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[Qemu-devel] [PATCH RFC] cpu-exec: Restructure cpu_exec()
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From: |
Sergey Fedorov |
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Subject: |
[Qemu-devel] [PATCH RFC] cpu-exec: Restructure cpu_exec() |
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Date: |
Wed, 4 May 2016 16:38:08 +0300 |
From: Sergey Fedorov <address@hidden>
cpu_exec() was a huge function also sprinkled with some preprocessor
directives. It's hard to read and see the main loop crowded by all this
code. Restructure cpu_exec() by moving its conceptual parts into
separate static in-line functions. That makes it possible to see the
whole main loop at once, especially its sigsetjmp() handling part.
Signed-off-by: Sergey Fedorov <address@hidden>
Signed-off-by: Sergey Fedorov <address@hidden>
---
This patch is based on a commit:
00bbce07745b ("tcg: Remove needless CPUState::current_tb")
from:
git://github.com/rth7680/qemu.git tcg-next
assiming that patch:
http://lists.nongnu.org/archive/html/qemu-devel/2016-05/msg00226.html
is also applied.
cpu-exec.c | 395 +++++++++++++++++++++++++++++++++----------------------------
1 file changed, 211 insertions(+), 184 deletions(-)
diff --git a/cpu-exec.c b/cpu-exec.c
index d55faa5114c7..2526df0e3e40 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -352,7 +352,30 @@ static inline TranslationBlock *tb_find_fast(CPUState *cpu,
return tb;
}
-static void cpu_handle_debug_exception(CPUState *cpu)
+static inline bool cpu_handle_halt(CPUState *cpu)
+{
+ if (cpu->halted) {
+#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
+ X86CPU *x86_cpu = X86_CPU(cpu);
+
+ if ((cpu->interrupt_request & CPU_INTERRUPT_POLL)
+ && replay_interrupt()) {
+ apic_poll_irq(x86_cpu->apic_state);
+ cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
+ }
+#endif
+ if (!cpu_has_work(cpu)) {
+ current_cpu = NULL;
+ return true;
+ }
+
+ cpu->halted = 0;
+ }
+
+ return false;
+}
+
+static inline void cpu_handle_debug_exception(CPUState *cpu)
{
CPUClass *cc = CPU_GET_CLASS(cpu);
CPUWatchpoint *wp;
@@ -366,37 +389,196 @@ static void cpu_handle_debug_exception(CPUState *cpu)
cc->debug_excp_handler(cpu);
}
+static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
+{
+ 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;
+ 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->do_interrupt(cpu);
+#endif
+ *ret = cpu->exception_index;
+ cpu->exception_index = -1;
+ return true;
+#else
+ if (replay_exception()) {
+ CPUClass *cc = CPU_GET_CLASS(cpu);
+ cc->do_interrupt(cpu);
+ cpu->exception_index = -1;
+ } else if (!replay_has_interrupt()) {
+ /* give a chance to iothread in replay mode */
+ *ret = EXCP_INTERRUPT;
+ return true;
+ }
+#endif
+ }
+#ifndef CONFIG_USER_ONLY
+ } else if (replay_has_exception()
+ && cpu->icount_decr.u16.low + cpu->icount_extra == 0) {
+ /* try to cause an exception pending in the log */
+ TranslationBlock *last_tb = NULL; /* Avoid chaining TBs */
+ cpu_exec_nocache(cpu, 1, tb_find_fast(cpu, &last_tb, 0), true);
+ *ret = -1;
+ return true;
+#endif
+ }
+
+ return false;
+}
+
+static inline void cpu_handle_interrupt(CPUState *cpu,
+ TranslationBlock **last_tb)
+{
+ CPUClass *cc = CPU_GET_CLASS(cpu);
+ int 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 (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;
+ cpu_loop_exit(cpu);
+ }
+#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);
+ do_cpu_init(x86_cpu);
+ cpu->exception_index = EXCP_HALTED;
+ cpu_loop_exit(cpu);
+ }
+#else
+ else if (interrupt_request & CPU_INTERRUPT_RESET) {
+ replay_interrupt();
+ cpu_reset(cpu);
+ cpu_loop_exit(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. */
+ else {
+ replay_interrupt();
+ if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
+ *last_tb = NULL;
+ }
+ }
+ /* 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 */
+ *last_tb = NULL;
+ }
+ }
+ if (unlikely(cpu->exit_request || replay_has_interrupt())) {
+ cpu->exit_request = 0;
+ cpu->exception_index = EXCP_INTERRUPT;
+ cpu_loop_exit(cpu);
+ }
+}
+
+static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
+ TranslationBlock **last_tb, int *tb_exit,
+ SyncClocks *sc)
+{
+ uintptr_t ret;
+
+ if (unlikely(cpu->exit_request)) {
+ return;
+ }
+
+ trace_exec_tb(tb, tb->pc);
+ ret = cpu_tb_exec(cpu, tb);
+ *last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
