Index: head/sys/i386/i386/sys_machdep.c
===================================================================
--- head/sys/i386/i386/sys_machdep.c (revision 343747)
+++ head/sys/i386/i386/sys_machdep.c (revision 343748)
@@ -1,809 +1,809 @@
/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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. 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
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_capsicum.h"
#include "opt_kstack_pages.h"
#include <sys/param.h>
#include <sys/capsicum.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/smp.h>
#include <sys/sysproto.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_extern.h>
#include <machine/atomic.h>
#include <machine/cpu.h>
#include <machine/pcb.h>
#include <machine/pcb_ext.h>
#include <machine/proc.h>
#include <machine/sysarch.h>
#include <security/audit/audit.h>
#include <vm/vm_kern.h> /* for kernel_map */
#define MAX_LD 8192
#define LD_PER_PAGE 512
#define NEW_MAX_LD(num) rounddown2(num + LD_PER_PAGE, LD_PER_PAGE)
#define SIZE_FROM_LARGEST_LD(num) (NEW_MAX_LD(num) << 3)
#define NULL_LDT_BASE ((caddr_t)NULL)
#ifdef SMP
static void set_user_ldt_rv(void *arg);
#endif
static int i386_set_ldt_data(struct thread *, int start, int num,
union descriptor *descs);
static int i386_ldt_grow(struct thread *td, int len);
void
fill_based_sd(struct segment_descriptor *sdp, uint32_t base)
{
sdp->sd_lobase = base & 0xffffff;
sdp->sd_hibase = (base >> 24) & 0xff;
sdp->sd_lolimit = 0xffff; /* 4GB limit, wraps around */
sdp->sd_hilimit = 0xf;
sdp->sd_type = SDT_MEMRWA;
sdp->sd_dpl = SEL_UPL;
sdp->sd_p = 1;
sdp->sd_xx = 0;
sdp->sd_def32 = 1;
sdp->sd_gran = 1;
}
/*
* Construct special descriptors for "base" selectors. Store them in
* the PCB for later use by cpu_switch(). Store them in the GDT for
* more immediate use. The GDT entries are part of the current
* context. Callers must load related segment registers to complete
* setting up the current context.
*/
void
set_fsbase(struct thread *td, uint32_t base)
{
struct segment_descriptor sd;
fill_based_sd(&sd, base);
critical_enter();
td->td_pcb->pcb_fsd = sd;
PCPU_GET(fsgs_gdt)[0] = sd;
critical_exit();
}
void
set_gsbase(struct thread *td, uint32_t base)
{
struct segment_descriptor sd;
fill_based_sd(&sd, base);
critical_enter();
td->td_pcb->pcb_gsd = sd;
PCPU_GET(fsgs_gdt)[1] = sd;
critical_exit();
}
#ifndef _SYS_SYSPROTO_H_
struct sysarch_args {
int op;
char *parms;
};
#endif
int
sysarch(struct thread *td, struct sysarch_args *uap)
{
int error;
union descriptor *lp;
union {
struct i386_ldt_args largs;
struct i386_ioperm_args iargs;
struct i386_get_xfpustate xfpu;
} kargs;
uint32_t base;
struct segment_descriptor *sdp;
AUDIT_ARG_CMD(uap->op);
#ifdef CAPABILITY_MODE
/*
* When adding new operations, add a new case statement here to
* explicitly indicate whether or not the operation is safe to
* perform in capability mode.
