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process_32.c

/*
 * arch/sh/kernel/process.c
 *
 * This file handles the architecture-dependent parts of process handling..
 *
 *  Copyright (C) 1995  Linus Torvalds
 *
 *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
 *               Copyright (C) 2006 Lineo Solutions Inc. support SH4A UBC
 *               Copyright (C) 2002 - 2007  Paul Mundt
 */
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/kallsyms.h>
#include <linux/kexec.h>
#include <linux/kdebug.h>
#include <linux/tick.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/preempt.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/ubc.h>
#include <asm/fpu.h>

static int hlt_counter;
int ubc_usercnt = 0;

void (*pm_idle)(void);
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);

static int __init nohlt_setup(char *__unused)
{
      hlt_counter = 1;
      return 1;
}
__setup("nohlt", nohlt_setup);

static int __init hlt_setup(char *__unused)
{
      hlt_counter = 0;
      return 1;
}
__setup("hlt", hlt_setup);

static void default_idle(void)
{
      if (!hlt_counter) {
            clear_thread_flag(TIF_POLLING_NRFLAG);
            smp_mb__after_clear_bit();
            set_bl_bit();
            while (!need_resched())
                  cpu_sleep();
            clear_bl_bit();
            set_thread_flag(TIF_POLLING_NRFLAG);
      } else
            while (!need_resched())
                  cpu_relax();
}

void cpu_idle(void)
{
      set_thread_flag(TIF_POLLING_NRFLAG);

      /* endless idle loop with no priority at all */
      while (1) {
            void (*idle)(void) = pm_idle;

            if (!idle)
                  idle = default_idle;

            tick_nohz_stop_sched_tick(1);
            while (!need_resched())
                  idle();
            tick_nohz_restart_sched_tick();

            preempt_enable_no_resched();
            schedule();
            preempt_disable();
            check_pgt_cache();
      }
}

void machine_restart(char * __unused)
{
      /* SR.BL=1 and invoke address error to let CPU reset (manual reset) */
      asm volatile("ldc %0, sr\n\t"
                 "mov.l @%1, %0" : : "r" (0x10000000), "r" (0x80000001));
}

void machine_halt(void)
{
      local_irq_disable();

      while (1)
            cpu_sleep();
}

void machine_power_off(void)
{
      if (pm_power_off)
            pm_power_off();
}

void show_regs(struct pt_regs * regs)
{
      printk("\n");
      printk("Pid : %d, Comm: %20s\n", task_pid_nr(current), current->comm);
      print_symbol("PC is at %s\n", instruction_pointer(regs));
      printk("PC  : %08lx SP  : %08lx SR  : %08lx ",
             regs->pc, regs->regs[15], regs->sr);
#ifdef CONFIG_MMU
      printk("TEA : %08x    ", ctrl_inl(MMU_TEA));
#else
      printk("                  ");
#endif
      printk("%s\n", print_tainted());

      printk("R0  : %08lx R1  : %08lx R2  : %08lx R3  : %08lx\n",
             regs->regs[0],regs->regs[1],
             regs->regs[2],regs->regs[3]);
      printk("R4  : %08lx R5  : %08lx R6  : %08lx R7  : %08lx\n",
             regs->regs[4],regs->regs[5],
             regs->regs[6],regs->regs[7]);
      printk("R8  : %08lx R9  : %08lx R10 : %08lx R11 : %08lx\n",
             regs->regs[8],regs->regs[9],
             regs->regs[10],regs->regs[11]);
      printk("R12 : %08lx R13 : %08lx R14 : %08lx\n",
             regs->regs[12],regs->regs[13],
             regs->regs[14]);
      printk("MACH: %08lx MACL: %08lx GBR : %08lx PR  : %08lx\n",
             regs->mach, regs->macl, regs->gbr, regs->pr);

      show_trace(NULL, (unsigned long *)regs->regs[15], regs);
}

/*
 * Create a kernel thread
 */

/*
 * This is the mechanism for creating a new kernel thread.
 *
 */
extern void kernel_thread_helper(void);
__asm__(".align 5\n"
      "kernel_thread_helper:\n\t"
      "jsr  @r5\n\t"
      " nop\n\t"
      "mov.l      1f, r1\n\t"
      "jsr  @r1\n\t"
      " mov r0, r4\n\t"
      ".align 2\n\t"
      "1:.long do_exit");

