diff options
Diffstat (limited to 'cpu-exec.c')
| -rw-r--r-- | cpu-exec.c | 119 |
1 files changed, 70 insertions, 49 deletions
diff --git a/cpu-exec.c b/cpu-exec.c index 6b6942de69..89455339ea 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -258,10 +258,10 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles, tb_free(tb); } -static TranslationBlock *tb_find_slow(CPUState *cpu, - target_ulong pc, - target_ulong cs_base, - uint64_t flags) +static TranslationBlock *tb_find_physical(CPUState *cpu, + target_ulong pc, + target_ulong cs_base, + uint64_t flags) { CPUArchState *env = (CPUArchState *)cpu->env_ptr; TranslationBlock *tb, **ptb1; @@ -278,8 +278,9 @@ static TranslationBlock *tb_find_slow(CPUState *cpu, ptb1 = &tcg_ctx.tb_ctx.tb_phys_hash[h]; for(;;) { tb = *ptb1; - if (!tb) - goto not_found; + if (!tb) { + return NULL; + } if (tb->pc == pc && tb->page_addr[0] == phys_page1 && tb->cs_base == cs_base && @@ -291,25 +292,59 @@ static TranslationBlock *tb_find_slow(CPUState *cpu, 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; + if (tb->page_addr[1] == phys_page2) { + break; + } } else { - goto found; + break; } } 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); - 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; + /* Move the TB to the head of the list */ + *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; + return tb; +} + +static TranslationBlock *tb_find_slow(CPUState *cpu, + target_ulong pc, + target_ulong cs_base, + uint64_t flags) +{ + TranslationBlock *tb; + + tb = tb_find_physical(cpu, pc, cs_base, flags); + if (tb) { + goto found; + } + +#ifdef CONFIG_USER_ONLY + /* mmap_lock is needed by tb_gen_code, and mmap_lock must be + * taken outside tb_lock. Since we're momentarily dropping + * tb_lock, there's a chance that our desired tb has been + * translated. + */ + tb_unlock(); + mmap_lock(); + tb_lock(); + tb = tb_find_physical(cpu, pc, cs_base, flags); + if (tb) { + mmap_unlock(); + goto found; } +#endif + + /* if no translated code available, then translate it now */ + tb = tb_gen_code(cpu, pc, cs_base, flags, 0); + +#ifdef CONFIG_USER_ONLY + mmap_unlock(); +#endif + +found: /* we add the TB in the virtual pc hash table */ cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)] = tb; return tb; @@ -350,7 +385,8 @@ static void cpu_handle_debug_exception(CPUState *cpu) /* main execution loop */ -volatile sig_atomic_t exit_request; +bool exit_request; +CPUState *tcg_current_cpu; int cpu_exec(CPUState *cpu) { @@ -365,9 +401,6 @@ int cpu_exec(CPUState *cpu) uintptr_t next_tb; SyncClocks sc; - /* 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; @@ -377,18 +410,10 @@ int cpu_exec(CPUState *cpu) } 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(); - + atomic_mb_set(&tcg_current_cpu, cpu); rcu_read_lock(); - if (unlikely(exit_request)) { + if (unlikely(atomic_mb_read(&exit_request))) { cpu->exit_request = 1; } @@ -484,8 +509,7 @@ int cpu_exec(CPUState *cpu) cpu->exception_index = EXCP_INTERRUPT; cpu_loop_exit(cpu); } - spin_lock(&tcg_ctx.tb_ctx.tb_lock); - have_tb_lock = true; + tb_lock(); tb = tb_find_fast(cpu); /* Note: we do it here to avoid a gcc bug on Mac OS X when doing it in tb_find_slow */ @@ -507,20 +531,14 @@ int cpu_exec(CPUState *cpu) 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(); + tb_unlock(); if (likely(!cpu->exit_request)) { trace_exec_tb(tb, tb->pc); tc_ptr = tb->tc_ptr; /* execute the generated code */ + cpu->current_tb = tb; next_tb = cpu_tb_exec(cpu, tc_ptr); + cpu->current_tb = NULL; switch (next_tb & TB_EXIT_MASK) { case TB_EXIT_REQUESTED: /* Something asked us to stop executing @@ -528,8 +546,12 @@ int cpu_exec(CPUState *cpu) * 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. + * 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(); next_tb = 0; break; case TB_EXIT_ICOUNT_EXPIRED: @@ -559,7 +581,6 @@ int cpu_exec(CPUState *cpu) break; } } - cpu->current_tb = NULL; /* Try to align the host and virtual clocks if the guest is in advance */ align_clocks(&sc, cpu); @@ -576,10 +597,7 @@ int cpu_exec(CPUState *cpu) x86_cpu = X86_CPU(cpu); env = &x86_cpu->env; #endif - if (have_tb_lock) { - spin_unlock(&tcg_ctx.tb_ctx.tb_lock); - have_tb_lock = false; - } + tb_lock_reset(); } } /* for(;;) */ @@ -588,5 +606,8 @@ int cpu_exec(CPUState *cpu) /* fail safe : never use current_cpu outside cpu_exec() */ current_cpu = NULL; + + /* Does not need atomic_mb_set because a spurious wakeup is okay. */ + atomic_set(&tcg_current_cpu, NULL); return ret; } |