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 [36.81.65.188]) by gnuweeb.org (Postfix) with ESMTPSA id 2D7DB800EF; Mon, 4 Jul 2022 19:32:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1656963155; bh=aWmyb7aWPqdN5BDugTVPn2wOOXVGY+QNYH3gJSW9y14=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mB8N2ulR5f1xAPQMnd9LlR/c15le12igHNl5ddt10PsnVK6phKSEs3hhcsPkHyroP frlt1WexxRLuKiwj5O29jJ9+BA+aurrgAizPSptSCU2xcjgIDN9y+TE2qusW2x3wB6 yVjlhuXevi37NBslipomhpNE06cwkNymB9HQdYJYuKVM9PLLIj9jWfesCvzIRl7vci DH+GdWDwvVv1f6LNW+lTW5y5sDhn8kK7LCCJWutJgTsHwZUfmpMufIaTtDwWgfuv7n 3tTo2y8C0ISRYan7LOimSKd6HGSzC2xCelbij43uMzZ3NDY0ICUBDhA5efEG3aEnBf ZvEYzgmd1pMFg== 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 v4 05/10] arch/aarch64: lib: Add `get_page_size()` function Date: Tue, 5 Jul 2022 02:31:50 +0700 Message-Id: <20220704192827.338771-6-ammar.faizi@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220704192827.338771-1-ammar.faizi@intel.com> References: <20220704192827.338771-1-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]. 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 */ -- Ammar Faizi