/* Don't use this in BL=1(cli).  Or else, CPU resets! */
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
      struct pt_regs regs;

      memset(&regs, 0, sizeof(regs));
      regs.regs[4] = (unsigned long)arg;
      regs.regs[5] = (unsigned long)fn;

      regs.pc = (unsigned long)kernel_thread_helper;
      regs.sr = (1 << 30);

      /* Ok, create the new process.. */
      return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0,
                   &regs, 0, NULL, NULL);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
      if (current->thread.ubc_pc) {
            current->thread.ubc_pc = 0;
            ubc_usercnt -= 1;
      }
}

void flush_thread(void)
{
#if defined(CONFIG_SH_FPU)
      struct task_struct *tsk = current;
      /* Forget lazy FPU state */
      clear_fpu(tsk, task_pt_regs(tsk));
      clear_used_math();
#endif
}

void release_thread(struct task_struct *dead_task)
{
      /* do nothing */
}

/* Fill in the fpu structure for a core dump.. */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
{
      int fpvalid = 0;

#if defined(CONFIG_SH_FPU)
      struct task_struct *tsk = current;

      fpvalid = !!tsk_used_math(tsk);
      if (fpvalid) {
            unlazy_fpu(tsk, regs);
            memcpy(fpu, &tsk->thread.fpu.hard, sizeof(*fpu));
      }
#endif

      return fpvalid;
}

asmlinkage void ret_from_fork(void);

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
            unsigned long unused,
            struct task_struct *p, struct pt_regs *regs)
{
      struct thread_info *ti = task_thread_info(p);
      struct pt_regs *childregs;
#if defined(CONFIG_SH_FPU)
      struct task_struct *tsk = current;

      unlazy_fpu(tsk, regs);
      p->thread.fpu = tsk->thread.fpu;
      copy_to_stopped_child_used_math(p);
#endif

      childregs = task_pt_regs(p);
      *childregs = *regs;

      if (user_mode(regs)) {
            childregs->regs[15] = usp;
            ti->addr_limit = USER_DS;
      } else {
            childregs->regs[15] = (unsigned long)childregs;
            ti->addr_limit = KERNEL_DS;
      }

      if (clone_flags & CLONE_SETTLS)
            childregs->gbr = childregs->regs[0];

      childregs->regs[0] = 0; /* Set return value for child */

      p->thread.sp = (unsigned long) childregs;
      p->thread.pc = (unsigned long) ret_from_fork;

      p->thread.ubc_pc = 0;

      return 0;
}

/* Tracing by user break controller.  */
static void ubc_set_tracing(int asid, unsigned long pc)
{
#if defined(CONFIG_CPU_SH4A)
      unsigned long val;

      val = (UBC_CBR_ID_INST | UBC_CBR_RW_READ | UBC_CBR_CE);
      val |= (UBC_CBR_AIE | UBC_CBR_AIV_SET(asid));

      ctrl_outl(val, UBC_CBR0);
      ctrl_outl(pc,  UBC_CAR0);
      ctrl_outl(0x0, UBC_CAMR0);
      ctrl_outl(0x0, UBC_CBCR);

      val = (UBC_CRR_RES | UBC_CRR_PCB | UBC_CRR_BIE);
      ctrl_outl(val, UBC_CRR0);

      /* Read UBC register that we wrote last, for checking update */
      val = ctrl_inl(UBC_CRR0);

#else /* CONFIG_CPU_SH4A */
      ctrl_outl(pc, UBC_BARA);

#ifdef CONFIG_MMU
      ctrl_outb(asid, UBC_BASRA);
#endif

      ctrl_outl(0, UBC_BAMRA);

      if (current_cpu_data.type == CPU_SH7729 ||
          current_cpu_data.type == CPU_SH7710 ||
          current_cpu_data.type == CPU_SH7712) {
            ctrl_outw(BBR_INST | BBR_READ | BBR_CPU, UBC_BBRA);
            ctrl_outl(BRCR_PCBA | BRCR_PCTE, UBC_BRCR);
      } else {
            ctrl_outw(BBR_INST | BBR_READ, UBC_BBRA);
            ctrl_outw(BRCR_PCBA, UBC_BRCR);
      }
#endif      /* CONFIG_CPU_SH4A */
}

