646 lines
20 KiB
C
646 lines
20 KiB
C
/*
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* emulator main execution loop
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*
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* Copyright (c) 2003-2005 Fabrice Bellard
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "cpu.h"
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#include "trace.h"
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#include "disas/disas.h"
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#include "exec/exec-all.h"
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#include "tcg.h"
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#include "qemu/atomic.h"
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#include "sysemu/qtest.h"
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#include "qemu/timer.h"
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#include "exec/address-spaces.h"
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#include "qemu/rcu.h"
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#include "exec/tb-hash.h"
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#include "exec/log.h"
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#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
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#include "hw/i386/apic.h"
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#endif
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#include "sysemu/replay.h"
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/* -icount align implementation. */
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typedef struct SyncClocks {
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int64_t diff_clk;
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int64_t last_cpu_icount;
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int64_t realtime_clock;
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} SyncClocks;
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#if !defined(CONFIG_USER_ONLY)
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/* Allow the guest to have a max 3ms advance.
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* The difference between the 2 clocks could therefore
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* oscillate around 0.
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*/
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#define VM_CLOCK_ADVANCE 3000000
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#define THRESHOLD_REDUCE 1.5
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#define MAX_DELAY_PRINT_RATE 2000000000LL
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#define MAX_NB_PRINTS 100
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static void align_clocks(SyncClocks *sc, const CPUState *cpu)
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{
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int64_t cpu_icount;
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if (!icount_align_option) {
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return;
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}
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cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low;
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sc->diff_clk += cpu_icount_to_ns(sc->last_cpu_icount - cpu_icount);
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sc->last_cpu_icount = cpu_icount;
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if (sc->diff_clk > VM_CLOCK_ADVANCE) {
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#ifndef _WIN32
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struct timespec sleep_delay, rem_delay;
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sleep_delay.tv_sec = sc->diff_clk / 1000000000LL;
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sleep_delay.tv_nsec = sc->diff_clk % 1000000000LL;
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if (nanosleep(&sleep_delay, &rem_delay) < 0) {
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sc->diff_clk = rem_delay.tv_sec * 1000000000LL + rem_delay.tv_nsec;
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} else {
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sc->diff_clk = 0;
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}
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#else
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Sleep(sc->diff_clk / SCALE_MS);
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sc->diff_clk = 0;
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#endif
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}
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}
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static void print_delay(const SyncClocks *sc)
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{
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static float threshold_delay;
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static int64_t last_realtime_clock;
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static int nb_prints;
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if (icount_align_option &&
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sc->realtime_clock - last_realtime_clock >= MAX_DELAY_PRINT_RATE &&
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nb_prints < MAX_NB_PRINTS) {
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if ((-sc->diff_clk / (float)1000000000LL > threshold_delay) ||
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(-sc->diff_clk / (float)1000000000LL <
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(threshold_delay - THRESHOLD_REDUCE))) {
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threshold_delay = (-sc->diff_clk / 1000000000LL) + 1;
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printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
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threshold_delay - 1,
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threshold_delay);
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nb_prints++;
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last_realtime_clock = sc->realtime_clock;
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}
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}
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}
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static void init_delay_params(SyncClocks *sc,
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const CPUState *cpu)
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{
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if (!icount_align_option) {
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return;
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}
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sc->realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT);
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sc->diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - sc->realtime_clock;
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sc->last_cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low;
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if (sc->diff_clk < max_delay) {
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max_delay = sc->diff_clk;
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}
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if (sc->diff_clk > max_advance) {
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max_advance = sc->diff_clk;
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}
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/* Print every 2s max if the guest is late. We limit the number
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of printed messages to NB_PRINT_MAX(currently 100) */
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print_delay(sc);
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}
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#else
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static void align_clocks(SyncClocks *sc, const CPUState *cpu)
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{
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}
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static void init_delay_params(SyncClocks *sc, const CPUState *cpu)
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{
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}
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#endif /* CONFIG USER ONLY */
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/* Execute a TB, and fix up the CPU state afterwards if necessary */
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static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb)
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{
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CPUArchState *env = cpu->env_ptr;
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uintptr_t ret;
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TranslationBlock *last_tb;
