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[linux-2.6.9-moxart.git] / arch / x86_64 / kernel / process.c

/*
 *  linux/arch/x86-64/kernel/process.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *
 *  Pentium III FXSR, SSE support
 *      Gareth Hughes <gareth@valinux.com>, May 2000
 * 
 *  X86-64 port
 *      Andi Kleen.
 * 
 *  $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
 */

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

#include <stdarg.h>

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/elfcore.h>
#include <linux/smp.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/module.h>
#include <linux/a.out.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/ptrace.h>
#include <linux/version.h>

#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/i387.h>
#include <asm/mmu_context.h>
#include <asm/pda.h>
#include <asm/prctl.h>
#include <asm/kdebug.h>
#include <asm/desc.h>
#include <asm/proto.h>
#include <asm/ia32.h>

asmlinkage extern void ret_from_fork(void);

unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;

atomic_t hlt_counter = ATOMIC_INIT(0);

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

void disable_hlt(void)
{
        atomic_inc(&hlt_counter);
}

EXPORT_SYMBOL(disable_hlt);

void enable_hlt(void)
{
        atomic_dec(&hlt_counter);
}

EXPORT_SYMBOL(enable_hlt);

/*
 * We use this if we don't have any better
 * idle routine..
 */
void default_idle(void)
{
        if (!atomic_read(&hlt_counter)) {
                local_irq_disable();
                if (!need_resched())
                        safe_halt();
                else
                        local_irq_enable();
        }
}

/*
 * On SMP it's slightly faster (but much more power-consuming!)
 * to poll the ->need_resched flag instead of waiting for the
 * cross-CPU IPI to arrive. Use this option with caution.
 */
static void poll_idle (void)
{
        int oldval;

        local_irq_enable();

        /*
         * Deal with another CPU just having chosen a thread to
         * run here:
         */
        oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);

        if (!oldval) {
                set_thread_flag(TIF_POLLING_NRFLAG); 
                asm volatile(
                        "2:"
                        "testl %0,%1;"
                        "rep; nop;"
                        "je 2b;"
                        : :
                        "i" (_TIF_NEED_RESCHED), 
                        "m" (current_thread_info()->flags));
        } else {
                set_need_resched();
        }
}

/*
 * The idle thread. There's no useful work to be
 * done, so just try to conserve power and have a
 * low exit latency (ie sit in a loop waiting for
 * somebody to say that they'd like to reschedule)
 */
void cpu_idle (void)
{
        /* endless idle loop with no priority at all */
        while (1) {
                while (!need_resched()) {
                        void (*idle)(void);
                        /*
                         * Mark this as an RCU critical section so that
                         * synchronize_kernel() in the unload path waits
                         * for our completion.
                         */
                        rcu_read_lock();
                        idle = pm_idle;
                        if (!idle)
                                idle = default_idle;
                        idle();
                        rcu_read_unlock();
                }
                schedule();
        }
}

/*
 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
 * which can obviate IPI to trigger checking of need_resched.
 * We execute MONITOR against need_resched and enter optimized wait state
 * through MWAIT. Whenever someone changes need_resched, we would be woken
 * up from MWAIT (without an IPI).
 */
static void mwait_idle(void)
{
        local_irq_enable();

        if (!need_resched()) {
                set_thread_flag(TIF_POLLING_NRFLAG);
                do {
                        __monitor((void *)&current_thread_info()->flags, 0, 0);
                        if (need_resched())
                                break;
                        __mwait(0, 0);
                } while (!need_resched());
                clear_thread_flag(TIF_POLLING_NRFLAG);
        }
}

void __init select_idle_routine(const struct cpuinfo_x86 *c)
{
        static int printed;
        if (cpu_has(c, X86_FEATURE_MWAIT)) {
                /*
                 * Skip, if setup has overridden idle.
                 * One CPU supports mwait => All CPUs supports mwait
                 */
                if (!pm_idle) {
                        if (!printed) {
                                printk("using mwait in idle threads.\n");
                                printed = 1;
                        }
                        pm_idle = mwait_idle;
                }
        }
}

static int __init idle_setup (char *str)
{
        if (!strncmp(str, "poll", 4)) {
                printk("using polling idle threads.\n");
                pm_idle = poll_idle;
        }

        return 1;
}

__setup("idle=", idle_setup);

/* Prints also some state that isn't saved in the pt_regs */ 
void __show_regs(struct pt_regs * regs)
{
        unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
        unsigned int fsindex,gsindex;
        unsigned int ds,cs,es; 

