/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* Copyright IBM Corp. 2007
*
* Authors: Hollis Blanchard <hollisb@us.ibm.com>
*/
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm_host.h>
#include <asm/dcr.h>
#include <asm/dcr-regs.h>
#include <asm/time.h>
#include <asm/byteorder.h>
#include <asm/kvm_ppc.h>
#include "44x_tlb.h"
/* Instruction decoding */
static inline unsigned int get_op(u32 inst)
{
return inst >> 26;
}
static inline unsigned int get_xop(u32 inst)
{
return (inst >> 1) & 0x3ff;
}
static inline unsigned int get_sprn(u32 inst)
{
return ((inst >> 16) & 0x1f) | ((inst >> 6) & 0x3e0);
}
static inline unsigned int get_dcrn(u32 inst)
{
return ((inst >> 16) & 0x1f) | ((inst >> 6) & 0x3e0);
}
static inline unsigned int get_rt(u32 inst)
{
return (inst >> 21) & 0x1f;
}
static inline unsigned int get_rs(u32 inst)
{
return (inst >> 21) & 0x1f;
}
static inline unsigned int get_ra(u32 inst)
{
return (inst >> 16) & 0x1f;
}
static inline unsigned int get_rb(u32 inst)
{
return (inst >> 11) & 0x1f;
}
static inline unsigned int get_rc(u32 inst)
{
return inst & 0x1;
}
static inline unsigned int get_ws(u32 inst)
{
return (inst >> 11) & 0x1f;
}
static inline unsigned int get_d(u32 inst)
{
return inst & 0xffff;
}
static int tlbe_is_host_safe(const struct kvm_vcpu *vcpu,
const struct tlbe *tlbe)
{
gpa_t gpa;
if (!get_tlb_v(tlbe))
return 0;
/* Does it match current guest AS? */
/* XXX what about IS != DS? */
if (get_tlb_ts(tlbe) != !!(vcpu->arch.msr & MSR_IS))
return 0;
gpa = get_tlb_raddr(tlbe);
if (!gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT))
/* Mapping is not for RAM. */
return 0;
return 1;
}
static int kvmppc_emul_tlbwe(struct kvm_vcpu *vcpu, u32 inst)
{
u64 eaddr;
u64 raddr;
u64 asid;
u32 flags;
struct tlbe *tlbe;
unsigned int ra;
unsigned int rs;
unsigned int ws;
unsigned int index;
ra = get_ra(inst);
rs = get_rs(inst);
ws = get_ws(inst);
index = vcpu->arch.gpr[ra];
if (index > PPC44x_TLB_SIZE) {
printk("%s: index %d\n", __func__, index);
kvmppc_dump_vcpu(vcpu);
return EMULATE_FAIL;
}
tlbe = &vcpu->arch.guest_tlb[index];
/* Invalidate shadow mappings for the about-to-be-clobbered TLBE. */
if (tlbe->word0 & PPC44x_TLB_VALID) {
eaddr = get_tlb_eaddr(tlbe);
asid = (tlbe->word0 & PPC44x_TLB_TS) | tlbe->tid;
kvmppc_mmu_invalidate(vcpu, eaddr, get_tlb_end(tlbe), asid);
}
switch (ws) {
case PPC44x_TLB_PAGEID:
tlbe->tid = vcpu->arch.mmucr & 0xff;
tlbe->word0 = vcpu->arch.gpr[rs];
break;
case PPC44x_TLB_XLAT:
tlbe->word1 = vcpu->arch.gpr[rs];
break;
case PPC44x_TLB_ATTRIB:
tlbe->word2 = vcpu->arch.gpr[rs];
break;
default:
return EMULATE_FAIL;
}
if (tlbe_is_host_safe(vcpu, tlbe)) {
eaddr = get_tlb_eaddr(tlbe);
raddr = get_tlb_raddr(tlbe);
asid = (tlbe->word0 & PPC44x_TLB_TS) | tlbe->tid;
flags = tlbe->word2 & 0xffff;
/* Create a 4KB mapping on the host. If the guest wanted a
* large page, only the first 4KB is mapped here and the rest
* are mapped on the fly. */
kvmppc_mmu_map(vcpu, eaddr, raddr >> PAGE_SHIFT, asid, flags);
}
return EMULATE_DONE;
}
