unicorn/qemu/cpu-exec.c
Paolo Bonzini 3907ea1a3b
cpu-exec: Fix compiler warning (-Werror=clobbered)
Reloading of local variables after sigsetjmp is only needed for some
buggy compilers.

The code which should reload these variables causes compiler warnings
with gcc 4.7 when compiler optimizations are enabled:

cpu-exec.c:204:15: error:
variable ‘cpu’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered]
cpu-exec.c:207:15: error:
variable ‘cc’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered]
cpu-exec.c:202:28: error:
argument ‘env’ might be clobbered by ‘longjmp’ or ‘vfork’ [-Werror=clobbered]

Now this code is only used for compilers which need it
(and gcc 4.5.x, x > 0 which does not need it but won't give warnings).

There were bug reports for clang and gcc 4.5.0, while gcc 4.5.1
was reported to work fine without the reload code. For clang it
is not clear which versions are affected, so simply keep the status quo
for all clang compilations. This can be improved later.

Backports commit 0448f5f8b816923b198ab6c32286fd1f3b2f3e45 from qemu
2018-02-17 15:24:15 -05:00

408 lines
15 KiB
C

/*
* 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 "exec/address-spaces.h"
#include "exec/tb-hash.h"
#include "uc_priv.h"
static tcg_target_ulong cpu_tb_exec(CPUState *cpu, uint8_t *tb_ptr);
static TranslationBlock *tb_find_slow(CPUState *cpu, target_ulong pc,
target_ulong cs_base, uint64_t flags);
static TranslationBlock *tb_find_fast(CPUState *cpu);
static void cpu_handle_debug_exception(CPUState *cpu);
/* main execution loop */
int cpu_exec(struct uc_struct *uc, CPUState *cpu)
{
CPUArchState *env = cpu->env_ptr;
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;
struct hook *hook;
if (cpu->halted) {
if (!cpu_has_work(cpu)) {
return EXCP_HALTED;
}
cpu->halted = 0;
}
uc->current_cpu = cpu;
atomic_mb_set(&uc->tcg_current_cpu, cpu);
if (unlikely(atomic_mb_read(&uc->exit_request))) {
cpu->exit_request = 1;
}
cc->cpu_exec_enter(cpu);
cpu->exception_index = -1;
env->invalid_error = UC_ERR_OK;
/* 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(cpu);
}
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
bool catched = false;
// Unicorn: call registered interrupt callbacks
HOOK_FOREACH_VAR_DECLARE;
HOOK_FOREACH(uc, hook, UC_HOOK_INTR) {
((uc_cb_hookintr_t)hook->callback)(uc, cpu->exception_index, hook->user_data);
catched = true;
}
// Unicorn: If un-catched interrupt, stop executions.
if (!catched) {
cpu->halted = 1;
uc->invalid_error = UC_ERR_EXCEPTION;
ret = EXCP_HLT;
break;
}
cpu->exception_index = -1;
#if defined(TARGET_X86_64)
if (env->exception_is_int) {
// 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);
}
tb = tb_find_fast(cpu); // UNICORN
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
&& !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
tb_add_jump((TranslationBlock *)(next_tb & ~TB_EXIT_MASK),
next_tb & TB_EXIT_MASK, tb);
}
if (likely(!cpu->exit_request)) {
tc_ptr = tb->tc_ptr;
cpu->current_tb = tb;
/* execute the generated code */
next_tb = cpu_tb_exec(cpu, tc_ptr); // UNICORN
cpu->current_tb = NULL;
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. But we need to
* ensure the tcg_exit_req read in generated code
* comes before the next read of cpu->exit_request
* or cpu->interrupt_request.
*/
smp_rmb();
tb = (TranslationBlock *)(next_tb & ~TB_EXIT_MASK);
next_tb = 0;
break;
default:
break;
}
}
/* reset soft MMU for next block (it can currently
only be set by a memory fault) */
} /* for(;;) */
} else {
#if defined(__clang__) || !QEMU_GNUC_PREREQ(4, 6)
/* Some compilers wrongly smash all local variables after
* siglongjmp. There were bug reports for gcc 4.5.0 and clang.
* Reload essential local variables here for those compilers.
* Newer versions of gcc would complain about this code (-Wclobbered). */
cpu = uc->current_cpu;
env = cpu->env_ptr;
cc = CPU_GET_CLASS(uc, cpu);
#ifdef TARGET_I386
x86_cpu = X86_CPU(uc, cpu);
#endif
#else /* buggy compiler */
/* Assert that the compiler does not smash local variables. */
g_assert(cpu == current_cpu);
g_assert(cc == CPU_GET_CLASS(cpu));
#ifdef TARGET_I386
g_assert(x86_cpu == X86_CPU(cpu));
g_assert(env == &x86_cpu->env);
#endif
#endif /* buggy compiler */
cpu->can_do_io = 1;
}
} /* 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(cpu);
/* fail safe : never use current_cpu outside cpu_exec() */
uc->current_cpu = NULL;
/* Does not need atomic_mb_set because a spurious wakeup is okay. */
atomic_set(&uc->tcg_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 && !env->uc->quit_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 && !env->uc->quit_request)
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(CPUState *cpu,
target_ulong pc,
target_ulong cs_base,
uint64_t flags)
{
CPUArchState *env = (CPUArchState *)cpu->env_ptr;
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, (int)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(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); // qq
}
return tb;
}
static void cpu_handle_debug_exception(CPUState *cpu)
{
CPUClass *cc = CPU_GET_CLASS(cpu->uc, cpu);
CPUWatchpoint *wp;
if (!cpu->watchpoint_hit) {
QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
wp->flags &= ~BP_WATCHPOINT_HIT;
}
}
cc->debug_excp_handler(cpu);
}