Received-SPF: pass (google.com: domain of linux-kernel+bounces-132168-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Date: Thu, 4 Apr 2024 14:39:20 -0700
From: Deepak Gupta <debug@rivosinc.com>
To: David Hildenbrand <david@redhat.com>
Cc: paul.walmsley@sifive.com, rick.p.edgecombe@intel.com,
	broonie@kernel.org, Szabolcs.Nagy@arm.com, kito.cheng@sifive.com,
	keescook@chromium.org, ajones@ventanamicro.com,
	conor.dooley@microchip.com, cleger@rivosinc.com,
	atishp@atishpatra.org, alex@ghiti.fr, bjorn@rivosinc.com,
	alexghiti@rivosinc.com, samuel.holland@sifive.com, conor@kernel.org,
	linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-kselftest@vger.kernel.org, corbet@lwn.net, palmer@dabbelt.com,
	aou@eecs.berkeley.edu, robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, oleg@redhat.com,
	akpm@linux-foundation.org, arnd@arndb.de, ebiederm@xmission.com,
	Liam.Howlett@oracle.com, vbabka@suse.cz, lstoakes@gmail.com,
	shuah@kernel.org, brauner@kernel.org, andy.chiu@sifive.com,
	jerry.shih@sifive.com, hankuan.chen@sifive.com,
	greentime.hu@sifive.com, evan@rivosinc.com, xiao.w.wang@intel.com,
	charlie@rivosinc.com, apatel@ventanamicro.com,
	mchitale@ventanamicro.com, dbarboza@ventanamicro.com,
	sameo@rivosinc.com, shikemeng@huaweicloud.com, willy@infradead.org,
	vincent.chen@sifive.com, guoren@kernel.org, samitolvanen@google.com,
	songshuaishuai@tinylab.org, gerg@kernel.org, heiko@sntech.de,
	bhe@redhat.com, jeeheng.sia@starfivetech.com, cyy@cyyself.name,
	maskray@google.com, ancientmodern4@gmail.com,
	mathis.salmen@matsal.de, cuiyunhui@bytedance.com,
	bgray@linux.ibm.com, mpe@ellerman.id.au, baruch@tkos.co.il,
	alx@kernel.org, catalin.marinas@arm.com, revest@chromium.org,
	josh@joshtriplett.org, shr@devkernel.io, deller@gmx.de,
	omosnace@redhat.com, ojeda@kernel.org, jhubbard@nvidia.com,
	Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH v3 09/29] mm: abstract shadow stack vma behind
 `vma_is_shadow_stack`
Message-ID: <Zg8eCPJvmk93vKQK@debug.ba.rivosinc.com>
References: <20240403234054.2020347-1-debug@rivosinc.com>
 <20240403234054.2020347-10-debug@rivosinc.com>
 <c438ea3a-24bc-470b-a2eb-6e7517bd4362@redhat.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <c438ea3a-24bc-470b-a2eb-6e7517bd4362@redhat.com>

On Thu, Apr 04, 2024 at 09:02:17PM +0200, David Hildenbrand wrote:
>On 04.04.24 01:34, Deepak Gupta wrote:
>>  		}
>>-	} else if (!(vm_flags & VM_READ)) {
>>+	} else if (!(vm_flags & VM_READ) && !vma_is_shadow_stack(vm_flags)) {
>>+	/* reads allowed if its shadow stack vma */
>>  		if (!(gup_flags & FOLL_FORCE))
>>  			return -EFAULT;
>>  		/*
>
>Unless I am missing something, this is not a simple cleanup. It should 
>go into a separate patch with a clearly documented reason for that 
>change.

I tried that here
https://lore.kernel.org/linux-mm/CAKC1njTPBqtsAOn-CWhB+-8FaZ2KWkkz-vRZr7MZq=0yLUdjcQ@mail.gmail.com/T/
But at that time, VM_SHADOW_STACK for riscv meant only VM_WRITE. So I think
there was obvious uneasiness with that part.

Now we have VM_SHADOW_STACK pretty much same for all arches and only 64bit.
I'll try it again as a separate patch.

>
>-- 
>Cheers,
>
>David / dhildenb
>