From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54168) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZdPP5-0003p1-S6 for qemu-devel@nongnu.org; Sat, 19 Sep 2015 17:10:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZdPP4-0001EE-Ar for qemu-devel@nongnu.org; Sat, 19 Sep 2015 17:10:39 -0400 Received: from mail-pa0-x22e.google.com ([2607:f8b0:400e:c03::22e]:33481) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZdPP3-0001E4-QY for qemu-devel@nongnu.org; Sat, 19 Sep 2015 17:10:38 -0400 Received: by pacex6 with SMTP id ex6so80628890pac.0 for ; Sat, 19 Sep 2015 14:10:37 -0700 (PDT) Sender: Richard Henderson From: Richard Henderson Date: Sat, 19 Sep 2015 14:10:32 -0700 Message-Id: <1442697033-22409-2-git-send-email-rth@twiddle.net> In-Reply-To: <1442697033-22409-1-git-send-email-rth@twiddle.net> References: <1442697033-22409-1-git-send-email-rth@twiddle.net> Subject: [Qemu-devel] [PATCH 1/2] tcg: Emit prologue to the beginning of code_gen_buffer List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: sw@weilnetz.de, peter.maydell@linaro.org By putting the prologue at the end, we risk overwriting the prologue should our estimate of maximum TB size. Given the two different placements of the call to tcg_prologue_init, move the high water mark computation into tcg_prologue_init. Signed-off-by: Richard Henderson --- tcg/tcg.c | 25 +++++++++++++++++++------ translate-all.c | 29 ++++++++++------------------- 2 files changed, 29 insertions(+), 25 deletions(-) diff --git a/tcg/tcg.c b/tcg/tcg.c index 8126af9..db4032a 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -363,17 +363,30 @@ void tcg_context_init(TCGContext *s) void tcg_prologue_init(TCGContext *s) { - /* init global prologue and epilogue */ - s->code_buf = s->code_gen_prologue; - s->code_ptr = s->code_buf; + size_t prologue_size, total_size; + + /* Put the prologue at the beginning of code_gen_buffer. */ + s->code_ptr = s->code_buf = s->code_gen_prologue = s->code_gen_buffer; + + /* Generate the prologue. */ tcg_target_qemu_prologue(s); flush_icache_range((uintptr_t)s->code_buf, (uintptr_t)s->code_ptr); + /* Deduct the prologue from the buffer. */ + prologue_size = tcg_current_code_size(s); + s->code_gen_ptr = s->code_gen_buffer = s->code_buf = s->code_ptr; + + /* Compute a high-water mark, at which we voluntarily flush the + buffer and start over. */ + total_size = s->code_gen_buffer_size -= prologue_size; + s->code_gen_buffer_max_size = total_size - TCG_MAX_OP_SIZE * OPC_BUF_SIZE; + + tcg_register_jit(s->code_gen_buffer, total_size); + #ifdef DEBUG_DISAS if (qemu_loglevel_mask(CPU_LOG_TB_OUT_ASM)) { - size_t size = tcg_current_code_size(s); - qemu_log("PROLOGUE: [size=%zu]\n", size); - log_disas(s->code_buf, size); + qemu_log("PROLOGUE: [size=%zu]\n", prologue_size); + log_disas(s->code_gen_prologue, prologue_size); qemu_log("\n"); qemu_log_flush(); } diff --git a/translate-all.c b/translate-all.c index f6b8148..4c994bb 100644 --- a/translate-all.c +++ b/translate-all.c @@ -689,23 +689,16 @@ static inline void code_gen_alloc(size_t tb_size) } qemu_madvise(tcg_ctx.code_gen_buffer, tcg_ctx.code_gen_buffer_size, - QEMU_MADV_HUGEPAGE); - - /* Steal room for the prologue at the end of the buffer. This ensures - (via the MAX_CODE_GEN_BUFFER_SIZE limits above) that direct branches - from TB's to the prologue are going to be in range. It also means - that we don't need to mark (additional) portions of the data segment - as executable. */ - tcg_ctx.code_gen_prologue = tcg_ctx.code_gen_buffer + - tcg_ctx.code_gen_buffer_size - 1024; - tcg_ctx.code_gen_buffer_size -= 1024; - - tcg_ctx.code_gen_buffer_max_size = tcg_ctx.code_gen_buffer_size - - (TCG_MAX_OP_SIZE * OPC_BUF_SIZE); - tcg_ctx.code_gen_max_blocks = tcg_ctx.code_gen_buffer_size / - CODE_GEN_AVG_BLOCK_SIZE; - tcg_ctx.tb_ctx.tbs = - g_malloc(tcg_ctx.code_gen_max_blocks * sizeof(TranslationBlock)); + QEMU_MADV_HUGEPAGE); + + /* Estimate a good size for the number of TBs we can support. We + still haven't deducted the prologue from the buffer size here, + but that's minimal and won't affect the estimate much. */ + tcg_ctx.code_gen_max_blocks + = tcg_ctx.code_gen_buffer_size / CODE_GEN_AVG_BLOCK_SIZE; + tcg_ctx.tb_ctx.tbs + = g_malloc(tcg_ctx.code_gen_max_blocks * sizeof(TranslationBlock)); + qemu_mutex_init(&tcg_ctx.tb_ctx.tb_lock); } @@ -716,8 +709,6 @@ void tcg_exec_init(unsigned long tb_size) { cpu_gen_init(); code_gen_alloc(tb_size); - tcg_ctx.code_gen_ptr = tcg_ctx.code_gen_buffer; - tcg_register_jit(tcg_ctx.code_gen_buffer, tcg_ctx.code_gen_buffer_size); page_init(); #if defined(CONFIG_SOFTMMU) /* There's no guest base to take into account, so go ahead and -- 2.4.3