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[Qemu-devel] [RFC v4 06/28] tcg: comment on which functions have to be c
From: |
Alex Bennée |
Subject: |
[Qemu-devel] [RFC v4 06/28] tcg: comment on which functions have to be called with tb_lock held |
Date: |
Thu, 11 Aug 2016 16:24:02 +0100 |
From: Paolo Bonzini <address@hidden>
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 <address@hidden>
Signed-off-by: Alex Bennée <address@hidden>
---
v1(ajb):
- just s-o-b
v2
- clarify write lock on tb_jump_cache
v3
- drop RCU comment for debug stuff (separate commit now)
---
include/exec/exec-all.h | 1 +
include/qom/cpu.h | 3 +++
tcg/tcg.h | 2 ++
translate-all.c | 30 ++++++++++++++++++++++++------
4 files changed, 30 insertions(+), 6 deletions(-)
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index d5f29bd..d73b0e6 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -315,6 +315,7 @@ 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 060a473..8ee770a 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -324,7 +324,10 @@ 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 6046dcd..a7f34db 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -712,6 +712,7 @@ 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);
@@ -720,6 +721,7 @@ 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 7ab1fd6..a3448e1 100644
--- a/translate-all.c
+++ b/translate-all.c
@@ -288,7 +288,9 @@ 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)
{
@@ -438,6 +440,7 @@ 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)
@@ -802,8 +805,12 @@ 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;
@@ -818,6 +825,7 @@ 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
@@ -927,7 +935,11 @@ do_tb_invalidate_check(struct qht *ht, void *p, uint32_t
hash, void *userp)
}
}
-static void tb_invalidate_check(target_ulong address)
+/* verify that all the pages have correct rights for code
+ *
+ * Called with tb_lock held.
+ */
+static void tb_page_check(void)
{
address &= TARGET_PAGE_MASK;
qht_iter(&tcg_ctx.tb_ctx.htable, do_tb_invalidate_check, &address);
@@ -1031,7 +1043,10 @@ 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;
@@ -1465,7 +1480,9 @@ 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) {
@@ -1606,6 +1623,7 @@ 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
- [Qemu-devel] [RFC v4 00/28] Base enabling patches for MTTCG, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 02/28] translate_all: DEBUG_FLUSH -> DEBUG_TB_FLUSH, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 04/28] cpu-exec: include cpu_index in CPU_LOG_EXEC messages, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 01/28] cpus: make all_vcpus_paused() return bool, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 03/28] translate-all: add DEBUG_LOCKING asserts, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 05/28] docs: new design document multi-thread-tcg.txt (DRAFTING), Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 08/28] translate-all: Add assert_(memory|tb)_lock annotations, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 10/28] target-arm/arm-powerctl: wake up sleeping CPUs, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 07/28] linux-user/elfload: ensure mmap_lock() held while setting up, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 06/28] tcg: comment on which functions have to be called with tb_lock held,
Alex Bennée <=
- [Qemu-devel] [RFC v4 15/28] tcg: rename tcg_current_cpu to tcg_current_rr_cpu, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 09/28] tcg: protect TBContext with tb_lock., Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 11/28] tcg: move tcg_exec_all and helpers above thread fn, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 14/28] tcg: add kick timer for single-threaded vCPU emulation, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 12/28] tcg: cpus rm tcg_exec_all(), Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 13/28] tcg: add options for enabling MTTCG, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 17/28] cpus: re-factor out handle_icount_deadline, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 18/28] tcg: remove global exit_request, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 19/28] tcg: move locking for tb_invalidate_phys_page_range up, Alex Bennée, 2016/08/11
- [Qemu-devel] [RFC v4 16/28] tcg: drop global lock during TCG code execution, Alex Bennée, 2016/08/11