From patchwork Tue Jul 5 07:43:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ammar Faizi X-Patchwork-Id: 12906039 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD4B6C43334 for ; Tue, 5 Jul 2022 07:45:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229917AbiGEHpV (ORCPT ); Tue, 5 Jul 2022 03:45:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229512AbiGEHpU (ORCPT ); Tue, 5 Jul 2022 03:45:20 -0400 Received: from gnuweeb.org (gnuweeb.org [51.81.211.47]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 198B012D06 for ; Tue, 5 Jul 2022 00:45:20 -0700 (PDT) Received: from integral2.. (unknown [36.81.65.188]) by gnuweeb.org (Postfix) with ESMTPSA id 2C546804D1; Tue, 5 Jul 2022 07:45:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1657007119; bh=aWmyb7aWPqdN5BDugTVPn2wOOXVGY+QNYH3gJSW9y14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fIv2dLbIi1FpcdQMxp0hBbv2adurvYhTSBOdU1V8xaBIvhnoCGEywF7T4blNsYoW7 pa5GLoc4fGsSjMIJvYutKbIfzkfinwQs4n48ygOqNQrhKjzVP87tg7wdvTgOPCRXjR qbcwHf67VvJposTWBMc0gQw4/YiHmGwqBU7kfPThsRL9netbvIZFizGxvC0A2mB2X2 hi+eoocg2A4OvI+0Wz/nV9OPRU/y1R8BURWEnuEPAzwtqluD3wow9Mbk/Aqlx1uAlG zds1H7Y/Ut35gTFZHC6eTAKm4n7bc4eCko3X7+Iclw+hruCxqL2JGO+lgkoJJ83PKY H1efs3YPqWmbA== From: Ammar Faizi To: Jens Axboe Cc: Ammar Faizi , Alviro Iskandar Setiawan , Fernanda Ma'rouf , Hao Xu , Pavel Begunkov , io-uring Mailing List , GNU/Weeb Mailing List Subject: [PATCH liburing v5 05/10] arch/aarch64: lib: Add `get_page_size()` function Date: Tue, 5 Jul 2022 14:43:55 +0700 Message-Id: <20220705073920.367794-6-ammar.faizi@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220705073920.367794-1-ammar.faizi@intel.com> References: <20220705073920.367794-1-ammar.faizi@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org From: Ammar Faizi A prep patch to add aarch64 nolibc support. aarch64 supports three values of page size: 4K, 16K, and 64K which are selected at kernel compilation time. Therefore, we can't hard code the page size for this arch. Utilize open(), read() and close() syscall to find the page size from /proc/self/auxv. For more details about the auxv data structure, check the link below [1]. v4: - Simplify __get_page_size() function (review from Alviro). v3: - Split open/read/close in get_page_size() into a new function. - Cache the fallback value when we fail on the syscalls. - No need to init the static var to zero. v2: - Fallback to 4K if the syscall fails. - Cache the page size after read as suggested by Jens. Link: https://github.com/torvalds/linux/blob/v5.19-rc4/fs/binfmt_elf.c#L260 [1] Link: https://lore.kernel.org/io-uring/3895dbe1-8d5f-cf53-e94b-5d1545466de1@kernel.dk Link: https://lore.kernel.org/io-uring/8bfba71c-55d7-fb49-6593-4d0f9d9c3611@kernel.dk Link: https://lore.kernel.org/io-uring/49ed1c4c-46ca-15c4-f288-f6808401b0ff@kernel.dk Suggested-by: Jens Axboe Reviewed-by: Alviro Iskandar Setiawan Signed-off-by: Ammar Faizi --- src/arch/aarch64/lib.h | 48 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 src/arch/aarch64/lib.h diff --git a/src/arch/aarch64/lib.h b/src/arch/aarch64/lib.h new file mode 100644 index 0000000..5a75c1a --- /dev/null +++ b/src/arch/aarch64/lib.h @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: MIT */ + +#ifndef LIBURING_ARCH_AARCH64_LIB_H +#define LIBURING_ARCH_AARCH64_LIB_H + +#include +#include +#include "../../syscall.h" + +static inline long __get_page_size(void) +{ + Elf64_Off buf[2]; + long ret = 4096; + int fd; + + fd = __sys_open("/proc/self/auxv", O_RDONLY, 0); + if (fd < 0) + return ret; + + while (1) { + ssize_t x; + + x = __sys_read(fd, buf, sizeof(buf)); + if (x < sizeof(buf)) + break; + + if (buf[0] == AT_PAGESZ) { + ret = buf[1]; + break; + } + } + + __sys_close(fd); + return ret; +} + +static inline long get_page_size(void) +{ + static long cache_val; + + if (cache_val) + return cache_val; + + cache_val = __get_page_size(); + return cache_val; +} + +#endif /* #ifndef LIBURING_ARCH_AARCH64_LIB_H */