*/
if (IN_CAPABILITY_MODE(td)) {
switch (uap->op) {
case I386_GET_LDT:
case I386_SET_LDT:
case I386_GET_IOPERM:
case I386_GET_FSBASE:
case I386_SET_FSBASE:
case I386_GET_GSBASE:
case I386_SET_GSBASE:
case I386_GET_XFPUSTATE:
break;
case I386_SET_IOPERM:
default:
#ifdef KTRACE
if (KTRPOINT(td, KTR_CAPFAIL))
ktrcapfail(CAPFAIL_SYSCALL, NULL, NULL);
#endif
return (ECAPMODE);
}
}
#endif
switch (uap->op) {
case I386_GET_IOPERM:
case I386_SET_IOPERM:
if ((error = copyin(uap->parms, &kargs.iargs,
sizeof(struct i386_ioperm_args))) != 0)
return (error);
break;
case I386_GET_LDT:
case I386_SET_LDT:
if ((error = copyin(uap->parms, &kargs.largs,
sizeof(struct i386_ldt_args))) != 0)
return (error);
break;
case I386_GET_XFPUSTATE:
if ((error = copyin(uap->parms, &kargs.xfpu,
sizeof(struct i386_get_xfpustate))) != 0)
return (error);
break;
default:
break;
}
switch (uap->op) {
case I386_GET_LDT:
error = i386_get_ldt(td, &kargs.largs);
break;
case I386_SET_LDT:
if (kargs.largs.descs != NULL) {
if (kargs.largs.num > MAX_LD)
return (EINVAL);
lp = malloc(kargs.largs.num * sizeof(union descriptor),
M_TEMP, M_WAITOK);
error = copyin(kargs.largs.descs, lp,
kargs.largs.num * sizeof(union descriptor));
if (error == 0)
error = i386_set_ldt(td, &kargs.largs, lp);
free(lp, M_TEMP);
} else {
error = i386_set_ldt(td, &kargs.largs, NULL);
}
break;
case I386_GET_IOPERM:
error = i386_get_ioperm(td, &kargs.iargs);
if (error == 0)
error = copyout(&kargs.iargs, uap->parms,
sizeof(struct i386_ioperm_args));
break;
case I386_SET_IOPERM:
error = i386_set_ioperm(td, &kargs.iargs);
break;
case I386_VM86:
error = vm86_sysarch(td, uap->parms);
break;
case I386_GET_FSBASE:
sdp = &td->td_pcb->pcb_fsd;
base = sdp->sd_hibase << 24 | sdp->sd_lobase;
error = copyout(&base, uap->parms, sizeof(base));
break;
case I386_SET_FSBASE:
error = copyin(uap->parms, &base, sizeof(base));
if (error == 0) {
/*
* Construct the special descriptor for fsbase
* and arrange for doreti to load its selector
* soon enough.
*/
set_fsbase(td, base);
td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
}
break;
case I386_GET_GSBASE:
sdp = &td->td_pcb->pcb_gsd;
base = sdp->sd_hibase << 24 | sdp->sd_lobase;
error = copyout(&base, uap->parms, sizeof(base));
break;
case I386_SET_GSBASE:
error = copyin(uap->parms, &base, sizeof(base));
if (error == 0) {
/*
* Construct the special descriptor for gsbase.
* The selector is loaded immediately, since we
* normally only reload %gs on context switches.
*/
set_gsbase(td, base);
load_gs(GSEL(GUGS_SEL, SEL_UPL));
}
break;
case I386_GET_XFPUSTATE:
if (kargs.xfpu.len > cpu_max_ext_state_size -
sizeof(union savefpu))
return (EINVAL);
npxgetregs(td);
error = copyout((char *)(get_pcb_user_save_td(td) + 1),
kargs.xfpu.addr, kargs.xfpu.len);
break;
default:
error = EINVAL;
break;
}
return (error);
}
int
i386_extend_pcb(struct thread *td)
{
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 = pmap_trm_alloc(ctob(IOPAGES + 1), M_WAITOK | M_ZERO);
/* -16 is so we can convert a trapframe into vm86trapframe inplace */
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);
KASSERT(td == curthread, ("giving TSS to !curthread"));
