From patchwork Thu Jan 25 06:21:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Deepak Gupta X-Patchwork-Id: 13530045 Received: from mail-oi1-f178.google.com (mail-oi1-f178.google.com [209.85.167.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF09717551 for ; Thu, 25 Jan 2024 06:29:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.178 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706164156; cv=none; b=F5ydxyX4V7zsA+ojXdYPspgqEYvGAZUY6AIqCkdrOX19rpOONO0VmmuTJcuywjxDTz19o4dDKZKuuUrPCrXparWmXb/AHIWQEcLSJhkL6CYuUic5FaAMfFYMTSkgPE8cpsp2waHHr67QcRrHRA/TWnQrgIYYM4v3B5pHx96S+VM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706164156; c=relaxed/simple; bh=LvZLfFtPohYNVrhlo8kXoghOnc8le0NrJCzRCX+N24Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SzneapMACV2YySW0XCJnSzKG8nbZl5a002lSpusWRXOwE1WNTdoRrAfGVVaaeDEazMdlM5DsLmiEuqbaHT+PRFhBgBcafahyLlgGAOYZdg0BLcWkNOUzkeN3XHzO7xK1t1bVDDOe1iYVSjuZaTjzi7SfIzx2SPtIfyoQhfdFQ2k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=rivosinc.com; spf=pass smtp.mailfrom=rivosinc.com; dkim=pass (2048-bit key) header.d=rivosinc-com.20230601.gappssmtp.com header.i=@rivosinc-com.20230601.gappssmtp.com header.b=UsrOrape; arc=none smtp.client-ip=209.85.167.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=rivosinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=rivosinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=rivosinc-com.20230601.gappssmtp.com header.i=@rivosinc-com.20230601.gappssmtp.com header.b="UsrOrape" Received: by mail-oi1-f178.google.com with SMTP id 5614622812f47-3bdbf401bd3so2359221b6e.0 for ; Wed, 24 Jan 2024 22:29:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1706164153; x=1706768953; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=T6jrxQTzk5v6yDwRhrNBVQOQ/gk4SzlXhOza5budY2g=; b=UsrOrapetzWJq063MRcQ0mXV0VrorxfFNWACj28CEwZMAbZE+VfaggVsMh80z6EbTm CmH7G6EvjiUHmKEUUgBlZ47/r3QGi/KfZUwCbp/xN4UXdhS06fnq1XnyxQ9Goyz8V6rg DrxLB1SmQ9kZMHMDgG+XZPr5sQ13kN+MmGOCL8EndylfyshIQdiSncQDi5xUkrOOy6tS CYSyWjz0c/8Ehq0ZmPRgsIP8YbEYhu3rbW0Gr8fFDfBr3LKa7CRWggc0uhu3lITacmf4 EZ5qCAclpQGrHjPC9syyIc2hQGFGsOzLKmtRN16pKgawKH1Il+weI9qf3HPsZmUf7+Lj q/aQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706164153; x=1706768953; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=T6jrxQTzk5v6yDwRhrNBVQOQ/gk4SzlXhOza5budY2g=; b=F/6W1SQfR0JmNThXK5/jJOOWkp0H6FMkaKI4Bk3GxUTwLt8hGYvhLRy5aX2A6My1pp vHpuxPq90s4+evKtQxx+soj294Vt2uTS0UD6dR8G+WZ9JbQLeu/s184Q0eXxZsLtjOJO sOZRW4eCI+15x4UPW0YlacvTRw5cEJaduEWsGKwflM3EXaJEtx/+mOzKOAsIL92EJPka JL7nSIH1RcL2Hk8gzP9h0e6nrRtJhpcd+C5EW/R+cpAN6niGOip+0kBdVDbt086qmaBK zZw9dWJlMPusijIoAqfWDDKrNjAvFwmGGKdJ+oVg+EyNjDMha0iEWFRuofM6WHkox5sE bsFg== X-Gm-Message-State: AOJu0YzFU7fcQFOPuJIzdbzIdlg/n8McpAAGwmG9g8+TXLBzBlYyVpCg a49dB9//o5fIyMGrFrQd/FuCqKdGO5XxA5QGHAjGabBeVKP403R+QDdHHTOqRSA= X-Google-Smtp-Source: AGHT+IE9c8MEdVglNRelh8ZMz256rscxIEtK+0cPNlGjBMQYH53mysOGbUh9rlxjO/qpIC+YDleATw== X-Received: by 2002:a54:478d:0:b0:3bd:be66:c0c7 with SMTP id o13-20020a54478d000000b003bdbe66c0c7mr441553oic.98.1706164153039; 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> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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); } /*