From patchwork Mon Dec 13 02:51:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rongwei Wang X-Patchwork-Id: 48855 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id B9BF73858031 for ; Mon, 13 Dec 2021 02:52:12 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B9BF73858031 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1639363932; bh=W71D/gPJ0qwy056rHu6XkVhkbKFLy1Ix+6Ga/v+mGjs=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=O3KFsGfKco+UcOTWPE3t6O5s9vImTcbIkD2JWpA7v/D6ScylXoExUACI6lbbQaAmg yEjhGi6rKDHzKt8tucWxAo+YCPoTf82ZgcAbxGX35vd26t4F36uKkOxmcoVraXf8jK Kx579ZR0bNsmjXnSf/Whdxio+uDoS0R4ThBzzYRw= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from out30-42.freemail.mail.aliyun.com (out30-42.freemail.mail.aliyun.com [115.124.30.42]) by sourceware.org (Postfix) with ESMTPS id 16717385840C for ; Mon, 13 Dec 2021 02:51:08 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 16717385840C X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R211e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04407; MF=rongwei.wang@linux.alibaba.com; NM=1; PH=DS; RN=6; SR=0; TI=SMTPD_---0V-MG8zK_1639363863; Received: from localhost.localdomain(mailfrom:rongwei.wang@linux.alibaba.com fp:SMTPD_---0V-MG8zK_1639363863) by smtp.aliyun-inc.com(127.0.0.1); Mon, 13 Dec 2021 10:51:05 +0800 To: libc-alpha@sourceware.org, hjl.tools@gmail.com, fweimer@redhat.com, adhemerval.zanella@linaro.org Subject: [PATCH v6 1/2] elf: Properly align PT_LOAD segments [BZ #28676] Date: Mon, 13 Dec 2021 10:51:02 +0800 Message-Id: <20211213025103.48472-2-rongwei.wang@linux.alibaba.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211213025103.48472-1-rongwei.wang@linux.alibaba.com> References: <20211204045848.71105-1-rongwei.wang@linux.alibaba.com> <20211213025103.48472-1-rongwei.wang@linux.alibaba.com> MIME-Version: 1.0 X-Spam-Status: No, score=-19.9 required=5.0 tests=BAYES_00, ENV_AND_HDR_SPF_MATCH, GIT_PATCH_0, KAM_DMARC_STATUS, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, UNPARSEABLE_RELAY, USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Rongwei Wang via Libc-alpha From: Rongwei Wang Reply-To: Rongwei Wang Cc: xuyu@linux.alibaba.com, gavin.dg@linux.alibaba.com Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" When PT_LOAD segment alignment > the page size, allocate enough space to ensure that the segment can be properly aligned. And this change helps code segments use huge pages become simple and available. This fixes [BZ #28676]. Signed-off-by: Xu Yu Signed-off-by: Rongwei Wang --- elf/dl-load.c | 2 ++ elf/dl-load.h | 3 ++- elf/dl-map-segments.h | 50 +++++++++++++++++++++++++++++++++++++++---- 3 files changed, 50 insertions(+), 5 deletions(-) diff --git a/elf/dl-load.c b/elf/dl-load.c index bf8957e73c..721593135e 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -1,5 +1,6 @@ /* Map in a shared object's segments from the file. Copyright (C) 1995-2021 Free Software Foundation, Inc. + Copyright The GNU Toolchain Authors. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -1150,6 +1151,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, c->mapend = ALIGN_UP (ph->p_vaddr + ph->p_filesz, GLRO(dl_pagesize)); c->dataend = ph->p_vaddr + ph->p_filesz; c->allocend = ph->p_vaddr + ph->p_memsz; + c->mapalign = ph->p_align; c->mapoff = ALIGN_DOWN (ph->p_offset, GLRO(dl_pagesize)); /* Determine whether there is a gap between the last segment diff --git a/elf/dl-load.h b/elf/dl-load.h index e329d49a81..e6dabcb336 100644 --- a/elf/dl-load.h +++ b/elf/dl-load.h @@ -1,5 +1,6 @@ /* Map in a shared object's segments from the file. Copyright (C) 1995-2021 Free Software Foundation, Inc. + Copyright The GNU Toolchain Authors. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -74,7 +75,7 @@ ELF_PREFERRED_ADDRESS_DATA; Its details have been expanded out and converted. */ struct loadcmd { - ElfW(Addr) mapstart, mapend, dataend, allocend; + ElfW(Addr) mapstart, mapend, dataend, allocend, mapalign; ElfW(Off) mapoff; int prot; /* PROT_* bits. */ }; diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h index f9fb110ee3..70a4c40695 100644 --- a/elf/dl-map-segments.h +++ b/elf/dl-map-segments.h @@ -1,5 +1,6 @@ /* Map in a shared object's segments. Generic version. Copyright (C) 1995-2021 Free Software Foundation, Inc. + Copyright The GNU Toolchain Authors. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -18,6 +19,50 @@ #include +/* Map a segment and align it properly. */ + +static __always_inline ElfW(Addr) +_dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref, + const size_t maplength, int fd) +{ + if (__glibc_likely (c->mapalign <= GLRO(dl_pagesize))) + return (ElfW(Addr)) __mmap ((void *) mappref, maplength, c->prot, + MAP_COPY|MAP_FILE, fd, c->mapoff); + + /* If the segment alignment > the page size, allocate enough space to + ensure that the segment can be properly aligned. */ + ElfW(Addr) maplen = (maplength >= c->mapalign + ? (maplength + c->mapalign) + : (2 * c->mapalign)); + ElfW(Addr) map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplen, + PROT_NONE, + MAP_ANONYMOUS|MAP_PRIVATE, + -1, 0); + if (__glibc_unlikely ((void *) map_start == MAP_FAILED)) + return map_start; + + ElfW(Addr) map_start_aligned = ALIGN_UP (map_start, c->mapalign); + map_start_aligned = (ElfW(Addr)) __mmap ((void *) map_start_aligned, + maplength, c->prot, + MAP_COPY|MAP_FILE|MAP_FIXED, + fd, c->mapoff); + if (__glibc_unlikely ((void *) map_start_aligned == MAP_FAILED)) + __munmap ((void *) map_start, maplen); + else + { + /* Unmap the unused regions. */ + ElfW(Addr) delta = map_start_aligned - map_start; + if (delta) + __munmap ((void *) map_start, delta); + ElfW(Addr) map_end = map_start_aligned + maplength; + delta = map_start + maplen - map_end; + if (delta) + __munmap ((void *) map_end, delta); + } + + return map_start_aligned; +} + /* This implementation assumes (as does the corresponding implementation of _dl_unmap_segments, in dl-unmap-segments.h) that shared objects are always laid out with all segments contiguous (or with gaps @@ -53,10 +98,7 @@ _dl_map_segments (struct link_map *l, int fd, - MAP_BASE_ADDR (l)); /* Remember which part of the address space this object uses. */ - l->l_map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplength, - c->prot, - MAP_COPY|MAP_FILE, - fd, c->mapoff); + l->l_map_start = _dl_map_segment (c, mappref, maplength, fd); if (__glibc_unlikely ((void *) l->l_map_start == MAP_FAILED)) return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT;