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Wed, 24 Jan 2024 22:29:13 -0800 (PST) Received: from debug.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id t19-20020a056a00139300b006dd870b51b8sm3201139pfg.126.2024.01.24.22.29.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jan 2024 22:29:12 -0800 (PST) From: debug@rivosinc.com To: rick.p.edgecombe@intel.com, broonie@kernel.org, Szabolcs.Nagy@arm.com, kito.cheng@sifive.com, keescook@chromium.org, ajones@ventanamicro.com, paul.walmsley@sifive.com, palmer@dabbelt.com, conor.dooley@microchip.com, cleger@rivosinc.com, atishp@atishpatra.org, alex@ghiti.fr, bjorn@rivosinc.com, alexghiti@rivosinc.com Cc: corbet@lwn.net, aou@eecs.berkeley.edu, oleg@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, ebiederm@xmission.com, shuah@kernel.org, brauner@kernel.org, debug@rivosinc.com, guoren@kernel.org, samitolvanen@google.com, evan@rivosinc.com, xiao.w.wang@intel.com, apatel@ventanamicro.com, mchitale@ventanamicro.com, waylingii@gmail.com, greentime.hu@sifive.com, heiko@sntech.de, jszhang@kernel.org, shikemeng@huaweicloud.com, david@redhat.com, charlie@rivosinc.com, panqinglin2020@iscas.ac.cn, willy@infradead.org, vincent.chen@sifive.com, andy.chiu@sifive.com, gerg@kernel.org, jeeheng.sia@starfivetech.com, mason.huo@starfivetech.com, ancientmodern4@gmail.com, mathis.salmen@matsal.de, cuiyunhui@bytedance.com, bhe@redhat.com, chenjiahao16@huawei.com, ruscur@russell.cc, bgray@linux.ibm.com, alx@kernel.org, baruch@tkos.co.il, zhangqing@loongson.cn, catalin.marinas@arm.com, revest@chromium.org, josh@joshtriplett.org, joey.gouly@arm.com, shr@devkernel.io, omosnace@redhat.com, ojeda@kernel.org, jhubbard@nvidia.com, linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [RFC PATCH v1 09/28] mm: abstract shadow stack vma behind `arch_is_shadow_stack` Date: Wed, 24 Jan 2024 22:21:34 -0800 Message-ID: <20240125062739.1339782-10-debug@rivosinc.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240125062739.1339782-1-debug@rivosinc.com> References: <20240125062739.1339782-1-debug@rivosinc.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: E7F551C000D X-Stat-Signature: fjdnr8ye6zz6k1b8gy93a3xqczrexei6 X-HE-Tag: 1706164153-581664 X-HE-Meta: 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 W+xuQcwB 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Deepak Gupta x86 has used VM_SHADOW_STACK (alias to VM_HIGH_ARCH_5) to encode shadow stack VMA. VM_SHADOW_STACK is thus not possible on 32bit. Some arches may need a way to encode shadow stack on 32bit and 64bit both and they may encode this information differently in VMAs. This patch changes checks of VM_SHADOW_STACK flag in generic code to call to a function `arch_is_shadow_stack` which will return true if arch supports shadow stack and vma is shadow stack else stub returns false. There was a suggestion to name it as `vma_is_shadow_stack`. I preferred to keep `arch` prefix in there because it's each arch specific. Signed-off-by: Deepak Gupta --- include/linux/mm.h | 18 +++++++++++++++++- mm/gup.c | 5 +++-- mm/internal.h | 2 +- 3 files changed, 21 insertions(+), 4 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index dfe0e8118669..15c70fc677a3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -352,6 +352,10 @@ extern unsigned int kobjsize(const void *objp); * for more details on the guard size. */ # define VM_SHADOW_STACK VM_HIGH_ARCH_5 +static inline bool arch_is_shadow_stack(vm_flags_t vm_flags) +{ + return (vm_flags & VM_SHADOW_STACK); +} #endif #ifdef CONFIG_RISCV_USER_CFI @@ -362,10 +366,22 @@ extern unsigned int kobjsize(const void *objp); * with VM_SHARED. */ #define VM_SHADOW_STACK VM_WRITE + +static inline bool arch_is_shadow_stack(vm_flags_t vm_flags) +{ + return ((vm_flags & (VM_WRITE | VM_READ | VM_EXEC)) == VM_WRITE); +} + #endif #ifndef VM_SHADOW_STACK # define VM_SHADOW_STACK VM_NONE + +static inline bool arch_is_shadow_stack(vm_flags_t vm_flags) +{ + return false; +} + #endif #if defined(CONFIG_X86) @@ -3464,7 +3480,7 @@ static inline unsigned long stack_guard_start_gap(struct vm_area_struct *vma) return stack_guard_gap; /* See reasoning around the VM_SHADOW_STACK definition */ - if (vma->vm_flags & VM_SHADOW_STACK) + if (vma->vm_flags && arch_is_shadow_stack(vma->vm_flags)) return PAGE_SIZE; return 0; diff --git a/mm/gup.c b/mm/gup.c index 231711efa390..45798782ed2c 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1051,7 +1051,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) !writable_file_mapping_allowed(vma, gup_flags)) return -EFAULT; - if (!(vm_flags & VM_WRITE) || (vm_flags & VM_SHADOW_STACK)) { + if (!(vm_flags & VM_WRITE) || arch_is_shadow_stack(vm_flags)) { if (!(gup_flags & FOLL_FORCE)) return -EFAULT; /* hugetlb does not support FOLL_FORCE|FOLL_WRITE. */ @@ -1069,7 +1069,8 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags) if (!is_cow_mapping(vm_flags)) return -EFAULT; } - } else if (!(vm_flags & VM_READ)) { + } else if (!(vm_flags & VM_READ) && !arch_is_shadow_stack(vm_flags)) { + /* reads allowed if its shadow stack vma */ if (!(gup_flags & FOLL_FORCE)) return -EFAULT; /* diff --git a/mm/internal.h b/mm/internal.h index b61034bd50f5..0abf00c93fe1 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -572,7 +572,7 @@ static inline bool is_exec_mapping(vm_flags_t flags) */ static inline bool is_stack_mapping(vm_flags_t flags) { - return ((flags & VM_STACK) == VM_STACK) || (flags & VM_SHADOW_STACK); + return ((flags & VM_STACK) == VM_STACK) || arch_is_shadow_stack(flags); } /*