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Date:   Tue, 25 May 2021 12:00:12 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc:     x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
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        linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Lutomirski <luto@kernel.org>,
        Balbir Singh <bsingharora@gmail.com>,
        Borislav Petkov <bp@alien8.de>,
        Cyrill Gorcunov <gorcunov@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Eugene Syromiatnikov <esyr@redhat.com>,
        Florian Weimer <fweimer@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Nadav Amit <nadav.amit@gmail.com>,
        Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
        Dave Martin <Dave.Martin@arm.com>,
        Weijiang Yang <weijiang.yang@intel.com>,
        Pengfei Xu <pengfei.xu@intel.com>,
        Haitao Huang <haitao.huang@intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Will Deacon <will@kernel.org>
Subject: Re: [PATCH v27 30/31] mm: Update arch_validate_flags() to test vma
 anonymous
Message-ID: <20210525110011.GD15564@arm.com>
References: <20210521221211.29077-1-yu-cheng.yu@intel.com>
 <20210521221211.29077-31-yu-cheng.yu@intel.com>
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On Fri, May 21, 2021 at 03:12:10PM -0700, Yu-cheng Yu wrote:
> When newer VM flags are being created, such as VM_MTE, it becomes necessary
> for mmap/mprotect to verify if certain flags are being applied to an
> anonymous VMA.
> 
> To solve this, one approach is adding a VM flag to track that MAP_ANONYMOUS
> is specified [1], and then using the flag in arch_validate_flags().
> 
> Another approach is passing the VMA to arch_validate_flags(), and check
> vma_is_anonymous().
> 
> To prepare the introduction of PROT_SHADOW_STACK, which creates a shadow
> stack mapping and can be applied only to an anonymous VMA, update
> arch_validate_flags() to pass in the VMA.
> 
> [1] commit 9f3419315f3c ("arm64: mte: Add PROT_MTE support to mmap() and mprotect()"),
> 
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Will Deacon <will@kernel.org>

For arm64:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>