arch/mips/kernel/process.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
   7  * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  * Copyright (C) 2004 Thiemo Seufer
  10  */
  11 #include <linux/config.h>
  12 #include <linux/errno.h>
  13 #include <linux/module.h>
  14 #include <linux/sched.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mm.h>
  17 #include <linux/stddef.h>
  18 #include <linux/unistd.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/slab.h>
  21 #include <linux/mman.h>
  22 #include <linux/personality.h>
  23 #include <linux/sys.h>
  24 #include <linux/user.h>
  25 #include <linux/a.out.h>
  26 #include <linux/init.h>
  27 #include <linux/completion.h>
  28 #include <linux/kallsyms.h>
  29
  30 #include <asm/abi.h>
  31 #include <asm/bootinfo.h>
  32 #include <asm/cpu.h>
  33 #include <asm/dsp.h>
  34 #include <asm/fpu.h>
  35 #include <asm/pgtable.h>
  36 #include <asm/system.h>
  37 #include <asm/mipsregs.h>
  38 #include <asm/processor.h>
  39 #include <asm/uaccess.h>
  40 #include <asm/io.h>
  41 #include <asm/elf.h>
  42 #include <asm/isadep.h>
  43 #include <asm/inst.h>
  44
  45 /*
  46  * The idle thread. There's no useful work to be done, so just try to conserve
  47  * power and have a low exit latency (ie sit in a loop waiting for somebody to
  48  * say that they'd like to reschedule)
  49  */
  50 ATTRIB_NORET void cpu_idle(void)
  51 {
  52         /* endless idle loop with no priority at all */
  53         while (1) {
  54                 while (!need_resched())
  55                         if (cpu_wait)
  56                                 (*cpu_wait)();
  57                 preempt_enable_no_resched();
  58                 schedule();
  59                 preempt_disable();
  60         }
  61 }
  62
  63 /*
  64  * Native o32 and N64 ABI without DSP ASE
  65  */
  66 struct mips_abi mips_abi = {
  67         .do_signal      = do_signal,
  68 #ifdef CONFIG_TRAD_SIGNALS
  69         .setup_frame    = setup_frame,
  70 #endif
  71         .setup_rt_frame = setup_rt_frame
  72 };
  73
  74 #ifdef CONFIG_MIPS32_O32
  75 /*
  76  * o32 compatibility on 64-bit kernels, without DSP ASE
  77  */
  78 struct mips_abi mips_abi_32 = {
  79         .do_signal      = do_signal32,
  80         .setup_frame    = setup_frame_32,
  81         .setup_rt_frame = setup_rt_frame_32
  82 };
  83 #endif /* CONFIG_MIPS32_O32 */
  84
  85 #ifdef CONFIG_MIPS32_N32
  86 /*
  87  * N32 on 64-bit kernels, without DSP ASE
  88  */
  89 struct mips_abi mips_abi_n32 = {
  90         .do_signal      = do_signal,
  91         .setup_rt_frame = setup_rt_frame_n32
  92 };
  93 #endif /* CONFIG_MIPS32_N32 */
  94
  95 asmlinkage void ret_from_fork(void);
  96
  97 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  98 {
  99         unsigned long status;
 100
 101         /* New thread loses kernel privileges. */
 102         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK);
 103 #ifdef CONFIG_64BIT
 104         status &= ~ST0_FR;
 105         status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
 106 #endif
 107         status |= KU_USER;
 108         regs->cp0_status = status;
 109         clear_used_math();
 110         lose_fpu();
 111         if (cpu_has_dsp)
 112                 __init_dsp();
 113         regs->cp0_epc = pc;
 114         regs->regs[29] = sp;
 115         current_thread_info()->addr_limit = USER_DS;
 116 }
 117
 118 void exit_thread(void)
 119 {
 120 }
 121
 122 void flush_thread(void)
 123 {
 124 }
 125
 126 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 127         unsigned long unused, struct task_struct *p, struct pt_regs *regs)
 128 {
 129         struct thread_info *ti = task_thread_info(p);
 130         struct pt_regs *childregs;
 131         long childksp;
 132         p->set_child_tid = p->clear_child_tid = NULL;
 133
 134         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 135
 136         preempt_disable();
 137
 138         if (is_fpu_owner())
 139                 save_fp(p);
 140
 141         if (cpu_has_dsp)
 142                 save_dsp(p);
 143
 144         preempt_enable();
 145
 146         /* set up new TSS. */
 147         childregs = (struct pt_regs *) childksp - 1;
 148         *childregs = *regs;
 149         childregs->regs[7] = 0; /* Clear error flag */
 150
 151 #if defined(CONFIG_BINFMT_IRIX)
 152         if (current->personality != PER_LINUX) {
 153                 /* Under IRIX things are a little different. */
 154                 childregs->regs[3] = 1;
 155                 regs->regs[3] = 0;
 156         }
 157 #endif
 158         childregs->regs[2] = 0; /* Child gets zero as return value */
 159         regs->regs[2] = p->pid;
 160
 161         if (childregs->cp0_status & ST0_CU0) {
 162                 childregs->regs[28] = (unsigned long) ti;
 163                 childregs->regs[29] = childksp;
 164                 ti->addr_limit = KERNEL_DS;
 165         } else {
 166                 childregs->regs[29] = usp;
 167                 ti->addr_limit = USER_DS;
 168         }
 169         p->thread.reg29 = (unsigned long) childregs;
 170         p->thread.reg31 = (unsigned long) ret_from_fork;
 171
 172         /*
 173          * New tasks lose permission to use the fpu. This accelerates context
 174          * switching for most programs since they don't use the fpu.
