0448f5f8b8
Reloading of local variables after sigsetjmp is only needed for some buggy compilers. The code which should reload these variables causes compiler warnings with gcc 4.7 when compiler optimizations are enabled: cpu-exec.c:204:15: error: variable ‘cpu’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered] cpu-exec.c:207:15: error: variable ‘cc’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered] cpu-exec.c:202:28: error: argument ‘env’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered] Now this code is only used for compilers which need it (and gcc 4.5.x, x > 0 which does not need it but won't give warnings). There were bug reports for clang and gcc 4.5.0, while gcc 4.5.1 was reported to work fine without the reload code. For clang it is not clear which versions are affected, so simply keep the status quo for all clang compilations. This can be improved later. Signed-off-by: Stefan Weil <sw@weilnetz.de> Message-Id: <1443266606-21400-1-git-send-email-sw@weilnetz.de> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
577 lines
20 KiB
C
577 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 "config.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 "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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#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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/* -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, uint8_t *tb_ptr)
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{
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CPUArchState *env = cpu->env_ptr;
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uintptr_t next_tb;
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#if defined(DEBUG_DISAS)
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if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) {
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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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next_tb = tcg_qemu_tb_exec(env, tb_ptr);
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cpu->can_do_io = 1;
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trace_exec_tb_exit((void *) (next_tb & ~TB_EXIT_MASK),
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next_tb & TB_EXIT_MASK);
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if ((next_tb & TB_EXIT_MASK) > 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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TranslationBlock *tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
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if (cc->synchronize_from_tb) {
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cc->synchronize_from_tb(cpu, tb);
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} else {
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assert(cc->set_pc);
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cc->set_pc(cpu, tb->pc);
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}
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}
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if ((next_tb & TB_EXIT_MASK) == 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 next_tb;
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}
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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)
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{
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TranslationBlock *tb;
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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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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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tb->orig_tb = tcg_ctx.tb_ctx.tb_invalidated_flag ? NULL : orig_tb;
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cpu->current_tb = tb;
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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->tc_ptr);
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cpu->current_tb = NULL;
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tb_phys_invalidate(tb, -1);
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tb_free(tb);
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}
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static TranslationBlock *tb_find_physical(CPUState *cpu,
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target_ulong pc,
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target_ulong cs_base,
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uint64_t flags)
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{
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CPUArchState *env = (CPUArchState *)cpu->env_ptr;
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TranslationBlock *tb, **ptb1;
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unsigned int h;
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tb_page_addr_t phys_pc, phys_page1;
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target_ulong virt_page2;
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tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
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/* find translated block using physical mappings */
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phys_pc = get_page_addr_code(env, pc);
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phys_page1 = phys_pc & TARGET_PAGE_MASK;
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h = tb_phys_hash_func(phys_pc);
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ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h];
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for(;;) {
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tb = *ptb1;
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if (!tb) {
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return NULL;
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}
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if (tb->pc == pc &&
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tb->page_addr[0] == phys_page1 &&
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tb->cs_base == cs_base &&
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tb->flags == flags) {
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/* check next page if needed */
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if (tb->page_addr[1] != -1) {
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tb_page_addr_t phys_page2;
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virt_page2 = (pc & TARGET_PAGE_MASK) +
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TARGET_PAGE_SIZE;
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phys_page2 = get_page_addr_code(env, virt_page2);
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if (tb->page_addr[1] == phys_page2) {
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break;
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}
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} else {
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break;
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}
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}
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ptb1 = &tb->phys_hash_next;
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}
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/* Move the TB to the head of the list */
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*ptb1 = tb->phys_hash_next;
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tb->phys_hash_next = tcg_ctx.tb_ctx.tb_phys_hash[h];
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tcg_ctx.tb_ctx.tb_phys_hash[h] = tb;
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return tb;
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}
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static TranslationBlock *tb_find_slow(CPUState *cpu,
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target_ulong pc,
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target_ulong cs_base,
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uint64_t flags)
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{
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TranslationBlock *tb;
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tb = tb_find_physical(cpu, pc, cs_base, flags);
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if (tb) {
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goto found;
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}
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#ifdef CONFIG_USER_ONLY
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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. Since we're momentarily dropping
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* tb_lock, there's a chance that our desired tb has been
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* translated.
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*/
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tb_unlock();
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mmap_lock();
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tb_lock();
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tb = tb_find_physical(cpu, pc, cs_base, flags);
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if (tb) {
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mmap_unlock();
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goto found;
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}
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#endif
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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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#ifdef CONFIG_USER_ONLY
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mmap_unlock();
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#endif
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found:
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/* we add the TB in the virtual pc hash table */
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cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
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return tb;
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}
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static inline TranslationBlock *tb_find_fast(CPUState *cpu)
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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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int flags;
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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 = 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_find_slow(cpu, pc, cs_base, flags);
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}
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return tb;
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}
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static 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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/* main execution loop */
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int cpu_exec(CPUState *cpu)
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{
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CPUClass *cc = CPU_GET_CLASS(cpu);
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#ifdef TARGET_I386
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X86CPU *x86_cpu = X86_CPU(cpu);
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CPUArchState *env = &x86_cpu->env;
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#endif
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int ret, interrupt_request;
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TranslationBlock *tb;
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uint8_t *tc_ptr;
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uintptr_t next_tb;
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SyncClocks sc;
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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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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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return EXCP_HALTED;
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}
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cpu->halted = 0;
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}
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current_cpu = cpu;
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atomic_mb_set(&tcg_current_cpu, cpu);
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rcu_read_lock();
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if (unlikely(atomic_mb_read(&exit_request))) {
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cpu->exit_request = 1;
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}
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cc->cpu_exec_enter(cpu);
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/* Calculate difference between guest clock and host clock.
