kernel - Fix some rare pmap races in i386 and x86_64.

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

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * 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: @(#)sys_machdep.c 5.5 (Berkeley) 1/19/91
 * $FreeBSD: src/sys/i386/i386/sys_machdep.c,v 1.47.2.3 2002/10/07 17:20:00 jhb Exp $
 * $DragonFly: src/sys/platform/pc32/i386/sys_machdep.c,v 1.32 2008/01/06 16:55:53 swildner Exp $
 *
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/malloc.h>
#include <sys/thread.h>
#include <sys/proc.h>
#include <sys/priv.h>
#include <sys/thread.h>
#include <sys/memrange.h>

#include <vm/vm.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_extern.h>

#include <sys/user.h>

#include <machine/cpu.h>
#include <machine/pcb_ext.h>    /* pcb.h included by sys/user.h */
#include <machine/sysarch.h>
#include <machine/smp.h>
#include <machine/globaldata.h> /* mdcpu */

#include <vm/vm_kern.h>         /* for kernel_map */

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

#define MAX_LD 8192
#define LD_PER_PAGE 512
#define NEW_MAX_LD(num)  ((num + LD_PER_PAGE) & ~(LD_PER_PAGE-1))
#define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3)



static int ki386_get_ldt(struct lwp *, char *, int *);
static int ki386_set_ldt(struct lwp *, char *, int *);
static int ki386_get_ioperm(struct lwp *, char *);
static int ki386_set_ioperm(struct lwp *, char *);
static int check_descs(union descriptor *, int);
int i386_extend_pcb(struct lwp *);

/*
 * sysarch_args(int op, char *params)
 *
 * MPALMOSTSAFE
 */
int
sys_sysarch(struct sysarch_args *uap)
{
        struct lwp *lp = curthread->td_lwp;
        int error = 0;

        get_mplock();

        switch(uap->op) {
        case I386_GET_LDT:
                error = ki386_get_ldt(lp, uap->parms, &uap->sysmsg_result);
                break;
        case I386_SET_LDT:
                error = ki386_set_ldt(lp, uap->parms, &uap->sysmsg_result);
                break;
        case I386_GET_IOPERM:
                error = ki386_get_ioperm(lp, uap->parms);
                break;
        case I386_SET_IOPERM:
                error = ki386_set_ioperm(lp, uap->parms);
                break;
        case I386_VM86:
                error = vm86_sysarch(lp, uap->parms);
                break;
        default:
                error = EOPNOTSUPP;
                break;
        }
        rel_mplock();
        return (error);
}

int
i386_extend_pcb(struct lwp *lp)
{
        int i, offset;
        u_long *addr;
        struct pcb_ext *ext;
        struct soft_segment_descriptor ssd = {
                0,                      /* segment base address (overwritten) */
                ctob(IOPAGES + 1) - 1,  /* length */
                SDT_SYS386TSS,          /* segment type */
                0,                      /* priority level */
                1,                      /* descriptor present */
                0, 0,
                0,                      /* default 32 size */
                0                       /* granularity */
        };

        ext = (struct pcb_ext *)kmem_alloc(&kernel_map, ctob(IOPAGES+1));
        if (ext == NULL)
                return (ENOMEM);
        bzero(ext, sizeof(struct pcb_ext)); 
        ext->ext_tss.tss_esp0 = (unsigned)((char *)lp->lwp_thread->td_pcb - 16);
        ext->ext_tss.tss_ss0 = GSEL(GDATA_SEL, SEL_KPL);
        /*
         * The last byte of the i/o map must be followed by an 0xff byte.
         * We arbitrarily allocate 16 bytes here, to keep the starting
         * address on a doubleword boundary.
         */
        offset = PAGE_SIZE - 16;
        ext->ext_tss.tss_ioopt = 
            (offset - ((unsigned)&ext->ext_tss - (unsigned)ext)) << 16;
        ext->ext_iomap = (caddr_t)ext + offset;
        ext->ext_vm86.vm86_intmap = (caddr_t)ext + offset - 32;

        addr = (u_long *)ext->ext_vm86.vm86_intmap;
        for (i = 0; i < (ctob(IOPAGES) + 32 + 16) / sizeof(u_long); i++)
                *addr++ = ~0;

        ssd.ssd_base = (unsigned)&ext->ext_tss;
        ssd.ssd_limit -= ((unsigned)&ext->ext_tss - (unsigned)ext);
        ssdtosd(&ssd, &ext->ext_tssd);