 175          */
 176         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 177         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 178         clear_tsk_thread_flag(p, TIF_USEDFPU);
 179
 180         if (clone_flags & CLONE_SETTLS)
 181                 ti->tp_value = regs->regs[7];
 182
 183         return 0;
 184 }
 185
 186 /* Fill in the fpu structure for a core dump.. */
 187 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 188 {
 189         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 190
 191         return 1;
 192 }
 193
 194 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 195 {
 196         int i;
 197
 198         for (i = 0; i < EF_R0; i++)
 199                 gp[i] = 0;
 200         gp[EF_R0] = 0;
 201         for (i = 1; i <= 31; i++)
 202                 gp[EF_R0 + i] = regs->regs[i];
 203         gp[EF_R26] = 0;
 204         gp[EF_R27] = 0;
 205         gp[EF_LO] = regs->lo;
 206         gp[EF_HI] = regs->hi;
 207         gp[EF_CP0_EPC] = regs->cp0_epc;
 208         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 209         gp[EF_CP0_STATUS] = regs->cp0_status;
 210         gp[EF_CP0_CAUSE] = regs->cp0_cause;
 211 #ifdef EF_UNUSED0
 212         gp[EF_UNUSED0] = 0;
 213 #endif
 214 }
 215
 216 int dump_task_regs (struct task_struct *tsk, elf_gregset_t *regs)
 217 {
 218         elf_dump_regs(*regs, task_pt_regs(tsk));
 219         return 1;
 220 }
 221
 222 int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr)
 223 {
 224         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
 225
 226         return 1;
 227 }
 228
 229 /*
 230  * Create a kernel thread
 231  */
 232 ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
 233 {
 234         do_exit(fn(arg));
 235 }
 236
 237 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 238 {
 239         struct pt_regs regs;
 240
 241         memset(&regs, 0, sizeof(regs));
 242
 243         regs.regs[4] = (unsigned long) arg;
 244         regs.regs[5] = (unsigned long) fn;
 245         regs.cp0_epc = (unsigned long) kernel_thread_helper;
 246         regs.cp0_status = read_c0_status();
 247 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 248         regs.cp0_status &= ~(ST0_KUP | ST0_IEC);
 249         regs.cp0_status |= ST0_IEP;
 250 #else
 251         regs.cp0_status |= ST0_EXL;
 252 #endif
 253
 254         /* Ok, create the new process.. */
 255         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 256 }
 257
 258 static struct mips_frame_info {
 259         void *func;
 260         unsigned long func_size;
 261         int frame_size;
 262         int pc_offset;
 263 } *schedule_frame, mfinfo[64];
 264 static int mfinfo_num;
 265
 266 static int __init get_frame_info(struct mips_frame_info *info)
 267 {
 268         int i;
 269         void *func = info->func;
 270         union mips_instruction *ip = (union mips_instruction *)func;
 271         info->pc_offset = -1;
 272         info->frame_size = 0;
 273         for (i = 0; i < 128; i++, ip++) {
 274                 /* if jal, jalr, jr, stop. */
 275                 if (ip->j_format.opcode == jal_op ||
 276                     (ip->r_format.opcode == spec_op &&
 277                      (ip->r_format.func == jalr_op ||
 278                       ip->r_format.func == jr_op)))
 279                         break;
 280
 281                 if (info->func_size && i >= info->func_size / 4)
 282                         break;
 283                 if (
 284 #ifdef CONFIG_32BIT
 285                     ip->i_format.opcode == addiu_op &&
 286 #endif
 287 #ifdef CONFIG_64BIT
 288                     ip->i_format.opcode == daddiu_op &&
 289 #endif
 290                     ip->i_format.rs == 29 &&
 291                     ip->i_format.rt == 29) {
 292                         /* addiu/daddiu sp,sp,-imm */
 293                         if (info->frame_size)
 294                                 continue;
 295                         info->frame_size = - ip->i_format.simmediate;
 296                 }
 297
 298                 if (
 299 #ifdef CONFIG_32BIT
 300                     ip->i_format.opcode == sw_op &&
 301 #endif
 302 #ifdef CONFIG_64BIT
 303                     ip->i_format.opcode == sd_op &&
