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process.c

/*  $Id: process.c,v 1.131 2002/02/09 19:49:30 davem Exp $
 *  arch/sparc64/kernel/process.c
 *
 *  Copyright (C) 1995, 1996 David S. Miller (davem@caip.rutgers.edu)
 *  Copyright (C) 1996       Eddie C. Dost   (ecd@skynet.be)
 *  Copyright (C) 1997, 1998 Jakub Jelinek   (jj@sunsite.mff.cuni.cz)
 */

/*
 * This file handles the architecture-dependent parts of process handling..
 */

#include <stdarg.h>

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/kallsyms.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/compat.h>
#include <linux/tick.h>
#include <linux/init.h>
#include <linux/cpu.h>

#include <asm/oplib.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
#include <asm/pstate.h>
#include <asm/elf.h>
#include <asm/fpumacro.h>
#include <asm/head.h>
#include <asm/cpudata.h>
#include <asm/mmu_context.h>
#include <asm/unistd.h>
#include <asm/hypervisor.h>
#include <asm/sstate.h>

/* #define VERBOSE_SHOWREGS */

static void sparc64_yield(int cpu)
{
      if (tlb_type != hypervisor)
            return;

      clear_thread_flag(TIF_POLLING_NRFLAG);
      smp_mb__after_clear_bit();

      while (!need_resched() && !cpu_is_offline(cpu)) {
            unsigned long pstate;

            /* Disable interrupts. */
            __asm__ __volatile__(
                  "rdpr %%pstate, %0\n\t"
                  "andn %0, %1, %0\n\t"
                  "wrpr %0, %%g0, %%pstate"
                  : "=&r" (pstate)
                  : "i" (PSTATE_IE));

            if (!need_resched() && !cpu_is_offline(cpu))
                  sun4v_cpu_yield();

            /* Re-enable interrupts. */
            __asm__ __volatile__(
                  "rdpr %%pstate, %0\n\t"
                  "or %0, %1, %0\n\t"
                  "wrpr %0, %%g0, %%pstate"
                  : "=&r" (pstate)
                  : "i" (PSTATE_IE));
      }

      set_thread_flag(TIF_POLLING_NRFLAG);
}

/* The idle loop on sparc64. */
void cpu_idle(void)
{
      int cpu = smp_processor_id();

      set_thread_flag(TIF_POLLING_NRFLAG);

      while(1) {
            tick_nohz_stop_sched_tick();

            while (!need_resched() && !cpu_is_offline(cpu))
                  sparc64_yield(cpu);

            tick_nohz_restart_sched_tick();

            preempt_enable_no_resched();

#ifdef CONFIG_HOTPLUG_CPU
            if (cpu_is_offline(cpu))
                  cpu_play_dead();
#endif

            schedule();
            preempt_disable();
      }
}

extern char reboot_command [];

extern void (*prom_palette)(int);
extern void (*prom_keyboard)(void);

void machine_halt(void)
{
      sstate_halt();
      if (prom_palette)
            prom_palette (1);
      if (prom_keyboard)
            prom_keyboard();
      prom_halt();
      panic("Halt failed!");
}

void machine_alt_power_off(void)
{
      sstate_poweroff();
      if (prom_palette)
            prom_palette(1);
      if (prom_keyboard)
            prom_keyboard();
      prom_halt_power_off();
      panic("Power-off failed!");
}

void machine_restart(char * cmd)
{
      char *p;
      
      sstate_reboot();
      p = strchr (reboot_command, '\n');
      if (p) *p = 0;
      if (prom_palette)
            prom_palette (1);
      if (prom_keyboard)
            prom_keyboard();
      if (cmd)
            prom_reboot(cmd);
      if (*reboot_command)
            prom_reboot(reboot_command);
      prom_reboot("");
      panic("Reboot failed!");
}

#ifdef CONFIG_COMPAT
static void show_regwindow32(struct pt_regs *regs)
{
      struct reg_window32 __user *rw;
      struct reg_window32 r_w;
      mm_segment_t old_fs;
      