KASSERT(td->td_pcb->pcb_ext == 0, ("already have a TSS!"));
/* Switch to the new TSS. */
critical_enter();
ext->ext_tss.tss_esp0 = PCPU_GET(trampstk);
td->td_pcb->pcb_ext = ext;
PCPU_SET(private_tss, 1);
*PCPU_GET(tss_gdt) = ext->ext_tssd;
ltr(GSEL(GPROC0_SEL, SEL_KPL));
critical_exit();
return 0;
}
int
i386_set_ioperm(td, uap)
struct thread *td;
struct i386_ioperm_args *uap;
{
char *iomap;
u_int i;
int error;
if ((error = priv_check(td, PRIV_IO)) != 0)
return (error);
if ((error = securelevel_gt(td->td_ucred, 0)) != 0)
return (error);
/*
* 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 (td->td_pcb->pcb_ext == 0)
if ((error = i386_extend_pcb(td)) != 0)
return (error);
iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
if (uap->start > uap->start + uap->length ||
uap->start + uap->length > IOPAGES * PAGE_SIZE * NBBY)
return (EINVAL);
for (i = uap->start; i < uap->start + uap->length; i++) {
if (uap->enable)
iomap[i >> 3] &= ~(1 << (i & 7));
else
iomap[i >> 3] |= (1 << (i & 7));
}
return (error);
}
int
i386_get_ioperm(td, uap)
struct thread *td;
struct i386_ioperm_args *uap;
{
int i, state;
char *iomap;
if (uap->start >= IOPAGES * PAGE_SIZE * NBBY)
return (EINVAL);
if (td->td_pcb->pcb_ext == 0) {
uap->length = 0;
goto done;
}
iomap = (char *)td->td_pcb->pcb_ext->ext_iomap;
i = uap->start;
state = (iomap[i >> 3] >> (i & 7)) & 1;
uap->enable = !state;
uap->length = 1;
for (i = uap->start + 1; i < IOPAGES * PAGE_SIZE * NBBY; i++) {
if (state != ((iomap[i >> 3] >> (i & 7)) & 1))
break;
uap->length++;
}
done:
return (0);
}
/*
* Update the GDT entry pointing to the LDT to point to the LDT of the
* current process. Manage dt_lock holding/unholding autonomously.
*/
static void
set_user_ldt_locked(struct mdproc *mdp)
{
struct proc_ldt *pldt;
int gdt_idx;
mtx_assert(&dt_lock, MA_OWNED);
pldt = mdp->md_ldt;
gdt_idx = GUSERLDT_SEL;
gdt_idx += PCPU_GET(cpuid) * NGDT; /* always 0 on UP */
gdt[gdt_idx].sd = pldt->ldt_sd;
lldt(GSEL(GUSERLDT_SEL, SEL_KPL));
PCPU_SET(currentldt, GSEL(GUSERLDT_SEL, SEL_KPL));
}
void
set_user_ldt(struct mdproc *mdp)
{
mtx_lock_spin(&dt_lock);
set_user_ldt_locked(mdp);
mtx_unlock_spin(&dt_lock);
}
#ifdef SMP
static void
set_user_ldt_rv(void *arg)
{
struct proc *p;
p = curproc;
if (arg == p->p_vmspace)
set_user_ldt(&p->p_md);
}
#endif
/*
* dt_lock must be held. Returns with dt_lock held.
*/
struct proc_ldt *
user_ldt_alloc(struct mdproc *mdp, int len)
{
struct proc_ldt *pldt, *new_ldt;
mtx_assert(&dt_lock, MA_OWNED);
mtx_unlock_spin(&dt_lock);
new_ldt = malloc(sizeof(struct proc_ldt), M_SUBPROC, M_WAITOK);
new_ldt->ldt_len = len = NEW_MAX_LD(len);
new_ldt->ldt_base = pmap_trm_alloc(len * sizeof(union descriptor),
M_WAITOK | M_ZERO);
new_ldt->ldt_refcnt = 1;
new_ldt->ldt_active = 0;
mtx_lock_spin(&dt_lock);
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 ((pldt = mdp->md_ldt) != NULL) {
if (len > pldt->ldt_len)
len = pldt->ldt_len;
bcopy(pldt->ldt_base, new_ldt->ldt_base,
len * sizeof(union descriptor));
} else
bcopy(ldt, new_ldt->ldt_base, sizeof(union descriptor) * NLDT);
return (new_ldt);
}
/*
* Must be called with dt_lock held. Returns with dt_lock unheld.
