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unicorn/qemu/cpu-exec.c

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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 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/>.
*/
/* Modified for Unicorn Engine by Nguyen Anh Quynh, 2015 */
#include "tcg.h"
#include "sysemu/sysemu.h"
#include "uc_priv.h"
static tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr);
static TranslationBlock *tb_find_slow(CPUArchState *env, target_ulong pc,
target_ulong cs_base, uint64_t flags);
static TranslationBlock *tb_find_fast(CPUArchState *env);
static void cpu_handle_debug_exception(CPUArchState *env);
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)
{
#endif
/* XXX: restore cpu registers saved in host registers */
cpu->exception_index = -1;
siglongjmp(cpu->jmp_env, 1);
}
/* main execution loop */
int cpu_exec(struct uc_struct *uc, CPUArchState *env) // qq
{
CPUState *cpu = ENV_GET_CPU(env);
TCGContext *tcg_ctx = env->uc->tcg_ctx;
CPUClass *cc = CPU_GET_CLASS(uc, cpu);
#ifdef TARGET_I386
X86CPU *x86_cpu = X86_CPU(uc, cpu);
#endif
int ret, interrupt_request;
TranslationBlock *tb;
uint8_t *tc_ptr;
uintptr_t next_tb;
/* 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;
}
uc->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();
if (unlikely(uc->exit_request)) {
cpu->exit_request = 1;
}
cc->cpu_exec_enter(cpu);
cpu->exception_index = -1;
/* prepare setjmp context for exception handling */
for(;;) {
if (sigsetjmp(cpu->jmp_env, 0) == 0) {
if (uc->stop_request || uc->invalid_error)
break;
/* if an exception is pending, we execute it here */
if (cpu->exception_index >= 0) {
//printf(">>> GOT INTERRUPT. exception idx = %x\n", cpu->exception_index); // qq
if (uc->stop_interrupt && uc->stop_interrupt(cpu->exception_index)) {
cpu->halted = 1;
uc->invalid_error = UC_ERR_INSN_INVALID;
ret = EXCP_HLT;
break;
}
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(env);
}
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;
break;
#else
// Unicorn: call interrupt callback if registered
if (uc->hook_intr_idx)
((uc_cb_hookintr_t)uc->hook_callbacks[uc->hook_intr_idx].callback)(
uc, cpu->exception_index,
uc->hook_callbacks[uc->hook_intr_idx].user_data);
cpu->exception_index = -1;
#if defined(TARGET_X86_64)
// point EIP to the next instruction after INT
env->eip = env->exception_next_eip;
#endif
#if defined(TARGET_MIPS) || defined(TARGET_MIPS64)
env->active_tc.PC = uc->next_pc;
#endif
#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(env); // qq
if (!tb) { // invalid TB due to invalid code?
uc->invalid_error = UC_ERR_FETCH_UNMAPPED;
ret = EXCP_HLT;
break;
}
/* 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;
}
/* 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)) {
tc_ptr = tb->tc_ptr;
/* execute the generated code */
next_tb = cpu_tb_exec(cpu, tc_ptr); // qq
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.
*/
tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
next_tb = 0;
break;
default:
break;
}
}
cpu->current_tb = NULL;
/* 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 = uc->current_cpu;
env = cpu->env_ptr;
cc = CPU_GET_CLASS(uc, cpu);
#ifdef TARGET_I386
x86_cpu = X86_CPU(uc, cpu);
#endif
if (have_tb_lock) {
spin_unlock(&tcg_ctx->tb_ctx.tb_lock);
have_tb_lock = false;
}
}
} /* for(;;) */
cc->cpu_exec_exit(cpu);
// Unicorn: flush JIT cache to because emulation might stop in
// the middle of translation, thus generate incomplete code.
// TODO: optimize this for better performance
tb_flush(env);
/* fail safe : never use current_cpu outside cpu_exec() */
uc->current_cpu = NULL;
return ret;
}
/* Execute a TB, and fix up the CPU state afterwards if necessary */
static tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr)
{
CPUArchState *env = cpu->env_ptr;
TCGContext *tcg_ctx = env->uc->tcg_ctx;
uintptr_t next_tb;
next_tb = tcg_qemu_tb_exec(env, tb_ptr);
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(env->uc, cpu);
TranslationBlock *tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
if (cc->synchronize_from_tb) {
// avoid sync twice when helper_uc_tracecode() already did this.
if (env->uc->emu_counter <= env->uc->emu_count && !env->uc->stop_request)
cc->synchronize_from_tb(cpu, tb);
} else {
assert(cc->set_pc);
// avoid sync twice when helper_uc_tracecode() already did this.
if (env->uc->emu_counter <= env->uc->emu_count)
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;
}
static TranslationBlock *tb_find_slow(CPUArchState *env, target_ulong pc,
target_ulong cs_base, uint64_t flags) // qq
{
CPUState *cpu = ENV_GET_CPU(env);
TCGContext *tcg_ctx = env->uc->tcg_ctx;
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); // qq
if (phys_pc == -1) { // invalid code?
return NULL;
}
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); // qq
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 TranslationBlock *tb_find_fast(CPUArchState *env) // qq
{
CPUState *cpu = ENV_GET_CPU(env);
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(env, pc, cs_base, flags); // qq
}
return tb;
}
static void cpu_handle_debug_exception(CPUArchState *env)
{
CPUState *cpu = ENV_GET_CPU(env);
CPUClass *cc = CPU_GET_CLASS(env->uc, cpu);
CPUWatchpoint *wp;
if (!cpu->watchpoint_hit) {
QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
wp->flags &= ~BP_WATCHPOINT_HIT;
}
}
cc->debug_excp_handler(cpu);
}
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