linux/arch/tile/kernel/process.c
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   1/*
   2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3 *
   4 *   This program is free software; you can redistribute it and/or
   5 *   modify it under the terms of the GNU General Public License
   6 *   as published by the Free Software Foundation, version 2.
   7 *
   8 *   This program is distributed in the hope that it will be useful, but
   9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11 *   NON INFRINGEMENT.  See the GNU General Public License for
  12 *   more details.
  13 */
  14
  15#include <linux/sched.h>
  16#include <linux/preempt.h>
  17#include <linux/module.h>
  18#include <linux/fs.h>
  19#include <linux/kprobes.h>
  20#include <linux/elfcore.h>
  21#include <linux/tick.h>
  22#include <linux/init.h>
  23#include <linux/mm.h>
  24#include <linux/compat.h>
  25#include <linux/hardirq.h>
  26#include <linux/syscalls.h>
  27#include <linux/kernel.h>
  28#include <linux/tracehook.h>
  29#include <linux/signal.h>
  30#include <asm/stack.h>
  31#include <asm/switch_to.h>
  32#include <asm/homecache.h>
  33#include <asm/syscalls.h>
  34#include <asm/traps.h>
  35#include <asm/setup.h>
  36#ifdef CONFIG_HARDWALL
  37#include <asm/hardwall.h>
  38#endif
  39#include <arch/chip.h>
  40#include <arch/abi.h>
  41#include <arch/sim_def.h>
  42
  43
  44/*
  45 * Use the (x86) "idle=poll" option to prefer low latency when leaving the
  46 * idle loop over low power while in the idle loop, e.g. if we have
  47 * one thread per core and we want to get threads out of futex waits fast.
  48 */
  49static int no_idle_nap;
  50static int __init idle_setup(char *str)
  51{
  52        if (!str)
  53                return -EINVAL;
  54
  55        if (!strcmp(str, "poll")) {
  56                pr_info("using polling idle threads.\n");
  57                no_idle_nap = 1;
  58        } else if (!strcmp(str, "halt"))
  59                no_idle_nap = 0;
  60        else
  61                return -1;
  62
  63        return 0;
  64}
  65early_param("idle", idle_setup);
  66
  67/*
  68 * The idle thread. There's no useful work to be
  69 * done, so just try to conserve power and have a
  70 * low exit latency (ie sit in a loop waiting for
  71 * somebody to say that they'd like to reschedule)
  72 */
  73void cpu_idle(void)
  74{
  75        int cpu = smp_processor_id();
  76
  77
  78        current_thread_info()->status |= TS_POLLING;
  79
  80        if (no_idle_nap) {
  81                while (1) {
  82                        while (!need_resched())
  83                                cpu_relax();
  84                        schedule();
  85                }
  86        }
  87
  88        /* endless idle loop with no priority at all */
  89        while (1) {
  90                tick_nohz_idle_enter();
  91                rcu_idle_enter();
  92                while (!need_resched()) {
  93                        if (cpu_is_offline(cpu))
  94                                BUG();  /* no HOTPLUG_CPU */
  95
  96                        local_irq_disable();
  97                        __get_cpu_var(irq_stat).idle_timestamp = jiffies;
  98                        current_thread_info()->status &= ~TS_POLLING;
  99                        /*
 100                         * TS_POLLING-cleared state must be visible before we
 101                         * test NEED_RESCHED:
 102                         */
 103                        smp_mb();
 104
 105                        if (!need_resched())
 106                                _cpu_idle();
 107                        else
 108                                local_irq_enable();
 109                        current_thread_info()->status |= TS_POLLING;
 110                }
 111                rcu_idle_exit();
 112                tick_nohz_idle_exit();
 113                schedule_preempt_disabled();
 114        }
 115}
 116
 117/*
 118 * Release a thread_info structure
 119 */
 120void arch_release_thread_info(struct thread_info *info)
 121{
 122        struct single_step_state *step_state = info->step_state;
 123
 124#ifdef CONFIG_HARDWALL
 125        /*
 126         * We free a thread_info from the context of the task that has
 127         * been scheduled next, so the original task is already dead.
 128         * Calling deactivate here just frees up the data structures.
 129         * If the task we're freeing held the last reference to a
 130         * hardwall fd, it would have been released prior to this point
 131         * anyway via exit_files(), and the hardwall_task.info pointers
 132         * would be NULL by now.