      __asm__ __volatile__ ("flushw");
      rw = compat_ptr((unsigned)regs->u_regs[14]);
      old_fs = get_fs();
      set_fs (USER_DS);
      if (copy_from_user (&r_w, rw, sizeof(r_w))) {
            set_fs (old_fs);
            return;
      }

      set_fs (old_fs);              
      printk("l0: %08x l1: %08x l2: %08x l3: %08x "
             "l4: %08x l5: %08x l6: %08x l7: %08x\n",
             r_w.locals[0], r_w.locals[1], r_w.locals[2], r_w.locals[3],
             r_w.locals[4], r_w.locals[5], r_w.locals[6], r_w.locals[7]);
      printk("i0: %08x i1: %08x i2: %08x i3: %08x "
             "i4: %08x i5: %08x i6: %08x i7: %08x\n",
             r_w.ins[0], r_w.ins[1], r_w.ins[2], r_w.ins[3],
             r_w.ins[4], r_w.ins[5], r_w.ins[6], r_w.ins[7]);
}
#else
#define show_regwindow32(regs)      do { } while (0)
#endif

static void show_regwindow(struct pt_regs *regs)
{
      struct reg_window __user *rw;
      struct reg_window *rwk;
      struct reg_window r_w;
      mm_segment_t old_fs;

      if ((regs->tstate & TSTATE_PRIV) || !(test_thread_flag(TIF_32BIT))) {
            __asm__ __volatile__ ("flushw");
            rw = (struct reg_window __user *)
                  (regs->u_regs[14] + STACK_BIAS);
            rwk = (struct reg_window *)
                  (regs->u_regs[14] + STACK_BIAS);
            if (!(regs->tstate & TSTATE_PRIV)) {
                  old_fs = get_fs();
                  set_fs (USER_DS);
                  if (copy_from_user (&r_w, rw, sizeof(r_w))) {
                        set_fs (old_fs);
                        return;
                  }
                  rwk = &r_w;
                  set_fs (old_fs);              
            }
      } else {
            show_regwindow32(regs);
            return;
      }
      printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n",
             rwk->locals[0], rwk->locals[1], rwk->locals[2], rwk->locals[3]);
      printk("l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n",
             rwk->locals[4], rwk->locals[5], rwk->locals[6], rwk->locals[7]);
      printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n",
             rwk->ins[0], rwk->ins[1], rwk->ins[2], rwk->ins[3]);
      printk("i4: %016lx i5: %016lx i6: %016lx i7: %016lx\n",
             rwk->ins[4], rwk->ins[5], rwk->ins[6], rwk->ins[7]);
      if (regs->tstate & TSTATE_PRIV)
            print_symbol("I7: <%s>\n", rwk->ins[7]);
}

void show_stackframe(struct sparc_stackf *sf)
{
      unsigned long size;
      unsigned long *stk;
      int i;

      printk("l0: %016lx l1: %016lx l2: %016lx l3: %016lx\n"
             "l4: %016lx l5: %016lx l6: %016lx l7: %016lx\n",
             sf->locals[0], sf->locals[1], sf->locals[2], sf->locals[3],
             sf->locals[4], sf->locals[5], sf->locals[6], sf->locals[7]);
      printk("i0: %016lx i1: %016lx i2: %016lx i3: %016lx\n"
             "i4: %016lx i5: %016lx fp: %016lx ret_pc: %016lx\n",
             sf->ins[0], sf->ins[1], sf->ins[2], sf->ins[3],
             sf->ins[4], sf->ins[5], (unsigned long)sf->fp, sf->callers_pc);
      printk("sp: %016lx x0: %016lx x1: %016lx x2: %016lx\n"
             "x3: %016lx x4: %016lx x5: %016lx xx: %016lx\n",
             (unsigned long)sf->structptr, sf->xargs[0], sf->xargs[1],
             sf->xargs[2], sf->xargs[3], sf->xargs[4], sf->xargs[5],
             sf->xxargs[0]);
      size = ((unsigned long)sf->fp) - ((unsigned long)sf);
      size -= STACKFRAME_SZ;
      stk = (unsigned long *)((unsigned long)sf + STACKFRAME_SZ);
      i = 0;
      do {
            printk("s%d: %016lx\n", i++, *stk++);
      } while ((size -= sizeof(unsigned long)));
}

void show_stackframe32(struct sparc_stackf32 *sf)
{
      unsigned long size;
      unsigned *stk;
      int i;