 304 #endif
 305                     ip->i_format.rs == 29 &&
 306                     ip->i_format.rt == 31) {
 307                         /* sw / sd $ra, offset($sp) */
 308                         if (info->pc_offset != -1)
 309                                 continue;
 310                         info->pc_offset =
 311                                 ip->i_format.simmediate / sizeof(long);
 312                 }
 313         }
 314         if (info->pc_offset == -1 || info->frame_size == 0) {
 315                 if (func == schedule)
 316                         printk("Can't analyze prologue code at %p\n", func);
 317                 info->pc_offset = -1;
 318                 info->frame_size = 0;
 319         }
 320
 321         return 0;
 322 }
 323
 324 static int __init frame_info_init(void)
 325 {
 326         int i;
 327 #ifdef CONFIG_KALLSYMS
 328         char *modname;
 329         char namebuf[KSYM_NAME_LEN + 1];
 330         unsigned long start, size, ofs;
 331         extern char __sched_text_start[], __sched_text_end[];
 332         extern char __lock_text_start[], __lock_text_end[];
 333
 334         start = (unsigned long)__sched_text_start;
 335         for (i = 0; i < ARRAY_SIZE(mfinfo); i++) {
 336                 if (start == (unsigned long)schedule)
 337                         schedule_frame = &mfinfo[i];
 338                 if (!kallsyms_lookup(start, &size, &ofs, &modname, namebuf))
 339                         break;
 340                 mfinfo[i].func = (void *)(start + ofs);
 341                 mfinfo[i].func_size = size;
 342                 start += size - ofs;
 343                 if (start >= (unsigned long)__lock_text_end)
 344                         break;
 345                 if (start == (unsigned long)__sched_text_end)
 346                         start = (unsigned long)__lock_text_start;
 347         }
 348 #else
 349         mfinfo[0].func = schedule;
 350         schedule_frame = &mfinfo[0];
 351 #endif
 352         for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++)
 353                 get_frame_info(&mfinfo[i]);
 354
 355         mfinfo_num = i;
 356         return 0;
 357 }
 358
 359 arch_initcall(frame_info_init);
 360
 361 /*
 362  * Return saved PC of a blocked thread.
 363  */
 364 unsigned long thread_saved_pc(struct task_struct *tsk)
 365 {
 366         struct thread_struct *t = &tsk->thread;
 367
 368         /* New born processes are a special case */
 369         if (t->reg31 == (unsigned long) ret_from_fork)
 370                 return t->reg31;
 371
 372         if (!schedule_frame || schedule_frame->pc_offset < 0)
 373                 return 0;
 374         return ((unsigned long *)t->reg29)[schedule_frame->pc_offset];
 375 }
 376
 377 /* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
 378 unsigned long get_wchan(struct task_struct *p)
 379 {
 380         unsigned long stack_page;
 381         unsigned long pc;
 382 #ifdef CONFIG_KALLSYMS
 383         unsigned long frame;
 384 #endif
 385
 386         if (!p || p == current || p->state == TASK_RUNNING)
 387                 return 0;
 388
 389         stack_page = (unsigned long)task_stack_page(p);
 390         if (!stack_page || !mfinfo_num)
 391                 return 0;
 392
 393         pc = thread_saved_pc(p);
 394 #ifdef CONFIG_KALLSYMS
 395         if (!in_sched_functions(pc))
 396                 return pc;
 397
 398         frame = p->thread.reg29 + schedule_frame->frame_size;
 399         do {
 400                 int i;
 401
 402                 if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
 403                         return 0;
 404
 405                 for (i = mfinfo_num - 1; i >= 0; i--) {
 406                         if (pc >= (unsigned long) mfinfo[i].func)
 407                                 break;
 408                 }
 409                 if (i < 0)
 410                         break;
 411
 412                 pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
 413                 if (!mfinfo[i].frame_size)
 414                         break;
 415                 frame += mfinfo[i].frame_size;
 416         } while (in_sched_functions(pc));
 417 #endif
 418
 419         return pc;
 420 }
 421
 422 EXPORT_SYMBOL(get_wchan);