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Wed, 10 Mar 2021 04:52:15 -0800 (PST) MIME-Version: 1.0 References: <20210309214301.678739-1-keescook@chromium.org> <20210309214301.678739-4-keescook@chromium.org> In-Reply-To: <20210309214301.678739-4-keescook@chromium.org> From: Andrey Konovalov Date: Wed, 10 Mar 2021 13:52:04 +0100 Message-ID: Subject: Re: [PATCH v5 3/7] init_on_alloc: Unpessimize default-on builds To: Kees Cook , Alexander Potapenko Cc: Thomas Gleixner , Elena Reshetova , "the arch/x86 maintainers" , Andy Lutomirski , Peter Zijlstra , Catalin Marinas , Will Deacon , Mark Rutland , Alexander Popov , Ard Biesheuvel , Jann Horn , kernel-hardening@lists.openwall.com, linux-hardening@vger.kernel.org, Linux ARM , Linux Memory Management List , LKML , Vlastimil Babka , David Hildenbrand , Mike Rapoport , Andrew Morton , Jonathan Corbet , Randy Dunlap Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: AA10FDA X-Stat-Signature: cdn1wjbx5th7t46jkm87ptgajzr8cg5t Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail-pf1-f170.google.com; client-ip=209.85.210.170 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615380733-618883 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: On Tue, Mar 9, 2021 at 10:43 PM Kees Cook wrote: > > Right now, the state of CONFIG_INIT_ON_ALLOC_DEFAULT_ON (and > ...ON_FREE...) did not change the assembly ordering of the static branch > tests. Use the new jump_label macro to check CONFIG settings to default > to the "expected" state, unpessimizes the resulting assembly code. > > Reviewed-by: Alexander Potapenko > Link: https://lore.kernel.org/lkml/CAG_fn=X0DVwqLaHJTO6Jw7TGcMSm77GKHinrd0m_6y0SzWOrFA@mail.gmail.com/ > Signed-off-by: Kees Cook > --- > include/linux/mm.h | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index bf341a9bfe46..2ccd856ac0d1 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2874,7 +2874,8 @@ static inline void kernel_unpoison_pages(struct page *page, int numpages) { } > DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc); > static inline bool want_init_on_alloc(gfp_t flags) > { > - if (static_branch_unlikely(&init_on_alloc)) > + if (static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, > + &init_on_alloc)) > return true; > return flags & __GFP_ZERO; > } > @@ -2882,7 +2883,8 @@ static inline bool want_init_on_alloc(gfp_t flags) > DECLARE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_FREE_DEFAULT_ON, init_on_free); > static inline bool want_init_on_free(void) > { > - return static_branch_unlikely(&init_on_free); > + return static_branch_maybe(CONFIG_INIT_ON_FREE_DEFAULT_ON, > + &init_on_free); > } > > extern bool _debug_pagealloc_enabled_early; Should we also update slab_want_init_on_alloc() and slab_want_init_on_free()?