kernel - (mainly x86_64) - Fix a number of rare races

[dragonfly.git] / sys / platform / pc32 / i386 / vm_machdep.c

/*-
 * Copyright (c) 1982, 1986 The Regents of the University of California.
 * Copyright (c) 1989, 1990 William Jolitz
 * Copyright (c) 1994 John Dyson
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department, and William Jolitz.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      from: @(#)vm_machdep.c  7.3 (Berkeley) 5/13/91
 *      Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
 * $FreeBSD: src/sys/i386/i386/vm_machdep.c,v 1.132.2.9 2003/01/25 19:02:23 dillon Exp $
 * $DragonFly: src/sys/platform/pc32/i386/vm_machdep.c,v 1.61 2008/08/02 01:14:43 dillon Exp $
 */

#include "use_npx.h"
#include "use_isa.h"
#include "opt_reset.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/interrupt.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/unistd.h>

#include <machine/clock.h>
#include <machine/cpu.h>
#include <machine/md_var.h>
#include <machine/smp.h>
#include <machine/pcb.h>
#include <machine/pcb_ext.h>
#include <machine/vm86.h>
#include <machine/segments.h>
#include <machine/globaldata.h> /* npxthread */

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <sys/lock.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_extern.h>

#include <sys/user.h>

#include <sys/thread2.h>
#include <sys/mplock2.h>

#include <bus/isa/isa.h>

static void     cpu_reset_real (void);
#ifdef SMP
static void     cpu_reset_proxy (void);
static u_int    cpu_reset_proxyid;
static volatile u_int   cpu_reset_proxy_active;
#endif
extern int      _ucodesel, _udatasel;


/*
 * Finish a fork operation, with lwp lp2 nearly set up.
 * Copy and update the pcb, set up the stack so that the child
 * ready to run and return to user mode.
 */
void
cpu_fork(struct lwp *lp1, struct lwp *lp2, int flags)
{
        struct pcb *pcb2;

        if ((flags & RFPROC) == 0) {
                if ((flags & RFMEM) == 0) {
                        /* unshare user LDT */
                        struct pcb *pcb1 = lp1->lwp_thread->td_pcb;
                        struct pcb_ldt *pcb_ldt = pcb1->pcb_ldt;
                        if (pcb_ldt && pcb_ldt->ldt_refcnt > 1) {
                                pcb_ldt = user_ldt_alloc(pcb1,pcb_ldt->ldt_len);
                                user_ldt_free(pcb1);
                                pcb1->pcb_ldt = pcb_ldt;
                                set_user_ldt(pcb1);
                        }
                }
                return;
        }

#if NNPX > 0
        /* Ensure that lp1's pcb is up to date. */
        if (mdcpu->gd_npxthread == lp1->lwp_thread)
                npxsave(lp1->lwp_thread->td_savefpu);
#endif
        
        /*
         * Copy lp1's PCB.  This really only applies to the
         * debug registers and FP state, but its faster to just copy the
         * whole thing.  Because we only save the PCB at switchout time,
         * the register state may not be current.
         */
        pcb2 = lp2->lwp_thread->td_pcb;
        *pcb2 = *lp1->lwp_thread->td_pcb;

        /*
         * Create a new fresh stack for the new process.
         * Copy the trap frame for the return to user mode as if from a
         * syscall.  This copies the user mode register values.  The
         * 16 byte offset saves space for vm86, and must match 
         * common_tss.esp0 (kernel stack pointer on entry from user mode)
         *
         * pcb_esp must allocate an additional call-return pointer below
         * the trap frame which will be restored by cpu_restore from
         * PCB_EIP, and the thread's td_sp pointer must allocate an
         * additonal two worsd below the pcb_esp call-return pointer to
         * hold the LWKT restore function pointer and eflags.
         *
         * The LWKT restore function pointer must be set to cpu_restore,
         * which is our standard heavy weight process switch-in function.
         * YYY eventually we should shortcut fork_return and fork_trampoline
         * to use the LWKT restore function directly so we can get rid of
         * all the extra crap we are setting up.
         */
        lp2->lwp_md.md_regs = (struct trapframe *)((char *)pcb2 - 16) - 1;
        bcopy(lp1->lwp_md.md_regs, lp2->lwp_md.md_regs, sizeof(*lp2->lwp_md.md_regs));