        /* 
         * Put the new TSS where the switch code can find it.  Do
         * a forced switch to ourself to activate it.
         */
        crit_enter();
        lp->lwp_thread->td_pcb->pcb_ext = ext;
        lp->lwp_thread->td_switch(lp->lwp_thread);
        crit_exit();
        
        return 0;
}

static int
ki386_set_ioperm(struct lwp *lp, char *args)
{
        int i, error;
        struct i386_ioperm_args ua;
        char *iomap;

        if ((error = copyin(args, &ua, sizeof(struct i386_ioperm_args))) != 0)
                return (error);

        if ((error = priv_check_cred(lp->lwp_thread->td_ucred, PRIV_ROOT, 0)) != 0)
                return (error);
        if (securelevel > 0)
                return (EPERM);
        /*
         * XXX 
         * While this is restricted to root, we should probably figure out
         * whether any other driver is using this i/o address, as so not to
         * cause confusion.  This probably requires a global 'usage registry'.
         */

        if (lp->lwp_thread->td_pcb->pcb_ext == 0)
                if ((error = i386_extend_pcb(lp)) != 0)
                        return (error);
        iomap = (char *)lp->lwp_thread->td_pcb->pcb_ext->ext_iomap;

        if (ua.start + ua.length > IOPAGES * PAGE_SIZE * NBBY)
                return (EINVAL);

        for (i = ua.start; i < ua.start + ua.length; i++) {
                if (ua.enable) 
                        iomap[i >> 3] &= ~(1 << (i & 7));
                else
                        iomap[i >> 3] |= (1 << (i & 7));
        }
        return (error);
}

static int
ki386_get_ioperm(struct lwp *lp, char *args)
{
        int i, state, error;
        struct i386_ioperm_args ua;
        char *iomap;

        if ((error = copyin(args, &ua, sizeof(struct i386_ioperm_args))) != 0)
                return (error);
        if (ua.start >= IOPAGES * PAGE_SIZE * NBBY)
                return (EINVAL);

        if (lp->lwp_thread->td_pcb->pcb_ext == 0) {
                ua.length = 0;
                goto done;
        }

        iomap = (char *)lp->lwp_thread->td_pcb->pcb_ext->ext_iomap;

        i = ua.start;
        state = (iomap[i >> 3] >> (i & 7)) & 1;
        ua.enable = !state;
        ua.length = 1;

        for (i = ua.start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) {
                if (state != ((iomap[i >> 3] >> (i & 7)) & 1))
                        break;
                ua.length++;
        }
                        
done:
        error = copyout(&ua, args, sizeof(struct i386_ioperm_args));
        return (error);
}

/*
 * Update the TLS entries for the process.  Used by assembly, do not staticize.
 *
 * Must be called from a critical section (else an interrupt thread preemption
 * may cause %gs to fault).  Normally called from the low level swtch.s code.
 *
 * MPSAFE
 */
void
set_user_TLS(void)
{
        struct thread *td = curthread;
        int i;
#ifdef SMP
        int off = GTLS_START + mycpu->gd_cpuid * NGDT;
#else
        const int off = GTLS_START;
#endif
        for (i = 0; i < NGTLS; ++i)
                gdt[off + i].sd = td->td_tls.tls[i];
}

#ifdef SMP
static
void
set_user_ldt_cpusync(struct lwkt_cpusync *cmd)
{
        set_user_ldt(cmd->cs_data);
}
#endif

/*
 * Update the GDT entry pointing to the LDT to point to the LDT of the
 * current process.  Used by assembly, do not staticize.
 *
 * Must be called from a critical section (else an interrupt thread preemption
 * may cause %gs to fault).  Normally called from the low level swtch.s code.
 */   
void
set_user_ldt(struct pcb *pcb)
{
        struct pcb_ldt *pcb_ldt;

        if (pcb != curthread->td_pcb)
                return;

        pcb_ldt = pcb->pcb_ldt;
#ifdef SMP
        gdt[mycpu->gd_cpuid * NGDT + GUSERLDT_SEL].sd = pcb_ldt->ldt_sd;
#else
        gdt[GUSERLDT_SEL].sd = pcb_ldt->ldt_sd;
#endif
        lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
        mdcpu->gd_currentldt = GSEL(GUSERLDT_SEL, SEL_KPL);
}

struct pcb_ldt *
user_ldt_alloc(struct pcb *pcb, int len)
{
        struct pcb_ldt *pcb_ldt, *new_ldt;

