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[60.242.98.186]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-71434250f5asm239836b3a.69.2024.08.21.17.30.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 21 Aug 2024 17:30:13 -0700 (PDT) Message-ID: <1cb8d332-4092-4a2d-be24-01280f91cb8c@linaro.org> Date: Thu, 22 Aug 2024 10:30:05 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 11/16] target/riscv: mmu changes for zicfiss shadow stack protection 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: <20240821215014.3859190-1-debug@rivosinc.com> <20240821215014.3859190-12-debug@rivosinc.com> Content-Language: en-US From: Richard Henderson In-Reply-To: <20240821215014.3859190-12-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::536; envelope-from=richard.henderson@linaro.org; helo=mail-pg1-x536.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 8/22/24 07:50, Deepak Gupta wrote: > zicfiss protects shadow stack using new page table encodings PTE.W=0, > PTE.R=0 and PTE.X=0. This encoding is reserved if zicfiss is not > implemented or if shadow stack are not enabled. > Loads on shadow stack memory are allowed while stores to shadow stack > memory leads to access faults. Shadow stack accesses to RO memory > leads to store page fault. > > To implement special nature of shadow stack memory where only selected > stores (shadow stack stores from sspush) have to be allowed while rest > of regular stores disallowed, new MMU TLB index is created for shadow > stack. > > Signed-off-by: Deepak Gupta > Suggested-by: Richard Henderson > --- > target/riscv/cpu_helper.c | 37 +++++++++++++++++++++++++++++++------ > target/riscv/internals.h | 3 +++ > 2 files changed, 34 insertions(+), 6 deletions(-) Reviewed-by: Richard Henderson r~