      printk("l0: %08x l1: %08x l2: %08x l3: %08x\n",
             sf->locals[0], sf->locals[1], sf->locals[2], sf->locals[3]);
      printk("l4: %08x l5: %08x l6: %08x l7: %08x\n",
             sf->locals[4], sf->locals[5], sf->locals[6], sf->locals[7]);
      printk("i0: %08x i1: %08x i2: %08x i3: %08x\n",
             sf->ins[0], sf->ins[1], sf->ins[2], sf->ins[3]);
      printk("i4: %08x i5: %08x fp: %08x ret_pc: %08x\n",
             sf->ins[4], sf->ins[5], sf->fp, sf->callers_pc);
      printk("sp: %08x x0: %08x x1: %08x x2: %08x\n"
             "x3: %08x x4: %08x x5: %08x xx: %08x\n",
             sf->structptr, sf->xargs[0], sf->xargs[1],
             sf->xargs[2], sf->xargs[3], sf->xargs[4], sf->xargs[5],
             sf->xxargs[0]);
      size = ((unsigned long)sf->fp) - ((unsigned long)sf);
      size -= STACKFRAME32_SZ;
      stk = (unsigned *)((unsigned long)sf + STACKFRAME32_SZ);
      i = 0;
      do {
            printk("s%d: %08x\n", i++, *stk++);
      } while ((size -= sizeof(unsigned)));
}

#ifdef CONFIG_SMP
static DEFINE_SPINLOCK(regdump_lock);
#endif

void __show_regs(struct pt_regs * regs)
{
#ifdef CONFIG_SMP
      unsigned long flags;

      /* Protect against xcall ipis which might lead to livelock on the lock */
      __asm__ __volatile__("rdpr      %%pstate, %0\n\t"
                       "wrpr      %0, %1, %%pstate"
                       : "=r" (flags)
                       : "i" (PSTATE_IE));
      spin_lock(&regdump_lock);
#endif
      printk("TSTATE: %016lx TPC: %016lx TNPC: %016lx Y: %08x    %s\n", regs->tstate,
             regs->tpc, regs->tnpc, regs->y, print_tainted());
      print_symbol("TPC: <%s>\n", regs->tpc);
      printk("g0: %016lx g1: %016lx g2: %016lx g3: %016lx\n",
             regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
             regs->u_regs[3]);
      printk("g4: %016lx g5: %016lx g6: %016lx g7: %016lx\n",
             regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
             regs->u_regs[7]);
      printk("o0: %016lx o1: %016lx o2: %016lx o3: %016lx\n",
             regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
             regs->u_regs[11]);
      printk("o4: %016lx o5: %016lx sp: %016lx ret_pc: %016lx\n",
             regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
             regs->u_regs[15]);
      print_symbol("RPC: <%s>\n", regs->u_regs[15]);
      show_regwindow(regs);
#ifdef CONFIG_SMP
      spin_unlock(&regdump_lock);
      __asm__ __volatile__("wrpr    %0, 0, %%pstate"
                       : : "r" (flags));
#endif
}

#ifdef VERBOSE_SHOWREGS
static void idump_from_user (unsigned int *pc)
{
      int i;
      int code;
      
      if((((unsigned long) pc) & 3))
            return;
      
      pc -= 3;
      for(i = -3; i < 6; i++) {
            get_user(code, pc);
            printk("%c%08x%c",i?' ':'<',code,i?' ':'>');
            pc++;
      }
      printk("\n");
}
#endif

void show_regs(struct pt_regs *regs)
{
#ifdef VERBOSE_SHOWREGS
      extern long etrap, etraptl1;
#endif
      __show_regs(regs);
#if 0
#ifdef CONFIG_SMP
      {
            extern void smp_report_regs(void);

            smp_report_regs();
      }
#endif
#endif

#ifdef VERBOSE_SHOWREGS 
      if (regs->tpc >= &etrap && regs->tpc < &etraptl1 &&
          regs->u_regs[14] >= (long)current - PAGE_SIZE &&
          regs->u_regs[14] < (long)current + 6 * PAGE_SIZE) {
            printk ("*********parent**********\n");
            __show_regs((struct pt_regs *)(regs->u_regs[14] + PTREGS_OFF));
            idump_from_user(((struct pt_regs *)(regs->u_regs[14] + PTREGS_OFF))->tpc);
            printk ("*********endpar**********\n");
      }
#endif
}

