/* $NetBSD: idt.c,v 1.17 2022/08/20 23:48:51 riastradh Exp $ */
/*-
* Copyright (c) 1996, 1997, 1998, 2000, 2009 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum, by Jason R. Thorpe of the Numerical Aerospace
* Simulation Facility NASA Ames Research Center, and by Andrew Doran.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*-
* Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* 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. 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.
*
* @(#)machdep.c 7.4 (Berkeley) 6/3/91
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: idt.c,v 1.17 2022/08/20 23:48:51 riastradh Exp $");
#include "opt_pcpu_idt.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mutex.h>
#include <sys/cpu.h>
#include <sys/atomic.h>
#include <uvm/uvm.h>
#include <machine/pmap_private.h>
#include <machine/segments.h>
/*
* XEN PV and native have a different idea of what idt entries should
* look like.
*/
/* Normalise across XEN PV and native */
#if defined(XENPV)
void
set_idtgate(struct trap_info *xen_idd, void *function, int ist,
int type, int dpl, int sel)
{
/*
* Find the page boundary in which the descriptor resides.
* We make an assumption here, that the descriptor is part of
* a table (array), which fits in a page and is page aligned.
*
* This assumption is from the usecases at early startup in
* machine/machdep.c
*
* Thus this function may not work in the "general" case of a
* randomly located idt entry template (for eg:).
*/
vaddr_t xen_idt_vaddr = ((vaddr_t) xen_idd) & ~PAGE_MASK;
//kpreempt_disable();
#if defined(__x86_64__)
/* Make it writeable, so we can update the values. */
pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ | VM_PROT_WRITE);
#endif /* __x86_64 */
xen_idd->cs = sel;
xen_idd->address = (unsigned long) function;
xen_idd->flags = dpl;
/*
* Again we make the assumption that the descriptor is
* implicitly part of an idt, which we infer as
* xen_idt_vaddr. (See above).
*/
xen_idd->vector = xen_idd - (struct trap_info *)xen_idt_vaddr;
/* Back to read-only, as it should be. */
#if defined(__x86_64__)
pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ);
#endif /* __x86_64 */
//kpreempt_enable();
}
void
unset_idtgate(struct trap_info *xen_idd)
{
#if defined(__x86_64__)
vaddr_t xen_idt_vaddr = ((vaddr_t) xen_idd) & ~PAGE_MASK;
/* Make it writeable, so we can update the values. */
pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ | VM_PROT_WRITE);
#endif /* __x86_64 */
/* Zero it */
memset(xen_idd, 0, sizeof (*xen_idd));
#if defined(__x86_64__)
/* Back to read-only, as it should be. */
pmap_changeprot_local(xen_idt_vaddr, VM_PROT_READ);
#endif /* __x86_64 */
}
#else /* XENPV */
void
set_idtgate(struct gate_descriptor *idd, void *function, int ist, int type, int dpl, int sel)
{
setgate(idd, function, ist, type, dpl, sel);
}
void
unset_idtgate(struct gate_descriptor *idd)
{
unsetgate(idd);
}
#endif /* XENPV */
/*
* Allocate an IDT vector slot within the given range.
* cpu_lock will be held unless single threaded during early boot.
*/
int
idt_vec_alloc(struct idt_vec *iv, int low, int high)
{
int vec;
char *idt_allocmap = iv->iv_allocmap;
KASSERT(mutex_owned(&cpu_lock) || !mp_online);
if (low < 0 || high >= __arraycount(iv->iv_allocmap))
return -1;
for (vec = low; vec <= high; vec++) {
/* pairs with atomic_store_release in idt_vec_free */
if (atomic_load_acquire(&idt_allocmap[vec]) == 0) {
/*
* No ordering needed here (`relaxed') because
* access to free entries is serialized by
* cpu_lock or single-threaded operation.
*/
atomic_store_relaxed(&idt_allocmap[vec], 1);
return vec;
}
}
return -1;
}
void
idt_vec_reserve(struct idt_vec *iv, int vec)
{
int result;
KASSERT(mutex_owned(&cpu_lock) || !mp_online);
result = idt_vec_alloc(iv, vec, vec);
if (result < 0) {
panic("%s: failed to reserve vec %d", __func__, vec);
}
}
void
idt_vec_set(struct idt_vec *iv, int vec, void (*function)(void))
{
idt_descriptor_t *idt;
char *idt_allocmap __diagused = iv->iv_allocmap;
KASSERT(atomic_load_relaxed(&idt_allocmap[vec]) == 1);
idt = iv->iv_idt;
set_idtgate(&idt[vec], function, 0, SDT_SYS386IGT, SEL_KPL,
GSEL(GCODE_SEL, SEL_KPL));
}
/*
* Free IDT vector. No locking required as release is atomic.
*/
void
idt_vec_free(struct idt_vec *iv, int vec)
{
idt_descriptor_t *idt;
char *idt_allocmap = iv->iv_allocmap;
KASSERT(atomic_load_relaxed(&idt_allocmap[vec]) == 1);
idt = iv->iv_idt;
unset_idtgate(&idt[vec]);
/* pairs with atomic_load_acquire in idt_vec_alloc */
atomic_store_release(&idt_allocmap[vec], 0);
}
bool
idt_vec_is_pcpu(void)
{
#ifdef PCPU_IDT
return true;
#else
return false;
#endif
}
struct idt_vec *
idt_vec_ref(struct idt_vec *iv)
{
if (idt_vec_is_pcpu())
return iv;
return &(cpu_info_primary.ci_idtvec);
}