| /* |
| * 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 "config.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 "exec/memory-internal.h" |
| #include "qemu/rcu.h" |
| #include "exec/tb-hash.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 */ |
| |
| void cpu_loop_exit(CPUState *cpu) |
| { |
| cpu->current_tb = NULL; |
| siglongjmp(cpu->jmp_env, 1); |
| } |
| |
| /* exit the current TB from a signal handler. The host registers are |
| restored in a state compatible with the CPU emulator |
| */ |
| #if defined(CONFIG_SOFTMMU) |
| void cpu_resume_from_signal(CPUState *cpu, void *puc) |
| { |
| /* XXX: restore cpu registers saved in host registers */ |
| |
| cpu->exception_index = -1; |
| siglongjmp(cpu->jmp_env, 1); |
| } |
| |
| void cpu_reload_memory_map(CPUState *cpu) |
| { |
| AddressSpaceDispatch *d; |
| |
| if (qemu_in_vcpu_thread()) { |
| /* Do not let the guest prolong the critical section as much as it |
| * as it desires. |
| * |
| * Currently, this is prevented by the I/O thread's periodinc kicking |
| * of the VCPU thread (iothread_requesting_mutex, qemu_cpu_kick_thread) |
| * but this will go away once TCG's execution moves out of the global |
| * mutex. |
| * |
| * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which |
| * only protects cpu->as->dispatch. Since we reload it below, we can |
| * split the critical section. |
| */ |
| rcu_read_unlock(); |
| rcu_read_lock(); |
| } |
| |
| /* The CPU and TLB are protected by the iothread lock. */ |
| d = atomic_rcu_read(&cpu->as->dispatch); |
| cpu->memory_dispatch = d; |
| tlb_flush(cpu, 1); |
| } |
| #endif |
| |
| /* Execute a TB, and fix up the CPU state afterwards if necessary */ |
| static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr) |
| { |
| CPUArchState *env = cpu->env_ptr; |
| uintptr_t next_tb; |
| |
| #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 = 0; |
| next_tb = tcg_qemu_tb_exec(env, tb_ptr); |
| cpu->can_do_io = 1; |
| trace_exec_tb_exit((void *) (next_tb & ~TB_EXIT_MASK), |
| next_tb & TB_EXIT_MASK); |
| |
| if ((next_tb & TB_EXIT_MASK) > 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); |
| TranslationBlock *tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK); |
| if (cc->synchronize_from_tb) { |
| cc->synchronize_from_tb(cpu, tb); |
| } else { |
| assert(cc->set_pc); |
| cc->set_pc(cpu, tb->pc); |
| } |
| } |
| if ((next_tb & TB_EXIT_MASK) == 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 next_tb; |
| } |
| |
| /* 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) |
| { |
| TranslationBlock *tb; |
| target_ulong pc = orig_tb->pc; |
| target_ulong cs_base = orig_tb->cs_base; |
| uint64_t flags = orig_tb->flags; |
| |
| /* 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_gen_code can flush our orig_tb, invalidate it now */ |
| tb_phys_invalidate(orig_tb, -1); |
| tb = tb_gen_code(cpu, pc, cs_base, flags, |
| max_cycles | CF_NOCACHE); |
| cpu->current_tb = tb; |
| /* execute the generated code */ |
| trace_exec_tb_nocache(tb, tb->pc); |
| cpu_tb_exec(cpu, tb->tc_ptr); |
| cpu->current_tb = NULL; |
| tb_phys_invalidate(tb, -1); |
| tb_free(tb); |
| } |
| |
| static TranslationBlock *tb_find_slow(CPUState *cpu, |
| target_ulong pc, |
| target_ulong cs_base, |
| uint64_t flags) |
| { |
| CPUArchState *env = (CPUArchState *)cpu->env_ptr; |
| TranslationBlock *tb, **ptb1; |
| unsigned int h; |
| tb_page_addr_t phys_pc, phys_page1; |
| target_ulong virt_page2; |
| |
| tcg_ctx.tb_ctx.tb_invalidated_flag = 0; |
| |
| /* 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); |
| ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h]; |
| for(;;) { |
| tb = *ptb1; |
| if (!tb) |
| goto not_found; |
| if (tb->pc == pc && |
| tb->page_addr[0] == phys_page1 && |
| tb->cs_base == cs_base && |
| tb->flags == flags) { |
| /* check next page if needed */ |
| if (tb->page_addr[1] != -1) { |
| tb_page_addr_t phys_page2; |
| |
| virt_page2 = (pc & TARGET_PAGE_MASK) + |
| TARGET_PAGE_SIZE; |
| phys_page2 = get_page_addr_code(env, virt_page2); |
| if (tb->page_addr[1] == phys_page2) |
| goto found; |
| } else { |
| goto found; |
| } |
| } |
| ptb1 = &tb->phys_hash_next; |
| } |
| not_found: |
| /* if no translated code available, then translate it now */ |
| tb = tb_gen_code(cpu, pc, cs_base, flags, 0); |
| |
| found: |
| /* Move the last found TB to the head of the list */ |
| if (likely(*ptb1)) { |
| *ptb1 = tb->phys_hash_next; |
| tb->phys_hash_next = tcg_ctx.tb_ctx.tb_phys_hash[h]; |
| tcg_ctx.tb_ctx.tb_phys_hash[h] = tb; |
| } |
| /* 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) |
| { |
| CPUArchState *env = (CPUArchState *)cpu->env_ptr; |
| TranslationBlock *tb; |
| target_ulong cs_base, pc; |
| int 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 = 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); |
| } |
| return tb; |
