[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / powerpc / kernel / process.c

/*
 *  arch/ppc/kernel/process.c
 *
 *  Derived from "arch/i386/kernel/process.c"
 *    Copyright (C) 1995  Linus Torvalds
 *
 *  Updated and modified by Cort Dougan (cort@cs.nmt.edu) and
 *  Paul Mackerras (paulus@cs.anu.edu.au)
 *
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/init.h>
#include <linux/prctl.h>
#include <linux/init_task.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/mqueue.h>
#include <linux/hardirq.h>
#include <linux/utsname.h>
#include <linux/kprobes.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/prom.h>
#include <asm/machdep.h>
#ifdef CONFIG_PPC64
#include <asm/firmware.h>
#include <asm/time.h>
#endif

extern unsigned long _get_SP(void);

#ifndef CONFIG_SMP
struct task_struct *last_task_used_math = NULL;
struct task_struct *last_task_used_altivec = NULL;
struct task_struct *last_task_used_spe = NULL;
#endif

/*
 * Make sure the floating-point register state in the
 * the thread_struct is up to date for task tsk.
 */
void flush_fp_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                /*
                 * We need to disable preemption here because if we didn't,
                 * another process could get scheduled after the regs->msr
                 * test but before we have finished saving the FP registers
                 * to the thread_struct.  That process could take over the
                 * FPU, and then when we get scheduled again we would store
                 * bogus values for the remaining FP registers.
                 */
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_FP) {
#ifdef CONFIG_SMP
                        /*
                         * This should only ever be called for current or
                         * for a stopped child process.  Since we save away
                         * the FP register state on context switch on SMP,
                         * there is something wrong if a stopped child appears
                         * to still have its FP state in the CPU registers.
                         */
                        BUG_ON(tsk != current);
#endif
                        giveup_fpu(current);
                }
                preempt_enable();
        }
}

void enable_kernel_fp(void)
{
        WARN_ON(preemptible());

#ifdef CONFIG_SMP
        if (current->thread.regs && (current->thread.regs->msr & MSR_FP))
                giveup_fpu(current);
        else
                giveup_fpu(NULL);       /* just enables FP for kernel */
#else
        giveup_fpu(last_task_used_math);
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL(enable_kernel_fp);

int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
{
        if (!tsk->thread.regs)
                return 0;
        flush_fp_to_thread(current);

        memcpy(fpregs, &tsk->thread.fpr[0], sizeof(*fpregs));

        return 1;
}

#ifdef CONFIG_ALTIVEC
void enable_kernel_altivec(void)
{
        WARN_ON(preemptible());

#ifdef CONFIG_SMP
        if (current->thread.regs && (current->thread.regs->msr & MSR_VEC))
                giveup_altivec(current);
        else
                giveup_altivec(NULL);   /* just enable AltiVec for kernel - force */
#else
        giveup_altivec(last_task_used_altivec);
#endif /* CONFIG_SMP */
}
EXPORT_SYMBOL(enable_kernel_altivec);

/*
 * Make sure the VMX/Altivec register state in the
 * the thread_struct is up to date for task tsk.
 */
void flush_altivec_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_VEC) {
#ifdef CONFIG_SMP
                        BUG_ON(tsk != current);
#endif
                        giveup_altivec(current);
                }
                preempt_enable();
        }
}

int dump_task_altivec(struct pt_regs *regs, elf_vrregset_t *vrregs)
{
        flush_altivec_to_thread(current);
        memcpy(vrregs, &current->thread.vr[0], sizeof(*vrregs));
        return 1;
}
#endif /* CONFIG_ALTIVEC */

#ifdef CONFIG_SPE

void enable_kernel_spe(void)
{
        WARN_ON(preemptible());

#ifdef CONFIG_SMP
        if (current->thread.regs && (current->thread.regs->msr & MSR_SPE))
                giveup_spe(current);
        else
                giveup_spe(NULL);       /* just enable SPE for kernel - force */
#else
        giveup_spe(last_task_used_spe);
#endif /* __SMP __ */
}
EXPORT_SYMBOL(enable_kernel_spe);

void flush_spe_to_thread(struct task_struct *tsk)
{
        if (tsk->thread.regs) {
                preempt_disable();
                if (tsk->thread.regs->msr & MSR_SPE) {
#ifdef CONFIG_SMP
                        BUG_ON(tsk != current);
#endif
                        giveup_spe(current);
                }
                preempt_enable();
        }
}

