freebsd-dev/sys/kern/kern_sharedpage.c
Kornel Dulęba 361971fbca Rework how shared page related data is stored
Store the shared page address in struct vmspace.
Also instead of storing absolute addresses of various shared page
segments save their offsets with respect to the shared page address.
This will be more useful when the shared page address is randomized.

Approved by:	mw(mentor)
Sponsored by:	Stormshield
Obtained from:	Semihalf
Reviewed by:	kib
Differential Revision: https://reviews.freebsd.org/D35393
2022-07-18 16:27:32 +02:00

395 lines
11 KiB
C

/*-
* 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;
u_int flags;
int res;
sv = param;
flags = sv->sv_flags;
if ((flags & SV_SHP) == 0)
return;
MPASS(sv->sv_shared_page_obj == NULL);
MPASS(sv->sv_shared_page_base != 0);
sv->sv_shared_page_obj = shared_page_obj;
if ((flags & SV_ABI_MASK) == SV_ABI_FREEBSD) {
if ((flags & SV_DSO_SIG) != 0) {
res = shared_page_fill((uintptr_t)sv->sv_szsigcode,
16, sv->sv_sigcode);
if (res == -1)
panic("copying vdso to shared page");
sv->sv_vdso_offset = res;
sv->sv_sigcode_offset = res + sv->sv_sigcodeoff;
} else {
res = shared_page_fill(*(sv->sv_szsigcode),
16, sv->sv_sigcode);
if (res == -1)
panic("copying sigtramp to shared page");
sv->sv_sigcode_offset = res;
}
}
if ((flags & SV_TIMEKEEP) != 0) {
#ifdef COMPAT_FREEBSD32
if ((flags & SV_ILP32) != 0) {
if ((flags & SV_ABI_MASK) == SV_ABI_FREEBSD) {
KASSERT(compat32_svtk == NULL,
("Compat32 already registered"));
compat32_svtk = alloc_sv_tk_compat32();
} else {
KASSERT(compat32_svtk != NULL,
("Compat32 not registered"));
}
sv->sv_timekeep_offset = compat32_svtk->sv_timekeep_off;
} else {
#endif
if ((flags & SV_ABI_MASK) == SV_ABI_FREEBSD) {
KASSERT(host_svtk == NULL,
("Host already registered"));
host_svtk = alloc_sv_tk();
} else {
KASSERT(host_svtk != NULL,
("Host not registered"));
}
sv->sv_timekeep_offset = host_svtk->sv_timekeep_off;
#ifdef COMPAT_FREEBSD32
}
#endif
}
#ifdef RANDOM_FENESTRASX
if ((flags & (SV_ABI_MASK | SV_RNG_SEED_VER)) ==
(SV_ABI_FREEBSD | SV_RNG_SEED_VER)) {
/*
* Only allocate a single VDSO entry for multiple sysentvecs,
* i.e., native and COMPAT32.
*/
if (fxrng_shpage_mapping == NULL)
alloc_sv_fxrng_generation();
sv->sv_fxrng_gen_offset =
(char *)fxrng_shpage_mapping - shared_page_mapping;
}
#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_DSO_SIG) == (sv->sv_flags & SV_DSO_SIG));
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_offset = sv->sv_sigcode_offset;
sv2->sv_vdso_offset = sv->sv_vdso_offset;
if ((sv2->sv_flags & SV_ABI_MASK) != SV_ABI_FREEBSD)
return;
sv2->sv_timekeep_offset = sv->sv_timekeep_offset;
sv2->sv_fxrng_gen_offset = sv->sv_fxrng_gen_offset;
}