From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58892) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d3PcJ-0002cO-Ny for qemu-devel@nongnu.org; Wed, 26 Apr 2017 12:16:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d3PcG-0001mk-Gr for qemu-devel@nongnu.org; Wed, 26 Apr 2017 12:16:35 -0400 Received: from mail-wm0-x233.google.com ([2a00:1450:400c:c09::233]:38911) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1d3PcG-0001mQ-AN for qemu-devel@nongnu.org; Wed, 26 Apr 2017 12:16:32 -0400 Received: by mail-wm0-x233.google.com with SMTP id r190so9690953wme.1 for ; Wed, 26 Apr 2017 09:16:31 -0700 (PDT) References: <1493187803-4510-1-git-send-email-cota@braap.org> <1493187803-4510-2-git-send-email-cota@braap.org> <87efwf8nsm.fsf@linaro.org> <5af8f37b-3ffa-6689-bcfa-4e5601fb2087@redhat.com> From: Alex =?utf-8?Q?Benn=C3=A9e?= In-reply-to: <5af8f37b-3ffa-6689-bcfa-4e5601fb2087@redhat.com> Date: Wed, 26 Apr 2017 17:16:58 +0100 Message-ID: <87a87387ph.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH v3 01/10] tcg-runtime: add lookup_tb_ptr helper List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: "Emilio G. Cota" , qemu-devel@nongnu.org, Peter Crosthwaite , Richard Henderson , Peter Maydell , Eduardo Habkost , Andrzej Zaborowski , Aurelien Jarno , Alexander Graf , Stefan Weil , qemu-arm@nongnu.org, Pranith Kumar Paolo Bonzini writes: > On 26/04/2017 12:29, Alex Bennée wrote: >> >> Emilio G. Cota writes: >> >>> This paves the way for upcoming work. >>> >>> Reviewed-by: Richard Henderson >>> Signed-off-by: Emilio G. Cota >>> --- >>> tcg-runtime.c | 21 +++++++++++++++++++++ >>> tcg/tcg-runtime.h | 2 ++ >>> tcg/tcg.h | 1 + >>> 3 files changed, 24 insertions(+) >>> >>> diff --git a/tcg-runtime.c b/tcg-runtime.c >>> index 4c60c96..90d2d4b 100644 >>> --- a/tcg-runtime.c >>> +++ b/tcg-runtime.c >>> @@ -27,6 +27,7 @@ >>> #include "exec/helper-proto.h" >>> #include "exec/cpu_ldst.h" >>> #include "exec/exec-all.h" >>> +#include "exec/tb-hash.h" >>> >>> /* 32-bit helpers */ >>> >>> @@ -141,6 +142,26 @@ uint64_t HELPER(ctpop_i64)(uint64_t arg) >>> return ctpop64(arg); >>> } >>> >>> +void *HELPER(lookup_tb_ptr)(CPUArchState *env, target_ulong addr) >>> +{ >>> + CPUState *cpu = ENV_GET_CPU(env); >>> + TranslationBlock *tb; >>> + target_ulong cs_base, pc; >>> + uint32_t flags; >>> + >>> + if (unlikely(atomic_read(&cpu->exit_request))) { >>> + goto out_epilogue; >>> + } >>> + cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); >>> + tb = atomic_rcu_read(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(addr)]); >>> + if (likely(tb && tb->pc == addr && tb->cs_base == cs_base && >>> + tb->flags == flags)) { >> >> Should we also not be checking the TB hasn't been invalidated: tb->invalid? > > It's not needed because this lookup is (if I understand it right) once > only and is not reused later. This is why tb_find doesn't check > tb->invalid, but uses it to avoid adding the TB to the chain. Right. And when tb->invalid = true is set we then flush it from the jump cache so it will never be found by the helper after. OK nothing to see here ;-) Reviewed-by: Alex Bennée > > Good: > > tb_find tb_phys_invalidate > tb_lock > tb->invalid = true > lookup cache > cache hit > tb_unlock > tb_lock > tb->invalid? > yes, skip tb_add_jump > tb_unlock > execute tb once > > Bad (doesn't happen): > > tb_find tb_phys_invalidate > tb_lock > tb->invalid = true > lookup cache > cache hit > tb_unlock > tb_lock > tb_add_jump > tb_unlock > execute tb many times > > Paolo > >>> + return tb->tc_ptr; >>> + } >>> + out_epilogue: >>> + return tcg_ctx.code_gen_epilogue; >>> +} >>> + >>> void HELPER(exit_atomic)(CPUArchState *env) >>> { >>> cpu_loop_exit_atomic(ENV_GET_CPU(env), GETPC()); >>> diff --git a/tcg/tcg-runtime.h b/tcg/tcg-runtime.h >>> index 114ea6f..c41d38a 100644 >>> --- a/tcg/tcg-runtime.h >>> +++ b/tcg/tcg-runtime.h >>> @@ -24,6 +24,8 @@ DEF_HELPER_FLAGS_1(clrsb_i64, TCG_CALL_NO_RWG_SE, i64, i64) >>> DEF_HELPER_FLAGS_1(ctpop_i32, TCG_CALL_NO_RWG_SE, i32, i32) >>> DEF_HELPER_FLAGS_1(ctpop_i64, TCG_CALL_NO_RWG_SE, i64, i64) >>> >>> +DEF_HELPER_FLAGS_2(lookup_tb_ptr, TCG_CALL_NO_WG_SE, ptr, env, tl) >>> + >>> DEF_HELPER_FLAGS_1(exit_atomic, TCG_CALL_NO_WG, noreturn, env) >>> >>> #ifdef CONFIG_SOFTMMU >>> diff --git a/tcg/tcg.h b/tcg/tcg.h >>> index 6c216bb..5ec48d1 100644 >>> --- a/tcg/tcg.h >>> +++ b/tcg/tcg.h >>> @@ -699,6 +699,7 @@ struct TCGContext { >>> extension that allows arithmetic on void*. */ >>> int code_gen_max_blocks; >>> void *code_gen_prologue; >>> + void *code_gen_epilogue; >>> void *code_gen_buffer; >>> size_t code_gen_buffer_size; >>> void *code_gen_ptr; >> >> >> -- >> Alex Bennée >> -- Alex Bennée