From patchwork Wed Feb 23 15:19:34 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 84189 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 07272B70DA for ; Thu, 24 Feb 2011 02:56:52 +1100 (EST) Received: from localhost ([127.0.0.1]:60528 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PsGYJ-000091-Fq for incoming@patchwork.ozlabs.org; Wed, 23 Feb 2011 10:22:55 -0500 Received: from [140.186.70.92] (port=42043 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PsGVK-0006tt-9T for qemu-devel@nongnu.org; Wed, 23 Feb 2011 10:19:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PsGVI-0006qf-CJ for qemu-devel@nongnu.org; Wed, 23 Feb 2011 10:19:50 -0500 Received: from mnementh.archaic.org.uk ([81.2.115.146]:40780) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PsGVH-0006o2-Tx for qemu-devel@nongnu.org; Wed, 23 Feb 2011 10:19:48 -0500 Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.72) (envelope-from ) id 1PsGV6-0005L2-55; Wed, 23 Feb 2011 15:19:36 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Date: Wed, 23 Feb 2011 15:19:34 +0000 Message-Id: <1298474376-20495-2-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: <1298474376-20495-1-git-send-email-peter.maydell@linaro.org> References: <1298474376-20495-1-git-send-email-peter.maydell@linaro.org> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-Received-From: 81.2.115.146 Cc: patches@linaro.org Subject: [Qemu-devel] [PATCH 1/3] tcg: Add support for debugging leakage of temporaries X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Add support (if CONFIG_DEBUG_TCG is defined) for debugging leakage of temporary variables. Generally any temporaries created by a target while it is translating an instruction should be freed by the end of that instruction; otherwise carefully crafted guest code could cause TCG to run out of temporaries and assert. By calling tcg_check_temp_count() after each instruction we can check that we are not leaking temporaries in this way. Signed-off-by: Peter Maydell --- tcg/tcg.c | 32 ++++++++++++++++++++++++++++++++ tcg/tcg.h | 17 +++++++++++++++++ 2 files changed, 49 insertions(+), 0 deletions(-) diff --git a/tcg/tcg.c b/tcg/tcg.c index 5dd6a2c..8748c05 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -450,6 +450,10 @@ static inline int tcg_temp_new_internal(TCGType type, int temp_local) s->nb_temps++; } } + +#if defined(CONFIG_DEBUG_TCG) + s->temps_in_use++; +#endif return idx; } @@ -475,6 +479,13 @@ static inline void tcg_temp_free_internal(int idx) TCGTemp *ts; int k; +#if defined(CONFIG_DEBUG_TCG) + s->temps_in_use--; + if (s->temps_in_use < 0) { + fprintf(stderr, "More temporaries freed than allocated!\n"); + } +#endif + assert(idx >= s->nb_globals && idx < s->nb_temps); ts = &s->temps[idx]; assert(ts->temp_allocated != 0); @@ -528,6 +539,27 @@ TCGv_i64 tcg_const_local_i64(int64_t val) return t0; } +#if defined(CONFIG_DEBUG_TCG) +void tcg_clear_temp_count(void) +{ + TCGContext *s = &tcg_ctx; + s->temps_in_use = 0; +} + +int tcg_check_temp_count(void) +{ + TCGContext *s = &tcg_ctx; + if (s->temps_in_use) { + /* Clear the count so that we don't give another + * warning immediately next time around. + */ + s->temps_in_use = 0; + return 1; + } + return 0; +} +#endif + void tcg_register_helper(void *func, const char *name) { TCGContext *s = &tcg_ctx; diff --git a/tcg/tcg.h b/tcg/tcg.h index e1afde2..5538db9 100644 --- a/tcg/tcg.h +++ b/tcg/tcg.h @@ -323,6 +323,10 @@ struct TCGContext { int64_t restore_count; int64_t restore_time; #endif + +#ifdef CONFIG_DEBUG_TCG + int temps_in_use; +#endif }; extern TCGContext tcg_ctx; @@ -392,6 +396,19 @@ static inline TCGv_i64 tcg_temp_local_new_i64(void) void tcg_temp_free_i64(TCGv_i64 arg); char *tcg_get_arg_str_i64(TCGContext *s, char *buf, int buf_size, TCGv_i64 arg); +#if defined(CONFIG_DEBUG_TCG) +/* If you call tcg_clear_temp_count() at the start of a section of + * code which is not supposed to leak any TCG temporaries, then + * calling tcg_check_temp_count() at the end of the section will + * return 1 if the section did in fact leak a temporary. + */ +void tcg_clear_temp_count(void); +int tcg_check_temp_count(void); +#else +#define tcg_clear_temp_count() +#define tcg_check_temp_count() 0 +#endif + void tcg_dump_info(FILE *f, fprintf_function cpu_fprintf); #define TCG_CT_ALIAS 0x80