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/*-
* Copyright (c) 2017 Andrew Turner
* All rights reserved.
*
* This software was developed by SRI International and the University of
* Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
* ("CTSRD"), as part of the DARPA CRASH research programme.
*
* 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 <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/signal.h>
#include <sys/signalvar.h>
#include <sys/sysent.h>
#include <machine/frame.h>
#include <machine/undefined.h>
#include <machine/vmparam.h>
MALLOC_DEFINE(M_UNDEF, "undefhandler", "Undefined instruction handler data");
struct undef_handler {
LIST_ENTRY(undef_handler) uh_link;
undef_handler_t uh_handler;
};
/*
* Create two undefined instruction handler lists, one for userspace, one for
* the kernel. This allows us to handle instructions that will trap
*/
LIST_HEAD(, undef_handler) undef_handlers[2];
/*
* Work around a bug in QEMU prior to 2.5.1 where reading unknown ID
* registers would raise an exception when they should return 0.
*/
static int
id_aa64mmfr2_handler(vm_offset_t va, uint32_t insn, struct trapframe *frame,
uint32_t esr)
{
int reg;
#define MRS_ID_AA64MMFR2_EL0_MASK (MRS_MASK | 0x000fffe0)
#define MRS_ID_AA64MMFR2_EL0_VALUE (MRS_VALUE | 0x00080740)
/* mrs xn, id_aa64mfr2_el1 */
if ((insn & MRS_ID_AA64MMFR2_EL0_MASK) == MRS_ID_AA64MMFR2_EL0_VALUE) {
reg = MRS_REGISTER(insn);
frame->tf_elr += INSN_SIZE;
if (reg < nitems(frame->tf_x)) {
frame->tf_x[reg] = 0;
} else if (reg == 30) {
frame->tf_lr = 0;
}
/* If reg is 32 then write to xzr, i.e. do nothing */
return (1);
}
return (0);
}
#ifdef COMPAT_FREEBSD32
/* arm32 GDB breakpoints */
#define GDB_BREAKPOINT 0xe6000011
#define GDB5_BREAKPOINT 0xe7ffdefe
static int
gdb_trapper(vm_offset_t va, uint32_t insn, struct trapframe *frame,
uint32_t esr)
{
struct thread *td = curthread;
if (insn == GDB_BREAKPOINT || insn == GDB5_BREAKPOINT) {
if (SV_PROC_FLAG(td->td_proc, SV_ILP32) &&
va < VM_MAXUSER_ADDRESS) {
ksiginfo_t ksi;
ksiginfo_init_trap(&ksi);
ksi.ksi_signo = SIGTRAP;
ksi.ksi_code = TRAP_TRACE;
ksi.ksi_addr = (void *)va;
trapsignal(td, &ksi);
return 1;
}
}
return 0;
}
#endif
void
undef_init(void)
{
LIST_INIT(&undef_handlers[0]);
LIST_INIT(&undef_handlers[1]);
install_undef_handler(false, id_aa64mmfr2_handler);
#ifdef COMPAT_FREEBSD32
install_undef_handler(true, gdb_trapper);
#endif
}
void *
install_undef_handler(bool user, undef_handler_t func)
{
struct undef_handler *uh;
uh = malloc(sizeof(*uh), M_UNDEF, M_WAITOK);
uh->uh_handler = func;
LIST_INSERT_HEAD(&undef_handlers[user ? 0 : 1], uh, uh_link);
return (uh);
}
void
remove_undef_handler(void *handle)
{
struct undef_handler *uh;
uh = handle;
LIST_REMOVE(uh, uh_link);
free(handle, M_UNDEF);
}
int
undef_insn(u_int el, struct trapframe *frame)
{
struct undef_handler *uh;
uint32_t insn;
int ret;
KASSERT(el < 2, ("Invalid exception level %u", el));
if (el == 0) {
ret = fueword32((uint32_t *)frame->tf_elr, &insn);
if (ret != 0)
panic("Unable to read userspace faulting instruction");
} else {
insn = *(uint32_t *)frame->tf_elr;
}
LIST_FOREACH(uh, &undef_handlers[el], uh_link) {
ret = uh->uh_handler(frame->tf_elr, insn, frame, frame->tf_esr);
if (ret)
return (1);
}
return (0);
}
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