linux/arch/xtensa/kernel/process.c
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   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/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
  47extern void ret_from_fork(void);
  48
  49struct task_struct *current_set[NR_CPUS] = {&init_task, };
  50
  51void (*pm_power_off)(void) = NULL;
  52EXPORT_SYMBOL(pm_power_off);
  53
  54
  55#if XTENSA_HAVE_COPROCESSORS
  56
  57void 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
  83void 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
 108void 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 */
 125void 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 */
 136void 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 */
 148void 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
 175int 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
 231unsigned 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
 268void 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
 300int dump_fpu(void)
 301{
 302        return 0;
 303}
 304
 305asmlinkage
 306long 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
 320asmlinkage
 321long xtensa_execve(const char __user *name,
 322                   const char __user *const __user *argv,
 323                   const char __user *const __user *envp,
 324                   long a3, long a4, long a5,
 325                   struct pt_regs *regs)
 326{
 327        long error;
 328        char * filename;
 329
 330        filename = getname(name);
 331        error = PTR_ERR(filename);
 332        if (IS_ERR(filename))
 333                goto out;
 334        error = do_execve(filename, argv, envp, regs);
 335        putname(filename);
 336out:
 337        return error;
 338}
 339
 340