void show_regs32(struct pt_regs32 *regs)
{
      printk("PSR: %08x PC: %08x NPC: %08x Y: %08x    %s\n", regs->psr,
             regs->pc, regs->npc, regs->y, print_tainted());
      printk("g0: %08x g1: %08x g2: %08x g3: %08x ",
             regs->u_regs[0], regs->u_regs[1], regs->u_regs[2],
             regs->u_regs[3]);
      printk("g4: %08x g5: %08x g6: %08x g7: %08x\n",
             regs->u_regs[4], regs->u_regs[5], regs->u_regs[6],
             regs->u_regs[7]);
      printk("o0: %08x o1: %08x o2: %08x o3: %08x ",
             regs->u_regs[8], regs->u_regs[9], regs->u_regs[10],
             regs->u_regs[11]);
      printk("o4: %08x o5: %08x sp: %08x ret_pc: %08x\n",
             regs->u_regs[12], regs->u_regs[13], regs->u_regs[14],
             regs->u_regs[15]);
}

unsigned long thread_saved_pc(struct task_struct *tsk)
{
      struct thread_info *ti = task_thread_info(tsk);
      unsigned long ret = 0xdeadbeefUL;
      
      if (ti && ti->ksp) {
            unsigned long *sp;
            sp = (unsigned long *)(ti->ksp + STACK_BIAS);
            if (((unsigned long)sp & (sizeof(long) - 1)) == 0UL &&
                sp[14]) {
                  unsigned long *fp;
                  fp = (unsigned long *)(sp[14] + STACK_BIAS);
                  if (((unsigned long)fp & (sizeof(long) - 1)) == 0UL)
                        ret = fp[15];
            }
      }
      return ret;
}

/* Free current thread data structures etc.. */
void exit_thread(void)
{
      struct thread_info *t = current_thread_info();

      if (t->utraps) {
            if (t->utraps[0] < 2)
                  kfree (t->utraps);
            else
                  t->utraps[0]--;
      }

      if (test_and_clear_thread_flag(TIF_PERFCTR)) {
            t->user_cntd0 = t->user_cntd1 = NULL;
            t->pcr_reg = 0;
            write_pcr(0);
      }
}

void flush_thread(void)
{
      struct thread_info *t = current_thread_info();
      struct mm_struct *mm;

      if (test_ti_thread_flag(t, TIF_ABI_PENDING)) {
            clear_ti_thread_flag(t, TIF_ABI_PENDING);
            if (test_ti_thread_flag(t, TIF_32BIT))
                  clear_ti_thread_flag(t, TIF_32BIT);
            else
                  set_ti_thread_flag(t, TIF_32BIT);
      }

      mm = t->task->mm;
      if (mm)
            tsb_context_switch(mm);

      set_thread_wsaved(0);

      /* Turn off performance counters if on. */
      if (test_and_clear_thread_flag(TIF_PERFCTR)) {
            t->user_cntd0 = t->user_cntd1 = NULL;
            t->pcr_reg = 0;
            write_pcr(0);
      }

      /* Clear FPU register state. */
      t->fpsaved[0] = 0;
      
      if (get_thread_current_ds() != ASI_AIUS)
            set_fs(USER_DS);

      /* Init new signal delivery disposition. */
      clear_thread_flag(TIF_NEWSIGNALS);
}

/* It's a bit more tricky when 64-bit tasks are involved... */
static unsigned long clone_stackframe(unsigned long csp, unsigned long psp)
{
      unsigned long fp, distance, rval;

      if (!(test_thread_flag(TIF_32BIT))) {
            csp += STACK_BIAS;
            psp += STACK_BIAS;
            __get_user(fp, &(((struct reg_window __user *)psp)->ins[6]));
            fp += STACK_BIAS;
      } else
            __get_user(fp, &(((struct reg_window32 __user *)psp)->ins[6]));

      /* Now 8-byte align the stack as this is mandatory in the
       * Sparc ABI due to how register windows work.  This hides
       * the restriction from thread libraries etc.  -DaveM
       */
      csp &= ~7UL;

      distance = fp - psp;
      rval = (csp - distance);
      if (copy_in_user((void __user *) rval, (void __user *) psp, distance))
            rval = 0;
      else if (test_thread_flag(TIF_32BIT)) {
            if (put_user(((u32)csp),
                       &(((struct reg_window32 __user *)rval)->ins[6])))
                  rval = 0;
      } else {
            if (put_user(((u64)csp - STACK_BIAS),
                       &(((struct reg_window __user *)rval)->ins[6])))
                  rval = 0;
            else
                  rval = rval - STACK_BIAS;
      }

      return rval;
}

/* Standard stuff. */
static inline void shift_window_buffer(int first_win, int last_win,
                               struct thread_info *t)
{
      int i;