 133         */
 134        hardwall_deactivate_all(info->task);
 135#endif
 136
 137        if (step_state) {
 138
 139                /*
 140                 * FIXME: we don't munmap step_state->buffer
 141                 * because the mm_struct for this process (info->task->mm)
 142                 * has already been zeroed in exit_mm().  Keeping a
 143                 * reference to it here seems like a bad move, so this
 144                 * means we can't munmap() the buffer, and therefore if we
 145                 * ptrace multiple threads in a process, we will slowly
 146                 * leak user memory.  (Note that as soon as the last
 147                 * thread in a process dies, we will reclaim all user
 148                 * memory including single-step buffers in the usual way.)
 149                 * We should either assign a kernel VA to this buffer
 150                 * somehow, or we should associate the buffer(s) with the
 151                 * mm itself so we can clean them up that way.
 152                 */
 153                kfree(step_state);
 154        }
 155}
 156
 157static void save_arch_state(struct thread_struct *t);
 158
 159int copy_thread(unsigned long clone_flags, unsigned long sp,
 160                unsigned long stack_size,
 161                struct task_struct *p, struct pt_regs *regs)
 162{
 163        struct pt_regs *childregs;
 164        unsigned long ksp;
 165
 166        /*
 167         * When creating a new kernel thread we pass sp as zero.
 168         * Assign it to a reasonable value now that we have the stack.
 169         */
 170        if (sp == 0 && regs->ex1 == PL_ICS_EX1(KERNEL_PL, 0))
 171                sp = KSTK_TOP(p);
 172
 173        /*
 174         * Do not clone step state from the parent; each thread
 175         * must make its own lazily.
 176         */
 177        task_thread_info(p)->step_state = NULL;
 178
 179        /*
 180         * Start new thread in ret_from_fork so it schedules properly
 181         * and then return from interrupt like the parent.
 182         */
 183        p->thread.pc = (unsigned long) ret_from_fork;
 184
 185        /* Save user stack top pointer so we can ID the stack vm area later. */
 186        p->thread.usp0 = sp;
 187
 188        /* Record the pid of the process that created this one. */
 189        p->thread.creator_pid = current->pid;
 190
 191        /*
 192         * Copy the registers onto the kernel stack so the
 193         * return-from-interrupt code will reload it into registers.
 194         */
 195        childregs = task_pt_regs(p);
 196        *childregs = *regs;
 197        childregs->regs[0] = 0;         /* return value is zero */
 198        childregs->sp = sp;  /* override with new user stack pointer */
 199
 200        /*
 201         * If CLONE_SETTLS is set, set "tp" in the new task to "r4",
 202         * which is passed in as arg #5 to sys_clone().
 203         */
 204        if (clone_flags & CLONE_SETTLS)
 205                childregs->tp = regs->regs[4];
 206
 207        /*
 208         * Copy the callee-saved registers from the passed pt_regs struct
 209         * into the context-switch callee-saved registers area.
 210         * This way when we start the interrupt-return sequence, the
 211         * callee-save registers will be correctly in registers, which
 212         * is how we assume the compiler leaves them as we start doing
 213         * the normal return-from-interrupt path after calling C code.
 214         * Zero out the C ABI save area to mark the top of the stack.
 215         */
 216        ksp = (unsigned long) childregs;
 217        ksp -= C_ABI_SAVE_AREA_SIZE;   /* interrupt-entry save area */
 218        ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
 219        ksp -= CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long);
 220        memcpy((void *)ksp, &regs->regs[CALLEE_SAVED_FIRST_REG],
 221               CALLEE_SAVED_REGS_COUNT * sizeof(unsigned long));
 222        ksp -= C_ABI_SAVE_AREA_SIZE;   /* __switch_to() save area */
 223        ((long *)ksp)[0] = ((long *)ksp)[1] = 0;
 224        p->thread.ksp = ksp;
 225
 226#if CHIP_HAS_TILE_DMA()
 227        /*
 228         * No DMA in the new thread.  We model this on the fact that
 229         * fork() clears the pending signals, alarms, and aio for the child.
