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process.c

/*
 * Blackfin architecture-dependent process handling
 *
 * Copyright 2004-2009 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later
 */

#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/unistd.h>
#include <linux/user.h>
#include <linux/uaccess.h>
#include <linux/sched.h>
#include <linux/tick.h>
#include <linux/fs.h>
#include <linux/err.h>

#include <asm/blackfin.h>
#include <asm/fixed_code.h>
#include <asm/mem_map.h>

asmlinkage void ret_from_fork(void);

/* Points to the SDRAM backup memory for the stack that is currently in
 * L1 scratchpad memory.
 */
void *current_l1_stack_save;

/* The number of tasks currently using a L1 stack area.  The SRAM is
 * allocated/deallocated whenever this changes from/to zero.
 */
int nr_l1stack_tasks;

/* Start and length of the area in L1 scratchpad memory which we've allocated
 * for process stacks.
 */
void *l1_stack_base;
unsigned long l1_stack_len;

/*
 * Powermanagement idle function, if any..
 */
void (*pm_idle)(void) = NULL;
EXPORT_SYMBOL(pm_idle);

void (*pm_power_off)(void) = NULL;
EXPORT_SYMBOL(pm_power_off);

/*
 * The idle loop on BFIN
 */
#ifdef CONFIG_IDLE_L1
static void default_idle(void)__attribute__((l1_text));
void cpu_idle(void)__attribute__((l1_text));
#endif

/*
 * This is our default idle handler.  We need to disable
 * interrupts here to ensure we don't miss a wakeup call.
 */
static void default_idle(void)
{
#ifdef CONFIG_IPIPE
      ipipe_suspend_domain();
#endif
      local_irq_disable_hw();
      if (!need_resched())
            idle_with_irq_disabled();

      local_irq_enable_hw();
}

/*
 * The idle thread.  We try to conserve power, while trying to keep
 * overall latency low.  The architecture specific idle is passed
 * a value to indicate the level of "idleness" of the system.
 */
void cpu_idle(void)
{
      /* endless idle loop with no priority at all */
      while (1) {
            void (*idle)(void) = pm_idle;

#ifdef CONFIG_HOTPLUG_CPU
            if (cpu_is_offline(smp_processor_id()))
                  cpu_die();
#endif
            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();
      }
}

/* Fill in the fpu structure for a core dump.  */

int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpregs)
{
      return 1;
}

/*
 * This gets run with P1 containing the
 * function to call, and R1 containing
 * the "args".  Note P0 is clobbered on the way here.
 */
void kernel_thread_helper(void);
__asm__(".section .text\n"
      ".align 4\n"
      "_kernel_thread_helper:\n\t"
      "\tsp += -12;\n\t"
      "\tr0 = r1;\n\t" "\tcall (p1);\n\t" "\tcall _do_exit;\n" ".previous");

/*
 * Create a kernel thread.
 */
pid_t kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
{
      struct pt_regs regs;

      memset(&regs, 0, sizeof(regs));

      regs.r1 = (unsigned long)arg;
      regs.p1 = (unsigned long)fn;
      regs.pc = (unsigned long)kernel_thread_helper;
      regs.orig_p0 = -1;
      /* Set bit 2 to tell ret_from_fork we should be returning to kernel
         mode.  */
      regs.ipend = 0x8002;
      __asm__ __volatile__("%0 = syscfg;":"=da"(regs.syscfg):);
      return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL,
                   NULL);
}
EXPORT_SYMBOL(kernel_thread);