        printk("\n");
        print_modules();
        printk("Pid: %d, comm: %.20s %s %s\n", 
               current->pid, current->comm, print_tainted(), UTS_RELEASE);
        printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
        printk_address(regs->rip); 
        printk("\nRSP: %04lx:%016lx  EFLAGS: %08lx\n", regs->ss, regs->rsp, regs->eflags);
        printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
               regs->rax, regs->rbx, regs->rcx);
        printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
               regs->rdx, regs->rsi, regs->rdi); 
        printk("RBP: %016lx R08: %016lx R09: %016lx\n",
               regs->rbp, regs->r8, regs->r9); 
        printk("R10: %016lx R11: %016lx R12: %016lx\n",
               regs->r10, regs->r11, regs->r12); 
        printk("R13: %016lx R14: %016lx R15: %016lx\n",
               regs->r13, regs->r14, regs->r15); 

        asm("movl %%ds,%0" : "=r" (ds)); 
        asm("movl %%cs,%0" : "=r" (cs)); 
        asm("movl %%es,%0" : "=r" (es)); 
        asm("movl %%fs,%0" : "=r" (fsindex));
        asm("movl %%gs,%0" : "=r" (gsindex));

        rdmsrl(MSR_FS_BASE, fs);
        rdmsrl(MSR_GS_BASE, gs); 
        rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); 

        asm("movq %%cr0, %0": "=r" (cr0));
        asm("movq %%cr2, %0": "=r" (cr2));
        asm("movq %%cr3, %0": "=r" (cr3));
        asm("movq %%cr4, %0": "=r" (cr4));

        printk("FS:  %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", 
               fs,fsindex,gs,gsindex,shadowgs); 
        printk("CS:  %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0); 
        printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
}

void show_regs(struct pt_regs *regs)
{
        __show_regs(regs);
        show_trace(&regs->rsp);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
        struct task_struct *me = current;
        struct thread_struct *t = &me->thread;
        if (me->thread.io_bitmap_ptr) { 
                struct tss_struct *tss = &per_cpu(init_tss, get_cpu());

                kfree(t->io_bitmap_ptr);
                t->io_bitmap_ptr = NULL;
                /*
                 * Careful, clear this in the TSS too:
                 */
                memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
                t->io_bitmap_max = 0;
                put_cpu();
        }
}

void flush_thread(void)
{
        struct task_struct *tsk = current;
        struct thread_info *t = current_thread_info();

        if (t->flags & _TIF_ABI_PENDING)
                t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32);

        tsk->thread.debugreg0 = 0;
        tsk->thread.debugreg1 = 0;
        tsk->thread.debugreg2 = 0;
        tsk->thread.debugreg3 = 0;
        tsk->thread.debugreg6 = 0;
        tsk->thread.debugreg7 = 0;
        memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));        
        /*
         * Forget coprocessor state..
         */
        clear_fpu(tsk);
        tsk->used_math = 0;
}

void release_thread(struct task_struct *dead_task)
{
        if (dead_task->mm) {
                if (dead_task->mm->context.size) {
                        printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
                                        dead_task->comm,
                                        dead_task->mm->context.ldt,
                                        dead_task->mm->context.size);
                        BUG();
                }
        }
}

static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
{
        struct user_desc ud = { 
                .base_addr = addr,
                .limit = 0xfffff,
                .seg_32bit = 1,
                .limit_in_pages = 1,
                .useable = 1,
        };
        struct n_desc_struct *desc = (void *)t->thread.tls_array;
        desc += tls;
        desc->a = LDT_entry_a(&ud); 
        desc->b = LDT_entry_b(&ud); 
}

static inline u32 read_32bit_tls(struct task_struct *t, int tls)
{
        struct desc_struct *desc = (void *)t->thread.tls_array;
        desc += tls;
        return desc->base0 | 
                (((u32)desc->base1) << 16) | 
                (((u32)desc->base2) << 24);
}

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

int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp, 
                unsigned long unused,
        struct task_struct * p, struct pt_regs * regs)
{
        int err;
        struct pt_regs * childregs;
        struct task_struct *me = current;

        childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;

        *childregs = *regs;

        childregs->rax = 0;
        childregs->rsp = rsp;
        if (rsp == ~0UL) {
                childregs->rsp = (unsigned long)childregs;
        }
        p->set_child_tid = p->clear_child_tid = NULL;

        p->thread.rsp = (unsigned long) childregs;
        p->thread.rsp0 = (unsigned long) (childregs+1);
        p->thread.userrsp = me->thread.userrsp; 

        set_ti_thread_flag(p->thread_info, TIF_FORK);

        p->thread.fs = me->thread.fs;
        p->thread.gs = me->thread.gs;

        asm("movl %%gs,%0" : "=m" (p->thread.gsindex));
        asm("movl %%fs,%0" : "=m" (p->thread.fsindex));
        asm("movl %%es,%0" : "=m" (p->thread.es));
        asm("movl %%ds,%0" : "=m" (p->thread.ds));

        if (unlikely(me->thread.io_bitmap_ptr != NULL)) { 
                p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
                if (!p->thread.io_bitmap_ptr) {
                        p->thread.io_bitmap_max = 0;
                        return -ENOMEM;
                }
                memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr, IO_BITMAP_BYTES);
        } 