 230         */
 231        memset(&p->thread.tile_dma_state, 0, sizeof(struct tile_dma_state));
 232        memset(&p->thread.dma_async_tlb, 0, sizeof(struct async_tlb));
 233#endif
 234
 235#if CHIP_HAS_SN_PROC()
 236        /* Likewise, the new thread is not running static processor code. */
 237        p->thread.sn_proc_running = 0;
 238        memset(&p->thread.sn_async_tlb, 0, sizeof(struct async_tlb));
 239#endif
 240
 241#if CHIP_HAS_PROC_STATUS_SPR()
 242        /* New thread has its miscellaneous processor state bits clear. */
 243        p->thread.proc_status = 0;
 244#endif
 245
 246#ifdef CONFIG_HARDWALL
 247        /* New thread does not own any networks. */
 248        memset(&p->thread.hardwall[0], 0,
 249               sizeof(struct hardwall_task) * HARDWALL_TYPES);
 250#endif
 251
 252
 253        /*
 254         * Start the new thread with the current architecture state
 255         * (user interrupt masks, etc.).
 256         */
 257        save_arch_state(&p->thread);
 258
 259        return 0;
 260}
 261
 262/*
 263 * Return "current" if it looks plausible, or else a pointer to a dummy.
 264 * This can be helpful if we are just trying to emit a clean panic.
 265 */
 266struct task_struct *validate_current(void)
 267{
 268        static struct task_struct corrupt = { .comm = "<corrupt>" };
 269        struct task_struct *tsk = current;
 270        if (unlikely((unsigned long)tsk < PAGE_OFFSET ||
 271                     (high_memory && (void *)tsk > high_memory) ||
 272                     ((unsigned long)tsk & (__alignof__(*tsk) - 1)) != 0)) {
 273                pr_err("Corrupt 'current' %p (sp %#lx)\n", tsk, stack_pointer);
 274                tsk = &corrupt;
 275        }
 276        return tsk;
 277}
 278
 279/* Take and return the pointer to the previous task, for schedule_tail(). */
 280struct task_struct *sim_notify_fork(struct task_struct *prev)
 281{
 282        struct task_struct *tsk = current;
 283        __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK_PARENT |
 284                     (tsk->thread.creator_pid << _SIM_CONTROL_OPERATOR_BITS));
 285        __insn_mtspr(SPR_SIM_CONTROL, SIM_CONTROL_OS_FORK |
 286                     (tsk->pid << _SIM_CONTROL_OPERATOR_BITS));
 287        return prev;
 288}
 289
 290int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 291{
 292        struct pt_regs *ptregs = task_pt_regs(tsk);
 293        elf_core_copy_regs(regs, ptregs);
 294        return 1;
 295}
 296
 297#if CHIP_HAS_TILE_DMA()
 298
 299/* Allow user processes to access the DMA SPRs */
 300void grant_dma_mpls(void)
 301{
 302#if CONFIG_KERNEL_PL == 2
 303        __insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
 304        __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
 305#else
 306        __insn_mtspr(SPR_MPL_DMA_CPL_SET_0, 1);
 307        __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_0, 1);
 308#endif
 309}
 310
 311/* Forbid user processes from accessing the DMA SPRs */
 312void restrict_dma_mpls(void)
 313{
 314#if CONFIG_KERNEL_PL == 2
 315        __insn_mtspr(SPR_MPL_DMA_CPL_SET_2, 1);
 316        __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_2, 1);
 317#else
 318        __insn_mtspr(SPR_MPL_DMA_CPL_SET_1, 1);
 319        __insn_mtspr(SPR_MPL_DMA_NOTIFY_SET_1, 1);
 320#endif
 321}
 322
 323/* Pause the DMA engine, then save off its state registers. */
 324static void save_tile_dma_state(struct tile_dma_state *dma)
 325{
 326        unsigned long state = __insn_mfspr(SPR_DMA_USER_STATUS);
 327        unsigned long post_suspend_state;
 328
 329        /* If we're running, suspend the engine. */
 330        if ((state & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK)
 331                __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__SUSPEND_MASK);
 332
 333        /*
 334         * Wait for the engine to idle, then save regs.  Note that we
 335         * want to record the "running" bit from before suspension,
 336         * and the "done" bit from after, so that we can properly
 337         * distinguish a case where the user suspended the engine from
 338         * the case where the kernel suspended as part of the context
 339         * swap.
