From 7d7500d99895f888f97397ef32bb536bb0df3b74 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 27 Oct 2016 16:10:03 +0100 Subject: [PATCH] tcg: comment on which functions have to be called with tb_lock held MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit softmmu requires more functions to be thread-safe, because translation blocks can be invalidated from e.g. notdirty callbacks. Probably the same holds for user-mode emulation, it's just that no one has ever tried to produce a coherent locking there. This patch will guide the introduction of more tb_lock and tb_unlock calls for system emulation. Note that after this patch some (most) of the mentioned functions are still called outside tb_lock/tb_unlock. The next one will rectify this. Signed-off-by: Paolo Bonzini Signed-off-by: Alex Bennée Reviewed-by: Richard Henderson Message-Id: <20161027151030.20863-7-alex.bennee@linaro.org> Signed-off-by: Paolo Bonzini --- include/exec/exec-all.h | 1 + include/qom/cpu.h | 3 +++ tcg/tcg.h | 2 ++ translate-all.c | 28 +++++++++++++++++++++++----- 4 files changed, 29 insertions(+), 5 deletions(-) diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 4d36ee38f7..a8c13cee66 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -316,6 +316,7 @@ static inline void tb_set_jmp_target(TranslationBlock *tb, #endif +/* Called with tb_lock held. */ static inline void tb_add_jump(TranslationBlock *tb, int n, TranslationBlock *tb_next) { diff --git a/include/qom/cpu.h b/include/qom/cpu.h index 633c3fc124..9f597bb0c0 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -319,7 +319,10 @@ struct CPUState { MemoryRegion *memory; void *env_ptr; /* CPUArchState */ + + /* Writes protected by tb_lock, reads not thread-safe */ struct TranslationBlock *tb_jmp_cache[TB_JMP_CACHE_SIZE]; + struct GDBRegisterState *gdb_regs; int gdb_num_regs; int gdb_num_g_regs; diff --git a/tcg/tcg.h b/tcg/tcg.h index b34b5fbc2f..dc1281fb4e 100644 --- a/tcg/tcg.h +++ b/tcg/tcg.h @@ -726,6 +726,7 @@ static inline bool tcg_op_buf_full(void) /* pool based memory allocation */ +/* tb_lock must be held for tcg_malloc_internal. */ void *tcg_malloc_internal(TCGContext *s, int size); void tcg_pool_reset(TCGContext *s); @@ -733,6 +734,7 @@ void tb_lock(void); void tb_unlock(void); void tb_lock_reset(void); +/* Called with tb_lock held. */ static inline void *tcg_malloc(int size) { TCGContext *s = &tcg_ctx; diff --git a/translate-all.c b/translate-all.c index 5aded3d3bd..fad2646ddd 100644 --- a/translate-all.c +++ b/translate-all.c @@ -308,7 +308,9 @@ static int encode_search(TranslationBlock *tb, uint8_t *block) return p - block; } -/* The cpu state corresponding to 'searched_pc' is restored. */ +/* The cpu state corresponding to 'searched_pc' is restored. + * Called with tb_lock held. + */ static int cpu_restore_state_from_tb(CPUState *cpu, TranslationBlock *tb, uintptr_t searched_pc) { @@ -462,6 +464,7 @@ static void page_init(void) } /* If alloc=1: + * Called with tb_lock held for system emulation. * Called with mmap_lock held for user-mode emulation. */ static PageDesc *page_find_alloc(tb_page_addr_t index, int alloc) @@ -826,8 +829,12 @@ bool tcg_enabled(void) return tcg_ctx.code_gen_buffer != NULL; } -/* Allocate a new translation block. Flush the translation buffer if - too many translation blocks or too much generated code. */ +/* + * Allocate a new translation block. Flush the translation buffer if + * too many translation blocks or too much generated code. + * + * Called with tb_lock held. + */ static TranslationBlock *tb_alloc(target_ulong pc) { TranslationBlock *tb; @@ -842,6 +849,7 @@ static TranslationBlock *tb_alloc(target_ulong pc) return tb; } +/* Called with tb_lock held. */ void tb_free(TranslationBlock *tb) { /* In practice this is mostly used for single use temporary TB @@ -966,6 +974,10 @@ do_tb_invalidate_check(struct qht *ht, void *p, uint32_t hash, void *userp) } } +/* verify that all the pages have correct rights for code + * + * Called with tb_lock held. + */ static void tb_invalidate_check(target_ulong address) { address &= TARGET_PAGE_MASK; @@ -1070,7 +1082,10 @@ static inline void tb_jmp_unlink(TranslationBlock *tb) } } -/* invalidate one TB */ +/* invalidate one TB + * + * Called with tb_lock held. + */ void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr) { CPUState *cpu; @@ -1504,7 +1519,9 @@ void tb_invalidate_phys_page_fast(tb_page_addr_t start, int len) } if (!p->code_bitmap && ++p->code_write_count >= SMC_BITMAP_USE_THRESHOLD) { - /* build code bitmap */ + /* build code bitmap. FIXME: writes should be protected by + * tb_lock, reads by tb_lock or RCU. + */ build_page_bitmap(p); } if (p->code_bitmap) { @@ -1645,6 +1662,7 @@ void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr) } #endif /* !defined(CONFIG_USER_ONLY) */ +/* Called with tb_lock held. */ void tb_check_watchpoint(CPUState *cpu) { TranslationBlock *tb;