/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2010, 2012 Konstantin Belousov <kib@FreeBSD.org>
* Copyright (c) 2015 The FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_vm.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/rwlock.h>
#include <sys/stddef.h>
#include <sys/sysent.h>
#include <sys/sysctl.h>
#include <sys/vdso.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
static struct sx shared_page_alloc_sx;
static vm_object_t shared_page_obj;
static int shared_page_free;
char *shared_page_mapping;
#ifdef RANDOM_FENESTRASX
static struct vdso_fxrng_generation *fxrng_shpage_mapping;
static bool fxrng_enabled = true;
SYSCTL_BOOL(_debug, OID_AUTO, fxrng_vdso_enable, CTLFLAG_RWTUN, &fxrng_enabled,
0, "Enable FXRNG VDSO");
#endif
void
shared_page_write(int base, int size, const void *data)
{
bcopy(data, shared_page_mapping + base, size);
}
static int
shared_page_alloc_locked(int size, int align)
{
int res;
res = roundup(shared_page_free, align);
if (res + size >= IDX_TO_OFF(shared_page_obj->size))
res = -1;
else
shared_page_free = res + size;
return (res);
}
int
shared_page_alloc(int size, int align)
{
int res;
sx_xlock(&shared_page_alloc_sx);
res = shared_page_alloc_locked(size, align);
sx_xunlock(&shared_page_alloc_sx);
return (res);
}
int
shared_page_fill(int size, int align, const void *data)
{
int res;
sx_xlock(&shared_page_alloc_sx);
res = shared_page_alloc_locked(size, align);
if (res != -1)
shared_page_write(res, size, data);
sx_xunlock(&shared_page_alloc_sx);
return (res);
}
static void
shared_page_init(void *dummy __unused)
{
vm_page_t m;
vm_offset_t addr;
sx_init(&shared_page_alloc_sx, "shpsx");
shared_page_obj = vm_pager_allocate(OBJT_PHYS, 0, PAGE_SIZE,
VM_PROT_DEFAULT, 0, NULL);
VM_OBJECT_WLOCK(shared_page_obj);
m = vm_page_grab(shared_page_obj, 0, VM_ALLOC_ZERO);
VM_OBJECT_WUNLOCK(shared_page_obj);
vm_page_valid(m);
vm_page_xunbusy(m);
addr = kva_alloc(PAGE_SIZE);
pmap_qenter(addr, &m, 1);
shared_page_mapping = (char *)addr;
}
SYSINIT(shp, SI_SUB_EXEC, SI_ORDER_FIRST, (sysinit_cfunc_t)shared_page_init,
NULL);
/*
* Push the timehands update to the shared page.
*
* The lockless update scheme is similar to the one used to update the
* in-kernel timehands, see sys/kern/kern_tc.c:tc_windup() (which
* calls us after the timehands are updated).
*/
static void
timehands_update(struct vdso_sv_tk *svtk)
{
struct vdso_timehands th;
struct vdso_timekeep *tk;
uint32_t enabled, idx;
enabled = tc_fill_vdso_timehands(&th);
th.th_gen = 0;
idx = svtk->sv_timekeep_curr;
if (++idx >= VDSO_TH_NUM)
idx = 0;
svtk->sv_timekeep_curr = idx;
if (++svtk->sv_timekeep_gen == 0)
svtk->sv_timekeep_gen = 1;
tk = (struct vdso_timekeep *)(shared_page_mapping +
svtk->sv_timekeep_off);
tk->tk_th[idx].th_gen = 0;
atomic_thread_fence_rel();
if (enabled)
tk->tk_th[idx] = th;
atomic_store_rel_32(&tk->tk_th[idx].th_gen, svtk->sv_timekeep_gen);
atomic_store_rel_32(&tk->tk_current, idx);
/*
* The ordering of the assignment to tk_enabled relative to
* the update of the vdso_timehands is not important.
