From patchwork Mon Sep 30 12:45:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 34726 Received: (qmail 34515 invoked by alias); 30 Sep 2019 12:45:59 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 34500 invoked by uid 89); 30 Sep 2019 12:45:58 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-17.7 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_SHORT, KAM_STOCKGEN, SPF_HELO_PASS autolearn=ham version=3.3.1 spammy=Juan, juan, ease, Rev X-HELO: mx1.redhat.com From: Florian Weimer To: libc-alpha@sourceware.org Cc: Palmer Dabbelt , Jim Wilson , DJ Delorie Subject: [PATCH] riscv: Remove support for variable page sizes Date: Mon, 30 Sep 2019 14:45:52 +0200 Message-ID: <87r23y2br3.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 [NB: I could use some help with testing here.] _dl_var_init is used to patch the read-only data section after relocation. Several architectures use this to update GLRO(page_size) with the correct value for the static dlopen case, where _rtld_global_ro has not been initialized by the dynamic loader. RISC-V does not need this. The RISC-V Instruction Set Manual, Volume II: Privileged Architecture, Document Version 20190608-Priv-MSU-Ratified says this: After much deliberation, we have settled on a conventional page size of 4 KiB for both RV32 and RV64. We expect this decision to ease the porting of low-level runtime software and device drivers. The TLB reach problem is ameliorated by transparent superpage support in modern operating systems [2]. Additionally, multi-level TLB hierarchies are quite inexpensive relative to the multi-level cache hierarchies whose address space they map. [2] Juan Navarro, Sitaram Iyer, Peter Druschel, and Alan Cox. Practical, transparent operating system support for superpages. SIGOPS Oper. Syst. Rev., 36(SI):89–104, December 2002. This means that the initialization of _rtld_global_ro._dl_page_size in elf/rtld.c with EXEC_PAGESIZE is sufficient for RISC-V. 2019-09-30 Florian Weimer riscv: Remove support for variable page sizes. * sysdeps/unix/sysv/linux/riscv/Makefile [$(subdir) == elf] (sysdep_routines): Do not add dl-static. * sysdeps/unix/sysv/linux/riscv/dl-static.c: Remove file. * sysdeps/unix/sysv/linux/riscv/ldsodefs.h: Likewise. Reviewed-by: Alistair Francis diff --git a/sysdeps/unix/sysv/linux/riscv/Makefile b/sysdeps/unix/sysv/linux/riscv/Makefile index b47858769f..b7ad31885c 100644 --- a/sysdeps/unix/sysv/linux/riscv/Makefile +++ b/sysdeps/unix/sysv/linux/riscv/Makefile @@ -1,9 +1,5 @@ ifeq ($(subdir),elf) sysdep_routines += dl-vdso -ifeq ($(build-shared),yes) -# This is needed for DSO loading from static binaries. -sysdep-dl-routines += dl-static -endif endif ifeq ($(subdir),misc) diff --git a/sysdeps/unix/sysv/linux/riscv/dl-static.c b/sysdeps/unix/sysv/linux/riscv/dl-static.c deleted file mode 100644 index e52612a267..0000000000 --- a/sysdeps/unix/sysv/linux/riscv/dl-static.c +++ /dev/null @@ -1,84 +0,0 @@ -/* Variable initialization. RISC-V version - Copyright (C) 2001-2019 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library. If not, see - . */ - -#include - -#ifdef SHARED - -void -_dl_var_init (void *array[]) -{ - /* It has to match "variables" below. */ - enum - { - DL_PAGESIZE = 0 - }; - - GLRO(dl_pagesize) = *((size_t *) array[DL_PAGESIZE]); -} - -#else - -static void *variables[] = -{ - &GLRO(dl_pagesize) -}; - -static void -_dl_unprotect_relro (struct link_map *l) -{ - ElfW(Addr) start = ((l->l_addr + l->l_relro_addr) - & ~(GLRO(dl_pagesize) - 1)); - ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size) - & ~(GLRO(dl_pagesize) - 1)); - - if (start != end) - __mprotect ((void *) start, end - start, PROT_READ | PROT_WRITE); -} - -void -_dl_static_init (struct link_map *l) -{ - struct link_map *rtld_map = l; - struct r_scope_elem **scope; - const ElfW(Sym) *ref = NULL; - lookup_t loadbase; - void (*f) (void *[]); - size_t i; - - loadbase = _dl_lookup_symbol_x ("_dl_var_init", l, &ref, l->l_local_scope, - NULL, 0, 1, NULL); - - for (scope = l->l_local_scope; *scope != NULL; scope++) - for (i = 0; i < (*scope)->r_nlist; i++) - if ((*scope)->r_list[i] == loadbase) - { - rtld_map = (*scope)->r_list[i]; - break; - } - - if (ref != NULL) - { - f = (void (*) (void *[])) DL_SYMBOL_ADDRESS (loadbase, ref); - _dl_unprotect_relro (rtld_map); - f (variables); - _dl_protect_relro (rtld_map); - } -} - -#endif diff --git a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h b/sysdeps/unix/sysv/linux/riscv/ldsodefs.h deleted file mode 100644 index a46e676752..0000000000 --- a/sysdeps/unix/sysv/linux/riscv/ldsodefs.h +++ /dev/null @@ -1,32 +0,0 @@ -/* RISC-V dynamic linker data structures for loaded ELF shared objects. - Copyright (C) 2001-2019 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library. If not, see - . */ - -#ifndef _LDSODEFS_H - -/* Get the real definitions. */ -#include_next - -/* Now define our stuff. */ - -/* We need special support to initialize DSO loaded for statically linked - binaries. */ -extern void _dl_static_init (struct link_map *map); -#undef DL_STATIC_INIT -#define DL_STATIC_INIT(map) _dl_static_init (map) - -#endif /* ldsodefs.h */