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https://github.com/yuzu-emu/unicorn.git
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73c59faad5
We don't take care of direct jumps when address mapping changes. Thus we must be sure to generate direct jumps so that they always keep valid even if address mapping changes. Luckily, we can only allow to execute a TB if it was generated from the pages which match with current mapping. Document tcg_gen_goto_tb() declaration and note the reason for destination PC limitations. Some targets with variable length instructions allow TB to straddle a page boundary. However, we make sure that both of TB pages match the current address mapping when looking up TBs. So it is safe to do direct jumps into the both pages. Correct the checks for some of those targets. Given that, we can safely patch a TB which spans two pages. Remove the unnecessary check in cpu_exec() and allow such TBs to be patched. Backports commit 5b053a4a28278bca606eeff7d1c0730df1b047e9 from qemu
415 lines
16 KiB
C
415 lines
16 KiB
C
/*
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* emulator main execution loop
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*
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* Copyright (c) 2003-2005 Fabrice Bellard
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*/
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/* Modified for Unicorn Engine by Nguyen Anh Quynh, 2015 */
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#include "qemu/osdep.h"
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#include "tcg.h"
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#include "sysemu/sysemu.h"
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#include "exec/address-spaces.h"
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#include "exec/tb-hash.h"
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#include "uc_priv.h"
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static tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb);
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static TranslationBlock *tb_find_slow(CPUState *cpu, target_ulong pc,
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target_ulong cs_base, uint64_t flags);
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static TranslationBlock *tb_find_fast(CPUState *cpu);
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static void cpu_handle_debug_exception(CPUState *cpu);
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/* main execution loop */
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int cpu_exec(struct uc_struct *uc, CPUState *cpu)
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{
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CPUArchState *env = cpu->env_ptr;
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TCGContext *tcg_ctx = env->uc->tcg_ctx;
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CPUClass *cc = CPU_GET_CLASS(uc, cpu);
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#ifdef TARGET_I386
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X86CPU *x86_cpu = X86_CPU(uc, cpu);
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#endif
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int ret, interrupt_request;
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TranslationBlock *tb;
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uintptr_t next_tb;
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struct hook *hook;
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if (cpu->halted) {
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if (!cpu_has_work(cpu)) {
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return EXCP_HALTED;
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}
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cpu->halted = 0;
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}
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uc->current_cpu = cpu;
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atomic_mb_set(&uc->tcg_current_cpu, cpu);
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if (unlikely(atomic_mb_read(&uc->exit_request))) {
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cpu->exit_request = 1;
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}
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cc->cpu_exec_enter(cpu);
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cpu->exception_index = -1;
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env->invalid_error = UC_ERR_OK;
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/* prepare setjmp context for exception handling */
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for(;;) {
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if (sigsetjmp(cpu->jmp_env, 0) == 0) {
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if (uc->stop_request || uc->invalid_error)
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break;
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/* if an exception is pending, we execute it here */
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if (cpu->exception_index >= 0) {
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//printf(">>> GOT INTERRUPT. exception idx = %x\n", cpu->exception_index); // qq
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if (uc->stop_interrupt && uc->stop_interrupt(cpu->exception_index)) {
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cpu->halted = 1;
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uc->invalid_error = UC_ERR_INSN_INVALID;
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ret = EXCP_HLT;
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break;
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}
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if (cpu->exception_index >= EXCP_INTERRUPT) {
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/* exit request from the cpu execution loop */
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ret = cpu->exception_index;
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if (ret == EXCP_DEBUG) {
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cpu_handle_debug_exception(cpu);
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}
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break;
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} else {
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#if defined(CONFIG_USER_ONLY)
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/* if user mode only, we simulate a fake exception
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which will be handled outside the cpu execution
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loop */
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#if defined(TARGET_I386)
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cc->do_interrupt(cpu);
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#endif
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ret = cpu->exception_index;
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break;
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#else
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bool catched = false;
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// Unicorn: call registered interrupt callbacks
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HOOK_FOREACH_VAR_DECLARE;
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HOOK_FOREACH(uc, hook, UC_HOOK_INTR) {
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((uc_cb_hookintr_t)hook->callback)(uc, cpu->exception_index, hook->user_data);
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catched = true;
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}
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// Unicorn: If un-catched interrupt, stop executions.
