From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44559) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZPrz4-0003pT-3x for qemu-devel@nongnu.org; Thu, 13 Aug 2015 08:51:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZPryv-00087x-Sv for qemu-devel@nongnu.org; Thu, 13 Aug 2015 08:51:50 -0400 Received: from greensocs.com ([193.104.36.180]:35034) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZPryv-00087n-IT for qemu-devel@nongnu.org; Thu, 13 Aug 2015 08:51:41 -0400 Message-ID: <55CC92CC.4020201@greensocs.com> Date: Thu, 13 Aug 2015 14:51:24 +0200 From: Frederic Konrad MIME-Version: 1.0 References: <1439397664-70734-1-git-send-email-pbonzini@redhat.com> <1439397664-70734-12-git-send-email-pbonzini@redhat.com> In-Reply-To: <1439397664-70734-12-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 11/10] tcg: comment on which functions have to be called with tb_lock held List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , qemu-devel@nongnu.org Cc: mttcg@greensocs.com On 12/08/2015 18:41, Paolo Bonzini wrote: > 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 > --- > exec.c | 1 + > include/exec/exec-all.h | 2 ++ > include/qom/cpu.h | 3 +++ > tcg/tcg.h | 2 ++ > translate-all.c | 35 ++++++++++++++++++++++++++++------- > 5 files changed, 36 insertions(+), 7 deletions(-) > > diff --git a/exec.c b/exec.c > index 54cd70a..856a859 100644 > --- a/exec.c > +++ b/exec.c > @@ -748,6 +748,7 @@ 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 b3f900a..943d97a 100644 > --- a/include/exec/exec-all.h > +++ b/include/exec/exec-all.h > @@ -74,6 +74,7 @@ typedef struct TranslationBlock TranslationBlock; > > void gen_intermediate_code(CPUArchState *env, struct TranslationBlock *tb); > void gen_intermediate_code_pc(CPUArchState *env, struct TranslationBlock *tb); > +/* Called with tb_lock held. */ > void restore_state_to_opc(CPUArchState *env, struct TranslationBlock *tb, > int pc_pos); > > @@ -278,6 +279,7 @@ 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 77bbff2..56b1f4d 100644 > --- a/include/qom/cpu.h > +++ b/include/qom/cpu.h > @@ -285,7 +285,10 @@ struct CPUState { > > void *env_ptr; /* CPUArchState */ > struct TranslationBlock *current_tb; > + > + /* Protected by tb_lock. */ > struct TranslationBlock *tb_jmp_cache[TB_JMP_CACHE_SIZE]; This is temporary as a first step? > + > struct GDBRegisterState *gdb_regs; > int gdb_num_regs; > int gdb_num_g_regs; > diff --git a/tcg/tcg.h b/tcg/tcg.h > index 0ae648f..a2cad31 100644 > --- a/tcg/tcg.h > +++ b/tcg/tcg.h > @@ -590,6 +590,7 @@ 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); > @@ -598,6 +599,7 @@ 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 edb9cb1..17d3cd1 100644 > --- a/translate-all.c > +++ b/translate-all.c > @@ -237,6 +237,7 @@ int cpu_gen_code(CPUArchState *env, TranslationBlock *tb, int *gen_code_size_ptr > } > > /* 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) > @@ -424,6 +425,7 @@ 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) > @@ -734,8 +736,12 @@ 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) > { There is the famous tb_flush which needs to be called with tb_lock held as well. There are several place where it's called. > TranslationBlock *tb; > @@ -751,6 +757,7 @@ 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 > @@ -859,7 +866,10 @@ 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; > @@ -947,7 +957,10 @@ static inline void tb_reset_jump(TranslationBlock *tb, int n) > tb_set_jmp_target(tb, n, (uintptr_t)(tb->tc_ptr + tb->tb_next_offset[n])); > } > > -/* 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; > @@ -1036,7 +1049,7 @@ 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) > @@ -1234,7 +1247,9 @@ 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) { > @@ -1324,6 +1339,7 @@ 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, > @@ -1383,6 +1399,7 @@ 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, > @@ -1423,7 +1440,10 @@ 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 > + * > + * Called with tb_lock held. > + */ > static TranslationBlock *tb_find_pc(uintptr_t tc_ptr) > { > int m_min, m_max, m; > @@ -1476,6 +1496,7 @@ 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;