 340         */
 341        do {
 342                post_suspend_state = __insn_mfspr(SPR_DMA_USER_STATUS);
 343        } while (post_suspend_state & SPR_DMA_STATUS__BUSY_MASK);
 344
 345        dma->src = __insn_mfspr(SPR_DMA_SRC_ADDR);
 346        dma->src_chunk = __insn_mfspr(SPR_DMA_SRC_CHUNK_ADDR);
 347        dma->dest = __insn_mfspr(SPR_DMA_DST_ADDR);
 348        dma->dest_chunk = __insn_mfspr(SPR_DMA_DST_CHUNK_ADDR);
 349        dma->strides = __insn_mfspr(SPR_DMA_STRIDE);
 350        dma->chunk_size = __insn_mfspr(SPR_DMA_CHUNK_SIZE);
 351        dma->byte = __insn_mfspr(SPR_DMA_BYTE);
 352        dma->status = (state & SPR_DMA_STATUS__RUNNING_MASK) |
 353                (post_suspend_state & SPR_DMA_STATUS__DONE_MASK);
 354}
 355
 356/* Restart a DMA that was running before we were context-switched out. */
 357static void restore_tile_dma_state(struct thread_struct *t)
 358{
 359        const struct tile_dma_state *dma = &t->tile_dma_state;
 360
 361        /*
 362         * The only way to restore the done bit is to run a zero
 363         * length transaction.
 364         */
 365        if ((dma->status & SPR_DMA_STATUS__DONE_MASK) &&
 366            !(__insn_mfspr(SPR_DMA_USER_STATUS) & SPR_DMA_STATUS__DONE_MASK)) {
 367                __insn_mtspr(SPR_DMA_BYTE, 0);
 368                __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
 369                while (__insn_mfspr(SPR_DMA_USER_STATUS) &
 370                       SPR_DMA_STATUS__BUSY_MASK)
 371                        ;
 372        }
 373
 374        __insn_mtspr(SPR_DMA_SRC_ADDR, dma->src);
 375        __insn_mtspr(SPR_DMA_SRC_CHUNK_ADDR, dma->src_chunk);
 376        __insn_mtspr(SPR_DMA_DST_ADDR, dma->dest);
 377        __insn_mtspr(SPR_DMA_DST_CHUNK_ADDR, dma->dest_chunk);
 378        __insn_mtspr(SPR_DMA_STRIDE, dma->strides);
 379        __insn_mtspr(SPR_DMA_CHUNK_SIZE, dma->chunk_size);
 380        __insn_mtspr(SPR_DMA_BYTE, dma->byte);
 381
 382        /*
 383         * Restart the engine if we were running and not done.
 384         * Clear a pending async DMA fault that we were waiting on return
 385         * to user space to execute, since we expect the DMA engine
 386         * to regenerate those faults for us now.  Note that we don't
 387         * try to clear the TIF_ASYNC_TLB flag, since it's relatively
 388         * harmless if set, and it covers both DMA and the SN processor.
 389         */
 390        if ((dma->status & DMA_STATUS_MASK) == SPR_DMA_STATUS__RUNNING_MASK) {
 391                t->dma_async_tlb.fault_num = 0;
 392                __insn_mtspr(SPR_DMA_CTR, SPR_DMA_CTR__REQUEST_MASK);
 393        }
 394}
 395
 396#endif
 397
 398static void save_arch_state(struct thread_struct *t)
 399{
 400#if CHIP_HAS_SPLIT_INTR_MASK()
 401        t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0_0) |
 402                ((u64)__insn_mfspr(SPR_INTERRUPT_MASK_0_1) << 32);
 403#else
 404        t->interrupt_mask = __insn_mfspr(SPR_INTERRUPT_MASK_0);
 405#endif
 406        t->ex_context[0] = __insn_mfspr(SPR_EX_CONTEXT_0_0);
 407        t->ex_context[1] = __insn_mfspr(SPR_EX_CONTEXT_0_1);
 408        t->system_save[0] = __insn_mfspr(SPR_SYSTEM_SAVE_0_0);
 409        t->system_save[1] = __insn_mfspr(SPR_SYSTEM_SAVE_0_1);