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int tb_exit;
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uint8_t *tb_ptr = itb->tc_ptr;
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qemu_log_mask_and_addr(CPU_LOG_EXEC, itb->pc,
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"Trace %p [" TARGET_FMT_lx "] %s\n",
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itb->tc_ptr, itb->pc, lookup_symbol(itb->pc));
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#if defined(DEBUG_DISAS)
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if (qemu_loglevel_mask(CPU_LOG_TB_CPU)
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&& qemu_log_in_addr_range(itb->pc)) {
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#if defined(TARGET_I386)
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log_cpu_state(cpu, CPU_DUMP_CCOP);
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#elif defined(TARGET_M68K)
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/* ??? Should not modify env state for dumping. */
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cpu_m68k_flush_flags(env, env->cc_op);
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env->cc_op = CC_OP_FLAGS;
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env->sr = (env->sr & 0xffe0) | env->cc_dest | (env->cc_x << 4);
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log_cpu_state(cpu, 0);
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#else
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log_cpu_state(cpu, 0);
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#endif
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}
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#endif /* DEBUG_DISAS */
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cpu->can_do_io = !use_icount;
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ret = tcg_qemu_tb_exec(env, tb_ptr);
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cpu->can_do_io = 1;
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last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
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tb_exit = ret & TB_EXIT_MASK;
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trace_exec_tb_exit(last_tb, tb_exit);
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if (tb_exit > TB_EXIT_IDX1) {
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/* We didn't start executing this TB (eg because the instruction
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* counter hit zero); we must restore the guest PC to the address
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* of the start of the TB.
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*/
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CPUClass *cc = CPU_GET_CLASS(cpu);
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qemu_log_mask_and_addr(CPU_LOG_EXEC, last_tb->pc,
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"Stopped execution of TB chain before %p ["
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TARGET_FMT_lx "] %s\n",
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last_tb->tc_ptr, last_tb->pc,
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lookup_symbol(last_tb->pc));
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if (cc->synchronize_from_tb) {
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cc->synchronize_from_tb(cpu, last_tb);
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} else {
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assert(cc->set_pc);
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cc->set_pc(cpu, last_tb->pc);
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}
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}
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if (tb_exit == TB_EXIT_REQUESTED) {
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/* We were asked to stop executing TBs (probably a pending
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* interrupt. We've now stopped, so clear the flag.
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*/
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cpu->tcg_exit_req = 0;
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}
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return ret;
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}
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#ifndef CONFIG_USER_ONLY
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/* Execute the code without caching the generated code. An interpreter
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could be used if available. */
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static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
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TranslationBlock *orig_tb, bool ignore_icount)
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{
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TranslationBlock *tb;
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bool old_tb_flushed;
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/* Should never happen.
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We only end up here when an existing TB is too long. */
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if (max_cycles > CF_COUNT_MASK)
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max_cycles = CF_COUNT_MASK;
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old_tb_flushed = cpu->tb_flushed;
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cpu->tb_flushed = false;
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tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags,
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max_cycles | CF_NOCACHE
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| (ignore_icount ? CF_IGNORE_ICOUNT : 0));
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tb->orig_tb = cpu->tb_flushed ? NULL : orig_tb;
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cpu->tb_flushed |= old_tb_flushed;
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/* execute the generated code */
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trace_exec_tb_nocache(tb, tb->pc);
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cpu_tb_exec(cpu, tb);
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tb_phys_invalidate(tb, -1);
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tb_free(tb);
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}
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#endif
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struct tb_desc {
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target_ulong pc;
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target_ulong cs_base;
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CPUArchState *env;
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tb_page_addr_t phys_page1;
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uint32_t flags;
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};
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static bool tb_cmp(const void *p, const void *d)
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{
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const TranslationBlock *tb = p;
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const struct tb_desc *desc = d;
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if (tb->pc == desc->pc &&
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tb->page_addr[0] == desc->phys_page1 &&
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tb->cs_base == desc->cs_base &&
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tb->flags == desc->flags &&
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!atomic_read(&tb->invalid)) {
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/* check next page if needed */
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if (tb->page_addr[1] == -1) {
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return true;
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} else {
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tb_page_addr_t phys_page2;
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target_ulong virt_page2;
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virt_page2 = (desc->pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
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phys_page2 = get_page_addr_code(desc->env, virt_page2);
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if (tb->page_addr[1] == phys_page2) {
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return true;
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}
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}
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}
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return false;
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}
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static TranslationBlock *tb_htable_lookup(CPUState *cpu,
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target_ulong pc,