static void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
{
if (vcpu->arch.tcr & TCR_DIE) {
/* The decrementer ticks at the same rate as the timebase, so
* that's how we convert the guest DEC value to the number of
* host ticks. */
unsigned long nr_jiffies;
nr_jiffies = vcpu->arch.dec / tb_ticks_per_jiffy;
mod_timer(&vcpu->arch.dec_timer,
get_jiffies_64() + nr_jiffies);
} else {
del_timer(&vcpu->arch.dec_timer);
}
}
static void kvmppc_emul_rfi(struct kvm_vcpu *vcpu)
{
vcpu->arch.pc = vcpu->arch.srr0;
kvmppc_set_msr(vcpu, vcpu->arch.srr1);
}
/* XXX to do:
* lhax
* lhaux
* lswx
* lswi
* stswx
* stswi
* lha
* lhau
* lmw
* stmw
*
* XXX is_bigendian should depend on MMU mapping or MSR[LE]
*/
int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
{
u32 inst = vcpu->arch.last_inst;
u32 ea;
int ra;
int rb;
int rc;
int rs;
int rt;
int sprn;
int dcrn;
enum emulation_result emulated = EMULATE_DONE;
int advance = 1;
switch (get_op(inst)) {
case 3: /* trap */
printk("trap!\n");
kvmppc_queue_exception(vcpu, BOOKE_INTERRUPT_PROGRAM);
advance = 0;
break;
case 19:
switch (get_xop(inst)) {
case 50: /* rfi */
kvmppc_emul_rfi(vcpu);
advance = 0;
break;
default:
emulated = EMULATE_FAIL;
break;
}
break;
case 31:
switch (get_xop(inst)) {
case 23: /* lwzx */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
break;
case 83: /* mfmsr */
rt = get_rt(inst);
vcpu->arch.gpr[rt] = vcpu->arch.msr;
break;
case 87: /* lbzx */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
break;
case 131: /* wrtee */
rs = get_rs(inst);
vcpu->arch.msr = (vcpu->arch.msr & ~MSR_EE)
| (vcpu->arch.gpr[rs] & MSR_EE);
break;
case 146: /* mtmsr */
rs = get_rs(inst);
kvmppc_set_msr(vcpu, vcpu->arch.gpr[rs]);
break;
case 151: /* stwx */
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu,
vcpu->arch.gpr[rs],
4, 1);
break;
case 163: /* wrteei */
vcpu->arch.msr = (vcpu->arch.msr & ~MSR_EE)
| (inst & MSR_EE);
break;
case 215: /* stbx */
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu,
vcpu->arch.gpr[rs],
1, 1);
break;
case 247: /* stbux */
rs = get_rs(inst);
ra = get_ra(inst);
rb = get_rb(inst);
ea = vcpu->arch.gpr[rb];
if (ra)
ea += vcpu->arch.gpr[ra];
emulated = kvmppc_handle_store(run, vcpu,
vcpu->arch.gpr[rs],
1, 1);
vcpu->arch.gpr[rs] = ea;
break;
case 279: /* lhzx */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
break;
case 311: /* lhzux */
rt = get_rt(inst);
ra = get_ra(inst);
rb = get_rb(inst);
ea = vcpu->arch.gpr[rb];
if (ra)
ea += vcpu->arch.gpr[ra];
emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
vcpu->arch.gpr[ra] = ea;
break;
case 323: /* mfdcr */
dcrn = get_dcrn(inst);
rt = get_rt(inst);
/* The guest may access CPR0 registers to determine the timebase
* frequency, and it must know the real host frequency because it
* can directly access the timebase registers.
*
* It would be possible to emulate those accesses in userspace,
* but userspace can really only figure out the end frequency.
* We could decompose that into the factors that compute it, but
* that's tricky math, and it's easier to just report the real
* CPR0 values.