+ *tb_exit = ret & TB_EXIT_MASK;
+ switch (*tb_exit) {
+ 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();
+ *last_tb = NULL;
+ break;
+ case TB_EXIT_ICOUNT_EXPIRED:
+ {
+ /* Instruction counter expired. */
+#ifdef CONFIG_USER_ONLY
+ abort();
+#else
+ 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. */
+ cpu_exec_nocache(cpu, insns_left, *last_tb, false);
+ align_clocks(sc, cpu);
+ }
+ cpu->exception_index = EXCP_INTERRUPT;
+ *last_tb = NULL;
+ cpu_loop_exit(cpu);
+ }
+ break;
+#endif
+ }
+ default:
+ break;
+ }
+}
+
/* main execution loop */
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, *last_tb;
- int tb_exit = 0;
+ int ret;
SyncClocks sc;
/* replay_interrupt may need current_cpu */
current_cpu = cpu;
- if (cpu->halted) {
-#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
- if ((cpu->interrupt_request & CPU_INTERRUPT_POLL)
- && replay_interrupt()) {
- apic_poll_irq(x86_cpu->apic_state);
- cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
- }
-#endif
- if (!cpu_has_work(cpu)) {
- current_cpu = NULL;
- return EXCP_HALTED;
- }
-
- cpu->halted = 0;
+ if (cpu_handle_halt(cpu)) {
+ return EXCP_HALTED;
}
atomic_mb_set(&tcg_current_cpu, cpu);
@@ -415,170 +597,23 @@ int cpu_exec(CPUState *cpu)
*/
init_delay_params(&sc, cpu);
- /* prepare setjmp context for exception handling */
for(;;) {
+ TranslationBlock *tb, *last_tb;
+ int tb_exit = 0;
+
+ /* prepare setjmp context for exception handling */
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
- if (replay_exception()) {
- cc->do_interrupt(cpu);
- cpu->exception_index = -1;
- } else if (!replay_has_interrupt()) {
- /* give a chance to iothread in replay mode */
- ret = EXCP_INTERRUPT;
- break;
- }
-#endif
- }
-#ifndef CONFIG_USER_ONLY
- } else if (replay_has_exception()
- && cpu->icount_decr.u16.low + cpu->icount_extra == 0) {
- /* try to cause an exception pending in the log */
- last_tb = NULL; /* Avoid chaining TBs */
- cpu_exec_nocache(cpu, 1, tb_find_fast(cpu, &last_tb, 0), true);
- ret = -1;
+ if (cpu_handle_exception(cpu, &ret)) {
break;
-#endif
}
last_tb = NULL; /* forget the last executed TB after exception */
cpu->tb_flushed = false; /* reset before first TB lookup */
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 (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;
- cpu_loop_exit(cpu);
- }
-#if defined(TARGET_I386)
- else if (interrupt_request & CPU_INTERRUPT_INIT) {
- replay_interrupt();
- 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
- else if (interrupt_request & CPU_INTERRUPT_RESET) {
- replay_interrupt();
- cpu_reset(cpu);
- cpu_loop_exit(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. */
- else {
- replay_interrupt();
- if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
- last_tb = NULL;
- }
- }
- /* 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 */
- last_tb = NULL;
- }
- }
- if (unlikely(cpu->exit_request
- || replay_has_interrupt())) {
- cpu->exit_request = 0;
- cpu->exception_index = EXCP_INTERRUPT;
- cpu_loop_exit(cpu);
- }
+ cpu_handle_interrupt(cpu, &last_tb);
tb = tb_find_fast(cpu, &last_tb, tb_exit);
- if (likely(!cpu->exit_request)) {
- uintptr_t ret;
- trace_exec_tb(tb, tb->pc);
- /* execute the generated code */
- ret = cpu_tb_exec(cpu, tb);
- last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
- tb_exit = ret & TB_EXIT_MASK;
- switch (tb_exit) {
- 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();
- last_tb = NULL;
- break;
- case TB_EXIT_ICOUNT_EXPIRED:
- {
- /* Instruction counter expired. */
-#ifdef CONFIG_USER_ONLY
- abort();
-#else
- 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. */
- cpu_exec_nocache(cpu, insns_left,
- last_tb, false);
- align_clocks(&sc, cpu);
- }
- cpu->exception_index = EXCP_INTERRUPT;
- last_tb = NULL;
- cpu_loop_exit(cpu);
- }
- break;
-#endif
- }
- default:
- break;
- }
- }
+ cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit, &sc);
/* Try to align the host and virtual clocks
if the guest is in advance */
align_clocks(&sc, cpu);
@@ -591,18 +626,10 @@ int cpu_exec(CPUState *cpu)
* Newer versions of gcc would complain about this code
(-Wclobbered). */
cpu = current_cpu;
cc = CPU_GET_CLASS(cpu);
-#ifdef TARGET_I386
- x86_cpu = X86_CPU(cpu);
- env = &x86_cpu->env;
-#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;
tb_lock_reset();
--
1.9.1
- [Qemu-devel] [PATCH RFC] cpu-exec: Restructure cpu_exec(),
Sergey Fedorov <=