From: Sergey Fedorov <serge.f...@gmail.com> 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 <serge.f...@gmail.com> Signed-off-by: Sergey Fedorov <sergey.fedo...@linaro.org> --- 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