*/
void
user_ldt_free(struct thread *td)
{
struct mdproc *mdp;
struct proc_ldt *pldt;
mtx_assert(&dt_lock, MA_OWNED);
mdp = &td->td_proc->p_md;
if ((pldt = mdp->md_ldt) == NULL) {
mtx_unlock_spin(&dt_lock);
return;
}
if (td == curthread) {
lldt(_default_ldt);
PCPU_SET(currentldt, _default_ldt);
}
mdp->md_ldt = NULL;
user_ldt_deref(pldt);
}
void
user_ldt_deref(struct proc_ldt *pldt)
{
mtx_assert(&dt_lock, MA_OWNED);
if (--pldt->ldt_refcnt == 0) {
mtx_unlock_spin(&dt_lock);
pmap_trm_free(pldt->ldt_base, pldt->ldt_len *
sizeof(union descriptor));
free(pldt, M_SUBPROC);
} else
mtx_unlock_spin(&dt_lock);
}
/*
* Note for the authors of compat layers (linux, etc): copyout() in
* the function below is not a problem since it presents data in
* arch-specific format (i.e. i386-specific in this case), not in
* the OS-specific one.
*/
int
i386_get_ldt(struct thread *td, struct i386_ldt_args *uap)
{
struct proc_ldt *pldt;
char *data;
u_int nldt, num;
int error;
#ifdef DEBUG
printf("i386_get_ldt: start=%u num=%u descs=%p\n",
uap->start, uap->num, (void *)uap->descs);
#endif
num = min(uap->num, MAX_LD);
data = malloc(num * sizeof(union descriptor), M_TEMP, M_WAITOK);
mtx_lock_spin(&dt_lock);
pldt = td->td_proc->p_md.md_ldt;
- nldt = pldt != NULL ? pldt->ldt_len : nitems(ldt);
+ nldt = pldt != NULL ? pldt->ldt_len : NLDT;
if (uap->start >= nldt) {
num = 0;
} else {
num = min(num, nldt - uap->start);
bcopy(pldt != NULL ?
&((union descriptor *)(pldt->ldt_base))[uap->start] :
&ldt[uap->start], data, num * sizeof(union descriptor));
}
mtx_unlock_spin(&dt_lock);
error = copyout(data, uap->descs, num * sizeof(union descriptor));
if (error == 0)
td->td_retval[0] = num;
free(data, M_TEMP);
return (error);
}
int
i386_set_ldt(struct thread *td, struct i386_ldt_args *uap,
union descriptor *descs)
{
struct mdproc *mdp;
struct proc_ldt *pldt;
union descriptor *dp;
u_int largest_ld, i;
int error;
#ifdef DEBUG
printf("i386_set_ldt: start=%u num=%u descs=%p\n",
uap->start, uap->num, (void *)uap->descs);
#endif
error = 0;
mdp = &td->td_proc->p_md;
if (descs == NULL) {
/* Free descriptors */
if (uap->start == 0 && uap->num == 0) {
/*
* Treat this as a special case, so userland needn't
* know magic number NLDT.
*/
uap->start = NLDT;
uap->num = MAX_LD - NLDT;
}
mtx_lock_spin(&dt_lock);
if ((pldt = mdp->md_ldt) == NULL ||
uap->start >= pldt->ldt_len) {
mtx_unlock_spin(&dt_lock);
return (0);
}
largest_ld = uap->start + uap->num;
if (largest_ld > pldt->ldt_len)
largest_ld = pldt->ldt_len;
for (i = uap->start; i < largest_ld; i++)
atomic_store_rel_64(&((uint64_t *)(pldt->ldt_base))[i],
0);
mtx_unlock_spin(&dt_lock);
return (0);
}
if (uap->start != LDT_AUTO_ALLOC || uap->num != 1) {
/* verify range of descriptors to modify */
largest_ld = uap->start + uap->num;
if (uap->start >= MAX_LD || largest_ld > MAX_LD)
return (EINVAL);
}
/* Check descriptors for access violations */
for (i = 0; i < uap->num; i++) {
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 */
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);
}
/* Only user (ring-3) descriptors may be present. */
if (dp->sd.sd_p != 0 && dp->sd.sd_dpl != SEL_UPL)
return (EACCES);
}
if (uap->start == LDT_AUTO_ALLOC && uap->num == 1) {
/* Allocate a free slot */
mtx_lock_spin(&dt_lock);
if ((pldt = mdp->md_ldt) == NULL) {
if ((error = i386_ldt_grow(td, NLDT + 1))) {
mtx_unlock_spin(&dt_lock);
return (error);
}
pldt = mdp->md_ldt;
}
again:
/*
* start scanning a bit up to leave room for NVidia and
* Wine, which still user the "Blat" method of allocation.
