include <linux/init.h>
  28 #include <linux/prctl.h>
  29 #include <linux/init_task.h>
  30 #include <linux/module.h>
  31 #include <linux/mqueue.h>
  32 #include <linux/fs.h>
  33 #include <linux/slab.h>
  34
  35 #include <asm/pgtable.h>
  36 #include <asm/uaccess.h>
  37 #include <asm/io.h>
  38 #include <asm/processor.h>
  39 #include <asm/platform.h>
  40 #include <asm/mmu.h>
  41 #include <asm/irq.h>
  42 #include <linux/atomic.h>
  43 #include <asm/asm-offsets.h>
  44 #include <asm/regs.h>
  45
  46 extern void ret_from_fork(void);
  47
  48 struct task_struct *current_set[NR_CPUS] = {&init_task, };
  49
  50 void (*pm_power_off)(void) = NULL;
  51 EXPORT_SYMBOL(pm_power_off);
  52
  53
  54 #if XTENSA_HAVE_COPROCESSORS
  55
  56 void coprocessor_release_all(struct thread_info *ti)
  57 {
  58         unsigned long cpenable;
  59         int i;
  60
  61         /* Make sure we don't switch tasks during this operation. */
  62
  63         preempt_disable();
  64
  65         /* Walk through all cp owners and release it for the requested one. */
  66
  67         cpenable = ti->cpenable;
  68
  69         for (i = 0; i < XCHAL_CP_MAX; i++) {
  70                 if (coprocessor_owner[i] == ti) {
  71                         coprocessor_owner[i] = 0;
  72                         cpenable &= ~(1 << i);
  73                 }
  74         }
  75
  76         ti->cpenable = cpenable;
  77         coprocessor_clear_cpenable();
  78
  79         preempt_enable();
  80 }
  81
  82 void coprocessor_flush_all(struct thread_info *ti)
  83 {
  84         unsigned long cpenable;
  85         int i;
  86
  87         preempt_disable();
  88
  89         cpenable = ti->cpenable;
  90
  91         for (i = 0; i < XCHAL_CP_MAX; i++) {
  92                 if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
  93                         coprocessor_flush(ti, i);
  94                 cpenable >>= 1;
  95         }
  96
  97         preempt_enable();
  98 }
  99
 100 #endif
 101
 102
 103 /*
 104  * Powermanagement idle function, if any is provided by the platform.
 105  */
 106
 107 void cpu_idle(void)
 108 {
 109         local_irq_enable();
 110
 111         /* endless idle loop with no priority at all */
 112         while (1) {
 113                 while (!need_resched())
 114                         platform_idle();
 115                 schedule_preempt_disabled();
 116         }
 117 }
 118
 119 /*
 120  * This is called when the thread calls exit().
 121  */
 122 void exit_thread(void)
 123 {
 124 #if XTENSA_HAVE_COPROCESSORS
 125         coprocessor_release_all(current_thread_info());
 126 #endif
 127 }
 128
 129 /*
 130  * Flush thread state. This is called when a thread does an execve()
 131  * Note that we flush coprocessor registers for the case execve fails.
 132  */
 133 void flush_thread(void)
 134 {
 135 #if XTENSA_HAVE_COPROCESSORS
 136         struct thread_info *ti = current_thread_info();
 137         coprocessor_flush_all(ti);
 138         coprocessor_release_all(ti);
 139 #endif
 140 }
 141
 142 /*
 143  * This is called before the thread is copied.
 144  */
 145 void prepare_to_copy(struct task_struct *tsk)
 146 {
 147 #if XTENSA_HAVE_COPROCESSORS
 148         coprocessor_flush_all(task_thread_info(tsk));
 149 #endif
 150 }
 151
 152 /*
 153  * Copy thread.
 154  *
 155  * The stack layout for the new thread looks like this:
 156  *
 157  *      +------------------------+ <- sp in childregs (= tos)
 158  *      |       childregs        |
 159  *      +------------------------+ <- thread.sp = sp in dummy-frame
 160  *      |      dummy-frame       |    (saved in dummy-frame spill-area)
 161  *      +------------------------+
 162  *
 163  * We create a dummy frame to return to ret_from_fork:
 164  *   a0 points to ret_from_fork (simulating a call4)
 165  *   sp points to itself (thread.sp)
 166  *   a2, a3 are unused.
 167  *
 168  * Note: This is a pristine frame, so we don't need any spill region on top of
 169  *       childregs.