*/
tk->tk_enabled = enabled;
}
#ifdef COMPAT_FREEBSD32
static void
timehands_update32(struct vdso_sv_tk *svtk)
{
struct vdso_timehands32 th;
struct vdso_timekeep32 *tk;
uint32_t enabled, idx;
enabled = tc_fill_vdso_timehands32(&th);
th.th_gen = 0;
idx = svtk->sv_timekeep_curr;
if (++idx >= VDSO_TH_NUM)
idx = 0;
svtk->sv_timekeep_curr = idx;
if (++svtk->sv_timekeep_gen == 0)
svtk->sv_timekeep_gen = 1;
tk = (struct vdso_timekeep32 *)(shared_page_mapping +
svtk->sv_timekeep_off);
tk->tk_th[idx].th_gen = 0;
atomic_thread_fence_rel();
if (enabled)
tk->tk_th[idx] = th;
atomic_store_rel_32(&tk->tk_th[idx].th_gen, svtk->sv_timekeep_gen);
atomic_store_rel_32(&tk->tk_current, idx);
tk->tk_enabled = enabled;
}
#endif
/*
* This is hackish, but easiest way to avoid creating list structures
* that needs to be iterated over from the hardclock interrupt
* context.
*/
static struct vdso_sv_tk *host_svtk;
#ifdef COMPAT_FREEBSD32
static struct vdso_sv_tk *compat32_svtk;
#endif
void
timekeep_push_vdso(void)
{
if (host_svtk != NULL)
timehands_update(host_svtk);
#ifdef COMPAT_FREEBSD32
if (compat32_svtk != NULL)
timehands_update32(compat32_svtk);
#endif
}
struct vdso_sv_tk *
alloc_sv_tk(void)
{
struct vdso_sv_tk *svtk;
int tk_base;
uint32_t tk_ver;
tk_ver = VDSO_TK_VER_CURR;
svtk = malloc(sizeof(struct vdso_sv_tk), M_TEMP, M_WAITOK | M_ZERO);
tk_base = shared_page_alloc(sizeof(struct vdso_timekeep) +
sizeof(struct vdso_timehands) * VDSO_TH_NUM, 16);
KASSERT(tk_base != -1, ("tk_base -1 for native"));
shared_page_write(tk_base + offsetof(struct vdso_timekeep, tk_ver),
sizeof(uint32_t), &tk_ver);
svtk->sv_timekeep_off = tk_base;
timekeep_push_vdso();
return (svtk);
}
#ifdef COMPAT_FREEBSD32
struct vdso_sv_tk *
alloc_sv_tk_compat32(void)
{
struct vdso_sv_tk *svtk;
int tk_base;
uint32_t tk_ver;
svtk = malloc(sizeof(struct vdso_sv_tk), M_TEMP, M_WAITOK | M_ZERO);
tk_ver = VDSO_TK_VER_CURR;
tk_base = shared_page_alloc(sizeof(struct vdso_timekeep32) +
sizeof(struct vdso_timehands32) * VDSO_TH_NUM, 16);
KASSERT(tk_base != -1, ("tk_base -1 for 32bit"));
shared_page_write(tk_base + offsetof(struct vdso_timekeep32,
tk_ver), sizeof(uint32_t), &tk_ver);
svtk->sv_timekeep_off = tk_base;
timekeep_push_vdso();
return (svtk);
}
#endif
#ifdef RANDOM_FENESTRASX
void
fxrng_push_seed_generation(uint64_t gen)
{
if (fxrng_shpage_mapping == NULL || !fxrng_enabled)
return;
KASSERT(gen < INT32_MAX,
("fxrng seed version shouldn't roll over a 32-bit counter "
"for approximately 456,000 years"));
atomic_store_rel_32(&fxrng_shpage_mapping->fx_generation32,
(uint32_t)gen);
}
static void
alloc_sv_fxrng_generation(void)
{
int base;
/*
* Allocate a full cache line for the fxrng root generation (64-bit
* counter, or truncated 32-bit counter on ILP32 userspace). It is
* important that the line is not shared with frequently dirtied data,
* and the shared page allocator lacks a __read_mostly mechanism.