| } |
| |
| static 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); |
| } |
| |
| /* main execution loop */ |
| |
| volatile sig_atomic_t exit_request; |
| |
| int cpu_exec(CPUState *cpu) |
| { |
| CPUClass *cc = CPU_GET_CLASS(cpu); |
| #ifdef TARGET_I386 |
| X86CPU *x86_cpu = X86_CPU(cpu); |
| CPUArchState *env = &x86_cpu->env; |
| #endif |
| int ret, interrupt_request; |
| TranslationBlock *tb; |
| uint8_t *tc_ptr; |
| uintptr_t next_tb; |
| SyncClocks sc; |
| |
| /* This must be volatile so it is not trashed by longjmp() */ |
| volatile bool have_tb_lock = false; |
| |
| if (cpu->halted) { |
| if (!cpu_has_work(cpu)) { |
| return EXCP_HALTED; |
| } |
| |
| cpu->halted = 0; |
| } |
| |
| current_cpu = cpu; |
| |
| /* As long as current_cpu is null, up to the assignment just above, |
| * requests by other threads to exit the execution loop are expected to |
| * be issued using the exit_request global. We must make sure that our |
| * evaluation of the global value is performed past the current_cpu |
| * value transition point, which requires a memory barrier as well as |
| * an instruction scheduling constraint on modern architectures. */ |
| smp_mb(); |
| |
| rcu_read_lock(); |
| |
| if (unlikely(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); |
| |
| /* prepare setjmp context for exception handling */ |
| for(;;) { |
| if (sigsetjmp(cpu->jmp_env, 0) == 0) { |
| /* if an exception is pending, we execute it here */ |
| 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; |
| break; |
| } 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) |
| cc->do_interrupt(cpu); |
| #endif |
| ret = cpu->exception_index; |
| cpu->exception_index = -1; |
| break; |
| #else |
| cc->do_interrupt(cpu); |
| cpu->exception_index = -1; |
| #endif |
| } |
| } |
| |
| next_tb = 0; /* force lookup of first TB */ |
| for(;;) { |
| 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 (interrupt_request & CPU_INTERRUPT_HALT) { |
| cpu->interrupt_request &= ~CPU_INTERRUPT_HALT; |
| cpu->halted = 1; |
| cpu->exception_index = EXCP_HLT; |
| cpu_loop_exit(cpu); |
| } |
| #if defined(TARGET_I386) |
| if (interrupt_request & CPU_INTERRUPT_INIT) { |
| 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 |
| if (interrupt_request & CPU_INTERRUPT_RESET) { |
| cpu_reset(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. */ |
| if (cc->cpu_exec_interrupt(cpu, interrupt_request)) { |
| next_tb = 0; |
| } |
| /* Don't use the cached interrupt_request value, |
| do_interrupt may have updated the EXITTB flag. */ |
| if (cpu->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 */ |
| next_tb = 0; |
| } |
| } |
| if (unlikely(cpu->exit_request)) { |
| cpu->exit_request = 0; |
| cpu->exception_index = EXCP_INTERRUPT; |
| cpu_loop_exit(cpu); |
| } |
| spin_lock(&tcg_ctx.tb_ctx.tb_lock); |
| have_tb_lock = true; |
| tb = tb_find_fast(cpu); |
| /* Note: we do it here to avoid a gcc bug on Mac OS X when |
| doing it in tb_find_slow */ |
| if (tcg_ctx.tb_ctx.tb_invalidated_flag) { |
| /* as some TB could have been invalidated because |
| of memory exceptions while generating the code, we |
| must recompute the hash index here */ |
| next_tb = 0; |
| tcg_ctx.tb_ctx.tb_invalidated_flag = 0; |
| } |
| if (qemu_loglevel_mask(CPU_LOG_EXEC)) { |
| qemu_log("Trace %p [" TARGET_FMT_lx "] %s\n", |
| tb->tc_ptr, tb->pc, lookup_symbol(tb->pc)); |
| } |
| /* 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) { |
| tb_add_jump((TranslationBlock *)(next_tb & ~TB_EXIT_MASK), |
| next_tb & TB_EXIT_MASK, tb); |
| } |
| have_tb_lock = false; |
| spin_unlock(&tcg_ctx.tb_ctx.tb_lock); |
| |
| /* cpu_interrupt might be called while translating the |
| TB, but before it is linked into a potentially |
| infinite loop and becomes env->current_tb. Avoid |
| starting execution if there is a pending interrupt. */ |
| cpu->current_tb = tb; |
| barrier(); |
| if (likely(!cpu->exit_request)) { |
| trace_exec_tb(tb, tb->pc); |
| tc_ptr = tb->tc_ptr; |
| /* execute the generated code */ |
| next_tb = cpu_tb_exec(cpu, tc_ptr); |
| 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. |
| */ |
| 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; |
| } |
| } |
| cpu->current_tb = NULL; |
| /* 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 { |
| /* Reload env after longjmp - the compiler may have smashed all |
| * local variables as longjmp is marked 'noreturn'. */ |
| cpu = current_cpu; |
| cc = CPU_GET_CLASS(cpu); |
| cpu->can_do_io = 1; |
| #ifdef TARGET_I386 |
| x86_cpu = X86_CPU(cpu); |
| env = &x86_cpu->env; |
| #endif |
| if (have_tb_lock) { |
| spin_unlock(&tcg_ctx.tb_ctx.tb_lock); |
| have_tb_lock = false; |
| } |
| } |
| } /* for(;;) */ |
| |
| cc->cpu_exec_exit(cpu); |
| rcu_read_unlock(); |
| |
| /* fail safe : never use current_cpu outside cpu_exec() */ |
| current_cpu = NULL; |
| return ret; |
| } |
