--- /dev/null
+/*
+ * 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;
+}
Code Review / kvmfornfv.git / blobdiff