/*
 * Do necessary setup to start up a newly executed thread.
 *
 * pass the data segment into user programs if it exists,
 * it can't hurt anything as far as I can tell
 */
void start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
{
      set_fs(USER_DS);
      regs->pc = new_ip;
      if (current->mm)
            regs->p5 = current->mm->start_data;
#ifndef CONFIG_SMP
      task_thread_info(current)->l1_task_info.stack_start =
            (void *)current->mm->context.stack_start;
      task_thread_info(current)->l1_task_info.lowest_sp = (void *)new_sp;
      memcpy(L1_SCRATCH_TASK_INFO, &task_thread_info(current)->l1_task_info,
             sizeof(*L1_SCRATCH_TASK_INFO));
#endif
      wrusp(new_sp);
}
EXPORT_SYMBOL_GPL(start_thread);

void flush_thread(void)
{
}

asmlinkage int bfin_vfork(struct pt_regs *regs)
{
      return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0, NULL,
                   NULL);
}

asmlinkage int bfin_clone(struct pt_regs *regs)
{
      unsigned long clone_flags;
      unsigned long newsp;

#ifdef __ARCH_SYNC_CORE_DCACHE
      if (current->rt.nr_cpus_allowed == num_possible_cpus()) {
            current->cpus_allowed = cpumask_of_cpu(smp_processor_id());
            current->rt.nr_cpus_allowed = 1;
      }
#endif

      /* syscall2 puts clone_flags in r0 and usp in r1 */
      clone_flags = regs->r0;
      newsp = regs->r1;
      if (!newsp)
            newsp = rdusp();
      else
            newsp -= 12;
      return do_fork(clone_flags, newsp, regs, 0, NULL, NULL);
}

int
copy_thread(unsigned long clone_flags,
          unsigned long usp, unsigned long topstk,
          struct task_struct *p, struct pt_regs *regs)
{
      struct pt_regs *childregs;

      childregs = (struct pt_regs *) (task_stack_page(p) + THREAD_SIZE) - 1;
      *childregs = *regs;
      childregs->r0 = 0;

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

      return 0;
}

/*
 * sys_execve() executes a new program.
 */

asmlinkage int sys_execve(char __user *name, char __user * __user *argv, char __user * __user *envp)
{
      int error;
      char *filename;
      struct pt_regs *regs = (struct pt_regs *)((&name) + 6);

      lock_kernel();
      filename = getname(name);
      error = PTR_ERR(filename);
      if (IS_ERR(filename))
            goto out;
      error = do_execve(filename, argv, envp, regs);
      putname(filename);
 out:
      unlock_kernel();
      return error;
}

unsigned long get_wchan(struct task_struct *p)
{
      unsigned long fp, pc;
      unsigned long stack_page;
      int count = 0;
      if (!p || p == current || p->state == TASK_RUNNING)
            return 0;

      stack_page = (unsigned long)p;
      fp = p->thread.usp;
      do {
            if (fp < stack_page + sizeof(struct thread_info) ||
                fp >= 8184 + stack_page)
                  return 0;
            pc = ((unsigned long *)fp)[1];
            if (!in_sched_functions(pc))
                  return pc;
            fp = *(unsigned long *)fp;
      }
      while (count++ < 16);
      return 0;
}

void finish_atomic_sections (struct pt_regs *regs)
{
      int __user *up0 = (int __user *)regs->p0;

      switch (regs->pc) {
      case ATOMIC_XCHG32 + 2:
            put_user(regs->r1, up0);
            regs->pc = ATOMIC_XCHG32 + 4;
            break;

      case ATOMIC_CAS32 + 2:
      case ATOMIC_CAS32 + 4:
            if (regs->r0 == regs->r1)
      case ATOMIC_CAS32 + 6:
                  put_user(regs->r2, up0);
            regs->pc = ATOMIC_CAS32 + 8;
            break;

      case ATOMIC_ADD32 + 2:
            regs->r0 = regs->r1 + regs->r0;
            /* fall through */
      case ATOMIC_ADD32 + 4:
            put_user(regs->r0, up0);
            regs->pc = ATOMIC_ADD32 + 6;
            break;

      case ATOMIC_SUB32 + 2:
            regs->r0 = regs->r1 - regs->r0;
            /* fall through */
      case ATOMIC_SUB32 + 4:
            put_user(regs->r0, up0);
            regs->pc = ATOMIC_SUB32 + 6;
            break;

      case ATOMIC_IOR32 + 2:
            regs->r0 = regs->r1 | regs->r0;
            /* fall through */
      case ATOMIC_IOR32 + 4:
            put_user(regs->r0, up0);
            regs->pc = ATOMIC_IOR32 + 6;
            break;