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target_ulong cs_base,
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uint32_t flags)
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{
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tb_page_addr_t phys_pc;
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struct tb_desc desc;
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uint32_t h;
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desc.env = (CPUArchState *)cpu->env_ptr;
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desc.cs_base = cs_base;
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desc.flags = flags;
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desc.pc = pc;
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phys_pc = get_page_addr_code(desc.env, pc);
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desc.phys_page1 = phys_pc & TARGET_PAGE_MASK;
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h = tb_hash_func(phys_pc, pc, flags);
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return qht_lookup(&tcg_ctx.tb_ctx.htable, tb_cmp, &desc, h);
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}
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static inline TranslationBlock *tb_find(CPUState *cpu,
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TranslationBlock *last_tb,
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int tb_exit)
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{
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CPUArchState *env = (CPUArchState *)cpu->env_ptr;
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TranslationBlock *tb;
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target_ulong cs_base, pc;
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uint32_t flags;
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bool have_tb_lock = false;
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/* we record a subset of the CPU state. It will
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always be the same before a given translated block
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is executed. */
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cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
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tb = atomic_rcu_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)]);
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if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
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tb->flags != flags)) {
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tb = tb_htable_lookup(cpu, pc, cs_base, flags);
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if (!tb) {
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/* mmap_lock is needed by tb_gen_code, and mmap_lock must be
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* taken outside tb_lock. As system emulation is currently
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* single threaded the locks are NOPs.
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*/
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mmap_lock();
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tb_lock();
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have_tb_lock = true;
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/* There's a chance that our desired tb has been translated while
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* taking the locks so we check again inside the lock.
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*/
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tb = tb_htable_lookup(cpu, pc, cs_base, flags);
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if (!tb) {
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/* if no translated code available, then translate it now */
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tb = tb_gen_code(cpu, pc, cs_base, flags, 0);
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}
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mmap_unlock();
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}
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/* We add the TB in the virtual pc hash table for the fast lookup */
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atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb);
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}
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#ifndef CONFIG_USER_ONLY
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/* We don't take care of direct jumps when address mapping changes in
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* system emulation. So it's not safe to make a direct jump to a TB
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* spanning two pages because the mapping for the second page can change.
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*/
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if (tb->page_addr[1] != -1) {
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last_tb = NULL;
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}
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#endif
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/* See if we can patch the calling TB. */
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if (last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
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if (!have_tb_lock) {
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tb_lock();
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have_tb_lock = true;
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}
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/* Check if translation buffer has been flushed */
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if (cpu->tb_flushed) {
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cpu->tb_flushed = false;
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} else if (!tb->invalid) {
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tb_add_jump(last_tb, tb_exit, tb);
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}
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}
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if (have_tb_lock) {
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tb_unlock();
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}
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return tb;
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}
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static inline bool cpu_handle_halt(CPUState *cpu)
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{
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if (cpu->halted) {
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#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
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if ((cpu->interrupt_request & CPU_INTERRUPT_POLL)
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&& replay_interrupt()) {
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X86CPU *x86_cpu = X86_CPU(cpu);
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apic_poll_irq(x86_cpu->apic_state);
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cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
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}
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#endif
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if (!cpu_has_work(cpu)) {
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current_cpu = NULL;
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return true;
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}
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cpu->halted = 0;
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}
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return false;
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}
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static inline void cpu_handle_debug_exception(CPUState *cpu)
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{
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CPUClass *cc = CPU_GET_CLASS(cpu);
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CPUWatchpoint *wp;
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if (!cpu->watchpoint_hit) {
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QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
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wp->flags &= ~BP_WATCHPOINT_HIT;
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}
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}
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cc->debug_excp_handler(cpu);
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}
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static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
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{
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if (cpu->exception_index >= 0) {