        /*
         * Set registers for trampoline to user mode.  Leave space for the
         * return address on stack.  These are the kernel mode register values.
         */
        pcb2->pcb_cr3 = vtophys(vmspace_pmap(lp2->lwp_proc->p_vmspace)->pm_pdir);
        pcb2->pcb_edi = 0;
        pcb2->pcb_esi = (int)fork_return;       /* fork_trampoline argument */
        pcb2->pcb_ebp = 0;
        pcb2->pcb_esp = (int)lp2->lwp_md.md_regs - sizeof(void *);
        pcb2->pcb_ebx = (int)lp2;               /* fork_trampoline argument */
        pcb2->pcb_eip = (int)fork_trampoline;
        lp2->lwp_thread->td_sp = (char *)(pcb2->pcb_esp - sizeof(void *));
        *(u_int32_t *)lp2->lwp_thread->td_sp = PSL_USER;
        lp2->lwp_thread->td_sp -= sizeof(void *);
        *(void **)lp2->lwp_thread->td_sp = (void *)cpu_heavy_restore;

        /*
         * pcb2->pcb_ldt:       duplicated below, if necessary.
         * pcb2->pcb_savefpu:   cloned above.
         * pcb2->pcb_flags:     cloned above (always 0 here?).
         * pcb2->pcb_onfault:   cloned above (always NULL here?).
         */

        /*
         * XXX don't copy the i/o pages.  this should probably be fixed.
         */
        pcb2->pcb_ext = 0;

        /* Copy the LDT, if necessary. */
        if (pcb2->pcb_ldt != 0) {
                if (flags & RFMEM) {
                        pcb2->pcb_ldt->ldt_refcnt++;
                } else {
                        pcb2->pcb_ldt = user_ldt_alloc(pcb2,
                                pcb2->pcb_ldt->ldt_len);
                }
        }
        bcopy(&lp1->lwp_thread->td_tls, &lp2->lwp_thread->td_tls,
              sizeof(lp2->lwp_thread->td_tls));
        /*
         * Now, cpu_switch() can schedule the new lwp.
         * pcb_esp is loaded pointing to the cpu_switch() stack frame
         * containing the return address when exiting cpu_switch.
         * This will normally be to fork_trampoline(), which will have
         * %ebx loaded with the new lwp's pointer.  fork_trampoline()
         * will set up a stack to call fork_return(lp, frame); to complete
         * the return to user-mode.
         */
}

/*
 * Prepare new lwp to return to the address specified in params.
 */
int
cpu_prepare_lwp(struct lwp *lp, struct lwp_params *params)
{
        struct trapframe *regs = lp->lwp_md.md_regs;
        void *bad_return = NULL;
        int error;

        regs->tf_eip = (int)params->func;
        regs->tf_esp = (int)params->stack;
        /* Set up argument for function call */
        regs->tf_esp -= sizeof(params->arg);
        error = 
            copyout(&params->arg, (void *)regs->tf_esp, sizeof(params->arg));
        if (error)
                return (error);
        /*
         * Set up fake return address.  As the lwp function may never return,
         * we simply copy out a NULL pointer and force the lwp to receive
         * a SIGSEGV if it returns anyways.
         */
        regs->tf_esp -= sizeof(void *);
        error = copyout(&bad_return, (void *)regs->tf_esp, sizeof(bad_return));
        if (error)
                return (error);

        cpu_set_fork_handler(lp,
            (void (*)(void *, struct trapframe *))generic_lwp_return, lp);
        return (0);
}

/*
 * Intercept the return address from a freshly forked process that has NOT
 * been scheduled yet.
 *
 * This is needed to make kernel threads stay in kernel mode.
 */
void
cpu_set_fork_handler(struct lwp *lp, void (*func)(void *, struct trapframe *),
                     void *arg)
{
        /*
         * Note that the trap frame follows the args, so the function
         * is really called like this:  func(arg, frame);
         */
        lp->lwp_thread->td_pcb->pcb_esi = (int) func;   /* function */
        lp->lwp_thread->td_pcb->pcb_ebx = (int) arg;    /* first arg */
}

void
cpu_set_thread_handler(thread_t td, void (*rfunc)(void), void *func, void *arg)
{
        td->td_pcb->pcb_esi = (int)func;
        td->td_pcb->pcb_ebx = (int) arg;
        td->td_switch = cpu_lwkt_switch;
        td->td_sp -= sizeof(void *);
        *(void **)td->td_sp = rfunc;    /* exit function on return */
        td->td_sp -= sizeof(void *);
        *(void **)td->td_sp = cpu_kthread_restore;
}

void
cpu_lwp_exit(void)
{
        struct thread *td = curthread;
        struct pcb *pcb;
        struct pcb_ext *ext;