        /*
         * Set a new TLS for the child thread?
         */
        if (clone_flags & CLONE_SETTLS) {
#ifdef CONFIG_IA32_EMULATION
                if (test_thread_flag(TIF_IA32))
                        err = ia32_child_tls(p, childregs); 
                else                    
#endif   
                        err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8); 
                if (err) 
                        goto out;
        }
        err = 0;
out:
        if (err && p->thread.io_bitmap_ptr) {
                kfree(p->thread.io_bitmap_ptr);
                p->thread.io_bitmap_max = 0;
        }
        return err;
}

/*
 * This special macro can be used to load a debugging register
 */
#define loaddebug(thread,r) set_debug(thread->debugreg ## r, r)

/*
 *      switch_to(x,y) should switch tasks from x to y.
 *
 * This could still be optimized: 
 * - fold all the options into a flag word and test it with a single test.
 * - could test fs/gs bitsliced
 */
struct task_struct *__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
{
        struct thread_struct *prev = &prev_p->thread,
                                 *next = &next_p->thread;
        int cpu = smp_processor_id();  
        struct tss_struct *tss = &per_cpu(init_tss, cpu);

        unlazy_fpu(prev_p);

        /*
         * Reload esp0, LDT and the page table pointer:
         */
        tss->rsp0 = next->rsp0;

        /* 
         * Switch DS and ES.
         * This won't pick up thread selector changes, but I guess that is ok.
         */
        asm volatile("movl %%es,%0" : "=m" (prev->es)); 
        if (unlikely(next->es | prev->es))
                loadsegment(es, next->es); 
        
        asm volatile ("movl %%ds,%0" : "=m" (prev->ds)); 
        if (unlikely(next->ds | prev->ds))
                loadsegment(ds, next->ds);

        load_TLS(next, cpu);

        /* 
         * Switch FS and GS.
         */
        { 
                unsigned fsindex;
                asm volatile("movl %%fs,%0" : "=g" (fsindex)); 
                /* segment register != 0 always requires a reload. 
                   also reload when it has changed. 
                   when prev process used 64bit base always reload
                   to avoid an information leak. */
                if (unlikely(fsindex | next->fsindex | prev->fs)) {
                        loadsegment(fs, next->fsindex);
                        /* check if the user used a selector != 0
                         * if yes clear 64bit base, since overloaded base
                         * is always mapped to the Null selector
                         */
                        if (fsindex)
                        prev->fs = 0;                           
                }
                /* when next process has a 64bit base use it */
                if (next->fs) 
                        wrmsrl(MSR_FS_BASE, next->fs); 
                prev->fsindex = fsindex;
        }
        { 
                unsigned gsindex;
                asm volatile("movl %%gs,%0" : "=g" (gsindex)); 
                if (unlikely(gsindex | next->gsindex | prev->gs)) {
                        load_gs_index(next->gsindex);
                        if (gsindex)
                        prev->gs = 0;                           
                }
                if (next->gs)
                        wrmsrl(MSR_KERNEL_GS_BASE, next->gs); 
                prev->gsindex = gsindex;
        }

        /* 
         * Switch the PDA context.
         */
        prev->userrsp = read_pda(oldrsp); 
        write_pda(oldrsp, next->userrsp); 
        write_pda(pcurrent, next_p); 
        write_pda(kernelstack, (unsigned long)next_p->thread_info + THREAD_SIZE - PDA_STACKOFFSET);

        /*
         * Now maybe reload the debug registers
         */
        if (unlikely(next->debugreg7)) {
                loaddebug(next, 0);
                loaddebug(next, 1);
                loaddebug(next, 2);
                loaddebug(next, 3);
                /* no 4 and 5 */
                loaddebug(next, 6);
                loaddebug(next, 7);
        }