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if (cpu->exception_index >= EXCP_INTERRUPT) {
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/* exit request from the cpu execution loop */
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*ret = cpu->exception_index;
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if (*ret == EXCP_DEBUG) {
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cpu_handle_debug_exception(cpu);
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}
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cpu->exception_index = -1;
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return true;
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} else {
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#if defined(CONFIG_USER_ONLY)
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/* if user mode only, we simulate a fake exception
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which will be handled outside the cpu execution
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loop */
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#if defined(TARGET_I386)
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CPUClass *cc = CPU_GET_CLASS(cpu);
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cc->do_interrupt(cpu);
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#endif
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*ret = cpu->exception_index;
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cpu->exception_index = -1;
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return true;
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#else
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if (replay_exception()) {
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CPUClass *cc = CPU_GET_CLASS(cpu);
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cc->do_interrupt(cpu);
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cpu->exception_index = -1;
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} else if (!replay_has_interrupt()) {
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/* give a chance to iothread in replay mode */
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*ret = EXCP_INTERRUPT;
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return true;
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}
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#endif
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}
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#ifndef CONFIG_USER_ONLY
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} else if (replay_has_exception()
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&& cpu->icount_decr.u16.low + cpu->icount_extra == 0) {
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/* try to cause an exception pending in the log */
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cpu_exec_nocache(cpu, 1, tb_find(cpu, NULL, 0), true);
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*ret = -1;
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return true;
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#endif
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}
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return false;
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}
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static inline void cpu_handle_interrupt(CPUState *cpu,
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TranslationBlock **last_tb)
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{
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CPUClass *cc = CPU_GET_CLASS(cpu);
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int interrupt_request = cpu->interrupt_request;
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if (unlikely(interrupt_request)) {
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if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
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/* Mask out external interrupts for this step. */
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interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
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}
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if (interrupt_request & CPU_INTERRUPT_DEBUG) {
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cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
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cpu->exception_index = EXCP_DEBUG;
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cpu_loop_exit(cpu);
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}
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if (replay_mode == REPLAY_MODE_PLAY && !replay_has_interrupt()) {
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/* Do nothing */
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} else if (interrupt_request & CPU_INTERRUPT_HALT) {
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replay_interrupt();
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cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
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cpu->halted = 1;
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cpu->exception_index = EXCP_HLT;
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cpu_loop_exit(cpu);
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}
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#if defined(TARGET_I386)
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else if (interrupt_request & CPU_INTERRUPT_INIT) {
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X86CPU *x86_cpu = X86_CPU(cpu);
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CPUArchState *env = &x86_cpu->env;
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replay_interrupt();
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cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0);
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do_cpu_init(x86_cpu);
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cpu->exception_index = EXCP_HALTED;
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cpu_loop_exit(cpu);
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}
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#else
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else if (interrupt_request & CPU_INTERRUPT_RESET) {
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replay_interrupt();
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cpu_reset(cpu);
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cpu_loop_exit(cpu);
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}
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#endif
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/* The target hook has 3 exit conditions:
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False when the interrupt isn't processed,
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True when it is, and we should restart on a new TB,
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and via longjmp via cpu_loop_exit. */
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else {
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replay_interrupt();
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if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
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*last_tb = NULL;
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}
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/* The target hook may have updated the 'cpu->interrupt_request';
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* reload the 'interrupt_request' value */
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interrupt_request = cpu->interrupt_request;
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}
|
|
if (interrupt_request & CPU_INTERRUPT_EXITTB) {
|
|
cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
|
|
/* ensure that no TB jump will be modified as
|
|
the program flow was changed */
|
|
*last_tb = NULL;
|
|
}
|
|
}
|
|
if (unlikely(cpu->exit_request || replay_has_interrupt())) {
|
|
cpu->exit_request = 0;
|
|
cpu->exception_index = EXCP_INTERRUPT;
|
|
cpu_loop_exit(cpu);
|
|
}
|
|
}
|
|
|
|
static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
|
|
TranslationBlock **last_tb, int *tb_exit,
|
|
SyncClocks *sc)
|
|
{
|
|
uintptr_t ret;
|
|
|
|
if (unlikely(cpu->exit_request)) {
|
|
return;
|
|
}
|
|
|
|
trace_exec_tb(tb, tb->pc);
|
|
ret = cpu_tb_exec(cpu, tb);
|
|
*last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
|
|
*tb_exit = ret & TB_EXIT_MASK;
|
|
switch (*tb_exit) {
|
|
case TB_EXIT_REQUESTED:
|
|
/* Something asked us to stop executing
|
|
* chained TBs; just continue round the main
|
|
* loop. Whatever requested the exit will also
|
|
* have set something else (eg exit_request or
|
|
* interrupt_request) which we will handle
|
|
* next time around the loop. But we need to
|
|
* ensure the tcg_exit_req read in generated code
|
|
* comes before the next read of cpu->exit_request
|
|
* or cpu->interrupt_request.