      for (i = first_win; i < last_win; i++) {
            t->rwbuf_stkptrs[i] = t->rwbuf_stkptrs[i+1];
            memcpy(&t->reg_window[i], &t->reg_window[i+1],
                   sizeof(struct reg_window));
      }
}

void synchronize_user_stack(void)
{
      struct thread_info *t = current_thread_info();
      unsigned long window;

      flush_user_windows();
      if ((window = get_thread_wsaved()) != 0) {
            int winsize = sizeof(struct reg_window);
            int bias = 0;

            if (test_thread_flag(TIF_32BIT))
                  winsize = sizeof(struct reg_window32);
            else
                  bias = STACK_BIAS;

            window -= 1;
            do {
                  unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
                  struct reg_window *rwin = &t->reg_window[window];

                  if (!copy_to_user((char __user *)sp, rwin, winsize)) {
                        shift_window_buffer(window, get_thread_wsaved() - 1, t);
                        set_thread_wsaved(get_thread_wsaved() - 1);
                  }
            } while (window--);
      }
}

static void stack_unaligned(unsigned long sp)
{
      siginfo_t info;

      info.si_signo = SIGBUS;
      info.si_errno = 0;
      info.si_code = BUS_ADRALN;
      info.si_addr = (void __user *) sp;
      info.si_trapno = 0;
      force_sig_info(SIGBUS, &info, current);
}

void fault_in_user_windows(void)
{
      struct thread_info *t = current_thread_info();
      unsigned long window;
      int winsize = sizeof(struct reg_window);
      int bias = 0;

      if (test_thread_flag(TIF_32BIT))
            winsize = sizeof(struct reg_window32);
      else
            bias = STACK_BIAS;

      flush_user_windows();
      window = get_thread_wsaved();

      if (likely(window != 0)) {
            window -= 1;
            do {
                  unsigned long sp = (t->rwbuf_stkptrs[window] + bias);
                  struct reg_window *rwin = &t->reg_window[window];

                  if (unlikely(sp & 0x7UL))
                        stack_unaligned(sp);

                  if (unlikely(copy_to_user((char __user *)sp,
                                      rwin, winsize)))
                        goto barf;
            } while (window--);
      }
      set_thread_wsaved(0);
      return;

barf:
      set_thread_wsaved(window + 1);
      do_exit(SIGILL);
}

asmlinkage long sparc_do_fork(unsigned long clone_flags,
                        unsigned long stack_start,
                        struct pt_regs *regs,
                        unsigned long stack_size)
{
      int __user *parent_tid_ptr, *child_tid_ptr;

#ifdef CONFIG_COMPAT
      if (test_thread_flag(TIF_32BIT)) {
            parent_tid_ptr = compat_ptr(regs->u_regs[UREG_I2]);
            child_tid_ptr = compat_ptr(regs->u_regs[UREG_I4]);
      } else
#endif
      {
            parent_tid_ptr = (int __user *) regs->u_regs[UREG_I2];
            child_tid_ptr = (int __user *) regs->u_regs[UREG_I4];
      }

      return do_fork(clone_flags, stack_start,
                   regs, stack_size,
                   parent_tid_ptr, child_tid_ptr);
}

/* Copy a Sparc thread.  The fork() return value conventions
 * under SunOS are nothing short of bletcherous:
 * Parent -->  %o0 == childs  pid, %o1 == 0
 * Child  -->  %o0 == parents pid, %o1 == 1
 */
int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
            unsigned long unused,
            struct task_struct *p, struct pt_regs *regs)
{
      struct thread_info *t = task_thread_info(p);
      char *child_trap_frame;

      /* Calculate offset to stack_frame & pt_regs */
      child_trap_frame = task_stack_page(p) + (THREAD_SIZE - (TRACEREG_SZ+STACKFRAME_SZ));
      memcpy(child_trap_frame, (((struct sparc_stackf *)regs)-1), (TRACEREG_SZ+STACKFRAME_SZ));

      t->flags = (t->flags & ~((0xffUL << TI_FLAG_CWP_SHIFT) | (0xffUL << TI_FLAG_CURRENT_DS_SHIFT))) |
            (((regs->tstate + 1) & TSTATE_CWP) << TI_FLAG_CWP_SHIFT);
      t->new_child = 1;
      t->ksp = ((unsigned long) child_trap_frame) - STACK_BIAS;
      t->kregs = (struct pt_regs *)(child_trap_frame+sizeof(struct sparc_stackf));
      t->fpsaved[0] = 0;