int dump_spe(struct pt_regs *regs, elf_vrregset_t *evrregs)
{
        flush_spe_to_thread(current);
        /* We copy u32 evr[32] + u64 acc + u32 spefscr -> 35 */
        memcpy(evrregs, &current->thread.evr[0], sizeof(u32) * 35);
        return 1;
}
#endif /* CONFIG_SPE */

int set_dabr(unsigned long dabr)
{
        if (ppc_md.set_dabr)
                return ppc_md.set_dabr(dabr);

        mtspr(SPRN_DABR, dabr);
        return 0;
}

#ifdef CONFIG_PPC64
DEFINE_PER_CPU(struct cpu_usage, cpu_usage_array);
static DEFINE_PER_CPU(unsigned long, current_dabr);
#endif

struct task_struct *__switch_to(struct task_struct *prev,
        struct task_struct *new)
{
        struct thread_struct *new_thread, *old_thread;
        unsigned long flags;
        struct task_struct *last;

#ifdef CONFIG_SMP
        /* avoid complexity of lazy save/restore of fpu
         * by just saving it every time we switch out if
         * this task used the fpu during the last quantum.
         *
         * If it tries to use the fpu again, it'll trap and
         * reload its fp regs.  So we don't have to do a restore
         * every switch, just a save.
         *  -- Cort
         */
        if (prev->thread.regs && (prev->thread.regs->msr & MSR_FP))
                giveup_fpu(prev);
#ifdef CONFIG_ALTIVEC
        /*
         * If the previous thread used altivec in the last quantum
         * (thus changing altivec regs) then save them.
         * We used to check the VRSAVE register but not all apps
         * set it, so we don't rely on it now (and in fact we need
         * to save & restore VSCR even if VRSAVE == 0).  -- paulus
         *
         * On SMP we always save/restore altivec regs just to avoid the
         * complexity of changing processors.
         *  -- Cort
         */
        if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
                giveup_altivec(prev);
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
        /*
         * If the previous thread used spe in the last quantum
         * (thus changing spe regs) then save them.
         *
         * On SMP we always save/restore spe regs just to avoid the
         * complexity of changing processors.
         */
        if ((prev->thread.regs && (prev->thread.regs->msr & MSR_SPE)))
                giveup_spe(prev);
#endif /* CONFIG_SPE */

#else  /* CONFIG_SMP */
#ifdef CONFIG_ALTIVEC
        /* Avoid the trap.  On smp this this never happens since
         * we don't set last_task_used_altivec -- Cort
         */
        if (new->thread.regs && last_task_used_altivec == new)
                new->thread.regs->msr |= MSR_VEC;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
        /* Avoid the trap.  On smp this this never happens since
         * we don't set last_task_used_spe
         */
        if (new->thread.regs && last_task_used_spe == new)
                new->thread.regs->msr |= MSR_SPE;
#endif /* CONFIG_SPE */

#endif /* CONFIG_SMP */

#ifdef CONFIG_PPC64     /* for now */
        if (unlikely(__get_cpu_var(current_dabr) != new->thread.dabr)) {
                set_dabr(new->thread.dabr);
                __get_cpu_var(current_dabr) = new->thread.dabr;
        }

        flush_tlb_pending();
#endif

        new_thread = &new->thread;
        old_thread = &current->thread;

#ifdef CONFIG_PPC64
        /*
         * Collect processor utilization data per process
         */
        if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
                struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
                long unsigned start_tb, current_tb;
                start_tb = old_thread->start_tb;
                cu->current_tb = current_tb = mfspr(SPRN_PURR);
                old_thread->accum_tb += (current_tb - start_tb);
                new_thread->start_tb = current_tb;
        }
#endif

        local_irq_save(flags);
        last = _switch(old_thread, new_thread);

        local_irq_restore(flags);

        return last;
}

static int instructions_to_print = 16;

#ifdef CONFIG_PPC64
#define BAD_PC(pc)      ((REGION_ID(pc) != KERNEL_REGION_ID) && \
                         (REGION_ID(pc) != VMALLOC_REGION_ID))
#else
#define BAD_PC(pc)      ((pc) < KERNELBASE)
#endif

static void show_instructions(struct pt_regs *regs)
{
        int i;
        unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
                        sizeof(int));

        printk("Instruction dump:");

        for (i = 0; i < instructions_to_print; i++) {
                int instr;

                if (!(i % 8))
                        printk("\n");