        MALLOC(new_ldt, struct pcb_ldt *, sizeof(struct pcb_ldt),
                M_SUBPROC, M_WAITOK);

        new_ldt->ldt_len = len = NEW_MAX_LD(len);
        new_ldt->ldt_base = (caddr_t)kmem_alloc(&kernel_map,
                                                len * sizeof(union descriptor));
        if (new_ldt->ldt_base == NULL) {
                FREE(new_ldt, M_SUBPROC);
                return NULL;
        }
        new_ldt->ldt_refcnt = 1;
        new_ldt->ldt_active = 0;

        gdt_segs[GUSERLDT_SEL].ssd_base = (unsigned)new_ldt->ldt_base;
        gdt_segs[GUSERLDT_SEL].ssd_limit = len * sizeof(union descriptor) - 1;
        ssdtosd(&gdt_segs[GUSERLDT_SEL], &new_ldt->ldt_sd);

        if ((pcb_ldt = pcb->pcb_ldt)) {
                if (len > pcb_ldt->ldt_len)
                        len = pcb_ldt->ldt_len;
                bcopy(pcb_ldt->ldt_base, new_ldt->ldt_base,
                        len * sizeof(union descriptor));
        } else {
                bcopy(ldt, new_ldt->ldt_base, sizeof(ldt));
        }
        return new_ldt;
}

void
user_ldt_free(struct pcb *pcb)
{
        struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;

        if (pcb_ldt == NULL)
                return;

        crit_enter();
        if (pcb == curthread->td_pcb) {
                lldt(_default_ldt);
                mdcpu->gd_currentldt = _default_ldt;
        }
        pcb->pcb_ldt = NULL;
        crit_exit();

        if (--pcb_ldt->ldt_refcnt == 0) {
                kmem_free(&kernel_map, (vm_offset_t)pcb_ldt->ldt_base,
                          pcb_ldt->ldt_len * sizeof(union descriptor));
                FREE(pcb_ldt, M_SUBPROC);
        }
}

static int
ki386_get_ldt(struct lwp *lwp, char *args, int *res)
{
        int error = 0;
        struct pcb *pcb = lwp->lwp_thread->td_pcb;
        struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
        unsigned int nldt, num;
        union descriptor *lp;
        struct i386_ldt_args ua, *uap = &ua;

        if ((error = copyin(args, uap, sizeof(struct i386_ldt_args))) < 0)
                return(error);

#ifdef  DEBUG
        kprintf("ki386_get_ldt: start=%d num=%d descs=%p\n",
            uap->start, uap->num, (void *)uap->descs);
#endif

        crit_enter();

        if (pcb_ldt) {
                nldt = (unsigned int)pcb_ldt->ldt_len;
                num = min(uap->num, nldt);
                lp = &((union descriptor *)(pcb_ldt->ldt_base))[uap->start];
        } else {
                nldt = (unsigned int)(sizeof(ldt) / sizeof(ldt[0]));
                num = min(uap->num, nldt);
                lp = &ldt[uap->start];
        }

        /*
         * note: uap->(args), num, and nldt are unsigned.  nldt and num
         * are limited in scope, but uap->start can be anything.
         */
        if (uap->start > nldt || uap->start + num > nldt) {
                crit_exit();
                return(EINVAL);
        }

        error = copyout(lp, uap->descs, num * sizeof(union descriptor));
        if (!error)
                *res = num;
        crit_exit();
        return(error);
}

static int
ki386_set_ldt(struct lwp *lp, char *args, int *res)
{
        int error = 0;
        int largest_ld;
        struct pcb *pcb = lp->lwp_thread->td_pcb;
        struct pcb_ldt *pcb_ldt = pcb->pcb_ldt;
        union descriptor *descs;
        int descs_size;
        struct i386_ldt_args ua, *uap = &ua;

        if ((error = copyin(args, uap, sizeof(struct i386_ldt_args))) < 0)
                return(error);

#ifdef  DEBUG
        kprintf("ki386_set_ldt: start=%d num=%d descs=%p\n",
            uap->start, uap->num, (void *)uap->descs);
#endif

        /* verify range of descriptors to modify */
        if ((uap->start < 0) || (uap->start >= MAX_LD) || (uap->num < 0) ||
                (uap->num > MAX_LD))
        {
                return(EINVAL);
        }
        largest_ld = uap->start + uap->num - 1;
        if (largest_ld >= MAX_LD)
                return(EINVAL);

        /* allocate user ldt */
        if (!pcb_ldt || largest_ld >= pcb_ldt->ldt_len) {
                struct pcb_ldt *new_ldt = user_ldt_alloc(pcb, largest_ld);
                if (new_ldt == NULL)
                        return ENOMEM;
                if (pcb_ldt) {
                        pcb_ldt->ldt_sd = new_ldt->ldt_sd;
                        kmem_free(&kernel_map, (vm_offset_t)pcb_ldt->ldt_base,
                                  pcb_ldt->ldt_len * sizeof(union descriptor));
                        pcb_ldt->ldt_base = new_ldt->ldt_base;
                        pcb_ldt->ldt_len = new_ldt->ldt_len;
                        FREE(new_ldt, M_SUBPROC);
                } else {
                        pcb->pcb_ldt = pcb_ldt = new_ldt;
                }
                /*
                 * Since the LDT may be shared, we must signal other cpus to
                 * reload it.  XXX we need to track which cpus might be
                 * using the shared ldt and only signal those.
                 */
#ifdef SMP
                lwkt_cpusync_simple(-1, set_user_ldt_cpusync, pcb);
#else
                set_user_ldt(pcb);
#endif
        }

