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qemu/accel/tcg/cpu-exec.c
Richard Henderson 258afb487f accel/tcg: Use CF_NO_GOTO_{TB, PTR} in cpu_exec_step_atomic 
Request that the one TB returns immediately, so that
we release the exclusive lock as soon as possible.

Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210717221851.2124573-7-richard.henderson@linaro.org>
2021-07-21 07:47:04 -10:00

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/*
* 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 <http://www.gnu.org/licenses/>.
*/
#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;
/*
* For singlestep and -d nochain, suppress goto_tb so that
* we can log -d cpu,exec after every TB.
*/
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 */
}
}
/**
* 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;
cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
tb = tb_lookup(cpu, pc, cs_base, flags, curr_cflags(cpu));
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;
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 TranslationBlock *tb_find(CPUState *cpu,
TranslationBlock *last_tb,
int tb_exit, uint32_t cflags)
{
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);
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);
}
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) {
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->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->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;
}
/*
* 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
}
static inline bool cpu_handle_interrupt(CPUState *cpu,
TranslationBlock **last_tb)
{
CPUClass *cc = CPU_GET_CLASS(cpu);
/* 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 (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->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;
}
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(CF_COUNT_MASK, 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 (!cpu->icount_extra && insns_left > 0 && insns_left < tb->icount) {
cpu->cflags_next_tb = (tb->cflags & ~CF_COUNT_MASK) | insns_left;
}
#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();
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 essential local variables 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;
cc = CPU_GET_CLASS(cpu);
#else
/*
* Non-buggy compilers preserve these locals; assert that
* they have the correct value.
*/
g_assert(cpu == current_cpu);
g_assert(cc == CPU_GET_CLASS(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)) {
uint32_t cflags = cpu->cflags_next_tb;
TranslationBlock *tb;
/* 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. */
if (cflags == -1) {
cflags = curr_cflags(cpu);
} else {
cpu->cflags_next_tb = -1;
}
tb = tb_find(cpu, last_tb, tb_exit, cflags);
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 */
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