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
v2
- clarify write lock on tb_jump_cache
---
exec.c | 1 +
include/exec/exec-all.h | 1 +
include/qom/cpu.h | 3 +++
tcg/tcg.h | 2 ++
translate-all.c | 32 ++++++++++++++++++++++++++------
5 files changed, 33 insertions(+), 6 deletions(-)
diff --git a/exec.c b/exec.c
index f46e596..17f390e 100644
--- a/exec.c
+++ b/exec.c
@@ -826,6 +826,7 @@ 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 bbd9807..60716ae 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -386,6 +386,7 @@ 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 6931db9..13eeaae 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -306,7 +306,10 @@ struct CPUState {
void *env_ptr; /* CPUArchState */
struct TranslationBlock *current_tb;
+
+ /* 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 ea4ff02..a46d17c 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);
@@ -617,6 +618,7 @@ 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 d923008..a7ff5e7 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -248,7 +248,9 @@ 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)
{
@@ -306,8 +308,10 @@ 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;
}
@@ -399,6 +403,7 @@ 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)
@@ -754,8 +759,12 @@ 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;
@@ -769,6 +778,7 @@ 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
@@ -874,7 +884,10 @@ 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;
@@ -985,7 +998,10 @@ 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;
@@ -1062,6 +1078,7 @@ static void build_page_bitmap(PageDesc *p)
/* 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,
@@ -1429,7 +1446,9 @@ 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) {
@@ -1571,6 +1590,7 @@ 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;
--
2.7.4
