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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id e16-20020a5d5950000000b0032f7d1e2c7csm5912914wri.95.2023.10.30.10.40.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Oct 2023 10:40:04 -0700 (PDT) From: Peter Maydell To: qemu-arm@nongnu.org, qemu-devel@nongnu.org Subject: [PATCH 3/3] target/arm: Make FEAT_MOPS SET* insns handle Xs == XZR correctly Date: Mon, 30 Oct 2023 17:40:00 +0000 Message-Id: <20231030174000.3792225-4-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231030174000.3792225-1-peter.maydell@linaro.org> References: <20231030174000.3792225-1-peter.maydell@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::435; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x435.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Most of the registers used by the FEAT_MOPS instructions cannot use 31 as a register field value; this is CONSTRAINED UNPREDICTABLE to NOP or UNDEF (we UNDEF). However, it is permitted for the "source value" register for the memset insns SET* to be 31, which (as usual for most data-processing insns) means it should be the zero register XZR. We forgot to handle this case, with the effect that trying to set memory to zero with a "SET* Xd, Xn, XZR" sets the memory to the value that happens to be in the low byte of SP. Handle XZR when getting the SET* data value from the register file. Signed-off-by: Peter Maydell --- target/arm/tcg/helper-a64.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c index 84f54750fc2..ce4800b8d13 100644 --- a/target/arm/tcg/helper-a64.c +++ b/target/arm/tcg/helper-a64.c @@ -1206,6 +1206,15 @@ static void check_setg_alignment(CPUARMState *env, uint64_t ptr, uint64_t size, } } +static uint64_t arm_reg_or_xzr(CPUARMState *env, int reg) +{ + /* + * Runtime equivalent of cpu_reg() -- return the CPU register value, + * for contexts when index 31 means XZR (not SP). + */ + return reg == 31 ? 0 : env->xregs[reg]; +} + /* * For the Memory Set operation, our implementation chooses * always to use "option A", where we update Xd to the final @@ -1226,7 +1235,7 @@ static void do_setp(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc, int rd = mops_destreg(syndrome); int rs = mops_srcreg(syndrome); int rn = mops_sizereg(syndrome); - uint8_t data = env->xregs[rs]; + uint8_t data = arm_reg_or_xzr(env, rs); uint32_t memidx = FIELD_EX32(mtedesc, MTEDESC, MIDX); uint64_t toaddr = env->xregs[rd]; uint64_t setsize = env->xregs[rn]; @@ -1286,7 +1295,7 @@ static void do_setm(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc, int rd = mops_destreg(syndrome); int rs = mops_srcreg(syndrome); int rn = mops_sizereg(syndrome); - uint8_t data = env->xregs[rs]; + uint8_t data = arm_reg_or_xzr(env, rs); uint64_t toaddr = env->xregs[rd] + env->xregs[rn]; uint64_t setsize = -env->xregs[rn]; uint32_t memidx = FIELD_EX32(mtedesc, MTEDESC, MIDX); @@ -1349,7 +1358,7 @@ static void do_sete(CPUARMState *env, uint32_t syndrome, uint32_t mtedesc, int rd = mops_destreg(syndrome); int rs = mops_srcreg(syndrome); int rn = mops_sizereg(syndrome); - uint8_t data = env->xregs[rs]; + uint8_t data = arm_reg_or_xzr(env, rs); uint64_t toaddr = env->xregs[rd] + env->xregs[rn]; uint64_t setsize = -env->xregs[rn]; uint32_t memidx = FIELD_EX32(mtedesc, MTEDESC, MIDX);