                if (BAD_PC(pc) || __get_user(instr, (unsigned int *)pc)) {
                        printk("XXXXXXXX ");
                } else {
                        if (regs->nip == pc)
                                printk("<%08x> ", instr);
                        else
                                printk("%08x ", instr);
                }

                pc += sizeof(int);
        }

        printk("\n");
}

static struct regbit {
        unsigned long bit;
        const char *name;
} msr_bits[] = {
        {MSR_EE,        "EE"},
        {MSR_PR,        "PR"},
        {MSR_FP,        "FP"},
        {MSR_ME,        "ME"},
        {MSR_IR,        "IR"},
        {MSR_DR,        "DR"},
        {0,             NULL}
};

static void printbits(unsigned long val, struct regbit *bits)
{
        const char *sep = "";

        printk("<");
        for (; bits->bit; ++bits)
                if (val & bits->bit) {
                        printk("%s%s", sep, bits->name);
                        sep = ",";
                }
        printk(">");
}

#ifdef CONFIG_PPC64
#define REG             "%016lX"
#define REGS_PER_LINE   4
#define LAST_VOLATILE   13
#else
#define REG             "%08lX"
#define REGS_PER_LINE   8
#define LAST_VOLATILE   12
#endif

void show_regs(struct pt_regs * regs)
{
        int i, trap;

        printk("NIP: "REG" LR: "REG" CTR: "REG"\n",
               regs->nip, regs->link, regs->ctr);
        printk("REGS: %p TRAP: %04lx   %s  (%s)\n",
               regs, regs->trap, print_tainted(), system_utsname.release);
        printk("MSR: "REG" ", regs->msr);
        printbits(regs->msr, msr_bits);
        printk("  CR: %08lX  XER: %08lX\n", regs->ccr, regs->xer);
        trap = TRAP(regs);
        if (trap == 0x300 || trap == 0x600)
                printk("DAR: "REG", DSISR: "REG"\n", regs->dar, regs->dsisr);
        printk("TASK = %p[%d] '%s' THREAD: %p",
               current, current->pid, current->comm, current->thread_info);

#ifdef CONFIG_SMP
        printk(" CPU: %d", smp_processor_id());
#endif /* CONFIG_SMP */

        for (i = 0;  i < 32;  i++) {
                if ((i % REGS_PER_LINE) == 0)
                        printk("\n" KERN_INFO "GPR%02d: ", i);
                printk(REG " ", regs->gpr[i]);
                if (i == LAST_VOLATILE && !FULL_REGS(regs))
                        break;
        }
        printk("\n");
#ifdef CONFIG_KALLSYMS
        /*
         * Lookup NIP late so we have the best change of getting the
         * above info out without failing
         */
        printk("NIP ["REG"] ", regs->nip);
        print_symbol("%s\n", regs->nip);
        printk("LR ["REG"] ", regs->link);
        print_symbol("%s\n", regs->link);
#endif
        show_stack(current, (unsigned long *) regs->gpr[1]);
        if (!user_mode(regs))
                show_instructions(regs);
}

void exit_thread(void)
{
        kprobe_flush_task(current);

#ifndef CONFIG_SMP
        if (last_task_used_math == current)
                last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
        if (last_task_used_altivec == current)
                last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
        if (last_task_used_spe == current)
                last_task_used_spe = NULL;
#endif
#endif /* CONFIG_SMP */
}

void flush_thread(void)
{
#ifdef CONFIG_PPC64
        struct thread_info *t = current_thread_info();

        if (t->flags & _TIF_ABI_PENDING)
                t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
#endif
        kprobe_flush_task(current);

#ifndef CONFIG_SMP
        if (last_task_used_math == current)
                last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
        if (last_task_used_altivec == current)
                last_task_used_altivec = NULL;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
        if (last_task_used_spe == current)
                last_task_used_spe = NULL;
#endif
#endif /* CONFIG_SMP */

#ifdef CONFIG_PPC64     /* for now */
        if (current->thread.dabr) {
                current->thread.dabr = 0;
                set_dabr(0);
        }
#endif
}

void
release_thread(struct task_struct *t)
{
}

/*
 * This gets called before we allocate a new thread and copy
 * the current task into it.
 */
void prepare_to_copy(struct task_struct *tsk)
{
        flush_fp_to_thread(current);
        flush_altivec_to_thread(current);
        flush_spe_to_thread(current);
}

/*
 * Copy a thread..
 */
int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
                unsigned long unused, struct task_struct *p,
                struct pt_regs *regs)
{
        struct pt_regs *childregs, *kregs;
        extern void ret_from_fork(void);
        unsigned long sp = (unsigned long)p->thread_info + THREAD_SIZE;

