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Tue, 02 Jan 2024 10:45:46 -0800 (PST) MIME-Version: 1.0 References: <20231222235248.576482-1-debug@rivosinc.com> <20231227134514.13629032c39decdf1dddcc75@linux-foundation.org> In-Reply-To: From: Deepak Gupta Date: Tue, 2 Jan 2024 10:45:36 -0800 Message-ID: Subject: Re: [PATCH v1] mm: abstract shadow stack vma behind arch_is_shadow_stack_vma To: Mike Rapoport Cc: Andrew Morton , rick.p.edgecombe@intel.com, broonie@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: D877E10000D X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: io65jtwbtsrqkg41qoawwxrdph8chmsn X-HE-Tag: 1704221147-237538 X-HE-Meta: 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 TYedrRr6 aCDw37iUHH+YXn9Lv5gwq/9renesTZjp/twashzMOFSgKzkJpSb7FmfmtZiqLOnG1F7/XH8QQBKCapAZwwM1jd1m6x+KTLzKtC3u3YMTsV9ptxyyAGUwPXqf73O1srtWU2owX2sbXzcgmfyMc79E4KkUIg12cKU29y1oYnbBjoKvE3nYMeIMz/B2aftpR7ohDJSHheCdavBTJ3yzLux5YGXpRZDtFxMCIxF9Sl3JMFboaRN9J7VweS1WgNT7SRfhSGIPETagWUWcaNRffiKaWYbgH4emgmMxCLtxUq3/RvmipvsyOEzE0lD4V8CkL4I/nU2nSNf0PIaFwbwMWLIBcQ8lmd+bAIe4tBaKd3mRaTV6O26yduqlO+/6d6xtb2pNjg+Bm/ufBi4FxxuFwoYsUATM4j9O4GD0z5WBoM6tXmcfoCfF6YcwMwJBe8NFC9hsmtM7OCEVzSVuGtqg1pI9sZw2eyPrFWj5VOZnTcsXr4RcBanY= 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 Tue, Jan 2, 2024 at 5:57=E2=80=AFAM Mike Rapoport wrot= e: > > On Wed, Dec 27, 2023 at 01:45:14PM -0800, Andrew Morton wrote: > > On Fri, 22 Dec 2023 15:51:04 -0800 Deepak Gupta wr= ote: > > > > > x86 has used VM_SHADOW_STACK (alias to VM_HIGH_ARCH_5) to encode shad= ow > > > 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 ma= y > > > encode this information differently in VMAs. > > > > Is such a patch in the pipeline? Otherwise we're making a change that > > serves no purpose. > > > > > This patch changes checks of VM_SHADOW_STACK flag in generic code to = call > > > to a function `arch_is_shadow_stack_vma` which will return true if ar= ch > > > supports shadow stack and vma is shadow stack else stub returns false= . > > > > > > ... > > > > > > --- a/include/linux/mm.h > > > +++ b/include/linux/mm.h > > > @@ -352,8 +352,21 @@ 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_vma(vm_flags_t vm_flags) > > > +{ > > > + return (vm_flags & VM_SHADOW_STACK) ? true : false; > > > +} > > > > The naming seems a little wrong. I'd expect it to take a vma* arg. > > Maybe just drop the "_vma"? > > I'd suggest to use vma_is_shadow_stack() to make it inline with other > vma_is_*() tests. Noted. Thanks > > -- > Sincerely yours, > Mike.