 410        t->system_save[2] = __insn_mfspr(SPR_SYSTEM_SAVE_0_2);
 411        t->system_save[3] = __insn_mfspr(SPR_SYSTEM_SAVE_0_3);
 412        t->intctrl_0 = __insn_mfspr(SPR_INTCTRL_0_STATUS);
 413#if CHIP_HAS_PROC_STATUS_SPR()
 414        t->proc_status = __insn_mfspr(SPR_PROC_STATUS);
 415#endif
 416#if !CHIP_HAS_FIXED_INTVEC_BASE()
 417        t->interrupt_vector_base = __insn_mfspr(SPR_INTERRUPT_VECTOR_BASE_0);
 418#endif
 419#if CHIP_HAS_TILE_RTF_HWM()
 420        t->tile_rtf_hwm = __insn_mfspr(SPR_TILE_RTF_HWM);
 421#endif
 422#if CHIP_HAS_DSTREAM_PF()
 423        t->dstream_pf = __insn_mfspr(SPR_DSTREAM_PF);
 424#endif
 425}
 426
 427static void restore_arch_state(const struct thread_struct *t)
 428{
 429#if CHIP_HAS_SPLIT_INTR_MASK()
 430        __insn_mtspr(SPR_INTERRUPT_MASK_0_0, (u32) t->interrupt_mask);
 431        __insn_mtspr(SPR_INTERRUPT_MASK_0_1, t->interrupt_mask >> 32);
 432#else
 433        __insn_mtspr(SPR_INTERRUPT_MASK_0, t->interrupt_mask);
 434#endif
 435        __insn_mtspr(SPR_EX_CONTEXT_0_0, t->ex_context[0]);
 436        __insn_mtspr(SPR_EX_CONTEXT_0_1, t->ex_context[1]);
 437        __insn_mtspr(SPR_SYSTEM_SAVE_0_0, t->system_save[0]);
 438        __insn_mtspr(SPR_SYSTEM_SAVE_0_1, t->system_save[1]);
 439        __insn_mtspr(SPR_SYSTEM_SAVE_0_2, t->system_save[2]);
 440        __insn_mtspr(SPR_SYSTEM_SAVE_0_3, t->system_save[3]);
 441        __insn_mtspr(SPR_INTCTRL_0_STATUS, t->intctrl_0);
 442#if CHIP_HAS_PROC_STATUS_SPR()
 443        __insn_mtspr(SPR_PROC_STATUS, t->proc_status);
 444#endif
 445#if !CHIP_HAS_FIXED_INTVEC_BASE()
 446        __insn_mtspr(SPR_INTERRUPT_VECTOR_BASE_0, t->interrupt_vector_base);
 447#endif
 448#if CHIP_HAS_TILE_RTF_HWM()
 449        __insn_mtspr(SPR_TILE_RTF_HWM, t->tile_rtf_hwm);
 450#endif
 451#if CHIP_HAS_DSTREAM_PF()
 452        __insn_mtspr(SPR_DSTREAM_PF, t->dstream_pf);
 453#endif
 454}
 455
 456
 457void _prepare_arch_switch(struct task_struct *next)
 458{
 459#if CHIP_HAS_SN_PROC()
 460        int snctl;
 461#endif
 462#if CHIP_HAS_TILE_DMA()
 463        struct tile_dma_state *dma = &current->thread.tile_dma_state;
 464        if (dma->enabled)
 465                save_tile_dma_state(dma);
 466#endif
 467#if CHIP_HAS_SN_PROC()
 468        /*
 469         * Suspend the static network processor if it was running.
 470         * We do not suspend the fabric itself, just like we don't
 471         * try to suspend the UDN.
 472         */
 473        snctl = __insn_mfspr(SPR_SNCTL);
 474        current->thread.sn_proc_running =
 475                (snctl & SPR_SNCTL__FRZPROC_MASK) == 0;
 476        if (current->thread.sn_proc_running)
 477                __insn_mtspr(SPR_SNCTL, snctl | SPR_SNCTL__FRZPROC_MASK);
 478#endif
 479}
 480
 481
 482struct task_struct *__sched _switch_to(struct task_struct *prev,
 483                                       struct task_struct *next)
 484{
 485        /* DMA state is already saved; save off other arch state. */
 486        save_arch_state(&prev->thread);
 487
 488#if CHIP_HAS_TILE_DMA()
 489        /*
 490         * Restore DMA in new task if desired.
 491         * Note that it is only safe to restart here since interrupts
 492         * are disabled, so we can't take any DMATLB miss or access
 493         * interrupts before we have finished switching stacks.
