/* * emulator main execution loop * * Copyright (c) 2003-2005 Fabrice Bellard * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, see <http://www.gnu.org/licenses/>. */ #include "qemu/osdep.h" #include "cpu.h" #include "trace-root.h" #include "disas/disas.h" #include "exec/exec-all.h" #include "tcg.h" #include "qemu/atomic.h" #include "sysemu/qtest.h" #include "qemu/timer.h" #include "exec/address-spaces.h" #include "qemu/rcu.h" #include "exec/tb-hash.h" #include "exec/log.h" #include "qemu/main-loop.h" #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY) #include "hw/i386/apic.h" #endif #include "sysemu/cpus.h" #include "sysemu/replay.h" /* -icount align implementation. */ typedef struct SyncClocks { int64_t diff_clk; int64_t last_cpu_icount; int64_t realtime_clock; } SyncClocks; #if !defined(CONFIG_USER_ONLY) /* Allow the guest to have a max 3ms advance. * The difference between the 2 clocks could therefore * oscillate around 0. */ #define VM_CLOCK_ADVANCE 3000000 #define THRESHOLD_REDUCE 1.5 #define MAX_DELAY_PRINT_RATE 2000000000LL #define MAX_NB_PRINTS 100 static void align_clocks(SyncClocks *sc, const CPUState *cpu) { int64_t cpu_icount; if (!icount_align_option) { return; } cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low; sc->diff_clk += cpu_icount_to_ns(sc->last_cpu_icount - cpu_icount); sc->last_cpu_icount = cpu_icount; if (sc->diff_clk > VM_CLOCK_ADVANCE) { #ifndef _WIN32 struct timespec sleep_delay, rem_delay; sleep_delay.tv_sec = sc->diff_clk / 1000000000LL; sleep_delay.tv_nsec = sc->diff_clk % 1000000000LL; if (nanosleep(&sleep_delay, &rem_delay) < 0) { sc->diff_clk = rem_delay.tv_sec * 1000000000LL + rem_delay.tv_nsec; } else { sc->diff_clk = 0; } #else Sleep(sc->diff_clk / SCALE_MS); sc->diff_clk = 0; #endif } } static void print_delay(const SyncClocks *sc) { static float threshold_delay; static int64_t last_realtime_clock; static int nb_prints; if (icount_align_option && sc->realtime_clock - last_realtime_clock >= MAX_DELAY_PRINT_RATE && nb_prints < MAX_NB_PRINTS) { if ((-sc->diff_clk / (float)1000000000LL > threshold_delay) || (-sc->diff_clk / (float)1000000000LL < (threshold_delay - THRESHOLD_REDUCE))) { threshold_delay = (-sc->diff_clk / 1000000000LL) + 1; printf("Warning: The guest is now late by %.1f to %.1f seconds\n", threshold_delay - 1, threshold_delay); nb_prints++; last_realtime_clock = sc->realtime_clock; } } } static void init_delay_params(SyncClocks *sc, const CPUState *cpu) { if (!icount_align_option) { return; } sc->realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT); sc->diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - sc->realtime_clock; sc->last_cpu_icount = cpu->icount_extra + cpu->icount_decr.u16.low; if (sc->diff_clk < max_delay) { max_delay = sc->diff_clk; } if (sc->diff_clk > max_advance) { max_advance = sc->diff_clk; } /* Print every 2s max if the guest is late. We limit the number of printed messages to NB_PRINT_MAX(currently 100) */ print_delay(sc); } #else static void align_clocks(SyncClocks *sc, const CPUState *cpu) { } static void init_delay_params(SyncClocks *sc, const CPUState *cpu) { } #endif /* CONFIG USER ONLY */ /* Execute a TB, and fix up the CPU state afterwards if necessary */ static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb) { CPUArchState *env = cpu->env_ptr; uintptr_t ret; TranslationBlock *last_tb; int tb_exit; uint8_t *tb_ptr = itb->tc_ptr; qemu_log_mask_and_addr(CPU_LOG_EXEC, itb->pc, "Trace %p [%d: " TARGET_FMT_lx "] %s\n", itb->tc_ptr, cpu->cpu_index, itb->pc, lookup_symbol(itb->pc)); #if defined(DEBUG_DISAS) if (qemu_loglevel_mask(CPU_LOG_TB_CPU) && qemu_log_in_addr_range(itb->pc)) { qemu_log_lock(); #if defined(TARGET_I386) log_cpu_state(cpu, CPU_DUMP_CCOP); #else log_cpu_state(cpu, 0); #endif qemu_log_unlock(); } #endif /* DEBUG_DISAS */ cpu->can_do_io = !use_icount; ret = tcg_qemu_tb_exec(env, tb_ptr); cpu->can_do_io = 1; last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK); tb_exit = ret & TB_EXIT_MASK; trace_exec_tb_exit(last_tb, tb_exit); if (tb_exit > TB_EXIT_IDX1) { /* We didn't start executing this TB (eg because the instruction * counter hit zero); we must restore the guest PC to the address * of the start of the TB. */ CPUClass *cc = CPU_GET_CLASS(cpu); qemu_log_mask_and_addr(CPU_LOG_EXEC, last_tb->pc, "Stopped execution of TB chain before %p [" TARGET_FMT_lx "] %s\n", last_tb->tc_ptr, last_tb->pc, lookup_symbol(last_tb->pc)); if (cc->synchronize_from_tb) { cc->synchronize_from_tb(cpu, last_tb); } else { assert(cc->set_pc); cc->set_pc(cpu, last_tb->pc); } } return ret; } #ifndef CONFIG_USER_ONLY /* Execute the code without caching the generated code. An interpreter could be used if available. */ static void cpu_exec_nocache(CPUState *cpu, int max_cycles, TranslationBlock *orig_tb, bool ignore_icount) { TranslationBlock *tb; /* Should never happen. We only end up here when an existing TB is too long. */ if (max_cycles > CF_COUNT_MASK) max_cycles = CF_COUNT_MASK; tb_lock(); tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags, max_cycles | CF_NOCACHE | (ignore_icount ? CF_IGNORE_ICOUNT : 0)); tb->orig_tb = orig_tb; tb_unlock(); /* execute the generated code */ trace_exec_tb_nocache(tb, tb->pc); cpu_tb_exec(cpu, tb); tb_lock(); tb_phys_invalidate(tb, -1); tb_free(tb); tb_unlock(); } #endif static void cpu_exec_step(CPUState *cpu) { CPUClass *cc = CPU_GET_CLASS(cpu); CPUArchState *env = (CPUArchState *)cpu->env_ptr; TranslationBlock *tb; target_ulong cs_base, pc; uint32_t flags; cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); if (sigsetjmp(cpu->jmp_env, 0) == 0) { mmap_lock(); tb_lock(); tb = tb_gen_code(cpu, pc, cs_base, flags, 1 | CF_NOCACHE | CF_IGNORE_ICOUNT); tb->orig_tb = NULL; tb_unlock(); mmap_unlock(); cc->cpu_exec_enter(cpu); /* execute the generated code */ trace_exec_tb_nocache(tb, pc); cpu_tb_exec(cpu, tb); cc->cpu_exec_exit(cpu); tb_lock(); tb_phys_invalidate(tb, -1); tb_free(tb); tb_unlock(); } else { /* We may have exited due to another problem here, so we need * to reset any tb_locks we may have taken but didn't release. * The mmap_lock is dropped by tb_gen_code if it runs out of * memory. */ #ifndef CONFIG_SOFTMMU tcg_debug_assert(!have_mmap_lock()); #endif tb_lock_reset(); } } void cpu_exec_step_atomic(CPUState *cpu) { start_exclusive(); /* Since we got here, we know that parallel_cpus must be true. */ parallel_cpus = false; cpu_exec_step(cpu); parallel_cpus = true; end_exclusive(); } struct tb_desc { target_ulong pc; target_ulong cs_base; CPUArchState *env; tb_page_addr_t phys_page1; uint32_t flags; }; static bool tb_cmp(const void *p, const void *d) { const TranslationBlock *tb = p; const struct tb_desc *desc = d; if (tb->pc == desc->pc && tb->page_addr[0] == desc->phys_page1 && tb->cs_base == desc->cs_base && tb->flags == desc->flags && !atomic_read(&tb->invalid)) { /* check next page if needed */ if (tb->page_addr[1] == -1) { return true; } else { tb_page_addr_t phys_page2; target_ulong virt_page2; virt_page2 = (desc->pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE; phys_page2 = get_page_addr_code(desc->env, virt_page2); if (tb->page_addr[1] == phys_page2) { return true; } } } return false; } static TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc, target_ulong cs_base, uint32_t flags) { tb_page_addr_t phys_pc; struct tb_desc desc; uint32_t h; desc.env = (CPUArchState *)cpu->env_ptr; desc.cs_base = cs_base; desc.flags = flags; desc.pc = pc; phys_pc = get_page_addr_code(desc.env, pc); desc.phys_page1 = phys_pc & TARGET_PAGE_MASK; h = tb_hash_func(phys_pc, pc, flags); return qht_lookup(&tcg_ctx.tb_ctx.htable, tb_cmp, &desc, h); } static inline TranslationBlock *tb_find(CPUState *cpu, TranslationBlock *last_tb, int tb_exit) { CPUArchState *env = (CPUArchState *)cpu->env_ptr; TranslationBlock *tb; target_ulong cs_base, pc; uint32_t flags; bool have_tb_lock = false; /* we record a subset of the CPU state. It will