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([2001:8004:5100:1c02:35b7:18d3:3fc5:9f02]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2d8446f3bd4sm5229210a91.53.2024.08.29.22.20.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Aug 2024 22:20:14 -0700 (PDT) Message-ID: Date: Fri, 30 Aug 2024 15:20:04 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 11/20] target/riscv: introduce ssp and enabling controls for zicfiss To: Deepak Gupta , qemu-riscv@nongnu.org, qemu-devel@nongnu.org Cc: palmer@dabbelt.com, Alistair.Francis@wdc.com, bmeng.cn@gmail.com, liwei1518@gmail.com, dbarboza@ventanamicro.com, zhiwei_liu@linux.alibaba.com, jim.shu@sifive.com, andy.chiu@sifive.com, kito.cheng@sifive.com References: <20240829233425.1005029-1-debug@rivosinc.com> <20240829233425.1005029-12-debug@rivosinc.com> Content-Language: en-US From: Richard Henderson In-Reply-To: <20240829233425.1005029-12-debug@rivosinc.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2607:f8b0:4864:20::433; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x433.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, T_SCC_BODY_TEXT_LINE=-0.01 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 8/30/24 09:34, Deepak Gupta wrote: > +bool cpu_get_bcfien(CPURISCVState *env) It occurs to me that a better name would be "cpu_get_sspen". The backward cfi is merely a consequence of the shadow stack. > +{ > + /* no cfi extension, return false */ > + if (!env_archcpu(env)->cfg.ext_zicfiss) { > + return false; > + } > + > + switch (env->priv) { > + case PRV_U: > + if (riscv_has_ext(env, RVS)) { > + return env->senvcfg & SENVCFG_SSE; > + } > + return env->menvcfg & MENVCFG_SSE; > +#ifndef CONFIG_USER_ONLY > + case PRV_S: > + if (env->virt_enabled) { > + return env->henvcfg & HENVCFG_SSE; > + } > + return env->menvcfg & MENVCFG_SSE; > + case PRV_M: /* M-mode shadow stack is always on if hart implements */ > + return true; From the manual: Activating Zicfiss in M-mode is currently not supported. Additionally, when S-mode is not implemented, activation in U-mode is also not supported. So two of the cases above are wrong. r~