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if (!catched) {
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cpu->halted = 1;
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uc->invalid_error = UC_ERR_EXCEPTION;
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ret = EXCP_HLT;
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break;
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}
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cpu->exception_index = -1;
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#if defined(TARGET_X86_64)
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if (env->exception_is_int) {
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// point EIP to the next instruction after INT
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env->eip = env->exception_next_eip;
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}
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#endif
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#if defined(TARGET_MIPS) || defined(TARGET_MIPS64)
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env->active_tc.PC = uc->next_pc;
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#endif
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#endif
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}
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}
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next_tb = 0; /* force lookup of first TB */
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for(;;) {
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interrupt_request = cpu->interrupt_request;
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if (unlikely(interrupt_request)) {
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if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
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/* Mask out external interrupts for this step. */
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interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
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}
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if (interrupt_request & CPU_INTERRUPT_DEBUG) {
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cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
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cpu->exception_index = EXCP_DEBUG;
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cpu_loop_exit(cpu);
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}
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if (interrupt_request & CPU_INTERRUPT_HALT) {
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cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
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cpu->halted = 1;
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cpu->exception_index = EXCP_HLT;
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cpu_loop_exit(cpu);
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}
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#if defined(TARGET_I386)
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if (interrupt_request & CPU_INTERRUPT_INIT) {
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cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0);
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do_cpu_init(x86_cpu);
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cpu->exception_index = EXCP_HALTED;
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cpu_loop_exit(cpu);
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}
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#else
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if (interrupt_request & CPU_INTERRUPT_RESET) {
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cpu_reset(cpu);
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}
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#endif
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/* The target hook has 3 exit conditions:
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False when the interrupt isn't processed,
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True when it is, and we should restart on a new TB,
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and via longjmp via cpu_loop_exit. */
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if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
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next_tb = 0;
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}
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/* Don't use the cached interrupt_request value,
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do_interrupt may have updated the EXITTB flag. */
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if (cpu->interrupt_request & CPU_INTERRUPT_EXITTB) {
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cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
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/* ensure that no TB jump will be modified as
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the program flow was changed */
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next_tb = 0;
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}
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}
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if (unlikely(cpu->exit_request)) {
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cpu->exit_request = 0;
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cpu->exception_index = EXCP_INTERRUPT;
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cpu_loop_exit(cpu);
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}
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tb = tb_find_fast(cpu); // UNICORN
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if (!tb) { // invalid TB due to invalid code?
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uc->invalid_error = UC_ERR_FETCH_UNMAPPED;
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ret = EXCP_HLT;
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break;
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}
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/* Note: we do it here to avoid a gcc bug on Mac OS X when
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doing it in tb_find_slow */
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if (tcg_ctx->tb_ctx.tb_invalidated_flag) {
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/* as some TB could have been invalidated because
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of memory exceptions while generating the code, we
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must recompute the hash index here */
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next_tb = 0;
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tcg_ctx->tb_ctx.tb_invalidated_flag = 0;
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}
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/* See if we can patch the calling TB. */
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if (next_tb != 0 && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
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tb_add_jump((TranslationBlock *)(next_tb & ~TB_EXIT_MASK),
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next_tb & TB_EXIT_MASK, tb);
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}
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if (likely(!cpu->exit_request)) {
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cpu->current_tb = tb;
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/* execute the generated code */
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next_tb = cpu_tb_exec(cpu, tb);
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cpu->current_tb = NULL;
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switch (next_tb & TB_EXIT_MASK) {
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case TB_EXIT_REQUESTED:
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/* Something asked us to stop executing
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* chained TBs; just continue round the main
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* loop. Whatever requested the exit will also
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* have set something else (eg exit_request or
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* interrupt_request) which we will handle
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* next time around the loop. But we need to
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* ensure the tcg_exit_req read in generated code
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* comes before the next read of cpu->exit_request
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* or cpu->interrupt_request.
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*/
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smp_rmb();
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tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
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next_tb = 0;
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break;
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default:
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break;
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}
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}
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/* reset soft MMU for next block (it can currently
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only be set by a memory fault) */
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} /* for(;;) */
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} else {
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#if defined(__clang__) || !QEMU_GNUC_PREREQ(4, 6)
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/* Some compilers wrongly smash all local variables after
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* siglongjmp. There were bug reports for gcc 4.5.0 and clang.
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* Reload essential local variables here for those compilers.
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* Newer versions of gcc would complain about this code (-Wclobbered). */
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cpu = uc->current_cpu;
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env = cpu->env_ptr;
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cc = CPU_GET_CLASS(uc, cpu);
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#ifdef TARGET_I386
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x86_cpu = X86_CPU(uc, cpu);
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#endif
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#else /* buggy compiler */
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/* Assert that the compiler does not smash local variables. */
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g_assert(cpu == current_cpu);
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g_assert(cc == CPU_GET_CLASS(cpu));
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#ifdef TARGET_I386
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g_assert(x86_cpu == X86_CPU(cpu));
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g_assert(env == &x86_cpu->env);
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#endif
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#endif /* buggy compiler */
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cpu->can_do_io = 1;
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}
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} /* for(;;) */
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cc->cpu_exec_exit(cpu);
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// Unicorn: flush JIT cache to because emulation might stop in
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// the middle of translation, thus generate incomplete code.
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// TODO: optimize this for better performance
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tb_flush(cpu);
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/* fail safe : never use current_cpu outside cpu_exec() */
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uc->current_cpu = NULL;
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/* Does not need atomic_mb_set because a spurious wakeup is okay. */
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atomic_set(&uc->tcg_current_cpu, NULL);
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return ret;
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}
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/* Execute a TB, and fix up the CPU state afterwards if necessary */
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static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb)
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{
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CPUArchState *env = cpu->env_ptr;
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TCGContext *tcg_ctx = env->uc->tcg_ctx;
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uintptr_t next_tb;
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uint8_t *tb_ptr = itb->tc_ptr;
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// Unicorn: commented out
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//qemu_log_mask_and_addr(CPU_LOG_EXEC, itb->pc,
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// "Trace %p [" TARGET_FMT_lx "] %s\n",
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// itb->tc_ptr, itb->pc, lookup_symbol(itb->pc));
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next_tb = tcg_qemu_tb_exec(env, tb_ptr);
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if ((next_tb & TB_EXIT_MASK) > TB_EXIT_IDX1) {
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/* We didn't start executing this TB (eg because the instruction
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* counter hit zero); we must restore the guest PC to the address
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* of the start of the TB.
