Commit 7d7500d9 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

tcg: comment on which functions have to be called with tb_lock held 



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: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Message-Id: <20161027151030.20863-7-alex.bennee@linaro.org>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4426f83a

include/exec/exec-all.h

+1 −0
Original line number Diff line number Diff line
@@ -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)

{

include/qom/cpu.h

+3 −0
Original line number Diff line number Diff line
@@ -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;

tcg/tcg.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

translate-all.c

+23 −5
Original line number Diff line number Diff line
@@ -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;