From patchwork Sun Mar 6 21:39:53 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 395 Return-Path: Delivered-To: unknown Received: from imap.gmail.com (74.125.159.109) by localhost6.localdomain6 with IMAP4-SSL; 08 Jun 2011 14:42:16 -0000 Delivered-To: patches@linaro.org Received: by 10.224.60.68 with SMTP id o4cs80652qah; Sun, 6 Mar 2011 13:39:59 -0800 (PST) Received: by 10.213.29.210 with SMTP id r18mr1985879ebc.36.1299447598522; Sun, 06 Mar 2011 13:39:58 -0800 (PST) Received: from mnementh.archaic.org.uk (mnementh.archaic.org.uk [81.2.115.146]) by mx.google.com with ESMTPS id w59si3752545eeh.63.2011.03.06.13.39.56 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 06 Mar 2011 13:39:57 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 81.2.115.146 as permitted sender) client-ip=81.2.115.146; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 81.2.115.146 as permitted sender) smtp.mail=pm215@archaic.org.uk Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.72) (envelope-from ) id 1PwLgB-0003Th-6K; Sun, 06 Mar 2011 21:39:55 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Cc: patches@linaro.org Subject: [PATCH v2 1/3] tcg: Add support for debugging leakage of temporaries Date: Sun, 6 Mar 2011 21:39:53 +0000 Message-Id: <1299447595-13344-2-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: <1299447595-13344-1-git-send-email-peter.maydell@linaro.org> References: <1299447595-13344-1-git-send-email-peter.maydell@linaro.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..3fab8d6 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() do { } while (0) +#define tcg_check_temp_count() 0 +#endif + void tcg_dump_info(FILE *f, fprintf_function cpu_fprintf); #define TCG_CT_ALIAS 0x80