      if (regs->tstate & TSTATE_PRIV) {
            /* Special case, if we are spawning a kernel thread from
             * a userspace task (via KMOD, NFS, or similar) we must
             * disable performance counters in the child because the
             * address space and protection realm are changing.
             */
            if (t->flags & _TIF_PERFCTR) {
                  t->user_cntd0 = t->user_cntd1 = NULL;
                  t->pcr_reg = 0;
                  t->flags &= ~_TIF_PERFCTR;
            }
            t->kregs->u_regs[UREG_FP] = t->ksp;
            t->flags |= ((long)ASI_P << TI_FLAG_CURRENT_DS_SHIFT);
            flush_register_windows();
            memcpy((void *)(t->ksp + STACK_BIAS),
                   (void *)(regs->u_regs[UREG_FP] + STACK_BIAS),
                   sizeof(struct sparc_stackf));
            t->kregs->u_regs[UREG_G6] = (unsigned long) t;
            t->kregs->u_regs[UREG_G4] = (unsigned long) t->task;
      } else {
            if (t->flags & _TIF_32BIT) {
                  sp &= 0x00000000ffffffffUL;
                  regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
            }
            t->kregs->u_regs[UREG_FP] = sp;
            t->flags |= ((long)ASI_AIUS << TI_FLAG_CURRENT_DS_SHIFT);
            if (sp != regs->u_regs[UREG_FP]) {
                  unsigned long csp;

                  csp = clone_stackframe(sp, regs->u_regs[UREG_FP]);
                  if (!csp)
                        return -EFAULT;
                  t->kregs->u_regs[UREG_FP] = csp;
            }
            if (t->utraps)
                  t->utraps[0]++;
      }

      /* Set the return value for the child. */
      t->kregs->u_regs[UREG_I0] = current->pid;
      t->kregs->u_regs[UREG_I1] = 1;

      /* Set the second return value for the parent. */
      regs->u_regs[UREG_I1] = 0;

      if (clone_flags & CLONE_SETTLS)
            t->kregs->u_regs[UREG_G7] = regs->u_regs[UREG_I3];

      return 0;
}

/*
 * This is the mechanism for creating a new kernel thread.
 *
 * NOTE! Only a kernel-only process(ie the swapper or direct descendants
 * who haven't done an "execve()") should use this: it will work within
 * a system call from a "real" process, but the process memory space will
 * not be freed until both the parent and the child have exited.
 */
pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
      long retval;

      /* If the parent runs before fn(arg) is called by the child,
       * the input registers of this function can be clobbered.
       * So we stash 'fn' and 'arg' into global registers which
       * will not be modified by the parent.
       */
      __asm__ __volatile__("mov %4, %%g2\n\t"      /* Save FN into global */
                       "mov %5, %%g3\n\t"    /* Save ARG into global */
                       "mov %1, %%g1\n\t"    /* Clone syscall nr. */
                       "mov %2, %%o0\n\t"    /* Clone flags. */
                       "mov 0, %%o1\n\t"     /* usp arg == 0 */
                       "t 0x6d\n\t"    /* Linux/Sparc clone(). */
                       "brz,a,pn %%o1, 1f\n\t" /* Parent, just return. */
                       " mov %%o0, %0\n\t"
                       "jmpl %%g2, %%o7\n\t"   /* Call the function. */
                       " mov %%g3, %%o0\n\t"   /* Set arg in delay. */
                       "mov %3, %%g1\n\t"
                       "t 0x6d\n\t"    /* Linux/Sparc exit(). */
                       /* Notreached by child. */
                       "1:" :
                       "=r" (retval) :
                       "i" (__NR_clone), "r" (flags | CLONE_VM | CLONE_UNTRACED),
                       "i" (__NR_exit),  "r" (fn), "r" (arg) :
                       "g1", "g2", "g3", "o0", "o1", "memory", "cc");
      return retval;
}

/*
 * fill in the user structure for a core dump..
 */
void dump_thread(struct pt_regs * regs, struct user * dump)
{
      /* Only should be used for SunOS and ancient a.out
       * SparcLinux binaries...  Not worth implementing.
       */
      memset(dump, 0, sizeof(struct user));
}

typedef struct {
      union {
            unsigned int      pr_regs[32];
            unsigned long     pr_dregs[16];
      } pr_fr;
      unsigned int __unused;
      unsigned int      pr_fsr;
      unsigned char     pr_qcnt;
      unsigned char     pr_q_entrysize;
      unsigned char     pr_en;
      unsigned int      pr_q[64];
} elf_fpregset_t32;

