From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by sourceware.org (Postfix) with ESMTPS id C0C3138515F9 for ; Fri, 17 Mar 2023 14:56:27 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org C0C3138515F9 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=rivosinc.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=rivosinc.com Received: by mail-pl1-x631.google.com with SMTP id a2so5558304plm.4 for ; Fri, 17 Mar 2023 07:56:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20210112.gappssmtp.com; s=20210112; t=1679064985; h=content-transfer-encoding:mime-version:message-id:to:from:cc :in-reply-to:subject:date:from:to:cc:subject:date:message-id :reply-to; bh=M4hEZFr8TXjZED2nVlTTNJsJP6D7tIOKm4KfLL5u6KI=; b=UX8xZG4BfYfBzkZcb+anLtcKHS2xvVEbNNymu8b1mptoR1uv3MkhFNJjsiNMjV+T59 U9gUAx0QUQUyT/SQjYxlFPxNYtAUF7lbU7PhxlcX6OkGGwN6MPdlLahSrUkCScCJ8HGc AkW1287CpaXqWinZJn+/wVjT6xPNYCj8Qf6hWkTAlhs5bkqWYaxDwhVNFn2y6WZvvo4+ 0TonmqlxqUlV6mIGy62rqpzU3bcVbsrmRMfGpYMAbobwIlpKvimouJ2bx5Fb9prfPp21 S8REuyGbeYKaueMfQPAdylW3yD3L2t9UeLPV/hsUZyz0B/3zBoicKFPGNpyTuqyV4QuE riSA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679064985; h=content-transfer-encoding:mime-version:message-id:to:from:cc :in-reply-to:subject:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=M4hEZFr8TXjZED2nVlTTNJsJP6D7tIOKm4KfLL5u6KI=; b=CpyHiO+6XD59J3JQFu4jL/3o8qOPfHSnwWMfLEEKkNkGem4k+yU3xJh7/TS1F0B3JF fWkEoDHehNTXV75vZM1PeuN50GBqhH3BwAly1U7ENGlAes8zIYXLd0DCoPTg1hPCt+iq 9O4WfLLwhKqW/QfUKw/z4maprM4gKr42TiXPYVwqcM9fNglRbmI17kAS44qfdA9Vvvoq BLuNQebM4GC6FQ/V9w4SUxYhHYexs/nL8JYKv+k0JR1dD3D9+iGc3Leid6PkWH8+ONak CR7QB3DYrdfdSsNiM/K+Tsqv2s/8rS3EkanN5LRR+GQTBULGk6aGdIE5QDmcUOS9XBXv tRGg== X-Gm-Message-State: AO0yUKVfSHdsXUf29aIBFX2W++8eqtOZ+gXzmQbhZchMLcRIOoedx/R9 eM7Jz+1nmGm0RTiNcQURpprxjLsjuueVRwqDNeQ= X-Google-Smtp-Source: AK7set8GELOgcpq+U0kJ3sErfyd8vw5N2m/ya9VZ0OtHBORGFeM6uPQHRMX65nuyCD/jf9TWCePvyg== X-Received: by 2002:a17:902:d501:b0:1a0:67e0:138f with SMTP id b1-20020a170902d50100b001a067e0138fmr9347388plg.1.1679064985574; Fri, 17 Mar 2023 07:56:25 -0700 (PDT) Received: from localhost ([135.180.227.0]) by smtp.gmail.com with ESMTPSA id n8-20020a170902968800b001a190baea88sm1668631plp.97.2023.03.17.07.56.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Mar 2023 07:56:25 -0700 (PDT) Date: Fri, 17 Mar 2023 07:56:25 -0700 (PDT) X-Google-Original-Date: Fri, 17 Mar 2023 07:43:21 PDT (-0700) Subject: Re: [PATCH v3] riscv: Resolve symbols directly for symbols with STO_RISCV_VARIANT_CC. In-Reply-To: <20230314162512.35802-1-kito.cheng@sifive.com> CC: libc-alpha@sourceware.org, jeffreyalaw@gmail.com, Darius Rad , christoph.muellner@vrull.eu, DJ Delorie , greentime.hu@sifive.com, Vineet Gupta , kai.wang@sifive.com, vincent.chen@sifive.com From: Palmer Dabbelt To: libc-alpha@sourceware.org Message-ID: Mime-Version: 1.0 (MHng) Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-12.7 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,GIT_PATCH_0,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Tue, 14 Mar 2023 09:25:12 PDT (-0700), libc-alpha@sourceware.org wrote: > From: Hsiangkai Wang > > In some cases, we do not want to go through the resolver for function > calls. For example, functions with vector arguments will use vector > registers to pass arguments. In the resolver, we do not save/restore the > vector argument registers for lazy binding efficiency. To avoid ruining > the vector arguments, functions with vector arguments will not go > through the resolver. > > To achieve the goal, we will annotate the function symbols with > STO_RISCV_VARIANT_CC flag and add DT_RISCV_VARIANT_CC tag in the dynamic > section. In the first pass on PLT relocations, we do not set up to call > _dl_runtime_resolve. Instead, we resolve the functions directly. > > Signed-off-by: Hsiangkai Wang > Signed-off-by: Vincent Chen > > --- > > Changes: > > - Update copyright