/* * 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 2.1 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 . */ #include "qemu/osdep.h" #include "qemu-common.h" #include "qemu/qemu-print.h" #include "hw/core/tcg-cpu-ops.h" #include "trace.h" #include "disas/disas.h" #include "exec/exec-all.h" #include "tcg/tcg.h" #include "qemu/atomic.h" #include "qemu/compiler.h" #include "qemu/timer.h" #include "qemu/rcu.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 "exec/cpu-all.h" #include "sysemu/cpu-timers.h" #include "sysemu/replay.h" #include "exec/helper-proto.h" #include "tb-hash.h" #include "tb-context.h" #include "internal.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 int64_t max_delay; static int64_t max_advance; static void align_clocks(SyncClocks *sc, CPUState *cpu) { int64_t cpu_icount; if (!icount_align_option) { return; } cpu_icount = cpu->icount_extra + cpu_neg(cpu)->icount_decr.u16.low; sc->diff_clk += 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; qemu_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, 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_neg(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 */ uint32_t curr_cflags(CPUState *cpu) { uint32_t cflags = cpu->tcg_cflags; /* * Record gdb single-step. We should be exiting the TB by raising * EXCP_DEBUG, but to simplify other tests, disable chaining too. * * For singlestep and -d nochain, suppress goto_tb so that * we can log -d cpu,exec after every TB. */ if (unlikely(cpu->singlestep_enabled)) { cflags |= CF_NO_GOTO_TB | CF_NO_GOTO_PTR | CF_SINGLE_STEP | 1; } else if (singlestep) { cflags |= CF_NO_GOTO_TB | 1; } else if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { cflags |= CF_NO_GOTO_TB; } return cflags; } /* Might cause an exception, so have a longjmp destination ready */ static inline TranslationBlock *tb_lookup(CPUState *cpu, target_ulong pc, target_ulong cs_base, uint32_t flags, uint32_t cflags) { TranslationBlock *tb; uint32_t hash; /* we should never be trying to look up an INVALID tb */ tcg_debug_assert(!(cflags & CF_INVALID)); hash = tb_jmp_cache_hash_func(pc); tb = qatomic_rcu_read(&cpu->tb_jmp_cache[hash]); if (likely(tb && tb->pc == pc && tb->cs_base == cs_base && tb->flags == flags && tb->trace_vcpu_dstate == *cpu->trace_dstate && tb_cflags(tb) == cflags)) { return tb; } tb = tb_htable_lookup(cpu, pc, cs_base, flags, cflags); if (tb == NULL) { return NULL; } qatomic_set(&cpu->tb_jmp_cache[hash], tb); return tb; } static inline void log_cpu_exec(target_ulong pc, CPUState *cpu, const TranslationBlock *tb) { if (unlikely(qemu_loglevel_mask(CPU_LOG_TB_CPU | CPU_LOG_EXEC)) && qemu_log_in_addr_range(pc)) { qemu_log_mask(CPU_LOG_EXEC, "Trace %d: %p [" TARGET_FMT_lx "/" TARGET_FMT_lx "/%08x/%08x] %s\n", cpu->cpu_index, tb->tc.ptr, tb->cs_base, pc, tb->flags, tb->cflags, lookup_symbol(pc)); #if defined(DEBUG_DISAS) if (qemu_loglevel_mask(CPU_LOG_TB_CPU)) { FILE *logfile = qemu_log_lock(); int flags = 0; if (qemu_loglevel_mask(CPU_LOG_TB_FPU)) { flags |= CPU_DUMP_FPU; } #if defined(TARGET_I386) flags |= CPU_DUMP_CCOP; #endif log_cpu_state(cpu, flags); qemu_log_unlock(logfile); } #endif /* DEBUG_DISAS */ } } static bool check_for_breakpoints(CPUState *cpu, target_ulong pc, uint32_t *cflags) { CPUBreakpoint *bp; bool match_page = false; if (likely(QTAILQ_EMPTY(&cpu->breakpoints))) { return false; } /* * Singlestep overrides breakpoints. * This requirement is visible in the record-replay tests, where * we would fail to make forward progress in reverse-continue. * * TODO: gdb singlestep should only override gdb breakpoints, * so that one could (gdb) singlestep into the guest kernel's * architectural breakpoint handler. */ if (cpu->singlestep_enabled) { return false; } QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) { /* * If we have an exact pc match, trigger the breakpoint. * Otherwise, note matches within the page. */ if (pc == bp->pc) { bool match_bp = false; if (bp->flags & BP_GDB) { match_bp = true; } else if (bp->flags & BP_CPU) { #ifdef CONFIG_USER_ONLY g_assert_not_reached(); #else CPUClass *cc = CPU_GET_CLASS(cpu); assert(cc->tcg_ops->debug_check_breakpoint); match_bp = cc->tcg_ops->debug_check_breakpoint(cpu); #endif } if (match_bp) { cpu->exception_index = EXCP_DEBUG; return true; } } else if (((pc ^ bp->pc) & TARGET_PAGE_MASK) == 0) { match_page = true; } } /* * Within the same page as a breakpoint, single-step, * returning to helper_lookup_tb_ptr after each insn looking * for the actual breakpoint. * * TODO: Perhaps better to record all of the TBs associated * with a given virtual page that contains a breakpoint, and * then invalidate them when a new overlapping breakpoint is * set on the page. Non-overlapping TBs would not be * invalidated, nor would any TB need to be invalidated as * breakpoints are removed. */ if (match_page) { *cflags = (*cflags & ~CF_COUNT_MASK) | CF_NO_GOTO_TB | 1; } return false; } /** * helper_lookup_tb_ptr: quick check for next tb * @env: current cpu state * * Look for an existing TB matching the current cpu state. * If found, return the code pointer. If not found, return * the tcg epilogue so that we return into cpu_tb_exec. */ const void *HELPER(lookup_tb_ptr)(CPUArchState *env) { CPUState *cpu = env_cpu(env); TranslationBlock *tb; target_ulong cs_base, pc; uint32_t flags, cflags; cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); cflags = curr_cflags(cpu); if (check_for_breakpoints(cpu, pc, &cflags)) { cpu_loop_exit(cpu); } tb = tb_lookup(cpu, pc, cs_base, flags, cflags); if (tb == NULL) { return tcg_code_gen_epilogue; } log_cpu_exec(pc, cpu, tb); return tb->tc.ptr; } /* Execute a TB, and fix up the CPU state afterwards if necessary */ /* * Disable CFI checks. * TCG creates binary blobs at runtime, with the transformed code. * A TB is a blob of binary code, created at runtime and called with an * indirect function call. Since such function did not exist at compile time, * the CFI runtime has no way to verify its signature and would fail. * TCG is not considered a security-sensitive part of QEMU so this does not * affect the impact of CFI in environment with high security requirements */ static inline TranslationBlock * QEMU_DISABLE_CFI cpu_tb_exec(CPUState *cpu, TranslationBlock *itb, int *tb_exit) { CPUArchState *env = cpu->env_ptr; uintptr_t ret; TranslationBlock *last_tb; const void *tb_ptr = itb->tc.ptr; log_cpu_exec(itb->pc, cpu, itb); qemu_thread_jit_execute(); ret = tcg_qemu_tb_exec(env, tb_ptr); cpu->can_do_io = 1; /* * TODO: Delay swapping back to the read-write region of the TB * until we actually need to modify the TB. The read-only copy, * coming from the rx region, shares the same host TLB entry as * the code that executed the exit_tb opcode that arrived here. * If we insist on touching both the RX and the RW pages, we * double the host TLB pressure. */ last_tb = tcg_splitwx_to_rw((void *)(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->tcg_ops->synchronize_from_tb) { cc->tcg_ops->synchronize_from_tb(cpu, last_tb); } else { assert(cc->set_pc); cc->set_pc(cpu, last_tb->pc); } } return last_tb; } static void cpu_exec_enter(CPUState *cpu) { CPUClass *cc = CPU_GET_CLASS(cpu); if (cc->tcg_ops->cpu_exec_enter) { cc->tcg_ops->cpu_exec_enter(cpu); } } static void cpu_exec_exit(CPUState *cpu) { CPUClass *cc = CPU_GET_CLASS(cpu); if (cc->tcg_ops->cpu_exec_exit) { cc->tcg_ops->cpu_exec_exit(cpu); } } void cpu_exec_step_atomic(CPUState *cpu) { CPUArchState *env = (CPUArchState *)cpu->env_ptr; TranslationBlock *tb; target_ulong cs_base, pc; uint32_t flags, cflags; int tb_exit; if (sigsetjmp(cpu->jmp_env, 0) == 0) { start_exclusive(); g_assert(cpu == current_cpu); g_assert(!cpu->running); cpu->running = true; cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); cflags = curr_cflags(cpu); /* Execute in a serial context. */ cflags &= ~CF_PARALLEL; /* After 1 insn, return and release the exclusive lock. */ cflags |= CF_NO_GOTO_TB | CF_NO_GOTO_PTR | 1; /* * No need to check_for_breakpoints here. * We only arrive in cpu_exec_step_atomic after beginning execution * of an insn that includes an atomic operation we can't handle. * Any breakpoint for this insn will have been recognized earlier. */ tb = tb_lookup(cpu, pc, cs_base, flags, cflags); if (tb == NULL) { mmap_lock(); tb = tb_gen_code(cpu, pc, cs_base, flags, cflags); mmap_unlock(); } cpu_exec_enter(cpu); /* execute the generated code */ trace_exec_tb(tb, pc); cpu_tb_exec(cpu, tb, &tb_exit); cpu_exec_exit(cpu); } else { /* * 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 if (qemu_mutex_iothread_locked()) { qemu_mutex_unlock_iothread(); } assert_no_pages_locked(); qemu_plugin_disable_mem_helpers(cpu); } /* * As we start the exclusive region before codegen we must still * be in the region if we longjump out of either the codegen or * the execution. */ g_assert(cpu_in_exclusive_context(cpu)); cpu->running = false; end_exclusive(); } struct tb_desc { target_ulong pc; target_ulong cs_base; CPUArchState *env; tb_page_addr_t phys_page1; uint32_t flags; uint32_t cflags; uint32_t trace_vcpu_dstate; }; static bool tb_lookup_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 && tb->trace_vcpu_dstate == desc->trace_vcpu_dstate && tb_cflags(tb) == desc->cflags) { /* 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; } TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc, target_ulong cs_base, uint32_t flags, uint32_t cflags) { 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.cflags = cflags; desc.trace_vcpu_dstate = *cpu->trace_dstate; desc.pc = pc; phys_pc = get_page_addr_code(desc.env, pc); if (phys_pc == -1) { return NULL; } desc.phys_page1 = phys_pc & TARGET_PAGE_MASK; h = tb_hash_func(phys_pc, pc, flags, cflags, *cpu->trace_dstate); return qht_lookup_custom(&tb_ctx.htable, &desc, h, tb_lookup_cmp); } void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr) { if (TCG_TARGET_HAS_direct_jump) { uintptr_t offset = tb->jmp_target_arg[n]; uintptr_t tc_ptr = (uintptr_t)tb->tc.ptr; uintptr_t jmp_rx = tc_ptr + offset; uintptr_t jmp_rw = jmp_rx - tcg_splitwx_diff; tb_target_set_jmp_target(tc_ptr, jmp_rx, jmp_rw, addr); } else { tb->jmp_target_arg[n] = addr; } } static inline void tb_add_jump(TranslationBlock *tb, int n, TranslationBlock *tb_next) { uintptr_t old; qemu_thread_jit_write(); assert(n < ARRAY_SIZE(tb->jmp_list_next)); qemu_spin_lock(&tb_next->jmp_lock); /* make sure the destination TB is valid */ if (tb_next->cflags & CF_INVALID) { goto out_unlock_next; } /* Atomically claim the jump destination slot only if it was NULL */ old = qatomic_cmpxchg(&tb->jmp_dest[n], (uintptr_t)NULL, (uintptr_t)tb_next); if (old) { goto out_unlock_next; } /* patch the native jump address */ tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc.ptr); /* add in TB jmp list */ tb->jmp_list_next[n] = tb_next->jmp_list_head; tb_next->jmp_list_head = (uintptr_t)tb | n; qemu_spin_unlock(&tb_next->jmp_lock); qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc, "Linking TBs %p [" TARGET_FMT_lx "] index %d -> %p [" TARGET_FMT_lx "]\n", tb->tc.ptr, tb->pc, n, tb_next->tc.ptr, tb_next->pc); return; out_unlock_next: qemu_spin_unlock(&tb_next->jmp_lock); return; } 