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[2003:cb:c70a:7600:9a0b:ceef:a304:b9a7]) by smtp.gmail.com with ESMTPSA id o14-20020a05600c4fce00b0040d30af488asm1658538wmq.40.2024.01.25.00.18.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Jan 2024 00:18:09 -0800 (PST) Message-ID: <2f34f6aa-99fa-4545-b706-a1d50864f9e9@redhat.com> Date: Thu, 25 Jan 2024 09:18:07 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1 09/28] mm: abstract shadow stack vma behind `arch_is_shadow_stack` To: debug@rivosinc.com, 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, 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, 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 References: <20240125062739.1339782-1-debug@rivosinc.com> <20240125062739.1339782-10-debug@rivosinc.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 26177140017 X-Stat-Signature: 1hrrujja49s7hybusytrhdppscrk8dzk X-HE-Tag: 1706170693-508797 X-HE-Meta: U2FsdGVkX1/45ZwK3TWwHEBsaJaFU/HNVmVESxhJspG/4dotA7/dd4CvnKs8GUVX3cUQSnwNpKOxpnFb4eJSSLuRa+45ZLom2beDcUDvyt/LHm+Cs5k8xQGyHMYbGwZ2FYwVWFr2j+Le7b5yP0YxD+ldJshyB0+WggYys6mThhUG2Bsyc537yLyBLzNLRL+tGcmM+uNKiHOHPPI/qEPzGG98RQtYDMxWAG5WcqacC5cbXFYbL5X65H3fcZ0OdTlPWIqWANeMWeAscmPzrZZ2Iuh3TDgVCkLYuwp256+0iQ1n7wBBa8AcDvQVSKGtUQ4PvWrCF6umPZweaUMyTfHyGIpmtg9Q5fjWTvJlY/5kWwpcWCH5iUDD6AH3ZRnsS61l56xqSN/dqhxoADtou+i+530QuRNJbzf85wHgY2sChaI6V7YFAU8tFwiRk4iacdpLHBmLvHIZh+gMszM8z26D0E+60NceO0zd0aKellA0E6VRWnv3sqYWNhAKd+5ZfOEqsl0R7O2RFSnv8hiRx0rBq/FMpvR0ffnfWiTvw78b21OeWBo5BG8i/zknfnY9JLLEwvMASZz0icsWRSaplRhZvfrJwgcEZmubx0MgDPPCcXbTJwjQ4BDGdE37XOSgdPNpl/j9jIokxquPnVVixaWTzvZIafSVizA1JOvx/8i9aa6OUBbMVd+EjqZbCmOiQp76WKFducyWzrvj7bqWslrdHNHTHNhgFLWzlIPqgPzZ2xZ8Y/DabCx4aPyU77iYfhDAPXBCExtysWaQaPyRbHI//whUJDb8UGF7bqtky6RMv6B3Hlvyr3vo1a3XXCB45AWsAh//LCoqG6oQyvZgyrDwIk6XXo43qN4Tw3N7aGgfsbeEu8VlTwK0mW2vSzk+GGE3z6TUR3ZwW+1K6lYXXxLK3PuxaeGhWYHtWOMq43kVsYSca7yVkpp4gcWvcU3GDukaWqzPnMzBnYEDisZ/92B SD0B2E03 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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: On 25.01.24 07:21, debug@rivosinc.com wrote: > 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); > +} > + Please no such hacks just to work around the 32bit vmflags limitation. -- Cheers, David / dhildenb