 494         */
 495        if (next->thread.tile_dma_state.enabled) {
 496                restore_tile_dma_state(&next->thread);
 497                grant_dma_mpls();
 498        } else {
 499                restrict_dma_mpls();
 500        }
 501#endif
 502
 503        /* Restore other arch state. */
 504        restore_arch_state(&next->thread);
 505
 506#if CHIP_HAS_SN_PROC()
 507        /*
 508         * Restart static network processor in the new process
 509         * if it was running before.
 510         */
 511        if (next->thread.sn_proc_running) {
 512                int snctl = __insn_mfspr(SPR_SNCTL);
 513                __insn_mtspr(SPR_SNCTL, snctl & ~SPR_SNCTL__FRZPROC_MASK);
 514        }
 515#endif
 516
 517#ifdef CONFIG_HARDWALL
 518        /* Enable or disable access to the network registers appropriately. */
 519        hardwall_switch_tasks(prev, next);
 520#endif
 521
 522        /*
 523         * Switch kernel SP, PC, and callee-saved registers.
 524         * In the context of the new task, return the old task pointer
 525         * (i.e. the task that actually called __switch_to).
 526         * Pass the value to use for SYSTEM_SAVE_K_0 when we reset our sp.
 527         */
 528        return __switch_to(prev, next, next_current_ksp0(next));
 529}
 530
 531/*
 532 * This routine is called on return from interrupt if any of the
 533 * TIF_WORK_MASK flags are set in thread_info->flags.  It is
 534 * entered with interrupts disabled so we don't miss an event
 535 * that modified the thread_info flags.  If any flag is set, we
 536 * handle it and return, and the calling assembly code will
 537 * re-disable interrupts, reload the thread flags, and call back
 538 * if more flags need to be handled.
 539 *
 540 * We return whether we need to check the thread_info flags again
 541 * or not.  Note that we don't clear TIF_SINGLESTEP here, so it's
 542 * important that it be tested last, and then claim that we don't
 543 * need to recheck the flags.
 544 */
 545int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
 546{
 547        /* If we enter in kernel mode, do nothing and exit the caller loop. */
 548        if (!user_mode(regs))
 549                return 0;
 550
 551        /* Enable interrupts; they are disabled again on return to caller. */
 552        local_irq_enable();
 553
 554        if (thread_info_flags & _TIF_NEED_RESCHED) {
 555                schedule();
 556                return 1;
 557        }
 558#if CHIP_HAS_TILE_DMA() || CHIP_HAS_SN_PROC()
 559        if (thread_info_flags & _TIF_ASYNC_TLB) {
 560                do_async_page_fault(regs);
 561                return 1;
 562        }
 563#endif
 564        if (thread_info_flags & _TIF_SIGPENDING) {
 565                do_signal(regs);
 566                return 1;
 567        }
 568        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 569                clear_thread_flag(TIF_NOTIFY_RESUME);
 570                tracehook_notify_resume(regs);
 571                return 1;
 572        }
 573        if (thread_info_flags & _TIF_SINGLESTEP) {
 574                single_step_once(regs);
 575                return 0;
 576        }
 577        panic("work_pending: bad flags %#x\n", thread_info_flags);
 578}
 579
 580/* Note there is an implicit fifth argument if (clone_flags & CLONE_SETTLS). */
 581SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
 582                void __user *, parent_tidptr, void __user *, child_tidptr,
 583                struct pt_regs *, regs)
 584{
 585        if (!newsp)
 586                newsp = regs->sp;
 587        return do_fork(clone_flags, newsp, regs, 0,
 588                       parent_tidptr, child_tidptr);
 589}
 590
 591/*
 592 * sys_execve() executes a new program.