      case ATOMIC_AND32 + 2:
            regs->r0 = regs->r1 & regs->r0;
            /* fall through */
      case ATOMIC_AND32 + 4:
            put_user(regs->r0, up0);
            regs->pc = ATOMIC_AND32 + 6;
            break;

      case ATOMIC_XOR32 + 2:
            regs->r0 = regs->r1 ^ regs->r0;
            /* fall through */
      case ATOMIC_XOR32 + 4:
            put_user(regs->r0, up0);
            regs->pc = ATOMIC_XOR32 + 6;
            break;
      }
}

static inline
int in_mem(unsigned long addr, unsigned long size,
           unsigned long start, unsigned long end)
{
      return addr >= start && addr + size <= end;
}
static inline
int in_mem_const_off(unsigned long addr, unsigned long size, unsigned long off,
                     unsigned long const_addr, unsigned long const_size)
{
      return const_size &&
             in_mem(addr, size, const_addr + off, const_addr + const_size);
}
static inline
int in_mem_const(unsigned long addr, unsigned long size,
                 unsigned long const_addr, unsigned long const_size)
{
      return in_mem_const_off(addr, size, 0, const_addr, const_size);
}
#define IN_ASYNC(bnum, bctlnum) \
({ \
      (bfin_read_EBIU_AMGCTL() & 0xe) < ((bnum + 1) << 1) ? -EFAULT : \
      bfin_read_EBIU_AMBCTL##bctlnum() & B##bnum##RDYEN ? -EFAULT : \
      BFIN_MEM_ACCESS_CORE; \
})

int bfin_mem_access_type(unsigned long addr, unsigned long size)
{
      int cpu = raw_smp_processor_id();

      /* Check that things do not wrap around */
      if (addr > ULONG_MAX - size)
            return -EFAULT;

      if (in_mem(addr, size, FIXED_CODE_START, physical_mem_end))
            return BFIN_MEM_ACCESS_CORE;

      if (in_mem_const(addr, size, L1_CODE_START, L1_CODE_LENGTH))
            return cpu == 0 ? BFIN_MEM_ACCESS_ITEST : BFIN_MEM_ACCESS_IDMA;
      if (in_mem_const(addr, size, L1_SCRATCH_START, L1_SCRATCH_LENGTH))
            return cpu == 0 ? BFIN_MEM_ACCESS_CORE_ONLY : -EFAULT;
      if (in_mem_const(addr, size, L1_DATA_A_START, L1_DATA_A_LENGTH))
            return cpu == 0 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
      if (in_mem_const(addr, size, L1_DATA_B_START, L1_DATA_B_LENGTH))
            return cpu == 0 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
#ifdef COREB_L1_CODE_START
      if (in_mem_const(addr, size, COREB_L1_CODE_START, COREB_L1_CODE_LENGTH))
            return cpu == 1 ? BFIN_MEM_ACCESS_ITEST : BFIN_MEM_ACCESS_IDMA;
      if (in_mem_const(addr, size, COREB_L1_SCRATCH_START, L1_SCRATCH_LENGTH))
            return cpu == 1 ? BFIN_MEM_ACCESS_CORE_ONLY : -EFAULT;
      if (in_mem_const(addr, size, COREB_L1_DATA_A_START, COREB_L1_DATA_A_LENGTH))
            return cpu == 1 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
      if (in_mem_const(addr, size, COREB_L1_DATA_B_START, COREB_L1_DATA_B_LENGTH))
            return cpu == 1 ? BFIN_MEM_ACCESS_CORE : BFIN_MEM_ACCESS_IDMA;
#endif
      if (in_mem_const(addr, size, L2_START, L2_LENGTH))
            return BFIN_MEM_ACCESS_CORE;

      if (addr >= SYSMMR_BASE)
            return BFIN_MEM_ACCESS_CORE_ONLY;