#if NNPX > 0
        npxexit();
#endif  /* NNPX */

        /*
         * If we were using a private TSS do a forced-switch to ourselves
         * to switch back to the common TSS before freeing it.
         */
        pcb = td->td_pcb;
        if ((ext = pcb->pcb_ext) != NULL) {
                crit_enter();
                pcb->pcb_ext = NULL;
                td->td_switch(td);
                crit_exit();
                kmem_free(&kernel_map, (vm_offset_t)ext, ctob(IOPAGES + 1));
        }
        user_ldt_free(pcb);
        if (pcb->pcb_flags & PCB_DBREGS) {
                /*
                 * disable all hardware breakpoints
                 */
                reset_dbregs();
                pcb->pcb_flags &= ~PCB_DBREGS;
        }
        td->td_gd->gd_cnt.v_swtch++;

        crit_enter_quick(td);
        if (td->td_flags & TDF_TSLEEPQ)
                tsleep_remove(td);
        lwkt_deschedule_self(td);
        lwkt_remove_tdallq(td);
        cpu_thread_exit();
}

/*
 * Terminate the current thread.  The caller must have already acquired
 * the thread's rwlock and placed it on a reap list or otherwise notified
 * a reaper of its existance.  We set a special assembly switch function which
 * releases td_rwlock after it has cleaned up the MMU state and switched
 * out the stack.
 *
 * Must be caller from a critical section and with the thread descheduled.
 */
void
cpu_thread_exit(void)
{
        curthread->td_switch = cpu_exit_switch;
        curthread->td_flags |= TDF_EXITING;
        lwkt_switch();
        panic("cpu_exit");
}

/*
 * Process Reaper.  Called after the caller has acquired the thread's
 * rwlock and removed it from the reap list.
 */
void
cpu_proc_wait(struct proc *p)
{
        /* drop per-process resources */
        pmap_dispose_proc(p);
}

#ifdef notyet
static void
setredzone(u_short *pte, caddr_t vaddr)
{
/* eventually do this by setting up an expand-down stack segment
   for ss0: selector, allowing stack access down to top of u.
   this means though that protection violations need to be handled
   thru a double fault exception that must do an integral task
   switch to a known good context, within which a dump can be
   taken. a sensible scheme might be to save the initial context
   used by sched (that has physical memory mapped 1:1 at bottom)
   and take the dump while still in mapped mode */
}
#endif

/*
 * Convert kernel VA to physical address
 */
vm_paddr_t
kvtop(void *addr)
{
        vm_paddr_t pa;

        pa = pmap_kextract((vm_offset_t)addr);
        if (pa == 0)
                panic("kvtop: zero page frame");
        return (pa);
}

/*
 * Force reset the processor by invalidating the entire address space!
 */

#ifdef SMP
static void
cpu_reset_proxy(void)
{
        u_int saved_mp_lock;

        cpu_reset_proxy_active = 1;
        while (cpu_reset_proxy_active == 1)
                ;        /* Wait for other cpu to disable interupts */
        saved_mp_lock = mp_lock;
        mp_lock = 0;    /* BSP */
        kprintf("cpu_reset_proxy: Grabbed mp lock for BSP\n");
        cpu_reset_proxy_active = 3;
        while (cpu_reset_proxy_active == 3)
                ;       /* Wait for other cpu to enable interrupts */
        stop_cpus((1<<cpu_reset_proxyid));
        kprintf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
        DELAY(1000000);
        cpu_reset_real();
}
#endif

void
cpu_reset(void)
{
#ifdef SMP
        if (smp_active_mask == 1) {
                cpu_reset_real();
                /* NOTREACHED */
        } else {
                u_int map;
                int cnt;
                kprintf("cpu_reset called on cpu#%d\n",mycpu->gd_cpuid);

                map = mycpu->gd_other_cpus & ~stopped_cpus & smp_active_mask;

                if (map != 0) {
                        kprintf("cpu_reset: Stopping other CPUs\n");
                        stop_cpus(map);         /* Stop all other CPUs */
                }

                if (mycpu->gd_cpuid == 0) {
                        DELAY(1000000);
                        cpu_reset_real();
                        /* NOTREACHED */
                } else {
                        /* We are not BSP (CPU #0) */

