From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0EA9173 for ; Tue, 14 Dec 2021 11:36:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9E65C34605; Tue, 14 Dec 2021 11:36:27 +0000 (UTC) Date: Tue, 14 Dec 2021 11:36:24 +0000 From: Catalin Marinas To: Ard Biesheuvel Cc: Nathan Chancellor , Arnd Bergmann , Linux ARM , Will Deacon , Mark Rutland , llvm@lists.linux.dev Subject: Re: [PATCH v2] arm64/xor: use EOR3 instructions when available Message-ID: References: <20211213140252.2856053-1-ardb@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Dec 14, 2021 at 12:05:34PM +0100, Ard Biesheuvel wrote: > On Tue, 14 Dec 2021 at 09:19, Ard Biesheuvel wrote: > > > > + Arnd > > > > On Tue, 14 Dec 2021 at 03:37, Nathan Chancellor wrote: > > > > > > Hi Ard, > > > > > > On Mon, Dec 13, 2021 at 03:02:52PM +0100, Ard Biesheuvel wrote: > > > > Use the EOR3 instruction to implement xor_blocks() if the instruction is > > > > available, which is the case if the CPU implements the SHA-3 extension. > > > > This is about 20% faster on Apple M1 when using the 5-way version. > > > > > > > > Signed-off-by: Ard Biesheuvel > > > > > > Our CI reported that this patch as commit ce9ba49a2460 ("arm64/xor: use > > > EOR3 instructions when available") in the arm64 tree breaks > > > allyesconfig: > > > > > > https://github.com/ClangBuiltLinux/continuous-integration2/runs/4514540083?check_suite_focus=true > > > > > > I also see this when building with GCC 11.2.0: > > > > > > WARNING: modpost: EXPORT symbol "xor_block_inner_neon" [vmlinux] version ... > > > Is "xor_block_inner_neon" prototyped in ? > > > aarch64-linux-gnu-ld: arch/arm64/lib/xor-neon.o: relocation R_AARCH64_ABS32 against `__crc_xor_block_inner_neon' can not be used when making a shared object > > > > I suspect this is another genksyms crash, preventing the > > __crc_xor_block_inner_neon symbol from ever being emitted. > > > > This is a recurring annoyance and I am not sure how to address this > > properly. Arnd might have some thoughts on the matter as well. > > I managed to reproduce this: it's not a crash but definitely a bug in > genksyms, as it simply fails to produce the output containing the > assignment of __crc_xor_block_inner_neon. > > Moving the definition of xor_block_inner_neon as below works around the issue. > > Catalin: would you like me to spin a v3? Or do your prefer to just > fold this into the existing one? I'll fold it in. Thanks. -- Catalin