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* This delay includes the delay of the last cycle, so
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* what we have to do is sleep until it is 0. As for the
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* advance/delay we gain here, we try to fix it next time.
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*/
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init_delay_params(&sc, cpu);
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/* prepare setjmp context for exception handling */
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for(;;) {
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if (sigsetjmp(cpu->jmp_env, 0) == 0) {
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/* if an exception is pending, we execute it here */
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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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break;
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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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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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break;
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#else
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cc->do_interrupt(cpu);
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cpu->exception_index = -1;
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#endif
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}
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}
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next_tb = 0; /* force lookup of first TB */
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for(;;) {
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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 (interrupt_request & CPU_INTERRUPT_HALT) {
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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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if (interrupt_request & CPU_INTERRUPT_INIT) {
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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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if (interrupt_request & CPU_INTERRUPT_RESET) {
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cpu_reset(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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if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
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next_tb = 0;
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}
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/* Don't use the cached interrupt_request value,
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do_interrupt may have updated the EXITTB flag. */
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if (cpu->interrupt_request & CPU_INTERRUPT_EXITTB) {
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cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
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/* ensure that no TB jump will be modified as
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the program flow was changed */
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next_tb = 0;
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}
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}
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if (unlikely(cpu->exit_request)) {
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cpu->exit_request = 0;
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cpu->exception_index = EXCP_INTERRUPT;
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cpu_loop_exit(cpu);
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}
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tb_lock();
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tb = tb_find_fast(cpu);
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/* Note: we do it here to avoid a gcc bug on Mac OS X when
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doing it in tb_find_slow */
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if (tcg_ctx.tb_ctx.tb_invalidated_flag) {
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/* as some TB could have been invalidated because
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of memory exceptions while generating the code, we
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must recompute the hash index here */
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next_tb = 0;
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tcg_ctx.tb_ctx.tb_invalidated_flag = 0;
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}
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if (qemu_loglevel_mask(CPU_LOG_EXEC)) {
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qemu_log("Trace %p [" TARGET_FMT_lx "] %s\n",
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tb->tc_ptr, tb->pc, lookup_symbol(tb->pc));
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|
}
|
|
/* see if we can patch the calling TB. When the TB
|
|
spans two pages, we cannot safely do a direct
|
|
jump. */
|
|
if (next_tb != 0 && tb->page_addr[1] == -1
|
|
&& !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
|
|
tb_add_jump((TranslationBlock *)(next_tb & ~TB_EXIT_MASK),
|
|
next_tb & TB_EXIT_MASK, tb);
|
|
}
|
|
tb_unlock();
|
|
if (likely(!cpu->exit_request)) {
|
|
trace_exec_tb(tb, tb->pc);
|
|
tc_ptr = tb->tc_ptr;
|
|
/* execute the generated code */
|
|
cpu->current_tb = tb;
|
|
next_tb = cpu_tb_exec(cpu, tc_ptr);
|
|
cpu->current_tb = NULL;
|
|
switch (next_tb & TB_EXIT_MASK) {
|
|
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();
|
|
next_tb = 0;
|
|
break;
|
|
case TB_EXIT_ICOUNT_EXPIRED:
|
|
{
|
|
/* Instruction counter expired. */
|
|
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. */
|
|
tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
|
|
cpu_exec_nocache(cpu, insns_left, tb);
|
|
align_clocks(&sc, cpu);
|
|
}
|
|
cpu->exception_index = EXCP_INTERRUPT;
|
|
next_tb = 0;
|
|
cpu_loop_exit(cpu);
|
|
}
|
|
break;
|
|
}
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
/* Try to align the host and virtual clocks
|
|
if the guest is in advance */
|
|
align_clocks(&sc, cpu);
|
|
/* reset soft MMU for next block (it can currently
|
|
only be set by a memory fault) */
|
|
} /* 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);
|
|
#ifdef TARGET_I386
|
|
x86_cpu = X86_CPU(cpu);
|
|
env = &x86_cpu->env;
|
|
#endif
|
|
#else /* buggy compiler */
|
|
/* Assert that the compiler does not smash local variables. */
|
|
g_assert(cpu == current_cpu);
|
|
g_assert(cc == CPU_GET_CLASS(cpu));
|
|
#ifdef TARGET_I386
|
|
g_assert(x86_cpu == X86_CPU(cpu));
|
|
g_assert(env == &x86_cpu->env);
|
|
#endif
|
|
#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;
|
|
}
|