                        cpu_reset_proxyid = mycpu->gd_cpuid;
                        cpustop_restartfunc = cpu_reset_proxy;
                        kprintf("cpu_reset: Restarting BSP\n");
                        started_cpus = (1<<0);          /* Restart CPU #0 */

                        cnt = 0;
                        while (cpu_reset_proxy_active == 0 && cnt < 10000000)
                                cnt++;  /* Wait for BSP to announce restart */
                        if (cpu_reset_proxy_active == 0)
                                kprintf("cpu_reset: Failed to restart BSP\n");
                        __asm __volatile("cli" : : : "memory");
                        cpu_reset_proxy_active = 2;
                        cnt = 0;
                        while (cpu_reset_proxy_active == 2 && cnt < 10000000)
                                cnt++;  /* Do nothing */
                        if (cpu_reset_proxy_active == 2) {
                                kprintf("cpu_reset: BSP did not grab mp lock\n");
                                cpu_reset_real();       /* XXX: Bogus ? */
                        }
                        cpu_reset_proxy_active = 4;
                        __asm __volatile("sti" : : : "memory");
                        while (1);
                        /* NOTREACHED */
                }
        }
#else
        cpu_reset_real();
#endif
}

static void
cpu_reset_real(void)
{
        /*
         * Attempt to do a CPU reset via the keyboard controller,
         * do not turn of the GateA20, as any machine that fails
         * to do the reset here would then end up in no man's land.
         */

#if !defined(BROKEN_KEYBOARD_RESET)
        outb(IO_KBD + 4, 0xFE);
        DELAY(500000);  /* wait 0.5 sec to see if that did it */
        kprintf("Keyboard reset did not work, attempting CPU shutdown\n");
        DELAY(1000000); /* wait 1 sec for kprintf to complete */
#endif
        /* force a shutdown by unmapping entire address space ! */
        bzero((caddr_t) PTD, PAGE_SIZE);

        /* "good night, sweet prince .... <THUNK!>" */
        cpu_invltlb();
        /* NOTREACHED */
        while(1);
}

SYSCTL_DECL(_vm_stats_misc);

static void
swi_vm(void *arg, void *frame)
{
        if (busdma_swi_pending != 0)
                busdma_swi();
}

static void
swi_vm_setup(void *arg)
{
        register_swi(SWI_VM, swi_vm, NULL, "swi_vm", NULL);
}

SYSINIT(vm_setup, SI_BOOT2_MACHDEP, SI_ORDER_ANY, swi_vm_setup, NULL);


/*
 * Tell whether this address is in some physical memory region.
 * Currently used by the kernel coredump code in order to avoid
 * dumping the ``ISA memory hole'' which could cause indefinite hangs,
 * or other unpredictable behaviour.
 */

int
is_physical_memory(vm_offset_t addr)
{

#if NISA > 0
        /* The ISA ``memory hole''. */
        if (addr >= 0xa0000 && addr < 0x100000)
                return 0;
#endif

        /*
         * stuff other tests for known memory-mapped devices (PCI?)
         * here
         */

        return 1;
}

/*
 * platform-specific vmspace initialization (nothing for i386)
 */
void
cpu_vmspace_alloc(struct vmspace *vm __unused)
{
}

void
cpu_vmspace_free(struct vmspace *vm __unused)
{
}

/*
 * Used by /dev/kmem to determine if we can safely read or write
 * the requested KVA range.
 */
int
kvm_access_check(vm_offset_t saddr, vm_offset_t eaddr, int prot)
{
        vm_offset_t addr;

        if (saddr < KvaStart)
                return EFAULT;
        if (eaddr >= KvaEnd)
                return EFAULT;
        for (addr = saddr; addr < eaddr; addr += PAGE_SIZE)  {
                if (pmap_extract(&kernel_pmap, addr) == 0)
                        return EFAULT;
        }
        if (!kernacc((caddr_t)saddr, eaddr - saddr, prot))
                return EFAULT;
        return 0;
}