 170  */
 171
 172 int copy_thread(unsigned long clone_flags, unsigned long usp,
 173                 unsigned long unused,
 174                 struct task_struct * p, struct pt_regs * regs)
 175 {
 176         struct pt_regs *childregs;
 177         struct thread_info *ti;
 178         unsigned long tos;
 179         int user_mode = user_mode(regs);
 180
 181         /* Set up new TSS. */
 182         tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
 183         if (user_mode)
 184                 childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
 185         else
 186                 childregs = (struct pt_regs*)tos - 1;
 187
 188         *childregs = *regs;
 189
 190         /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
 191         *((int*)childregs - 3) = (unsigned long)childregs;
 192         *((int*)childregs - 4) = 0;
 193
 194         childregs->areg[1] = tos;
 195         childregs->areg[2] = 0;
 196         p->set_child_tid = p->clear_child_tid = NULL;
 197         p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
 198         p->thread.sp = (unsigned long)childregs;
 199
 200         if (user_mode(regs)) {
 201
 202                 int len = childregs->wmask & ~0xf;
 203                 childregs->areg[1] = usp;
 204                 memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
 205                        &regs->areg[XCHAL_NUM_AREGS - len/4], len);
 206 // FIXME: we need to set THREADPTR in thread_info...
 207                 if (clone_flags & CLONE_SETTLS)
 208                         childregs->areg[2] = childregs->areg[6];
 209
 210         } else {
 211                 /* In kernel space, we start a new thread with a new stack. */
 212                 childregs->wmask = 1;
 213         }
 214
 215 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
 216         ti = task_thread_info(p);
 217         ti->cpenable = 0;
 218 #endif
 219
 220         return 0;
 221 }
 222
 223
 224 /*
 225  * These bracket the sleeping functions..
 226  */
 227
 228 unsigned long get_wchan(struct task_struct *p)
 229 {
 230         unsigned long sp, pc;
 231         unsigned long stack_page = (unsigned long) task_stack_page(p);
 232         int count = 0;
 233
 234         if (!p || p == current || p->state == TASK_RUNNING)
 235                 return 0;
 236
 237         sp = p->thread.sp;
 238         pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
 239
 240         do {
 241                 if (sp < stack_page + sizeof(struct task_struct) ||
 242                     sp >= (stack_page + THREAD_SIZE) ||
 243                     pc == 0)
 244                         return 0;
 245                 if (!in_sched_functions(pc))
 246                         return pc;
 247
 248                 /* Stack layout: sp-4: ra, sp-3: sp' */
 249
 250                 pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
 251                 sp = *(unsigned long *)sp - 3;
 252         } while (count++ < 16);
 253         return 0;
 254 }
 255
 256 /*
 257  * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
 258  * of processor registers.  Besides different ordering,
 259  * xtensa_gregset_t contains non-live register information that
 260  * 'struct pt_regs' does not.  Exception handling (primarily) uses
 261  * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
 262  *
 263  */
 264
 265 void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
 266 {
 267         unsigned long wb, ws, wm;
 268         int live, last;
 269
 270         wb = regs->windowbase;
 271         ws = regs->windowstart;
 272         wm = regs->wmask;
 273         ws = ((ws >> wb) | (ws << (WSBITS - wb))) & ((1 << WSBITS) - 1);
 274
 275         /* Don't leak any random bits. */
 276
 277         memset(elfregs, 0, sizeof (elfregs));
 278
 279         /* Note:  PS.EXCM is not set while user task is running; its
 280          * being set in regs->ps is for exception handling convenience.
 281          */
 282
 283         elfregs->pc             = regs->pc;
 284         elfregs->ps             = (regs->ps & ~(1 << PS_EXCM_BIT));
 285         elfregs->lbeg           = regs->lbeg;
 286         elfregs->lend           = regs->lend;
 287         elfregs->lcount         = regs->lcount;
 288         elfregs->sar            = regs->sar;
 289         elfregs->windowstart    = ws;
 290
 291         live = (wm & 2) ? 4 : (wm & 4) ? 8 : (wm & 8) ? 12 : 16;
 292         last = XCHAL_NUM_AREGS - (wm >> 4) * 4;
 293         memcpy(elfregs->a, regs->areg, live * 4);
 294         memcpy(elfregs->a + last, regs->areg + last, (wm >> 4) * 16);
 295 }
 296
 297 int dump_fpu(void)
 298 {
 299         return 0;
 300 }
 301
 302 asmlinkage
 303 long xtensa_clone(unsigned long clone_flags, unsigned long newsp,
 304                   void __user *parent_tid, void *child_tls,
 305                   void __user *child_tid, long a5,
 306                   struct pt_regs *regs)
 307 {
 308         if (!newsp)
 309                 newsp = regs->areg[1];
 310         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
 311 }
 312
 313 /*
 314  * xtensa_execve() executes a new program.
 315  */
 316
 317 asmlinkage
 318 long xtensa_execve(const char __user *name,
 319                    const char __user *const __user *argv,
 320                    const char __user *const __user *envp,
 321                    long a3, long a4, long a5,
 322                    struct pt_regs *regs)
 323 {
 324         long error;
 325         char * filename;
 326
 327         filename = getname(name);
 328         error = PTR_ERR(filename);
 329         if (IS_ERR(filename))
 330                 goto out;
 331         error = do_execve(filename, argv, envp, regs);
 332         putname(filename);
 333 out:
 334         return error;
 335 }
 336