* However, PAGE_SIZE is typically large relative to the amount of
* stuff we've got in it so far, so maybe the possible waste isn't an
* issue.
*/
base = shared_page_alloc(CACHE_LINE_SIZE, CACHE_LINE_SIZE);
KASSERT(base != -1, ("%s: base allocation failed", __func__));
fxrng_shpage_mapping = (void *)(shared_page_mapping + base);
*fxrng_shpage_mapping = (struct vdso_fxrng_generation) {
.fx_vdso_version = VDSO_FXRNG_VER_CURR,
};
}
#endif /* RANDOM_FENESTRASX */
void
exec_sysvec_init(void *param)
{
struct sysentvec *sv;
#ifdef RANDOM_FENESTRASX
ptrdiff_t base;
#endif
sv = (struct sysentvec *)param;
if ((sv->sv_flags & SV_SHP) == 0)
return;
sv->sv_shared_page_obj = shared_page_obj;
sv->sv_sigcode_base = sv->sv_shared_page_base +
shared_page_fill(*(sv->sv_szsigcode), 16, sv->sv_sigcode);
if ((sv->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
return;
if ((sv->sv_flags & SV_TIMEKEEP) != 0) {
#ifdef COMPAT_FREEBSD32
if ((sv->sv_flags & SV_ILP32) != 0) {
KASSERT(compat32_svtk == NULL,
("Compat32 already registered"));
compat32_svtk = alloc_sv_tk_compat32();
sv->sv_timekeep_base = sv->sv_shared_page_base +
compat32_svtk->sv_timekeep_off;
} else {
#endif
KASSERT(host_svtk == NULL, ("Host already registered"));
host_svtk = alloc_sv_tk();
sv->sv_timekeep_base = sv->sv_shared_page_base +
host_svtk->sv_timekeep_off;
#ifdef COMPAT_FREEBSD32
}
#endif
}
#ifdef RANDOM_FENESTRASX
if ((sv->sv_flags & SV_RNG_SEED_VER) != 0) {
/*
* Only allocate a single VDSO entry for multiple sysentvecs,
* i.e., native and COMPAT32.
*/
if (fxrng_shpage_mapping == NULL)
alloc_sv_fxrng_generation();
base = (char *)fxrng_shpage_mapping - shared_page_mapping;
sv->sv_fxrng_gen_base = sv->sv_shared_page_base + base;
}
#endif
}
void
exec_sysvec_init_secondary(struct sysentvec *sv, struct sysentvec *sv2)
{
MPASS((sv2->sv_flags & SV_ABI_MASK) == (sv->sv_flags & SV_ABI_MASK));
MPASS((sv2->sv_flags & SV_TIMEKEEP) == (sv->sv_flags & SV_TIMEKEEP));
MPASS((sv2->sv_flags & SV_SHP) != 0 && (sv->sv_flags & SV_SHP) != 0);
MPASS((sv2->sv_flags & SV_RNG_SEED_VER) ==
(sv->sv_flags & SV_RNG_SEED_VER));
sv2->sv_shared_page_obj = sv->sv_shared_page_obj;
sv2->sv_sigcode_base = sv2->sv_shared_page_base +
(sv->sv_sigcode_base - sv->sv_shared_page_base);
if ((sv2->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
return;
if ((sv2->sv_flags & SV_TIMEKEEP) != 0) {
sv2->sv_timekeep_base = sv2->sv_shared_page_base +
(sv->sv_timekeep_base - sv->sv_shared_page_base);
}
if ((sv2->sv_flags & SV_RNG_SEED_VER) != 0) {
sv2->sv_fxrng_gen_base = sv2->sv_shared_page_base +
(sv->sv_fxrng_gen_base - sv->sv_shared_page_base);
}
}