        CHECK_FULL_REGS(regs);
        /* Copy registers */
        sp -= sizeof(struct pt_regs);
        childregs = (struct pt_regs *) sp;
        *childregs = *regs;
        if ((childregs->msr & MSR_PR) == 0) {
                /* for kernel thread, set `current' and stackptr in new task */
                childregs->gpr[1] = sp + sizeof(struct pt_regs);
#ifdef CONFIG_PPC32
                childregs->gpr[2] = (unsigned long) p;
#else
                clear_ti_thread_flag(p->thread_info, TIF_32BIT);
#endif
                p->thread.regs = NULL;  /* no user register state */
        } else {
                childregs->gpr[1] = usp;
                p->thread.regs = childregs;
                if (clone_flags & CLONE_SETTLS) {
#ifdef CONFIG_PPC64
                        if (!test_thread_flag(TIF_32BIT))
                                childregs->gpr[13] = childregs->gpr[6];
                        else
#endif
                                childregs->gpr[2] = childregs->gpr[6];
                }
        }
        childregs->gpr[3] = 0;  /* Result from fork() */
        sp -= STACK_FRAME_OVERHEAD;

        /*
         * The way this works is that at some point in the future
         * some task will call _switch to switch to the new task.
         * That will pop off the stack frame created below and start
         * the new task running at ret_from_fork.  The new task will
         * do some house keeping and then return from the fork or clone
         * system call, using the stack frame created above.
         */
        sp -= sizeof(struct pt_regs);
        kregs = (struct pt_regs *) sp;
        sp -= STACK_FRAME_OVERHEAD;
        p->thread.ksp = sp;

#ifdef CONFIG_PPC64
        if (cpu_has_feature(CPU_FTR_SLB)) {
                unsigned long sp_vsid = get_kernel_vsid(sp);
                unsigned long llp = mmu_psize_defs[mmu_linear_psize].sllp;

                sp_vsid <<= SLB_VSID_SHIFT;
                sp_vsid |= SLB_VSID_KERNEL | llp;
                p->thread.ksp_vsid = sp_vsid;
        }

        /*
         * The PPC64 ABI makes use of a TOC to contain function 
         * pointers.  The function (ret_from_except) is actually a pointer
         * to the TOC entry.  The first entry is a pointer to the actual
         * function.
         */
        kregs->nip = *((unsigned long *)ret_from_fork);
#else
        kregs->nip = (unsigned long)ret_from_fork;
        p->thread.last_syscall = -1;
#endif

        return 0;
}

/*
 * Set up a thread for executing a new program
 */
void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
{
#ifdef CONFIG_PPC64
        unsigned long load_addr = regs->gpr[2]; /* saved by ELF_PLAT_INIT */
#endif

        set_fs(USER_DS);

        /*
         * If we exec out of a kernel thread then thread.regs will not be
         * set.  Do it now.
         */
        if (!current->thread.regs) {
                unsigned long childregs = (unsigned long)current->thread_info +
                                                THREAD_SIZE;
                childregs -= sizeof(struct pt_regs);
                current->thread.regs = (struct pt_regs *)childregs;
        }

        memset(regs->gpr, 0, sizeof(regs->gpr));
        regs->ctr = 0;
        regs->link = 0;
        regs->xer = 0;
        regs->ccr = 0;
        regs->gpr[1] = sp;

#ifdef CONFIG_PPC32
        regs->mq = 0;
        regs->nip = start;
        regs->msr = MSR_USER;
#else
        if (!test_thread_flag(TIF_32BIT)) {
                unsigned long entry, toc;

                /* start is a relocated pointer to the function descriptor for
                 * the elf _start routine.  The first entry in the function
                 * descriptor is the entry address of _start and the second
                 * entry is the TOC value we need to use.
                 */
                __get_user(entry, (unsigned long __user *)start);
                __get_user(toc, (unsigned long __user *)start+1);

                /* Check whether the e_entry function descriptor entries
                 * need to be relocated before we can use them.
                 */
                if (load_addr != 0) {
                        entry += load_addr;
                        toc   += load_addr;
                }
                regs->nip = entry;
                regs->gpr[2] = toc;
                regs->msr = MSR_USER64;
        } else {
                regs->nip = start;
                regs->gpr[2] = 0;
                regs->msr = MSR_USER32;
        }
#endif

