From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40792) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WTZ9L-0004It-HZ for qemu-devel@nongnu.org; Fri, 28 Mar 2014 11:56:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WTZ9K-0002of-F4 for qemu-devel@nongnu.org; Fri, 28 Mar 2014 11:56:55 -0400 Received: from mnementh.archaic.org.uk ([2001:8b0:1d0::1]:47189) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WTZ9K-0002o7-8v for qemu-devel@nongnu.org; Fri, 28 Mar 2014 11:56:54 -0400 From: Peter Maydell Date: Fri, 28 Mar 2014 15:29:48 +0000 Message-Id: <1396020588-2137-4-git-send-email-peter.maydell@linaro.org> In-Reply-To: <1396020588-2137-1-git-send-email-peter.maydell@linaro.org> References: <1396020588-2137-1-git-send-email-peter.maydell@linaro.org> Subject: [Qemu-devel] [RFC 3/3] tcg: Avoid undefined behaviour patching code at unaligned addresses List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Richard Henderson , patches@linaro.org 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, -- 1.9.0