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Tue, 09 Mar 2021 05:09:32 -0800 (PST) MIME-Version: 1.0 References: <755161094eac5b0fc15273d609c78a459d4d07b9.1615218180.git.andreyknvl@google.com> <20210308165847.GF15644@arm.com> In-Reply-To: <20210308165847.GF15644@arm.com> From: Andrey Konovalov Date: Tue, 9 Mar 2021 14:09:21 +0100 Message-ID: Subject: Re: [PATCH v2 1/5] arm64: kasan: allow to init memory when setting tags To: Catalin Marinas Cc: Vincenzo Frascino , Alexander Potapenko , Marco Elver , Andrew Morton , Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev , Linux ARM , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: g9o95sztx4qn13imeb5xzog3od7ty36m X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3E72BE4 Received-SPF: none (google.com>: No applicable sender policy available) receiver=imf20; identity=mailfrom; envelope-from=""; helo=mail-pg1-f175.google.com; client-ip=209.85.215.175 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615295370-946529 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 Mon, Mar 8, 2021 at 5:58 PM Catalin Marinas wrote: > > On Mon, Mar 08, 2021 at 04:55:14PM +0100, Andrey Konovalov wrote: > > @@ -68,10 +69,16 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag) > > * 'asm volatile' is required to prevent the compiler to move > > * the statement outside of the loop. > > */ > > - asm volatile(__MTE_PREAMBLE "stg %0, [%0]" > > - : > > - : "r" (curr) > > - : "memory"); > > + if (init) > > + asm volatile(__MTE_PREAMBLE "stzg %0, [%0]" > > + : > > + : "r" (curr) > > + : "memory"); > > + else > > + asm volatile(__MTE_PREAMBLE "stg %0, [%0]" > > + : > > + : "r" (curr) > > + : "memory"); > > > > curr += MTE_GRANULE_SIZE; > > } while (curr != end); > > Is 'init' always a built-in constant here? If not, checking it once > outside the loop may be better (or check the code generation, maybe the > compiler is smart enough). I think it's worth moving the init check outside the loop anyway. Will do in v3. Thanks!