always be the same before a given translated block is executed. */ cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); tb = atomic_rcu_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)]); if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base || tb->flags != flags)) { tb = tb_htable_lookup(cpu, pc, cs_base, flags); if (!tb) { /* mmap_lock is needed by tb_gen_code, and mmap_lock must be * taken outside tb_lock. As system emulation is currently * single threaded the locks are NOPs. */ mmap_lock(); tb_lock(); have_tb_lock = true; /* There's a chance that our desired tb has been translated while * taking the locks so we check again inside the lock. */ tb = tb_htable_lookup(cpu, pc, cs_base, flags); if (!tb) { /* if no translated code available, then translate it now */ tb = tb_gen_code(cpu, pc, cs_base, flags, 0); } mmap_unlock(); } /* We add the TB in the virtual pc hash table for the fast lookup */ atomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb); } #ifndef CONFIG_USER_ONLY /* We don't take care of direct jumps when address mapping changes in * system emulation. So it's not safe to make a direct jump to a TB * spanning two pages because the mapping for the second page can change. */ if (tb->page_addr[1] != -1) { last_tb = NULL; } #endif /* See if we can patch the calling TB. */ if (last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { if (!have_tb_lock) { tb_lock(); have_tb_lock = true; } if (!tb->invalid) { tb_add_jump(last_tb, tb_exit, tb); } } if (have_tb_lock) { tb_unlock(); } return tb; } static inline bool cpu_handle_halt(CPUState *cpu) { if (cpu->halted) { #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY) if ((cpu->interrupt_request & CPU_INTERRUPT_POLL) && replay_interrupt()) { X86CPU *x86_cpu = X86_CPU(cpu); qemu_mutex_lock_iothread(); apic_poll_irq(x86_cpu->apic_state); cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL); qemu_mutex_unlock_iothread(); } #endif if (!cpu_has_work(cpu)) { return true; } cpu->halted = 0; } return false; } static inline void cpu_handle_debug_exception(CPUState *cpu) { CPUClass *cc = CPU_GET_CLASS(cpu); CPUWatchpoint *wp; if (!cpu->watchpoint_hit) { QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) { wp->flags &= ~BP_WATCHPOINT_HIT; } } cc->debug_excp_handler(cpu); } static inline bool cpu_handle_exception(CPUState *cpu, int *ret) { if (cpu->exception_index >= 0) { if (cpu->exception_index >= EXCP_INTERRUPT) { /* exit request from the cpu execution loop */ *ret = cpu->exception_index; if (*ret == EXCP_DEBUG) { cpu_handle_debug_exception(cpu); } cpu->exception_index = -1; return true; } else { #if defined(CONFIG_USER_ONLY) /* if user mode only, we simulate a fake exception which will be handled outside the cpu execution loop */ #if defined(TARGET_I386) CPUClass *cc = CPU_GET_CLASS(cpu); cc->do_interrupt(cpu); #endif *ret = cpu->exception_index; cpu->exception_index = -1; return true; #else if (replay_exception()) { CPUClass *cc = CPU_GET_CLASS(cpu); qemu_mutex_lock_iothread(); cc->do_interrupt(cpu); qemu_mutex_unlock_iothread(); cpu->exception_index = -1; } else if (!replay_has_interrupt()) { /* give a chance to iothread in replay mode */ *ret = EXCP_INTERRUPT; return true; } #endif } #ifndef CONFIG_USER_ONLY } else if (replay_has_exception() && cpu->icount_decr.u16.low + cpu->icount_extra == 0) { /* try to cause an exception pending in the log */ cpu_exec_nocache(cpu, 1, tb_find(cpu, NULL, 0), true); *ret = -1; return true; #endif } return false; } static inline bool cpu_handle_interrupt(CPUState *cpu, TranslationBlock **last_tb) { CPUClass *cc = CPU_GET_CLASS(cpu); if (unlikely(atomic_read(&cpu->interrupt_request))) { int interrupt_request; qemu_mutex_lock_iothread(); interrupt_request = cpu->interrupt_request; if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) { /* Mask out external interrupts for this step. */ interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK; } if (interrupt_request & CPU_INTERRUPT_DEBUG) { cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG; cpu->exception_index = EXCP_DEBUG; qemu_mutex_unlock_iothread(); return true; } if (replay_mode == REPLAY_MODE_PLAY && !replay_has_interrupt()) { /* Do nothing */ } else if (interrupt_request & CPU_INTERRUPT_HALT) { replay_interrupt(); cpu->interrupt_request &= ~CPU_INTERRUPT_HALT; cpu->halted = 1; cpu->exception_index = EXCP_HLT; qemu_mutex_unlock_iothread(); return true; } #if defined(TARGET_I386) else if (interrupt_request & CPU_INTERRUPT_INIT) { X86CPU *x86_cpu = X86_CPU(cpu); CPUArchState *env = &x86_cpu->env; replay_interrupt(); cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0, 0); do_cpu_init(x86_cpu); cpu->exception_index = EXCP_HALTED; qemu_mutex_unlock_iothread(); return true; } #else else if (interrupt_request & CPU_INTERRUPT_RESET) { replay_interrupt(); cpu_reset(cpu); qemu_mutex_unlock_iothread(); return true; } #endif /* The target hook has 3 exit conditions: False when the interrupt isn't processed, True when it is, and we should restart on a new TB, and via longjmp via cpu_loop_exit. */ else { if (cc->cpu_exec_interrupt(cpu, interrupt_request)) { replay_interrupt(); *last_tb = NULL; } /* The target hook may have updated the 'cpu->interrupt_request'; * reload the 'interrupt_request' value */ interrupt_request = cpu->interrupt_request; } 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 we exit via cpu_loop_exit/longjmp it is reset in cpu_exec */ qemu_mutex_unlock_iothread(); } /* Finally, check if we need to exit to the main loop. */ if (unlikely(atomic_read(&cpu->exit_request) || (use_icount && cpu->icount_decr.u16.low + cpu->icount_extra == 0))) { atomic_set(&cpu->exit_request, 0); cpu->exception_index = EXCP_INTERRUPT; return true; } return false; } static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb, TranslationBlock **last_tb, int *tb_exit) { uintptr_t ret; int32_t insns_left; trace_exec_tb(tb, tb->pc); ret = cpu_tb_exec(cpu, tb); tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK); *tb_exit = ret & TB_EXIT_MASK; if (*tb_exit != TB_EXIT_REQUESTED) { *last_tb = tb; return; } *last_tb = NULL; insns_left = atomic_read(&cpu->icount_decr.u32); atomic_set(&cpu->icount_decr.u16.high, 0); if (insns_left < 0) { /* 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 zeroing of icount_decr * comes before the next read of cpu->exit_request * or cpu->interrupt_request. */ smp_mb(); return; } /* Instruction counter expired. */ assert(use_icount); #ifndef CONFIG_USER_ONLY /* Ensure global icount has gone forward */ cpu_update_icount(cpu); /* Refill decrementer and continue execution. */ insns_left = MIN(0xffff, cpu->icount_budget); cpu->icount_decr.u16.low = insns_left; cpu->icount_extra = cpu->icount_budget - insns_left; if (!cpu->icount_extra) { /* Execute any remaining instructions, then let the main loop * handle the next event. */ if (insns_left > 0) { cpu_exec_nocache(cpu, insns_left, tb, false); } } #endif } /* main execution loop */ int cpu_exec(CPUState *cpu) { CPUClass *cc = CPU_GET_CLASS(cpu); int ret; SyncClocks sc = { 0 }; /* replay_interrupt may need current_cpu */ current_cpu = cpu; if (cpu_handle_halt(cpu)) { return EXCP_HALTED; } rcu_read_lock(); 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); /* prepare setjmp context for exception handling */ if (sigsetjmp(cpu->jmp_env, 0) != 0) { #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(); if (qemu_mutex_iothread_locked()) { qemu_mutex_unlock_iothread(); } } /* if an exception is pending, we execute it here */ while (!cpu_handle_exception(cpu, &ret)) { TranslationBlock *last_tb = NULL; int tb_exit = 0; while (!cpu_handle_interrupt(cpu, &last_tb)) { TranslationBlock *tb = tb_find(cpu, last_tb, tb_exit); cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit); /* Try to align the host and virtual clocks if the guest is in advance */ align_clocks(&sc, cpu); } } cc->cpu_exec_exit(cpu); rcu_read_unlock(); return ret; }