|
|
*/
|
|
smp_rmb();
|
|
*last_tb = NULL;
|
|
break;
|
|
case TB_EXIT_ICOUNT_EXPIRED:
|
|
{
|
|
/* Instruction counter expired. */
|
|
#ifdef CONFIG_USER_ONLY
|
|
abort();
|
|
#else
|
|
int insns_left = cpu->icount_decr.u32;
|
|
if (cpu->icount_extra && insns_left >= 0) {
|
|
/* Refill decrementer and continue execution. */
|
|
cpu->icount_extra += insns_left;
|
|
insns_left = MIN(0xffff, cpu->icount_extra);
|
|
cpu->icount_extra -= insns_left;
|
|
cpu->icount_decr.u16.low = insns_left;
|
|
} else {
|
|
if (insns_left > 0) {
|
|
/* Execute remaining instructions. */
|
|
cpu_exec_nocache(cpu, insns_left, *last_tb, false);
|
|
align_clocks(sc, cpu);
|
|
}
|
|
cpu->exception_index = EXCP_INTERRUPT;
|
|
*last_tb = NULL;
|
|
cpu_loop_exit(cpu);
|
|
}
|
|
break;
|
|
#endif
|
|
}
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* main execution loop */
|
|
|
|
int cpu_exec(CPUState *cpu)
|
|
{
|
|
CPUClass *cc = CPU_GET_CLASS(cpu);
|
|
int ret;
|
|
SyncClocks sc;
|
|
|
|
/* replay_interrupt may need current_cpu */
|
|
current_cpu = cpu;
|
|
|
|
if (cpu_handle_halt(cpu)) {
|
|
return EXCP_HALTED;
|
|
}
|
|
|
|
atomic_mb_set(&tcg_current_cpu, cpu);
|
|
rcu_read_lock();
|
|
|
|
if (unlikely(atomic_mb_read(&exit_request))) {
|
|
cpu->exit_request = 1;
|
|
}
|
|
|
|
cc->cpu_exec_enter(cpu);
|
|
|
|
/* Calculate difference between guest clock and host clock.
|
|
* This delay includes the delay of the last cycle, so
|
|
* what we have to do is sleep until it is 0. As for the
|
|
* advance/delay we gain here, we try to fix it next time.
|
|
*/
|
|
init_delay_params(&sc, cpu);
|
|
|
|
for(;;) {
|
|
/* prepare setjmp context for exception handling */
|
|
if (sigsetjmp(cpu->jmp_env, 0) == 0) {
|
|
TranslationBlock *tb, *last_tb = NULL;
|
|
int tb_exit = 0;
|
|
|
|
/* if an exception is pending, we execute it here */
|
|
if (cpu_handle_exception(cpu, &ret)) {
|
|
break;
|
|
}
|
|
|
|
atomic_mb_set(&cpu->tb_flushed, false); /* reset before first TB lookup */
|
|
for(;;) {
|
|
cpu_handle_interrupt(cpu, &last_tb);
|
|
tb = tb_find(cpu, last_tb, tb_exit);
|
|
cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit, &sc);
|
|
/* Try to align the host and virtual clocks
|
|
if the guest is in advance */
|
|
align_clocks(&sc, cpu);
|
|
} /* for(;;) */
|
|
} else {
|
|
#if defined(__clang__) || !QEMU_GNUC_PREREQ(4, 6)
|
|
/* Some compilers wrongly smash all local variables after
|
|
* siglongjmp. There were bug reports for gcc 4.5.0 and clang.
|
|
* Reload essential local variables here for those compilers.
|
|
* Newer versions of gcc would complain about this code (-Wclobbered). */
|
|
cpu = current_cpu;
|
|
cc = CPU_GET_CLASS(cpu);
|
|
#else /* buggy compiler */
|
|
/* Assert that the compiler does not smash local variables. */
|
|
g_assert(cpu == current_cpu);
|
|
g_assert(cc == CPU_GET_CLASS(cpu));
|
|
#endif /* buggy compiler */
|
|
cpu->can_do_io = 1;
|
|
tb_lock_reset();
|
|
}
|
|
} /* for(;;) */
|
|
|
|
cc->cpu_exec_exit(cpu);
|
|
rcu_read_unlock();
|
|
|
|
/* fail safe : never use current_cpu outside cpu_exec() */
|
|
current_cpu = NULL;
|
|
|
|
/* Does not need atomic_mb_set because a spurious wakeup is okay. */
|
|
atomic_set(&tcg_current_cpu, NULL);
|
|
return ret;
|
|
}
|