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) { 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; } } if (cc->tcg_ops->debug_excp_handler) { cc->tcg_ops->debug_excp_handler(cpu); } } static inline bool cpu_handle_exception(CPUState *cpu, int *ret) { if (cpu->exception_index < 0) { #ifndef CONFIG_USER_ONLY if (replay_has_exception() && cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0) { /* Execute just one insn to trigger exception pending in the log */ cpu->cflags_next_tb = (curr_cflags(cpu) & ~CF_USE_ICOUNT) | 1; } #endif return false; } 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->tcg_ops->fake_user_interrupt(cpu); #endif /* TARGET_I386 */ *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->tcg_ops->do_interrupt(cpu); qemu_mutex_unlock_iothread(); cpu->exception_index = -1; if (unlikely(cpu->singlestep_enabled)) { /* * After processing the exception, ensure an EXCP_DEBUG is * raised when single-stepping so that GDB doesn't miss the * next instruction. */ *ret = EXCP_DEBUG; cpu_handle_debug_exception(cpu); return true; } } else if (!replay_has_interrupt()) { /* give a chance to iothread in replay mode */ *ret = EXCP_INTERRUPT; return true; } #endif } return false; } #ifndef CONFIG_USER_ONLY /* * CPU_INTERRUPT_POLL is a virtual event which gets converted into a * "real" interrupt event later. It does not need to be recorded for * replay purposes. */ static inline bool need_replay_interrupt(int interrupt_request) { #if defined(TARGET_I386) return !(interrupt_request & CPU_INTERRUPT_POLL); #else return true; #endif } #endif /* !CONFIG_USER_ONLY */ static inline bool cpu_handle_interrupt(CPUState *cpu, TranslationBlock **last_tb) { /* Clear the interrupt flag now since we're processing * cpu->interrupt_request and cpu->exit_request. * Ensure zeroing happens before reading cpu->exit_request or * cpu->interrupt_request (see also smp_wmb in cpu_exit()) */ qatomic_mb_set(&cpu_neg(cpu)->icount_decr.u16.high, 0); if (unlikely(qatomic_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 !defined(CONFIG_USER_ONLY) 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 /* !TARGET_I386 */ /* 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 { CPUClass *cc = CPU_GET_CLASS(cpu); if (cc->tcg_ops->cpu_exec_interrupt && cc->tcg_ops->cpu_exec_interrupt(cpu, interrupt_request)) { if (need_replay_interrupt(interrupt_request)) { replay_interrupt(); } /* * After processing the interrupt, ensure an EXCP_DEBUG is * raised when single-stepping so that GDB doesn't miss the * next instruction. */ cpu->exception_index = (cpu->singlestep_enabled ? EXCP_DEBUG : -1); *last_tb = NULL; } /* The target hook may have updated the 'cpu->interrupt_request'; * reload the 'interrupt_request' value */ interrupt_request = cpu->interrupt_request; } #endif /* !CONFIG_USER_ONLY */ 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(qatomic_read(&cpu->exit_request)) || (icount_enabled() && (cpu->cflags_next_tb == -1 || cpu->cflags_next_tb & CF_USE_ICOUNT) && cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0)) { qatomic_set(&cpu->exit_request, 0); if (cpu->exception_index == -1) { 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) { int32_t insns_left; trace_exec_tb(tb, tb->pc); tb = cpu_tb_exec(cpu, tb, tb_exit); if (*tb_exit != TB_EXIT_REQUESTED) { *last_tb = tb; return; } *last_tb = NULL; insns_left = qatomic_read(&cpu_neg(cpu)->icount_decr.u32); 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 will be handled by * cpu_handle_interrupt. cpu_handle_interrupt will also * clear cpu->icount_decr.u16.high. */ return; } /* Instruction counter expired. */ assert(icount_enabled()); #ifndef CONFIG_USER_ONLY /* Ensure global icount has gone forward */ icount_update(cpu); /* Refill decrementer and