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*/
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CPUClass *cc = CPU_GET_CLASS(env->uc, cpu);
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TranslationBlock *tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
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// Unicorn: commented out
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//qemu_log_mask_and_addr(CPU_LOG_EXEC, itb->pc,
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// "Stopped execution of TB chain before %p ["
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// TARGET_FMT_lx "] %s\n",
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// itb->tc_ptr, itb->pc, lookup_symbol(itb->pc));
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if (cc->synchronize_from_tb) {
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// avoid sync twice when helper_uc_tracecode() already did this.
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if (env->uc->emu_counter <= env->uc->emu_count &&
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!env->uc->stop_request && !env->uc->quit_request)
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cc->synchronize_from_tb(cpu, tb);
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} else {
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assert(cc->set_pc);
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// avoid sync twice when helper_uc_tracecode() already did this.
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if (env->uc->emu_counter <= env->uc->emu_count && !env->uc->quit_request)
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cc->set_pc(cpu, tb->pc);
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}
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}
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if ((next_tb & TB_EXIT_MASK) == TB_EXIT_REQUESTED) {
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/* We were asked to stop executing TBs (probably a pending
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* interrupt. We've now stopped, so clear the flag.
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*/
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cpu->tcg_exit_req = 0;
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}
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return next_tb;
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}
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static TranslationBlock *tb_find_slow(CPUState *cpu,
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target_ulong pc,
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target_ulong cs_base,
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uint64_t flags)
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{
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CPUArchState *env = (CPUArchState *)cpu->env_ptr;
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TCGContext *tcg_ctx = env->uc->tcg_ctx;
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TranslationBlock *tb, **ptb1;
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unsigned int h;
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tb_page_addr_t phys_pc, phys_page1;
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target_ulong virt_page2;
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tcg_ctx->tb_ctx.tb_invalidated_flag = 0;
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/* find translated block using physical mappings */
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phys_pc = get_page_addr_code(env, pc); // qq
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if (phys_pc == -1) { // invalid code?
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return NULL;
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}
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phys_page1 = phys_pc & TARGET_PAGE_MASK;
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h = tb_phys_hash_func(phys_pc);
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ptb1 = &tcg_ctx->tb_ctx.tb_phys_hash[h];
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for(;;) {
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tb = *ptb1;
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if (!tb)
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goto not_found;
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if (tb->pc == pc &&
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tb->page_addr[0] == phys_page1 &&
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tb->cs_base == cs_base &&
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tb->flags == flags) {
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/* check next page if needed */
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if (tb->page_addr[1] != -1) {
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tb_page_addr_t phys_page2;
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virt_page2 = (pc & TARGET_PAGE_MASK) +
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TARGET_PAGE_SIZE;
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phys_page2 = get_page_addr_code(env, virt_page2);
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if (tb->page_addr[1] == phys_page2)
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goto found;
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} else {
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goto found;
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}
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}
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ptb1 = &tb->phys_hash_next;
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}
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not_found:
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/* if no translated code available, then translate it now */
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tb = tb_gen_code(cpu, pc, cs_base, (int)flags, 0); // qq
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found:
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/* Move the last found TB to the head of the list */
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if (likely(*ptb1)) {
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*ptb1 = tb->phys_hash_next;
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tb->phys_hash_next = tcg_ctx->tb_ctx.tb_phys_hash[h];
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tcg_ctx->tb_ctx.tb_phys_hash[h] = tb;
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}
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/* we add the TB in the virtual pc hash table */
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cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb;
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return tb;
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}
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static TranslationBlock *tb_find_fast(CPUState *cpu)
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{
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CPUArchState *env = (CPUArchState *)cpu->env_ptr;
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TranslationBlock *tb;
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target_ulong cs_base, pc;
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uint32_t flags;
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/* we record a subset of the CPU state. It will
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always be the same before a given translated block
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is executed. */
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cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags);
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tb = cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
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if (unlikely(!tb || tb->pc != pc || tb->cs_base != cs_base ||
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tb->flags != flags)) {
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tb = tb_find_slow(cpu, pc, cs_base, flags); // qq
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}
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return tb;
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}
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static void cpu_handle_debug_exception(CPUState *cpu)
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{
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CPUClass *cc = CPU_GET_CLASS(cpu->uc, cpu);
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CPUWatchpoint *wp;
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if (!cpu->watchpoint_hit) {
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QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
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wp->flags &= ~BP_WATCHPOINT_HIT;
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}
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}
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cc->debug_excp_handler(cpu);
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}
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