/*
 * fill in the fpu structure for a core dump.
 */
int dump_fpu (struct pt_regs * regs, elf_fpregset_t * fpregs)
{
      unsigned long *kfpregs = current_thread_info()->fpregs;
      unsigned long fprs = current_thread_info()->fpsaved[0];

      if (test_thread_flag(TIF_32BIT)) {
            elf_fpregset_t32 *fpregs32 = (elf_fpregset_t32 *)fpregs;

            if (fprs & FPRS_DL)
                  memcpy(&fpregs32->pr_fr.pr_regs[0], kfpregs,
                         sizeof(unsigned int) * 32);
            else
                  memset(&fpregs32->pr_fr.pr_regs[0], 0,
                         sizeof(unsigned int) * 32);
            fpregs32->pr_qcnt = 0;
            fpregs32->pr_q_entrysize = 8;
            memset(&fpregs32->pr_q[0], 0,
                   (sizeof(unsigned int) * 64));
            if (fprs & FPRS_FEF) {
                  fpregs32->pr_fsr = (unsigned int) current_thread_info()->xfsr[0];
                  fpregs32->pr_en = 1;
            } else {
                  fpregs32->pr_fsr = 0;
                  fpregs32->pr_en = 0;
            }
      } else {
            if(fprs & FPRS_DL)
                  memcpy(&fpregs->pr_regs[0], kfpregs,
                         sizeof(unsigned int) * 32);
            else
                  memset(&fpregs->pr_regs[0], 0,
                         sizeof(unsigned int) * 32);
            if(fprs & FPRS_DU)
                  memcpy(&fpregs->pr_regs[16], kfpregs+16,
                         sizeof(unsigned int) * 32);
            else
                  memset(&fpregs->pr_regs[16], 0,
                         sizeof(unsigned int) * 32);
            if(fprs & FPRS_FEF) {
                  fpregs->pr_fsr = current_thread_info()->xfsr[0];
                  fpregs->pr_gsr = current_thread_info()->gsr[0];
            } else {
                  fpregs->pr_fsr = fpregs->pr_gsr = 0;
            }
            fpregs->pr_fprs = fprs;
      }
      return 1;
}

/*
 * sparc_execve() executes a new program after the asm stub has set
 * things up for us.  This should basically do what I want it to.
 */
asmlinkage int sparc_execve(struct pt_regs *regs)
{
      int error, base = 0;
      char *filename;

      /* User register window flush is done by entry.S */

      /* Check for indirect call. */
      if (regs->u_regs[UREG_G1] == 0)
            base = 1;

      filename = getname((char __user *)regs->u_regs[base + UREG_I0]);
      error = PTR_ERR(filename);
      if (IS_ERR(filename))
            goto out;
      error = do_execve(filename,
                    (char __user * __user *)
                    regs->u_regs[base + UREG_I1],
                    (char __user * __user *)
                    regs->u_regs[base + UREG_I2], regs);
      putname(filename);
      if (!error) {
            fprs_write(0);
            current_thread_info()->xfsr[0] = 0;
            current_thread_info()->fpsaved[0] = 0;
            regs->tstate &= ~TSTATE_PEF;
            task_lock(current);
            current->ptrace &= ~PT_DTRACE;
            task_unlock(current);
      }
out:
      return error;
}

unsigned long get_wchan(struct task_struct *task)
{
      unsigned long pc, fp, bias = 0;
      unsigned long thread_info_base;
      struct reg_window *rw;
        unsigned long ret = 0;
      int count = 0; 

      if (!task || task == current ||
            task->state == TASK_RUNNING)
            goto out;

      thread_info_base = (unsigned long) task_stack_page(task);
      bias = STACK_BIAS;
      fp = task_thread_info(task)->ksp + bias;

      do {
            /* Bogus frame pointer? */
            if (fp < (thread_info_base + sizeof(struct thread_info)) ||
                fp >= (thread_info_base + THREAD_SIZE))
                  break;
            rw = (struct reg_window *) fp;
            pc = rw->ins[7];
            if (!in_sched_functions(pc)) {
                  ret = pc;
                  goto out;
            }
            fp = rw->ins[6] + bias;
      } while (++count < 16);

out:
      return ret;
}

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