From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on gnuweeb.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=ALL_TRUSTED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NO_DNS_FOR_FROM,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.6 Received: from integral2.. (unknown [180.245.197.13]) by gnuweeb.org (Postfix) with ESMTPSA id 4D2517FC07; Wed, 29 Jun 2022 17:59:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1656525586; bh=8rvYQ2Hh72AHYXlNPnhKEoTXHZExITmndsEjdUWGuMk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d+LH6j+K5Jv3tIt5NLDp6deGJNTmtbs6kFZubD8Bk25yTF3/7EUh8JPC7/4Tja78g t5jaUsAprYzPdbpgidJTLPA3uYmO3HS4cYePkrgvWp6O5stcH11KhRiN0blIS398I2 iKuh6IJu9tOJNxA+73zhhQVY92vZo6lvisYTt3YmGZjUeksO4u6d0jHbk9OlU2cHa6 rDlKTDmSxl19yzKX6Ugv6dMxfAeA5K0r0X/u/+vCNruHhbyQeIvj1WqF0jE2FHBjfw LpmKEkQLaaNRmUmczJ9m9gaYi3sgfkzB2NnkJWAbg2uBG/ZWy+h9lRX/L5lguwHRAV BC3KJiko97OBw== From: Ammar Faizi To: Jens Axboe Cc: Ammar Faizi , Alviro Iskandar Setiawan , Fernanda Ma'rouf , Pavel Begunkov , Hao Xu , io-uring Mailing List , GNU/Weeb Mailing List Subject: [PATCH liburing v2 5/8] arch/aarch64: lib: Add `get_page_size()` function Date: Thu, 30 Jun 2022 00:58:27 +0700 Message-Id: <20220629175255.1377052-6-ammar.faizi@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220629175255.1377052-1-ammar.faizi@intel.com> References: <20220629175255.1377052-1-ammar.faizi@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: 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]. 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 Suggested-by: Jens Axboe Signed-off-by: Ammar Faizi --- src/arch/aarch64/lib.h | 45 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 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..adba512 --- /dev/null +++ b/src/arch/aarch64/lib.h @@ -0,0 +1,45 @@ +/* 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) +{ + static const long fallback_ret = 4096; + static long cache_val = 0; + Elf64_Off buf[2]; + long page_size; + int fd; + + if (cache_val) + return cache_val; + + fd = __sys_open("/proc/self/auxv", O_RDONLY, 0); + if (fd < 0) + return fallback_ret; + + while (1) { + ssize_t x; + + x = __sys_read(fd, buf, sizeof(buf)); + if (x < sizeof(buf)) { + page_size = fallback_ret; + break; + } + + if (buf[0] == AT_PAGESZ) { + page_size = buf[1]; + cache_val = page_size; + break; + } + } + + __sys_close(fd); + return page_size; +} + +#endif /* #ifndef LIBURING_ARCH_AARCH64_LIB_H */ -- Ammar Faizi