From: Paolo Bonzini <pbonz...@redhat.com> 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 <pbonz...@redhat.com> Signed-off-by: Alex Bennée <alex.ben...@linaro.org> --- v1(ajb): - just s-o-b --- exec.c | 1 + include/exec/exec-all.h | 1 + include/qom/cpu.h | 3 +++ tcg/tcg.h | 2 ++ translate-all.c | 38 ++++++++++++++++++++++++++++++-------- 5 files changed, 37 insertions(+), 8 deletions(-) diff --git a/exec.c b/exec.c index f09dd4e..4f0e5ed 100644 --- a/exec.c +++ b/exec.c @@ -825,6 +825,7 @@ int cpu_breakpoint_insert(CPUState *cpu, vaddr pc, int flags, { CPUBreakpoint *bp; + /* TODO: locking (RCU?) */ bp = g_malloc(sizeof(*bp)); bp->pc = pc; diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 0ef6ea5..c41d680 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -372,6 +372,7 @@ 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 4132108..9124b6d 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -310,7 +310,10 @@ struct CPUState { void *env_ptr; /* CPUArchState */ struct TranslationBlock *current_tb; + + /* Protected by tb_lock. */ 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 aa4e123..cd7cde7 100644 --- a/tcg/tcg.h +++ b/tcg/tcg.h @@ -609,6 +609,7 @@ 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); void tcg_pool_delete(TCGContext *s); @@ -618,6 +619,7 @@ void tb_unlock(void); bool tb_lock_recursive(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 f68dcbc..1a02450 100644 --- a/translate-all.c +++ b/translate-all.c @@ -260,7 +260,9 @@ 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) { @@ -318,8 +320,10 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t retaddr) if (tb->cflags & CF_NOCACHE) { /* one-shot translation, invalidate it immediately */ cpu->current_tb = NULL; + tb_lock(); tb_phys_invalidate(tb, -1); tb_free(tb); + tb_unlock(); } return true; } @@ -411,6 +415,7 @@ 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) @@ -766,8 +771,12 @@ 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; @@ -781,6 +790,7 @@ 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 @@ -888,7 +898,10 @@ static void tb_invalidate_check(target_ulong address) } } -/* verify that all the pages have correct rights for code */ +/* verify that all the pages have correct rights for code + * + * Called with tb_lock held. + */ static void tb_page_check(void) { TranslationBlock *tb; @@ -976,7 +989,10 @@ static inline void tb_jmp_remove(TranslationBlock *tb, int n) } } -/* invalidate one TB */ +/* invalidate one TB + * + * Called with tb_lock held. + */ void tb_phys_invalidate(TranslationBlock *tb, tb_page_addr_t page_addr) { PageDesc *p; @@ -1067,7 +1083,7 @@ static void build_page_bitmap(PageDesc *p) } #endif -/* Called with mmap_lock held for user mode emulation. */ +/* Called with tb_lock held, and mmap_lock too for user mode emulation. */ TranslationBlock *tb_gen_code(CPUState *cpu, target_ulong pc, target_ulong cs_base, int flags, int cflags) @@ -1333,7 +1349,9 @@ 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) { @@ -1423,6 +1441,7 @@ static void tb_invalidate_phys_page(tb_page_addr_t addr, /* add the tb in the target page and protect it if necessary * + * Called with tb_lock held. * Called with mmap_lock held for user-mode emulation. */ static inline void tb_alloc_page(TranslationBlock *tb, @@ -1482,6 +1501,7 @@ static inline void tb_alloc_page(TranslationBlock *tb, /* add a new TB and link it to the physical page tables. phys_page2 is * (-1) to indicate that only one page contains the TB. * + * Called with tb_lock held. * Called with mmap_lock held for user-mode emulation. */ static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc, @@ -1528,7 +1548,8 @@ static void tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc, } /* find the TB 'tb' such that tb[0].tc_ptr <= tc_ptr < - tb[1].tc_ptr. Return NULL if not found */ + * tb[1].tc_ptr. Return NULL if not found + */ static TranslationBlock *tb_find_pc(uintptr_t tc_ptr) { int m_min, m_max, m; @@ -1581,6 +1602,7 @@ 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; -- 2.7.3