Message-ID: <1467f1b3-a529-50d3-9539-1056b2912d48@redhat.com>
Date:   Tue, 7 Mar 2023 11:42:53 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.8.0
Subject: Re: [PATCH v7 22/41] mm/mmap: Add shadow stack pages to memory
 accounting
Content-Language: en-US
To:     Rick Edgecombe <rick.p.edgecombe@intel.com>, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-mm@kvack.org,
        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>,
        Weijiang Yang <weijiang.yang@intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        John Allen <john.allen@amd.com>, kcc@google.com,
        eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com,
        dethoma@microsoft.com, akpm@linux-foundation.org,
        Andrew.Cooper3@citrix.com, christina.schimpe@intel.com,
        debug@rivosinc.com
Cc:     Yu-cheng Yu <yu-cheng.yu@intel.com>
References: <20230227222957.24501-1-rick.p.edgecombe@intel.com>
 <20230227222957.24501-23-rick.p.edgecombe@intel.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
In-Reply-To: <20230227222957.24501-23-rick.p.edgecombe@intel.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 27.02.23 23:29, Rick Edgecombe wrote:
> From: Yu-cheng Yu <yu-cheng.yu@intel.com>
> 
> The x86 Control-flow Enforcement Technology (CET) feature includes a new
> type of memory called shadow stack. This shadow stack memory has some
> unusual properties, which requires some core mm changes to function
> properly.
> 
> Account shadow stack pages to stack memory. Do this by adding a
> VM_SHADOW_STACK check in is_stack_mapping().
> 
> Tested-by: Pengfei Xu <pengfei.xu@intel.com>
> Tested-by: John Allen <john.allen@amd.com>
> Tested-by: Kees Cook <keescook@chromium.org>
> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> Cc: Kees Cook <keescook@chromium.org>
> 
> ---
> v7:
>   - Change is_stack_mapping() to know about VM_SHADOW_STACK so the
>     additions in vm_stat_account() can be dropped. (David Hildenbrand)
> 
> v3:
>   - Remove unneeded VM_SHADOW_STACK check in accountable_mapping()
>     (Kirill)
> 
> v2:
>   - Remove is_shadow_stack_mapping() and just change it to directly bitwise
>     and VM_SHADOW_STACK.
> 
> Yu-cheng v26:
>   - Remove redundant #ifdef CONFIG_MMU.
> 
> Yu-cheng v25:
>   - Remove #ifdef CONFIG_ARCH_HAS_SHADOW_STACK for is_shadow_stack_mapping().
> ---
>   mm/internal.h | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/internal.h b/mm/internal.h
> index 7920a8b7982e..1d13d5580f64 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -491,14 +491,14 @@ static inline bool is_exec_mapping(vm_flags_t flags)
>   }
>   
>   /*
> - * Stack area - automatically grows in one direction
> + * Stack area


Maybe "Stack area (including shadow stacks)"


Acked-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb