process.c

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

#include <linux/module.h>
#include <linux/unistd.h>
#include <linux/user.h>
#include <linux/uaccess.h>
#include <linux/slab.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>
#include <asm/irq.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
    hard_local_irq_disable();
    if (!need_resched())
        idle_with_irq_disabled();

    hard_local_irq_enable();
}

/*
 * 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_idle_enter();
        rcu_idle_enter();
        while (!need_resched())
            idle();
        rcu_idle_exit();
        tick_nohz_idle_exit();
        preempt_enable_no_resched();
        schedule();
        preempt_disable();
    }
}

/*
 * 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)
{
    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->nr_cpus_allowed == num_possible_cpus())
        set_cpus_allowed_ptr(current, cpumask_of(smp_processor_id()));
#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(const char __user *name,
              const char __user *const __user *argv,
              const char __user *const __user *envp)
{
    int error;
    struct filename *filename;
    struct pt_regs *regs = (struct pt_regs *)((&name) + 6);

    filename = getname(name);
    error = PTR_ERR(filename);
    if (IS_ERR(filename))
        return error;
    error = do_execve(filename->name, argv, envp, regs);
    putname(filename);
    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) {
    default:
        /* not in middle of an atomic step, so resume like normal */
        return;

    case ATOMIC_XCHG32 + 2:
        put_user(regs->r1, up0);
        break;

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

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

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

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

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

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

    /*
     * We've finished the atomic section, and the only thing left for
     * userspace is to do a RTS, so we might as well handle that too
     * since we need to update the PC anyways.
     */
    regs->pc = regs->rets;
}

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);
}
#ifdef CONFIG_BF60x
#define ASYNC_ENABLED(bnum, bctlnum)    1
#else
#define ASYNC_ENABLED(bnum, bctlnum) \
({ \
    (bfin_read_EBIU_AMGCTL() & 0xe) < ((bnum + 1) << 1) ? 0 : \
    bfin_read_EBIU_AMBCTL##bctlnum() & B##bnum##RDYEN ? 0 : \
    1; \
})
#endif
/*
 * We can't read EBIU banks that aren't enabled or we end up hanging
 * on the access to the async space.  Make sure we validate accesses
 * that cross async banks too.
 *  0 - found, but unusable
 *  1 - found & usable
 *  2 - not found
 */
static
int in_async(unsigned long addr, unsigned long size)
{
    if (addr >= ASYNC_BANK0_BASE && addr < ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE) {
        if (!ASYNC_ENABLED(0, 0))
            return 0;
        if (addr + size <= ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE)
            return 1;
        size -= ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE - addr;
        addr = ASYNC_BANK0_BASE + ASYNC_BANK0_SIZE;
    }
    if (addr >= ASYNC_BANK1_BASE && addr < ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE) {
        if (!ASYNC_ENABLED(1, 0))
            return 0;
        if (addr + size <= ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE)
            return 1;
        size -= ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE - addr;
        addr = ASYNC_BANK1_BASE + ASYNC_BANK1_SIZE;
    }
    if (addr >= ASYNC_BANK2_BASE && addr < ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE) {
        if (!ASYNC_ENABLED(2, 1))
            return 0;
        if (addr + size <= ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE)
            return 1;
        size -= ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE - addr;
        addr = ASYNC_BANK2_BASE + ASYNC_BANK2_SIZE;
    }
    if (addr >= ASYNC_BANK3_BASE && addr < ASYNC_BANK3_BASE + ASYNC_BANK3_SIZE) {
        if (ASYNC_ENABLED(3, 1))
            return 0;
        if (addr + size <= ASYNC_BANK3_BASE + ASYNC_BANK3_SIZE)
            return 1;
        return 0;
    }

    /* not within async bounds */
    return 2;
}

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;

    switch (in_async(addr, size)) {
    case 0: return -EFAULT;
    case 1: return BFIN_MEM_ACCESS_CORE;
    case 2: /* fall through */;
    }

    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)
{
    int aret;

    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

#ifndef CONFIG_EXCEPTION_L1_SCRATCH
    if (in_mem_const(addr, size, (unsigned long)l1_stack_base, l1_stack_len))
        return 1;
#endif

    aret = in_async(addr, size);
    if (aret < 2)
        return aret;

    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 */