        descs_size = uap->num * sizeof(union descriptor);
        descs = (union descriptor *)kmem_alloc(&kernel_map, descs_size);
        if (descs == NULL)
                return (ENOMEM);
        error = copyin(&uap->descs[0], descs, descs_size);
        if (error) {
                kmem_free(&kernel_map, (vm_offset_t)descs, descs_size);
                return (error);
        }
        /* Check descriptors for access violations */
        error = check_descs(descs, uap->num);
        if (error) {
                kmem_free(&kernel_map, (vm_offset_t)descs, descs_size);
                return (error);
        }

        /*
         * Fill in the actual ldt entries.  Since %fs or %gs might point to
         * one of these entries a critical section is required to prevent an
         * interrupt thread from preempting us, switch back, and faulting
         * on the load of %fs due to a half-formed descriptor.
         */
        crit_enter();
        bcopy(descs, 
                 &((union descriptor *)(pcb_ldt->ldt_base))[uap->start],
                uap->num * sizeof(union descriptor));
        *res = uap->start;

        crit_exit();
        kmem_free(&kernel_map, (vm_offset_t)descs, descs_size);
        return (0);
}

static int
check_descs(union descriptor *descs, int num)
{
        int i;

        /* Check descriptors for access violations */
        for (i = 0; i < num; i++) {
                union descriptor *dp;
                dp = &descs[i];

                switch (dp->sd.sd_type) {
                case SDT_SYSNULL:       /* system null */ 
                        dp->sd.sd_p = 0;
                        break;
                case SDT_SYS286TSS: /* system 286 TSS available */
                case SDT_SYSLDT:    /* system local descriptor table */
                case SDT_SYS286BSY: /* system 286 TSS busy */
                case SDT_SYSTASKGT: /* system task gate */
                case SDT_SYS286IGT: /* system 286 interrupt gate */
                case SDT_SYS286TGT: /* system 286 trap gate */
                case SDT_SYSNULL2:  /* undefined by Intel */ 
                case SDT_SYS386TSS: /* system 386 TSS available */
                case SDT_SYSNULL3:  /* undefined by Intel */
                case SDT_SYS386BSY: /* system 386 TSS busy */
                case SDT_SYSNULL4:  /* undefined by Intel */ 
                case SDT_SYS386IGT: /* system 386 interrupt gate */
                case SDT_SYS386TGT: /* system 386 trap gate */
                case SDT_SYS286CGT: /* system 286 call gate */ 
                case SDT_SYS386CGT: /* system 386 call gate */
                        /* I can't think of any reason to allow a user proc
                         * to create a segment of these types.  They are
                         * for OS use only.
                         */
                        return EACCES;

                /* memory segment types */
                case SDT_MEMEC:   /* memory execute only conforming */
                case SDT_MEMEAC:  /* memory execute only accessed conforming */
                case SDT_MEMERC:  /* memory execute read conforming */
                case SDT_MEMERAC: /* memory execute read accessed conforming */
                        /* Must be "present" if executable and conforming. */
                        if (dp->sd.sd_p == 0)
                                return (EACCES);
                        break;
                case SDT_MEMRO:   /* memory read only */
                case SDT_MEMROA:  /* memory read only accessed */
                case SDT_MEMRW:   /* memory read write */
                case SDT_MEMRWA:  /* memory read write accessed */
                case SDT_MEMROD:  /* memory read only expand dwn limit */
                case SDT_MEMRODA: /* memory read only expand dwn lim accessed */
                case SDT_MEMRWD:  /* memory read write expand dwn limit */  
                case SDT_MEMRWDA: /* memory read write expand dwn lim acessed */
                case SDT_MEME:    /* memory execute only */ 
                case SDT_MEMEA:   /* memory execute only accessed */
                case SDT_MEMER:   /* memory execute read */
                case SDT_MEMERA:  /* memory execute read accessed */
                        break;
                default:
                        return(EINVAL);
                        /*NOTREACHED*/
                }

                /* Only user (ring-3) descriptors may be present. */
                if ((dp->sd.sd_p != 0) && (dp->sd.sd_dpl != SEL_UPL))
                        return (EACCES);
        }
        return (0);
}

/*
 * Called when /dev/io is opened
 */
int
cpu_set_iopl(void)
{
        curthread->td_lwp->lwp_md.md_regs->tf_eflags |= PSL_IOPL;
        return(0);
}

/*
 * Called when /dev/io is closed
 */
int
cpu_clr_iopl(void)
{
        curthread->td_lwp->lwp_md.md_regs->tf_eflags &= ~PSL_IOPL;
        return(0);
}