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[2001:8b0:1d0::1]) by mx.google.com with ESMTPS id qj1si3885975pbb.299.2014.03.28.08.29.51 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Fri, 28 Mar 2014 08:29:51 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 2001:8b0:1d0::1 as permitted sender) client-ip=2001:8b0:1d0::1; Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.80) (envelope-from ) id 1WTYj6-0000Z7-TO; Fri, 28 Mar 2014 15:29:48 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Cc: patches@linaro.org, Richard Henderson Subject: [RFC 3/3] tcg: Avoid undefined behaviour patching code at unaligned addresses Date: Fri, 28 Mar 2014 15:29:48 +0000 Message-Id: <1396020588-2137-4-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1396020588-2137-1-git-send-email-peter.maydell@linaro.org> References: <1396020588-2137-1-git-send-email-peter.maydell@linaro.org> X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: peter.maydell@linaro.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 209.85.220.178 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Precedence: list Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org List-ID: X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , To avoid C undefined behaviour when patching generated code, provide wrappers tcg_patch8/16/32/64 which use the usual memcpy trick, and use them in the i386 backend. Signed-off-by: Peter Maydell --- tcg/i386/tcg-target.c | 12 ++++++------ tcg/tcg.c | 20 ++++++++++++++++++++ 2 files changed, 26 insertions(+), 6 deletions(-) diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c index f832282..a0f9dff 100644 --- a/tcg/i386/tcg-target.c +++ b/tcg/i386/tcg-target.c @@ -151,14 +151,14 @@ static void patch_reloc(uint8_t *code_ptr, int type, if (value != (int32_t)value) { tcg_abort(); } - *(uint32_t *)code_ptr = value; + tcg_patch32(code_ptr, value); break; case R_386_PC8: value -= (uintptr_t)code_ptr; if (value != (int8_t)value) { tcg_abort(); } - *(uint8_t *)code_ptr = value; + tcg_patch8(code_ptr, value); break; default: tcg_abort(); @@ -1276,9 +1276,9 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *l) uint8_t **label_ptr = &l->label_ptr[0]; /* resolve label address */ - *(uint32_t *)label_ptr[0] = (uint32_t)(s->code_ptr - label_ptr[0] - 4); + tcg_patch32(label_ptr[0], s->code_ptr - label_ptr[0] - 4); if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) { - *(uint32_t *)label_ptr[1] = (uint32_t)(s->code_ptr - label_ptr[1] - 4); + tcg_patch32(label_ptr[1], s->code_ptr - label_ptr[1] - 4); } if (TCG_TARGET_REG_BITS == 32) { @@ -1360,9 +1360,9 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *l) TCGReg retaddr; /* resolve label address */ - *(uint32_t *)label_ptr[0] = (uint32_t)(s->code_ptr - label_ptr[0] - 4); + tcg_patch32(label_ptr[0], s->code_ptr - label_ptr[0] - 4); if (TARGET_LONG_BITS > TCG_TARGET_REG_BITS) { - *(uint32_t *)label_ptr[1] = (uint32_t)(s->code_ptr - label_ptr[1] - 4); + tcg_patch32(label_ptr[1], s->code_ptr - label_ptr[1] - 4); } if (TCG_TARGET_REG_BITS == 32) { diff --git a/tcg/tcg.c b/tcg/tcg.c index 60f06c5..727112d 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -143,6 +143,26 @@ static inline void tcg_out64(TCGContext *s, uint64_t v) s->code_ptr = p + 8; } +static inline void tcg_patch8(uint8_t *p, uint8_t v) +{ + memcpy(p, &v, sizeof(v)); +} + +static inline void tcg_patch16(uint8_t *p, uint16_t v) +{ + memcpy(p, &v, sizeof(v)); +} + +static inline void tcg_patch32(uint8_t *p, uint32_t v) +{ + memcpy(p, &v, sizeof(v)); +} + +static inline void tcg_patch64(uint8_t *p, uint64_t v) +{ + memcpy(p, &v, sizeof(v)); +} + /* label relocation processing */ static void tcg_out_reloc(TCGContext *s, uint8_t *code_ptr, int type,