*/
switch (dcrn) {
case DCRN_CPR0_CONFIG_ADDR:
vcpu->arch.gpr[rt] = vcpu->arch.cpr0_cfgaddr;
break;
case DCRN_CPR0_CONFIG_DATA:
local_irq_disable();
mtdcr(DCRN_CPR0_CONFIG_ADDR,
vcpu->arch.cpr0_cfgaddr);
vcpu->arch.gpr[rt] = mfdcr(DCRN_CPR0_CONFIG_DATA);
local_irq_enable();
break;
default:
run->dcr.dcrn = dcrn;
run->dcr.data = 0;
run->dcr.is_write = 0;
vcpu->arch.io_gpr = rt;
vcpu->arch.dcr_needed = 1;
emulated = EMULATE_DO_DCR;
}
break;
case 339: /* mfspr */
sprn = get_sprn(inst);
rt = get_rt(inst);
switch (sprn) {
case SPRN_SRR0:
vcpu->arch.gpr[rt] = vcpu->arch.srr0; break;
case SPRN_SRR1:
vcpu->arch.gpr[rt] = vcpu->arch.srr1; break;
case SPRN_MMUCR:
vcpu->arch.gpr[rt] = vcpu->arch.mmucr; break;
case SPRN_PID:
vcpu->arch.gpr[rt] = vcpu->arch.pid; break;
case SPRN_IVPR:
vcpu->arch.gpr[rt] = vcpu->arch.ivpr; break;
case SPRN_CCR0:
vcpu->arch.gpr[rt] = vcpu->arch.ccr0; break;
case SPRN_CCR1:
vcpu->arch.gpr[rt] = vcpu->arch.ccr1; break;
case SPRN_PVR:
vcpu->arch.gpr[rt] = vcpu->arch.pvr; break;
case SPRN_DEAR:
vcpu->arch.gpr[rt] = vcpu->arch.dear; break;
case SPRN_ESR:
vcpu->arch.gpr[rt] = vcpu->arch.esr; break;
case SPRN_DBCR0:
vcpu->arch.gpr[rt] = vcpu->arch.dbcr0; break;
case SPRN_DBCR1:
vcpu->arch.gpr[rt] = vcpu->arch.dbcr1; break;
/* Note: mftb and TBRL/TBWL are user-accessible, so
* the guest can always access the real TB anyways.
* In fact, we probably will never see these traps. */
case SPRN_TBWL:
vcpu->arch.gpr[rt] = mftbl(); break;
case SPRN_TBWU:
vcpu->arch.gpr[rt] = mftbu(); break;
case SPRN_SPRG0:
vcpu->arch.gpr[rt] = vcpu->arch.sprg0; break;
case SPRN_SPRG1:
vcpu->arch.gpr[rt] = vcpu->arch.sprg1; break;
case SPRN_SPRG2:
vcpu->arch.gpr[rt] = vcpu->arch.sprg2; break;
case SPRN_SPRG3:
vcpu->arch.gpr[rt] = vcpu->arch.sprg3; break;
/* Note: SPRG4-7 are user-readable, so we don't get
* a trap. */
case SPRN_IVOR0:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[0]; break;
case SPRN_IVOR1:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[1]; break;
case SPRN_IVOR2:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[2]; break;
case SPRN_IVOR3:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[3]; break;
case SPRN_IVOR4:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[4]; break;
case SPRN_IVOR5:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[5]; break;
case SPRN_IVOR6:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[6]; break;
case SPRN_IVOR7:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[7]; break;
case SPRN_IVOR8:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[8]; break;
case SPRN_IVOR9:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[9]; break;
case SPRN_IVOR10:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[10]; break;
case SPRN_IVOR11:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[11]; break;
case SPRN_IVOR12:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[12]; break;
case SPRN_IVOR13:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[13]; break;
case SPRN_IVOR14:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[14]; break;
case SPRN_IVOR15:
vcpu->arch.gpr[rt] = vcpu->arch.ivor[15]; break;
default:
printk("mfspr: unknown spr %x\n", sprn);
vcpu->arch.gpr[rt] = 0;
break;
}
break;
case 407: /* sthx */
rs = get_rs(inst);
ra = get_ra(inst);
rb = get_rb(inst);
emulated = kvmppc_handle_store(run, vcpu,
vcpu->arch.gpr[rs],
2, 1);
break;
