/* * 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.h" #include "disas/disas.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" #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY) #include "hw/i386/apic.h" #endif #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 [" TARGET_FMT_lx "] %s\n", itb->tc_ptr, itb->pc, lookup_symbol(itb->pc)); #if defined(DEBUG_DISAS) if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) { #if defined(TARGET_I386) log_cpu_state(cpu, CPU_DUMP_CCOP); #elif defined(TARGET_M68K) /* ??? Should not modify env state for dumping. */ cpu_m68k_flush_flags(env, env->cc_op); env->cc_op = CC_OP_FLAGS; env->sr = (env->sr & 0xffe0) | env->cc_dest | (env->cc_x << 4); log_cpu_state(cpu, 0); #else log_cpu_state(cpu, 0); #endif } #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); } } if (tb_exit == TB_EXIT_REQUESTED) { /* We were asked to stop executing TBs (probably a pending * interrupt. We've now stopped, so clear the flag. */ cpu->tcg_exit_req = 0; } 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; bool old_tb_flushed; /* 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; old_tb_flushed = cpu->tb_flushed; cpu->tb_flushed = false; 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 = cpu->tb_flushed ? NULL : orig_tb; cpu->tb_flushed |= old_tb_flushed; /* execute the generated code */ trace_exec_tb_nocache(tb, tb->pc); cpu_tb_exec(cpu, tb); tb_phys_invalidate(tb, -1); tb_free(tb); } #endif static TranslationBlock *tb_find_physical(CPUState *cpu, target_ulong pc, target_ulong cs_base, uint32_t flags) { CPUArchState *env = (CPUArchState *)cpu->env_ptr; TranslationBlock *tb, **tb_hash_head, **ptb1; unsigned int h; tb_page_addr_t phys_pc, phys_page1; /* find translated block using physical mappings */ phys_pc = get_page_addr_code(env, pc); phys_page1 = phys_pc & TARGET_PAGE_MASK; h = tb_phys_hash_func(phys_pc); /* Start at head of the hash entry */ ptb1 = tb_hash_head = &tcg_ctx.tb_ctx.tb_phys_hash[h]; tb = *ptb1; while (tb) { if (tb->pc == pc && tb->page_addr[0] == phys_page1 && tb->cs_base == cs_base && tb->flags == flags) { if (tb->page_addr[1] == -1) { /* done, we have a match */ break; } else { /* check next page if needed */ target_ulong virt_page2 = (pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE; tb_page_addr_t phys_page2 = get_page_addr_code(env, virt_page2); if (tb->page_addr[1] == phys_page2) { break; } } } ptb1 = &tb->phys_hash_next; tb = *ptb1; } if (tb) { /* Move the TB to the head of the list */ *ptb1 = tb->phys_hash_next; tb->phys_hash_next = *tb_hash_head; *tb_hash_head = tb; } return tb; } static TranslationBlock *tb_find_slow(CPUState *cpu, target_ulong pc, target_ulong cs_base, uint32_t flags) { TranslationBlock *tb; tb = tb_find_physical(cpu, pc, cs_base, flags); if (tb) { goto found; } #ifdef CONFIG_USER_ONLY /* mmap_lock is needed by tb_gen_code, and mmap_lock must be * taken outside tb_lock. Since we're momentarily dropping * tb_lock, there's a chance that our desired tb has been * translated. */ tb_unlock(); mmap_lock(); tb_lock(); tb = tb_find_physical(cpu, pc, cs_base, flags); if (tb) { mmap_unlock(); goto found; } #endif /* if no translated code available, then translate it now */ tb = tb_gen_code(cpu, pc, cs_base, flags, 0); #ifdef CONFIG_USER_ONLY mmap_unlock(); #endif found: /* we add the TB in the virtual pc hash table */ cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb; return tb; } static inline TranslationBlock *tb_find_fast(CPUState *cpu, TranslationBlock **last_tb, int tb_exit) { CPUArchState *env = (CPUArchState *)cpu->env_ptr; TranslationBlock *tb; target_ulong cs_base, pc; uint32_t flags; /* 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_lock(); tb = 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_find_slow(cpu, pc, cs_base, flags); } if (cpu->tb_flushed) { /* Ensure that no TB jump will be modified as the * translation buffer has been flushed. */ *last_tb = NULL; cpu->tb_flushed = false; } /* See if we can patch the calling TB. */ if (*last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { tb_add_jump(*last_tb, tb_exit, tb); } 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); apic_poll_irq(x86_cpu->apic_state); cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL); } #endif if (!cpu_has_work(cpu)) { current_cpu = NULL; 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); cc->do_interrupt(cpu); 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 */ TranslationBlock *last_tb = NULL; /* Avoid chaining TBs */ cpu_exec_nocache(cpu, 1, tb_find_fast(cpu, &last_tb, 0), true); *ret = -1; return true; #endif } return false; } static inline void cpu_handle_interrupt(CPUState *cpu, TranslationBlock **last_tb) { CPUClass *cc = CPU_GET_CLASS(cpu); int interrupt_request = cpu->interrupt_request; if (unlikely(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; cpu_loop_exit(cpu); } 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; cpu_loop_exit(cpu); } #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); do_cpu_init(x86_cpu); cpu->exception_index = EXCP_HALTED; cpu_loop_exit(cpu); } #else else if (interrupt_request & CPU_INTERRUPT_RESET) { replay_interrupt(); cpu_reset(cpu); cpu_loop_exit(cpu); } #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 { replay_interrupt(); if (cc->cpu_exec_interrupt(cpu, interrupt_request)) { *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 (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(;;) { TranslationBlock *tb, *last_tb; int tb_exit = 0; /* prepare setjmp context for exception handling */ if (sigsetjmp(cpu->jmp_env, 0) == 0) { /* if an exception is pending, we execute it here */ if (cpu_handle_exception(cpu, &ret)) { break; } last_tb = NULL; /* forget the last executed TB after exception */ cpu->tb_flushed = false; /* reset before first TB lookup */ for(;;) { cpu_handle_interrupt(cpu, &last_tb); tb = tb_find_fast(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; }