*/
dp = &((union descriptor *)(pldt->ldt_base))[NLDT];
for (i = NLDT; i < pldt->ldt_len; ++i) {
if (dp->sd.sd_type == SDT_SYSNULL)
break;
dp++;
}
if (i >= pldt->ldt_len) {
if ((error = i386_ldt_grow(td, pldt->ldt_len+1))) {
mtx_unlock_spin(&dt_lock);
return (error);
}
goto again;
}
uap->start = i;
error = i386_set_ldt_data(td, i, 1, descs);
mtx_unlock_spin(&dt_lock);
} else {
largest_ld = uap->start + uap->num;
mtx_lock_spin(&dt_lock);
if (!(error = i386_ldt_grow(td, largest_ld))) {
error = i386_set_ldt_data(td, uap->start, uap->num,
descs);
}
mtx_unlock_spin(&dt_lock);
}
if (error == 0)
td->td_retval[0] = uap->start;
return (error);
}
static int
i386_set_ldt_data(struct thread *td, int start, int num,
union descriptor *descs)
{
struct mdproc *mdp;
struct proc_ldt *pldt;
uint64_t *dst, *src;
int i;
mtx_assert(&dt_lock, MA_OWNED);
mdp = &td->td_proc->p_md;
pldt = mdp->md_ldt;
dst = (uint64_t *)(pldt->ldt_base);
src = (uint64_t *)descs;
/*
* Atomic(9) is used only to get 64bit atomic store with
* cmpxchg8b when available. There is no op without release
* semantic.
*/
for (i = 0; i < num; i++)
atomic_store_rel_64(&dst[start + i], src[i]);
return (0);
}
static int
i386_ldt_grow(struct thread *td, int len)
{
struct mdproc *mdp;
struct proc_ldt *new_ldt, *pldt;
caddr_t old_ldt_base;
int old_ldt_len;
mtx_assert(&dt_lock, MA_OWNED);
if (len > MAX_LD)
return (ENOMEM);
if (len < NLDT + 1)
len = NLDT + 1;
mdp = &td->td_proc->p_md;
old_ldt_base = NULL_LDT_BASE;
old_ldt_len = 0;
/* Allocate a user ldt. */
if ((pldt = mdp->md_ldt) == NULL || len > pldt->ldt_len) {
new_ldt = user_ldt_alloc(mdp, len);
if (new_ldt == NULL)
return (ENOMEM);
pldt = mdp->md_ldt;
if (pldt != NULL) {
if (new_ldt->ldt_len <= pldt->ldt_len) {
/*
* We just lost the race for allocation, so
* free the new object and return.
*/
mtx_unlock_spin(&dt_lock);
pmap_trm_free(new_ldt->ldt_base,
new_ldt->ldt_len * sizeof(union descriptor));
free(new_ldt, M_SUBPROC);
mtx_lock_spin(&dt_lock);
return (0);
}
/*
* We have to substitute the current LDT entry for
* curproc with the new one since its size grew.
*/
old_ldt_base = pldt->ldt_base;
old_ldt_len = pldt->ldt_len;
pldt->ldt_sd = new_ldt->ldt_sd;
pldt->ldt_base = new_ldt->ldt_base;
pldt->ldt_len = new_ldt->ldt_len;
} else
mdp->md_ldt = pldt = new_ldt;
#ifdef SMP
/*
* Signal other cpus to reload ldt. We need to unlock dt_lock
* here because other CPU will contest on it since their
* curthreads won't hold the lock and will block when trying
* to acquire it.
*/
mtx_unlock_spin(&dt_lock);
smp_rendezvous(NULL, set_user_ldt_rv, NULL,
td->td_proc->p_vmspace);
#else
set_user_ldt_locked(&td->td_proc->p_md);
mtx_unlock_spin(&dt_lock);
#endif
if (old_ldt_base != NULL_LDT_BASE) {
pmap_trm_free(old_ldt_base, old_ldt_len *
sizeof(union descriptor));
free(new_ldt, M_SUBPROC);
}
mtx_lock_spin(&dt_lock);
}
return (0);
}