continue execution. */ insns_left = MIN(0xffff, cpu->icount_budget); cpu_neg(cpu)->icount_decr.u16.low = insns_left; cpu->icount_extra = cpu->icount_budget - insns_left; /* * If the next tb has more instructions than we have left to * execute we need to ensure we find/generate a TB with exactly * insns_left instructions in it. */ if (insns_left > 0 && insns_left < tb->icount) { assert(insns_left <= CF_COUNT_MASK); assert(cpu->icount_extra == 0); cpu->cflags_next_tb = (tb->cflags & ~CF_COUNT_MASK) | insns_left; } #endif } /* main execution loop */ int cpu_exec(CPUState *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(); 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__) /* * Some compilers wrongly smash all local variables after * siglongjmp (the spec requires that only non-volatile locals * which are changed between the sigsetjmp and siglongjmp are * permitted to be trashed). There were bug reports for gcc * 4.5.0 and clang. The bug is fixed in all versions of gcc * that we support, but is still unfixed in clang: * https://bugs.llvm.org/show_bug.cgi?id=21183 * * Reload an essential local variable here for those compilers. * Newer versions of gcc would complain about this code (-Wclobbered), * so we only perform the workaround for clang. */ cpu = current_cpu; #else /* Non-buggy compilers preserve this; assert the correct value. */ g_assert(cpu == current_cpu); #endif #ifndef CONFIG_SOFTMMU tcg_debug_assert(!have_mmap_lock()); #endif if (qemu_mutex_iothread_locked()) { qemu_mutex_unlock_iothread(); } qemu_plugin_disable_mem_helpers(cpu); assert_no_pages_locked(); } /* 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; target_ulong cs_base, pc; uint32_t flags, cflags; cpu_get_tb_cpu_state(cpu->env_ptr, &pc, &cs_base, &flags); /* * When requested, use an exact setting for cflags for the next * execution. This is used for icount, precise smc, and stop- * after-access watchpoints. Since this request should never * have CF_INVALID set, -1 is a convenient invalid value that * does not require tcg headers for cpu_common_reset. */ cflags = cpu->cflags_next_tb; if (cflags == -1) { cflags = curr_cflags(cpu); } else { cpu->cflags_next_tb = -1; } if (check_for_breakpoints(cpu, pc, &cflags)) { break; } tb = tb_lookup(cpu, pc, cs_base, flags, cflags); if (tb == NULL) { mmap_lock(); tb = tb_gen_code(cpu, pc, cs_base, flags, cflags); mmap_unlock(); /* * We add the TB in the virtual pc hash table * for the fast lookup */ qatomic_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) { tb_add_jump(last_tb, tb_exit, tb); } 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); } } cpu_exec_exit(cpu); rcu_read_unlock(); return ret; } void tcg_exec_realizefn(CPUState *cpu, Error **errp) { static bool tcg_target_initialized; CPUClass *cc = CPU_GET_CLASS(cpu); if (!tcg_target_initialized) { cc->tcg_ops->initialize(); tcg_target_initialized = true; } tlb_init(cpu); qemu_plugin_vcpu_init_hook(cpu); #ifndef CONFIG_USER_ONLY tcg_iommu_init_notifier_list(cpu); #endif /* !CONFIG_USER_ONLY */ } /* undo the initializations in reverse order */ void tcg_exec_unrealizefn(CPUState *cpu) { #ifndef CONFIG_USER_ONLY tcg_iommu_free_notifier_list(cpu); #endif /* !CONFIG_USER_ONLY */ qemu_plugin_vcpu_exit_hook(cpu); tlb_destroy(cpu); } #ifndef CONFIG_USER_ONLY void dump_drift_info(void) { if (!icount_enabled()) { return; } qemu_printf("Host - Guest clock %"PRIi64" ms\n", (cpu_get_clock() - icount_get()) / SCALE_MS); if (icount_align_option) { qemu_printf("Max guest delay %"PRIi64" ms\n", -max_delay / SCALE_MS); qemu_printf("Max guest advance %"PRIi64" ms\n", max_advance / SCALE_MS); } else { qemu_printf("Max guest delay NA\n"); qemu_printf("Max guest advance NA\n"); } } #endif /* !CONFIG_USER_ONLY */