year. > - Seperated from the original patchset, it could be used for vector ISA support, > but NOT only used for vector support. > --- > elf/elf.h | 7 +++++++ > manual/platform.texi | 6 ++++++ > sysdeps/riscv/dl-dtprocnum.h | 21 +++++++++++++++++++++ > sysdeps/riscv/dl-machine.h | 26 ++++++++++++++++++++++++++ > 4 files changed, 60 insertions(+) > create mode 100644 sysdeps/riscv/dl-dtprocnum.h > > diff --git a/elf/elf.h b/elf/elf.h > index 4bc0e4299c..1eef1a7184 100644 > --- a/elf/elf.h > +++ b/elf/elf.h > @@ -3932,6 +3932,13 @@ enum > > #define R_TILEGX_NUM 130 > > +/* RISC-V specific values for the Dyn d_tag field. */ > +#define DT_RISCV_VARIANT_CC (DT_LOPROC + 1) > +#define DT_RISCV_NUM 2 > + > +/* RISC-V specific values for the st_other field. */ > +#define STO_RISCV_VARIANT_CC 0x80 > + > /* RISC-V ELF Flags */ > #define EF_RISCV_RVC 0x0001 > #define EF_RISCV_FLOAT_ABI 0x0006 > diff --git a/manual/platform.texi b/manual/platform.texi > index d5fdc5bd05..a1a740f381 100644 > --- a/manual/platform.texi > +++ b/manual/platform.texi > @@ -121,6 +121,12 @@ when it is not allowed, the priority is set to medium. > @node RISC-V > @appendixsec RISC-V-specific Facilities > > +Functions that are lazily bound must be compatible with the standard calling > +convention. When a function is annotated with STO_RISCV_VARIANT_CC, it means > +this function is not compatible with the standard calling convention. The > +dynamic linker will directly resolve it instead of using the lazy binding > +mechanism. > + > Cache management facilities specific to RISC-V systems that implement the Linux > ABI are declared in @file{sys/cachectl.h}. > > diff --git a/sysdeps/riscv/dl-dtprocnum.h b/sysdeps/riscv/dl-dtprocnum.h > new file mode 100644 > index 0000000000..281c5aadeb > --- /dev/null > +++ b/sysdeps/riscv/dl-dtprocnum.h > @@ -0,0 +1,21 @@ > +/* Configuration of lookup functions. RISC-V version. > + Copyright (C) 2023 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 > + . */ > + > +/* Number of extra dynamic section entries for this architecture. By > + default there are none. */ > +#define DT_THISPROCNUM DT_RISCV_NUM > diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h > index c0c9bd93ad..0e6c0bb155 100644 > --- a/sysdeps/riscv/dl-machine.h > +++ b/sysdeps/riscv/dl-machine.h > @@ -53,6 +53,9 @@ > || (__WORDSIZE == 64 && (type) == R_RISCV_TLS_TPREL64))) \ > | (ELF_RTYPE_CLASS_COPY * ((type) == R_RISCV_COPY))) > > +//* Translate a processor specific dynamic tag to the index in l_info array. */ > +#define DT_RISCV(x) (DT_RISCV_##x - DT_LOPROC + DT_NUM) > + > /* Return nonzero iff ELF header is compatible with the running host. */ > static inline int __attribute_used__ > elf_machine_matches_host (const ElfW(Ehdr) *ehdr) > @@ -281,6 +284,29 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], > /* Check for unexpected PLT reloc type. */ > if (__glibc_likely (r_type == R_RISCV_JUMP_SLOT)) > { > + if (__glibc_unlikely (map->l_info[DT_RISCV (VARIANT_CC)] != NULL)) > + { > + /* Check the symbol table for variant CC symbols. */ > + const Elf_Symndx symndx = ELFW(R_SYM) (reloc->r_info); > + const ElfW(Sym) *symtab = > + (const void *)D_PTR (map, l_info[DT_SYMTAB]); > + const ElfW(Sym) *sym = &symtab[symndx]; > + if (__glibc_unlikely (sym->st_other & STO_RISCV_VARIANT_CC)) > + { > + /* Avoid lazy resolution of variant CC symbols. */ > + const struct r_found_version *version = NULL; > + if (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL) > + { > + const ElfW(Half) *vernum = > + (const void *)D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]); > + version = &map->l_versions[vernum[symndx] & 0x7fff]; > + } > + elf_machine_rela (map, scope, reloc, sym, version, reloc_addr, > + skip_ifunc); > + return; > + } > + } > + > if (__glibc_unlikely (map->l_mach.plt == 0)) > { > if (l_addr) Reviewed-by: Palmer Dabbelt Acked-by: Palmer Dabbelt