#ifndef CONFIG_SMP
        if (last_task_used_math == current)
                last_task_used_math = NULL;
#ifdef CONFIG_ALTIVEC
        if (last_task_used_altivec == current)
                last_task_used_altivec = NULL;
#endif
#ifdef CONFIG_SPE
        if (last_task_used_spe == current)
                last_task_used_spe = NULL;
#endif
#endif /* CONFIG_SMP */
        memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
        current->thread.fpscr.val = 0;
#ifdef CONFIG_ALTIVEC
        memset(current->thread.vr, 0, sizeof(current->thread.vr));
        memset(&current->thread.vscr, 0, sizeof(current->thread.vscr));
        current->thread.vscr.u[3] = 0x00010000; /* Java mode disabled */
        current->thread.vrsave = 0;
        current->thread.used_vr = 0;
#endif /* CONFIG_ALTIVEC */
#ifdef CONFIG_SPE
        memset(current->thread.evr, 0, sizeof(current->thread.evr));
        current->thread.acc = 0;
        current->thread.spefscr = 0;
        current->thread.used_spe = 0;
#endif /* CONFIG_SPE */
}

#define PR_FP_ALL_EXCEPT (PR_FP_EXC_DIV | PR_FP_EXC_OVF | PR_FP_EXC_UND \
                | PR_FP_EXC_RES | PR_FP_EXC_INV)

int set_fpexc_mode(struct task_struct *tsk, unsigned int val)
{
        struct pt_regs *regs = tsk->thread.regs;

        /* This is a bit hairy.  If we are an SPE enabled  processor
         * (have embedded fp) we store the IEEE exception enable flags in
         * fpexc_mode.  fpexc_mode is also used for setting FP exception
         * mode (asyn, precise, disabled) for 'Classic' FP. */
        if (val & PR_FP_EXC_SW_ENABLE) {
#ifdef CONFIG_SPE
                tsk->thread.fpexc_mode = val &
                        (PR_FP_EXC_SW_ENABLE | PR_FP_ALL_EXCEPT);
                return 0;
#else
                return -EINVAL;
#endif
        }

        /* on a CONFIG_SPE this does not hurt us.  The bits that
         * __pack_fe01 use do not overlap with bits used for
         * PR_FP_EXC_SW_ENABLE.  Additionally, the MSR[FE0,FE1] bits
         * on CONFIG_SPE implementations are reserved so writing to
         * them does not change anything */
        if (val > PR_FP_EXC_PRECISE)
                return -EINVAL;
        tsk->thread.fpexc_mode = __pack_fe01(val);
        if (regs != NULL && (regs->msr & MSR_FP) != 0)
                regs->msr = (regs->msr & ~(MSR_FE0|MSR_FE1))
                        | tsk->thread.fpexc_mode;
        return 0;
}

int get_fpexc_mode(struct task_struct *tsk, unsigned long adr)
{
        unsigned int val;

        if (tsk->thread.fpexc_mode & PR_FP_EXC_SW_ENABLE)
#ifdef CONFIG_SPE
                val = tsk->thread.fpexc_mode;
#else
                return -EINVAL;
#endif
        else
                val = __unpack_fe01(tsk->thread.fpexc_mode);
        return put_user(val, (unsigned int __user *) adr);
}

#define TRUNC_PTR(x)    ((typeof(x))(((unsigned long)(x)) & 0xffffffff))

int sys_clone(unsigned long clone_flags, unsigned long usp,
              int __user *parent_tidp, void __user *child_threadptr,
              int __user *child_tidp, int p6,
              struct pt_regs *regs)
{
        CHECK_FULL_REGS(regs);
        if (usp == 0)
                usp = regs->gpr[1];     /* stack pointer for child */
#ifdef CONFIG_PPC64
        if (test_thread_flag(TIF_32BIT)) {
                parent_tidp = TRUNC_PTR(parent_tidp);
                child_tidp = TRUNC_PTR(child_tidp);
        }
#endif
        return do_fork(clone_flags, usp, regs, 0, parent_tidp, child_tidp);
}

int sys_fork(unsigned long p1, unsigned long p2, unsigned long p3,
             unsigned long p4, unsigned long p5, unsigned long p6,
             struct pt_regs *regs)
{
        CHECK_FULL_REGS(regs);
        return do_fork(SIGCHLD, regs->gpr[1], regs, 0, NULL, NULL);
}

int sys_vfork(unsigned long p1, unsigned long p2, unsigned long p3,
              unsigned long p4, unsigned long p5, unsigned long p6,
              struct pt_regs *regs)
{
        CHECK_FULL_REGS(regs);
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->gpr[1],
                        regs, 0, NULL, NULL);
}

