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[97.113.13.231]) by smtp.gmail.com with ESMTPSA id m9sm2751274pgd.23.2019.05.18.12.02.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 18 May 2019 12:02:19 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Date: Sat, 18 May 2019 12:01:57 -0700 Message-Id: <20190518190157.21255-17-richard.henderson@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190518190157.21255-1-richard.henderson@linaro.org> References: <20190518190157.21255-1-richard.henderson@linaro.org> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::442 Subject: [Qemu-devel] [PATCH 16/16] tcg/i386: Use MOVDQA for TCG_TYPE_V128 load/store X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This instruction raises #GP, aka SIGSEGV, if the effective address is not aligned to 16-bytes. We have assertions in tcg-op-gvec.c that the offset from ENV is aligned, for vector types <= V128. But the offset itself does not validate that the final pointer is aligned -- one must also remember to use the QEMU_ALIGNED() attribute on the vector member within ENV. PowerPC Altivec has vector load/store instructions that silently discard the low 4 bits of the address, making alignment mistakes difficult to discover. Aid that by making the most popular host visibly signal the error. Signed-off-by: Richard Henderson --- tcg/i386/tcg-target.inc.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/tcg/i386/tcg-target.inc.c b/tcg/i386/tcg-target.inc.c index 6ec5e60448..c0443da4af 100644 --- a/tcg/i386/tcg-target.inc.c +++ b/tcg/i386/tcg-target.inc.c @@ -1082,14 +1082,24 @@ static void tcg_out_ld(TCGContext *s, TCGType type, TCGReg ret, } /* FALLTHRU */ case TCG_TYPE_V64: + /* There is no instruction that can validate 8-byte alignment. */ tcg_debug_assert(ret >= 16); tcg_out_vex_modrm_offset(s, OPC_MOVQ_VqWq, ret, 0, arg1, arg2); break; case TCG_TYPE_V128: + /* + * The gvec infrastructure is asserts that v128 vector loads + * and stores use a 16-byte aligned offset. Validate that the + * final pointer is aligned by using an insn that will SIGSEGV. + */ tcg_debug_assert(ret >= 16); - tcg_out_vex_modrm_offset(s, OPC_MOVDQU_VxWx, ret, 0, arg1, arg2); + tcg_out_vex_modrm_offset(s, OPC_MOVDQA_VxWx, ret, 0, arg1, arg2); break; case TCG_TYPE_V256: + /* + * The gvec infrastructure only requires 16-byte alignment, + * so here we must use an unaligned load. + */ tcg_debug_assert(ret >= 16); tcg_out_vex_modrm_offset(s, OPC_MOVDQU_VxWx | P_VEXL, ret, 0, arg1, arg2); @@ -1117,14 +1127,24 @@ static void tcg_out_st(TCGContext *s, TCGType type, TCGReg arg, } /* FALLTHRU */ case TCG_TYPE_V64: + /* There is no instruction that can validate 8-byte alignment. */ tcg_debug_assert(arg >= 16); tcg_out_vex_modrm_offset(s, OPC_MOVQ_WqVq, arg, 0, arg1, arg2); break; case TCG_TYPE_V128: + /* + * The gvec infrastructure is asserts that v128 vector loads + * and stores use a 16-byte aligned offset. Validate that the + * final pointer is aligned by using an insn that will SIGSEGV. + */ tcg_debug_assert(arg >= 16); - tcg_out_vex_modrm_offset(s, OPC_MOVDQU_WxVx, arg, 0, arg1, arg2); + tcg_out_vex_modrm_offset(s, OPC_MOVDQA_WxVx, arg, 0, arg1, arg2); break; case TCG_TYPE_V256: + /* + * The gvec infrastructure only requires 16-byte alignment, + * so here we must use an unaligned store. + */ tcg_debug_assert(arg >= 16); tcg_out_vex_modrm_offset(s, OPC_MOVDQU_WxVx | P_VEXL, arg, 0, arg1, arg2); -- 2.17.1