/*
 *    switch_to(x,y) should switch tasks from x to y.
 *
 */
struct task_struct *__switch_to(struct task_struct *prev,
                        struct task_struct *next)
{
#if defined(CONFIG_SH_FPU)
      unlazy_fpu(prev, task_pt_regs(prev));
#endif

#ifdef CONFIG_MMU
      /*
       * Restore the kernel mode register
       *    k7 (r7_bank1)
       */
      asm volatile("ldc %0, r7_bank"
                 : /* no output */
                 : "r" (task_thread_info(next)));
#endif

      /* If no tasks are using the UBC, we're done */
      if (ubc_usercnt == 0)
            /* If no tasks are using the UBC, we're done */;
      else if (next->thread.ubc_pc && next->mm) {
            int asid = 0;
#ifdef CONFIG_MMU
            asid |= cpu_asid(smp_processor_id(), next->mm);
#endif
            ubc_set_tracing(asid, next->thread.ubc_pc);
      } else {
#if defined(CONFIG_CPU_SH4A)
            ctrl_outl(UBC_CBR_INIT, UBC_CBR0);
            ctrl_outl(UBC_CRR_INIT, UBC_CRR0);
#else
            ctrl_outw(0, UBC_BBRA);
            ctrl_outw(0, UBC_BBRB);
#endif
      }

      return prev;
}

asmlinkage int sys_fork(unsigned long r4, unsigned long r5,
                  unsigned long r6, unsigned long r7,
                  struct pt_regs __regs)
{
#ifdef CONFIG_MMU
      struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
      return do_fork(SIGCHLD, regs->regs[15], regs, 0, NULL, NULL);
#else
      /* fork almost works, enough to trick you into looking elsewhere :-( */
      return -EINVAL;
#endif
}

asmlinkage int sys_clone(unsigned long clone_flags, unsigned long newsp,
                   unsigned long parent_tidptr,
                   unsigned long child_tidptr,
                   struct pt_regs __regs)
{
      struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
      if (!newsp)
            newsp = regs->regs[15];
      return do_fork(clone_flags, newsp, regs, 0,
                  (int __user *)parent_tidptr,
                  (int __user *)child_tidptr);
}

/*
 * This is trivial, and on the face of it looks like it
 * could equally well be done in user mode.
 *
 * Not so, for quite unobvious reasons - register pressure.
 * In user mode vfork() cannot have a stack frame, and if
 * done by calling the "clone()" system call directly, you
 * do not have enough call-clobbered registers to hold all
 * the information you need.
 */
asmlinkage int sys_vfork(unsigned long r4, unsigned long r5,
                   unsigned long r6, unsigned long r7,
                   struct pt_regs __regs)
{
      struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
      return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->regs[15], regs,
                   0, NULL, NULL);
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage int sys_execve(char __user *ufilename, char __user * __user *uargv,
                    char __user * __user *uenvp, unsigned long r7,
                    struct pt_regs __regs)
{
      struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
      int error;
      char *filename;

      filename = getname(ufilename);
      error = PTR_ERR(filename);
      if (IS_ERR(filename))
            goto out;

      error = do_execve(filename, uargv, uenvp, regs);
      if (error == 0) {
            task_lock(current);
            current->ptrace &= ~PT_DTRACE;
            task_unlock(current);
      }
      putname(filename);
out:
      return error;
}

unsigned long get_wchan(struct task_struct *p)
{
      unsigned long pc;

      if (!p || p == current || p->state == TASK_RUNNING)
            return 0;

      /*
       * The same comment as on the Alpha applies here, too ...
       */
      pc = thread_saved_pc(p);

#ifdef CONFIG_FRAME_POINTER
      if (in_sched_functions(pc)) {
            unsigned long schedule_frame = (unsigned long)p->thread.sp;
            return ((unsigned long *)schedule_frame)[21];
      }
#endif

      return pc;
}

asmlinkage void break_point_trap(void)
{
      /* Clear tracing.  */
#if defined(CONFIG_CPU_SH4A)
      ctrl_outl(UBC_CBR_INIT, UBC_CBR0);
      ctrl_outl(UBC_CRR_INIT, UBC_CRR0);
#else
      ctrl_outw(0, UBC_BBRA);
      ctrl_outw(0, UBC_BBRB);
#endif
      current->thread.ubc_pc = 0;
      ubc_usercnt -= 1;

      force_sig(SIGTRAP, current);
}

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