        /* 
         * Handle the IO bitmap 
         */ 
        if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
                if (next->io_bitmap_ptr)
                        /*
                         * Copy the relevant range of the IO bitmap.
                         * Normally this is 128 bytes or less:
                         */
                        memcpy(tss->io_bitmap, next->io_bitmap_ptr,
                                max(prev->io_bitmap_max, next->io_bitmap_max));
                else {
                        /*
                         * Clear any possible leftover bits:
                         */
                        memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
                }
        }

        return prev_p;
}

/*
 * sys_execve() executes a new program.
 */
asmlinkage 
long sys_execve(char __user *name, char __user * __user *argv,
                char __user * __user *envp, struct pt_regs regs)
{
        long error;
        char * filename;

        filename = getname(name);
        error = PTR_ERR(filename);
        if (IS_ERR(filename)) 
                return error;
        error = do_execve(filename, argv, envp, &regs); 
        if (error == 0)
                current->ptrace &= ~PT_DTRACE;
        putname(filename);
        return error;
}

void set_personality_64bit(void)
{
        /* inherit personality from parent */

        /* Make sure to be in 64bit mode */
        clear_thread_flag(TIF_IA32); 
}

asmlinkage long sys_fork(struct pt_regs *regs)
{
        return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
}

asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp, void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
{
        if (!newsp)
                newsp = regs->rsp;
        return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
}

/*
 * 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 long sys_vfork(struct pt_regs *regs)
{
        return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
                    NULL, NULL);
}

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long stack;
        u64 fp,rip;
        int count = 0;

        if (!p || p == current || p->state==TASK_RUNNING)
                return 0; 
        stack = (unsigned long)p->thread_info; 
        if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
                return 0;
        fp = *(u64 *)(p->thread.rsp);
        do { 
                if (fp < (unsigned long)stack || fp > (unsigned long)stack+THREAD_SIZE)
                        return 0; 
                rip = *(u64 *)(fp+8); 
                if (!in_sched_functions(rip))
                        return rip; 
                fp = *(u64 *)fp; 
        } while (count++ < 16); 
        return 0;
}

long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
{ 
        int ret = 0; 
        int doit = task == current;
        int cpu;

        switch (code) { 
        case ARCH_SET_GS:
                if (addr >= TASK_SIZE) 
                        return -EPERM; 
                cpu = get_cpu();
                /* handle small bases via the GDT because that's faster to 
                   switch. */
                if (addr <= 0xffffffff) {  
                        set_32bit_tls(task, GS_TLS, addr); 
                        if (doit) { 
                                load_TLS(&task->thread, cpu);
                                load_gs_index(GS_TLS_SEL); 
                        }
                        task->thread.gsindex = GS_TLS_SEL; 
                        task->thread.gs = 0;
                } else { 
                        task->thread.gsindex = 0;
                        task->thread.gs = addr;
                        if (doit) {
                load_gs_index(0);
                ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr); 
                        } 
                }
                put_cpu();
                break;
        case ARCH_SET_FS:
                /* Not strictly needed for fs, but do it for symmetry
                   with gs */
                if (addr >= TASK_SIZE)
                        return -EPERM; 
                cpu = get_cpu();
                /* handle small bases via the GDT because that's faster to 
                   switch. */
                if (addr <= 0xffffffff) { 
                        set_32bit_tls(task, FS_TLS, addr);
                        if (doit) { 
                                load_TLS(&task->thread, cpu); 
                                asm volatile("movl %0,%%fs" :: "r" (FS_TLS_SEL));
                        }
                        task->thread.fsindex = FS_TLS_SEL;
                        task->thread.fs = 0;
                } else { 
                        task->thread.fsindex = 0;
                        task->thread.fs = addr;
                        if (doit) {
                                /* set the selector to 0 to not confuse
                                   __switch_to */
                asm volatile("movl %0,%%fs" :: "r" (0));
                ret = checking_wrmsrl(MSR_FS_BASE, addr); 
                        }
                }
                put_cpu();
                break;
        case ARCH_GET_FS: { 
                unsigned long base; 
                if (task->thread.fsindex == FS_TLS_SEL)
                        base = read_32bit_tls(task, FS_TLS);
                else if (doit) {
                        rdmsrl(MSR_FS_BASE, base);
                } else
                        base = task->thread.fs;
                ret = put_user(base, (unsigned long __user *)addr); 
                break; 
        }
        case ARCH_GET_GS: { 
                unsigned long base;
                if (task->thread.gsindex == GS_TLS_SEL)
                        base = read_32bit_tls(task, GS_TLS);
                else if (doit) {
                        rdmsrl(MSR_KERNEL_GS_BASE, base);
                } else
                        base = task->thread.gs;
                ret = put_user(base, (unsigned long __user *)addr); 
                break;
        }

        default:
                ret = -EINVAL;
                break;
        } 

        return ret;     
} 

long sys_arch_prctl(int code, unsigned long addr)
{
        return do_arch_prctl(current, code, addr);
} 

/* 
 * Capture the user space registers if the task is not running (in user space)
 */
int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
{
        struct pt_regs *pp, ptregs;

        pp = (struct pt_regs *)(tsk->thread.rsp0);
        --pp; 

        ptregs = *pp; 
        ptregs.cs &= 0xffff;
        ptregs.ss &= 0xffff;

        elf_core_copy_regs(regs, &ptregs);
 
        return 1;
}