case 439: /* sthux */
rs = get_rs(inst);
ra = get_ra(inst);
rb = get_rb(inst);
ea = vcpu->arch.gpr[rb];
if (ra)
ea += vcpu->arch.gpr[ra];
emulated = kvmppc_handle_store(run, vcpu,
vcpu->arch.gpr[rs],
2, 1);
vcpu->arch.gpr[ra] = ea;
break;
case 451: /* mtdcr */
dcrn = get_dcrn(inst);
rs = get_rs(inst);
/* emulate some access in kernel */
switch (dcrn) {
case DCRN_CPR0_CONFIG_ADDR:
vcpu->arch.cpr0_cfgaddr = vcpu->arch.gpr[rs];
break;
default:
run->dcr.dcrn = dcrn;
run->dcr.data = vcpu->arch.gpr[rs];
run->dcr.is_write = 1;
vcpu->arch.dcr_needed = 1;
emulated = EMULATE_DO_DCR;
}
break;
case 467: /* mtspr */
sprn = get_sprn(inst);
rs = get_rs(inst);
switch (sprn) {
case SPRN_SRR0:
vcpu->arch.srr0 = vcpu->arch.gpr[rs]; break;
case SPRN_SRR1:
vcpu->arch.srr1 = vcpu->arch.gpr[rs]; break;
case SPRN_MMUCR:
vcpu->arch.mmucr = vcpu->arch.gpr[rs]; break;
case SPRN_PID:
vcpu->arch.pid = vcpu->arch.gpr[rs]; break;
case SPRN_CCR0:
vcpu->arch.ccr0 = vcpu->arch.gpr[rs]; break;
case SPRN_CCR1:
vcpu->arch.ccr1 = vcpu->arch.gpr[rs]; break;
case SPRN_DEAR:
vcpu->arch.dear = vcpu->arch.gpr[rs]; break;
case SPRN_ESR:
vcpu->arch.esr = vcpu->arch.gpr[rs]; break;
case SPRN_DBCR0:
vcpu->arch.dbcr0 = vcpu->arch.gpr[rs]; break;
case SPRN_DBCR1:
vcpu->arch.dbcr1 = vcpu->arch.gpr[rs]; break;
/* XXX We need to context-switch the timebase for
* watchdog and FIT. */
case SPRN_TBWL: break;
case SPRN_TBWU: break;
case SPRN_DEC:
vcpu->arch.dec = vcpu->arch.gpr[rs];
kvmppc_emulate_dec(vcpu);
break;
case SPRN_TSR:
vcpu->arch.tsr &= ~vcpu->arch.gpr[rs]; break;
case SPRN_TCR:
vcpu->arch.tcr = vcpu->arch.gpr[rs];
kvmppc_emulate_dec(vcpu);
break;
case SPRN_SPRG0:
vcpu->arch.sprg0 = vcpu->arch.gpr[rs]; break;
case SPRN_SPRG1:
vcpu->arch.sprg1 = vcpu->arch.gpr[rs]; break;
case SPRN_SPRG2:
vcpu->arch.sprg2 = vcpu->arch.gpr[rs]; break;
case SPRN_SPRG3:
vcpu->arch.sprg3 = vcpu->arch.gpr[rs]; break;
/* Note: SPRG4-7 are user-readable. These values are
* loaded into the real SPRGs when resuming the
* guest. */
case SPRN_SPRG4:
vcpu->arch.sprg4 = vcpu->arch.gpr[rs]; break;
case SPRN_SPRG5:
vcpu->arch.sprg5 = vcpu->arch.gpr[rs]; break;
case SPRN_SPRG6:
vcpu->arch.sprg6 = vcpu->arch.gpr[rs]; break;
case SPRN_SPRG7:
vcpu->arch.sprg7 = vcpu->arch.gpr[rs]; break;
case SPRN_IVPR:
vcpu->arch.ivpr = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR0:
vcpu->arch.ivor[0] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR1:
vcpu->arch.ivor[1] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR2:
vcpu->arch.ivor[2] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR3:
vcpu->arch.ivor[3] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR4:
vcpu->arch.ivor[4] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR5:
vcpu->arch.ivor[5] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR6:
vcpu->arch.ivor[6] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR7:
vcpu->arch.ivor[7] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR8:
vcpu->arch.ivor[8] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR9:
vcpu->arch.ivor[9] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR10:
vcpu->arch.ivor[10] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR11:
vcpu->arch.ivor[11] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR12:
vcpu->arch.ivor[12] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR13:
vcpu->arch.ivor[13] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR14:
vcpu->arch.ivor[14] = vcpu->arch.gpr[rs]; break;
case SPRN_IVOR15:
vcpu->arch.ivor[15] = vcpu->arch.gpr[rs]; break;
default:
printk("mtspr: unknown spr %x\n", sprn);
emulated = EMULATE_FAIL;
break;
}
break;
case 470: /* dcbi */
/* Do nothing. The guest is performing dcbi because
* hardware DMA is not snooped by the dcache, but
* emulated DMA either goes through the dcache as
* normal writes, or the host kernel has handled dcache
* coherence. */
break;
case 534: /* lwbrx */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 4, 0);
break;
case 566: /* tlbsync */
break;
case 662: /* stwbrx */
rs = get_rs(inst);
ra = get_ra(inst);
rb = get_rb(inst);
emulated = kvmppc_handle_store(run, vcpu,
vcpu->arch.gpr[rs],
4, 0);
break;
case 978: /* tlbwe */
emulated = kvmppc_emul_tlbwe(vcpu, inst);
break;
case 914: { /* tlbsx */
int index;
unsigned int as = get_mmucr_sts(vcpu);
unsigned int pid = get_mmucr_stid(vcpu);
rt = get_rt(inst);
ra = get_ra(inst);
rb = get_rb(inst);
rc = get_rc(inst);
ea = vcpu->arch.gpr[rb];
if (ra)
ea += vcpu->arch.gpr[ra];
index = kvmppc_44x_tlb_index(vcpu, ea, pid, as);
if (rc) {
if (index < 0)
vcpu->arch.cr &= ~0x20000000;
else
vcpu->arch.cr |= 0x20000000;
}
vcpu->arch.gpr[rt] = index;
}
break;
case 790: /* lhbrx */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 2, 0);
break;
case 918: /* sthbrx */
rs = get_rs(inst);
ra = get_ra(inst);
rb = get_rb(inst);
emulated = kvmppc_handle_store(run, vcpu,
vcpu->arch.gpr[rs],
2, 0);
break;
case 966: /* iccci */
break;
default:
printk("unknown: op %d xop %d\n", get_op(inst),
get_xop(inst));
emulated = EMULATE_FAIL;
break;
}
break;
case 32: /* lwz */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
break;
case 33: /* lwzu */
ra = get_ra(inst);
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
vcpu->arch.gpr[ra] = vcpu->arch.paddr_accessed;
break;
case 34: /* lbz */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
break;
case 35: /* lbzu */
ra = get_ra(inst);
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
vcpu->arch.gpr[ra] = vcpu->arch.paddr_accessed;
break;
case 36: /* stw */
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu, vcpu->arch.gpr[rs],
4, 1);
break;
case 37: /* stwu */
ra = get_ra(inst);
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu, vcpu->arch.gpr[rs],
4, 1);
vcpu->arch.gpr[ra] = vcpu->arch.paddr_accessed;
break;
case 38: /* stb */
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu, vcpu->arch.gpr[rs],
1, 1);
break;
case 39: /* stbu */
ra = get_ra(inst);
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu, vcpu->arch.gpr[rs],
1, 1);
vcpu->arch.gpr[ra] = vcpu->arch.paddr_accessed;
break;
case 40: /* lhz */
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
break;
case 41: /* lhzu */
ra = get_ra(inst);
rt = get_rt(inst);
emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
vcpu->arch.gpr[ra] = vcpu->arch.paddr_accessed;
break;
case 44: /* sth */
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu, vcpu->arch.gpr[rs],
2, 1);
break;
case 45: /* sthu */
ra = get_ra(inst);
rs = get_rs(inst);
emulated = kvmppc_handle_store(run, vcpu, vcpu->arch.gpr[rs],
2, 1);
vcpu->arch.gpr[ra] = vcpu->arch.paddr_accessed;
break;
default:
printk("unknown op %d\n", get_op(inst));
emulated = EMULATE_FAIL;
break;
}
if (advance)
vcpu->arch.pc += 4; /* Advance past emulated instruction. */
return emulated;
}