 593 */
 594SYSCALL_DEFINE4(execve, const char __user *, path,
 595                const char __user *const __user *, argv,
 596                const char __user *const __user *, envp,
 597                struct pt_regs *, regs)
 598{
 599        long error;
 600        struct filename *filename;
 601
 602        filename = getname(path);
 603        error = PTR_ERR(filename);
 604        if (IS_ERR(filename))
 605                goto out;
 606        error = do_execve(filename->name, argv, envp, regs);
 607        putname(filename);
 608        if (error == 0)
 609                single_step_execve();
 610out:
 611        return error;
 612}
 613
 614#ifdef CONFIG_COMPAT
 615long compat_sys_execve(const char __user *path,
 616                       compat_uptr_t __user *argv,
 617                       compat_uptr_t __user *envp,
 618                       struct pt_regs *regs)
 619{
 620        long error;
 621        struct filename *filename;
 622
 623        filename = getname(path);
 624        error = PTR_ERR(filename);
 625        if (IS_ERR(filename))
 626                goto out;
 627        error = compat_do_execve(filename->name, argv, envp, regs);
 628        putname(filename);
 629        if (error == 0)
 630                single_step_execve();
 631out:
 632        return error;
 633}
 634#endif
 635
 636unsigned long get_wchan(struct task_struct *p)
 637{
 638        struct KBacktraceIterator kbt;
 639
 640        if (!p || p == current || p->state == TASK_RUNNING)
 641                return 0;
 642
 643        for (KBacktraceIterator_init(&kbt, p, NULL);
 644             !KBacktraceIterator_end(&kbt);
 645             KBacktraceIterator_next(&kbt)) {
 646                if (!in_sched_functions(kbt.it.pc))
 647                        return kbt.it.pc;
 648        }
 649
 650        return 0;
 651}
 652
 653/*
 654 * We pass in lr as zero (cleared in kernel_thread) and the caller
 655 * part of the backtrace ABI on the stack also zeroed (in copy_thread)
 656 * so that backtraces will stop with this function.
 657 * Note that we don't use r0, since copy_thread() clears it.
 658 */
 659static void start_kernel_thread(int dummy, int (*fn)(int), int arg)
 660{
 661        do_exit(fn(arg));
 662}
 663
 664/*
 665 * Create a kernel thread
 666 */
 667int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
 668{
 669        struct pt_regs regs;
 670
 671        memset(&regs, 0, sizeof(regs));
 672        regs.ex1 = PL_ICS_EX1(KERNEL_PL, 0);  /* run at kernel PL, no ICS */
 673        regs.pc = (long) start_kernel_thread;
 674        regs.flags = PT_FLAGS_CALLER_SAVES;   /* need to restore r1 and r2 */
 675        regs.regs[1] = (long) fn;             /* function pointer */
 676        regs.regs[2] = (long) arg;            /* parameter register */
 677
 678        /* Ok, create the new process.. */
 679        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs,
 680                       0, NULL, NULL);
 681}
 682EXPORT_SYMBOL(kernel_thread);
 683
 684/* Flush thread state. */
 685void flush_thread(void)
 686{
 687        /* Nothing */
 688}
 689
 690/*
 691 * Free current thread data structures etc..
 692 */
 693void exit_thread(void)
 694{
 695        /* Nothing */
 696}
 697
 698void show_regs(struct pt_regs *regs)
 699{
 700        struct task_struct *tsk = validate_current();
 701        int i;
 702
 703        pr_err("\n");
 704        pr_err(" Pid: %d, comm: %20s, CPU: %d\n",
 705               tsk->pid, tsk->comm, smp_processor_id());
 706#ifdef __tilegx__
 707        for (i = 0; i < 51; i += 3)
 708                pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
 709                       i, regs->regs[i], i+1, regs->regs[i+1],
 710                       i+2, regs->regs[i+2]);
 711        pr_err(" r51: "REGFMT" r52: "REGFMT" tp : "REGFMT"\n",
 712               regs->regs[51], regs->regs[52], regs->tp);
 713        pr_err(" sp : "REGFMT" lr : "REGFMT"\n", regs->sp, regs->lr);
 714#else
 715        for (i = 0; i < 52; i += 4)
 716                pr_err(" r%-2d: "REGFMT" r%-2d: "REGFMT
 717                       " r%-2d: "REGFMT" r%-2d: "REGFMT"\n",
 718                       i, regs->regs[i], i+1, regs->regs[i+1],
 719                       i+2, regs->regs[i+2], i+3, regs->regs[i+3]);
 720        pr_err(" r52: "REGFMT" tp : "REGFMT" sp : "REGFMT" lr : "REGFMT"\n",
 721               regs->regs[52], regs->tp, regs->sp, regs->lr);
 722#endif
 723        pr_err(" pc : "REGFMT" ex1: %ld     faultnum: %ld\n",
 724               regs->pc, regs->ex1, regs->faultnum);
 725
 726        dump_stack_regs(regs);
 727}
 728