      /* We can't read EBIU banks that aren't enabled or we end up hanging
       * on the access to the async space.
       */
      if (in_mem_const(addr, size, ASYNC_BANK0_BASE, ASYNC_BANK0_SIZE))
            return IN_ASYNC(0, 0);
      if (in_mem_const(addr, size, ASYNC_BANK1_BASE, ASYNC_BANK1_SIZE))
            return IN_ASYNC(1, 0);
      if (in_mem_const(addr, size, ASYNC_BANK2_BASE, ASYNC_BANK2_SIZE))
            return IN_ASYNC(2, 1);
      if (in_mem_const(addr, size, ASYNC_BANK3_BASE, ASYNC_BANK3_SIZE))
            return IN_ASYNC(3, 1);

      if (in_mem_const(addr, size, BOOT_ROM_START, BOOT_ROM_LENGTH))
            return BFIN_MEM_ACCESS_CORE;
      if (in_mem_const(addr, size, L1_ROM_START, L1_ROM_LENGTH))
            return BFIN_MEM_ACCESS_DMA;

      return -EFAULT;
}

#if defined(CONFIG_ACCESS_CHECK)
#ifdef CONFIG_ACCESS_OK_L1
__attribute__((l1_text))
#endif
/* Return 1 if access to memory range is OK, 0 otherwise */
int _access_ok(unsigned long addr, unsigned long size)
{
      if (size == 0)
            return 1;
      /* Check that things do not wrap around */
      if (addr > ULONG_MAX - size)
            return 0;
      if (segment_eq(get_fs(), KERNEL_DS))
            return 1;
#ifdef CONFIG_MTD_UCLINUX
      if (1)
#else
      if (0)
#endif
      {
            if (in_mem(addr, size, memory_start, memory_end))
                  return 1;
            if (in_mem(addr, size, memory_mtd_end, physical_mem_end))
                  return 1;
# ifndef CONFIG_ROMFS_ON_MTD
            if (0)
# endif
                  /* For XIP, allow user space to use pointers within the ROMFS.  */
                  if (in_mem(addr, size, memory_mtd_start, memory_mtd_end))
                        return 1;
      } else {
            if (in_mem(addr, size, memory_start, physical_mem_end))
                  return 1;
      }

      if (in_mem(addr, size, (unsigned long)__init_begin, (unsigned long)__init_end))
            return 1;

      if (in_mem_const(addr, size, L1_CODE_START, L1_CODE_LENGTH))
            return 1;
      if (in_mem_const_off(addr, size, _etext_l1 - _stext_l1, L1_CODE_START, L1_CODE_LENGTH))
            return 1;
      if (in_mem_const_off(addr, size, _ebss_l1 - _sdata_l1, L1_DATA_A_START, L1_DATA_A_LENGTH))
            return 1;
      if (in_mem_const_off(addr, size, _ebss_b_l1 - _sdata_b_l1, L1_DATA_B_START, L1_DATA_B_LENGTH))
            return 1;
#ifdef COREB_L1_CODE_START
      if (in_mem_const(addr, size, COREB_L1_CODE_START, COREB_L1_CODE_LENGTH))
            return 1;
      if (in_mem_const(addr, size, COREB_L1_SCRATCH_START, L1_SCRATCH_LENGTH))
            return 1;
      if (in_mem_const(addr, size, COREB_L1_DATA_A_START, COREB_L1_DATA_A_LENGTH))
            return 1;
      if (in_mem_const(addr, size, COREB_L1_DATA_B_START, COREB_L1_DATA_B_LENGTH))
            return 1;
#endif
      if (in_mem_const_off(addr, size, _ebss_l2 - _stext_l2, L2_START, L2_LENGTH))
            return 1;

      if (in_mem_const(addr, size, BOOT_ROM_START, BOOT_ROM_LENGTH))
            return 1;
      if (in_mem_const(addr, size, L1_ROM_START, L1_ROM_LENGTH))
            return 1;

      return 0;
}
EXPORT_SYMBOL(_access_ok);
#endif /* CONFIG_ACCESS_CHECK */

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