int sys_execve(unsigned long a0, unsigned long a1, unsigned long a2,
               unsigned long a3, unsigned long a4, unsigned long a5,
               struct pt_regs *regs)
{
        int error;
        char *filename;

        filename = getname((char __user *) a0);
        error = PTR_ERR(filename);
        if (IS_ERR(filename))
                goto out;
        flush_fp_to_thread(current);
        flush_altivec_to_thread(current);
        flush_spe_to_thread(current);
        error = do_execve(filename, (char __user * __user *) a1,
                          (char __user * __user *) a2, regs);
        if (error == 0) {
                task_lock(current);
                current->ptrace &= ~PT_DTRACE;
                task_unlock(current);
        }
        putname(filename);
out:
        return error;
}

static int validate_sp(unsigned long sp, struct task_struct *p,
                       unsigned long nbytes)
{
        unsigned long stack_page = (unsigned long)p->thread_info;

        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

#ifdef CONFIG_IRQSTACKS
        stack_page = (unsigned long) hardirq_ctx[task_cpu(p)];
        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;

        stack_page = (unsigned long) softirq_ctx[task_cpu(p)];
        if (sp >= stack_page + sizeof(struct thread_struct)
            && sp <= stack_page + THREAD_SIZE - nbytes)
                return 1;
#endif

        return 0;
}

#ifdef CONFIG_PPC64
#define MIN_STACK_FRAME 112     /* same as STACK_FRAME_OVERHEAD, in fact */
#define FRAME_LR_SAVE   2
#define INT_FRAME_SIZE  (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD + 288)
#define REGS_MARKER     0x7265677368657265ul
#define FRAME_MARKER    12
#else
#define MIN_STACK_FRAME 16
#define FRAME_LR_SAVE   1
#define INT_FRAME_SIZE  (sizeof(struct pt_regs) + STACK_FRAME_OVERHEAD)
#define REGS_MARKER     0x72656773ul
#define FRAME_MARKER    2
#endif

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long ip, sp;
        int count = 0;

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

        sp = p->thread.ksp;
        if (!validate_sp(sp, p, MIN_STACK_FRAME))
                return 0;

        do {
                sp = *(unsigned long *)sp;
                if (!validate_sp(sp, p, MIN_STACK_FRAME))
                        return 0;
                if (count > 0) {
                        ip = ((unsigned long *)sp)[FRAME_LR_SAVE];
                        if (!in_sched_functions(ip))
                                return ip;
                }
        } while (count++ < 16);
        return 0;
}
EXPORT_SYMBOL(get_wchan);

static int kstack_depth_to_print = 64;

void show_stack(struct task_struct *tsk, unsigned long *stack)
{
        unsigned long sp, ip, lr, newsp;
        int count = 0;
        int firstframe = 1;

        sp = (unsigned long) stack;
        if (tsk == NULL)
                tsk = current;
        if (sp == 0) {
                if (tsk == current)
                        asm("mr %0,1" : "=r" (sp));
                else
                        sp = tsk->thread.ksp;
        }

        lr = 0;
        printk("Call Trace:\n");
        do {
                if (!validate_sp(sp, tsk, MIN_STACK_FRAME))
                        return;

                stack = (unsigned long *) sp;
                newsp = stack[0];
                ip = stack[FRAME_LR_SAVE];
                if (!firstframe || ip != lr) {
                        printk("["REG"] ["REG"] ", sp, ip);
                        print_symbol("%s", ip);
                        if (firstframe)
                                printk(" (unreliable)");
                        printk("\n");
                }
                firstframe = 0;

                /*
                 * See if this is an exception frame.
                 * We look for the "regshere" marker in the current frame.
                 */
                if (validate_sp(sp, tsk, INT_FRAME_SIZE)
                    && stack[FRAME_MARKER] == REGS_MARKER) {
                        struct pt_regs *regs = (struct pt_regs *)
                                (sp + STACK_FRAME_OVERHEAD);
                        printk("--- Exception: %lx", regs->trap);
                        print_symbol(" at %s\n", regs->nip);
                        lr = regs->link;
                        print_symbol("    LR = %s\n", lr);
                        firstframe = 1;
                }

                sp = newsp;
        } while (count++ < kstack_depth_to_print);
}

void dump_stack(void)
{
        show_stack(current, NULL);
}
EXPORT_SYMBOL(dump_stack);