From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-x835.google.com (mail-qt1-x835.google.com [IPv6:2607:f8b0:4864:20::835]) by sourceware.org (Postfix) with ESMTPS id 46108385828C for ; Wed, 10 Aug 2022 19:49:24 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 46108385828C Received: by mail-qt1-x835.google.com with SMTP id a4so7305091qto.10 for ; Wed, 10 Aug 2022 12:49:24 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc; bh=i+7TySh2z8H5ZT11LD71P41FpWrWQZ8ovCI1LBzrvmI=; b=1quzu/+A9wPpFZBd6b0EXzzZwlkw+YL8HZc7LY+A+qCK1FxngfC+XEfFa1h+J5GnWv sSOUF4Owv0oySB4tLi/A9iSytFJ4jzygQEo09PBa4y6sCK8j8SzDdS0NhCfBkC8FAyUE O64OQ0/oIkd4zS8wWdMJzAwNwyzQEcKWaAzyLZmvA3jM90l9az2MVozp/Te009Im4F+u Y8lupNMn1/YQs5IOBmr1Y2ISrF/dkc2Y7g8PPgTsoWFUXp9Evr+uoNib9D5UHEhEKBoe Qlc53DMfQJmRe/B69AavQMWNAUOl3POyFbvO1jm+gpEhJa5+ymWpnrARTc1IT7vsiVs7 dFzw== X-Gm-Message-State: ACgBeo0kkSnoOLRRk2dTFdhkOr8LpRLnnBH6nkKNitTIr124h10pzLcy I3lOa/pfBjEm8m0Y44CKAMLJJy4g5lwlOneWnsFvt0cYzPQ= X-Google-Smtp-Source: AA6agR4p6KR/N/+JmmS82nPb7EjxBQpHQ12ex2BRSlsFM/z26wj1hCfDCKGBYLiMio/wfo/fIYO2B6KWW8UHI/X5ho8= X-Received: by 2002:ac8:7d13:0:b0:343:33d:f03a with SMTP id g19-20020ac87d13000000b00343033df03amr11044201qtb.500.1660160963243; Wed, 10 Aug 2022 12:49:23 -0700 (PDT) MIME-Version: 1.0 References: <20220810154028.662395-1-adhemerval.zanella@linaro.org> <32912533-3afe-e78f-1880-595dbce90e2b@linaro.org> In-Reply-To: <32912533-3afe-e78f-1880-595dbce90e2b@linaro.org> From: "H.J. Lu" Date: Wed, 10 Aug 2022 12:48:46 -0700 Message-ID: Subject: Re: [PATCH v2] elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support To: Adhemerval Zanella Netto Cc: GNU C Library Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3024.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, KAM_SHORT, KAM_STOCKGEN, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) 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-List-Received-Date: Wed, 10 Aug 2022 19:49:27 -0000 On Wed, Aug 10, 2022 at 11:58 AM Adhemerval Zanella Netto wrote: > > > > On 10/08/22 14:24, H.J. Lu wrote: > > On Wed, Aug 10, 2022 at 8:40 AM Adhemerval Zanella > > wrote: > >> > >> Besides the option being gcc specific, this approach is still fragile > >> and not future proof since we do not if this will be the only > >> optimization option gcc will add that transform loops to memset > >> (or any libcall). > >> > >> This patch add a new header dl-symbol-hacks.h that can be used to > >> redirect the compiler generated libcalls to port specific string > >> implementatation if required (defined by dl-ifunc-generic.h). > >> > >> Checked on x86_64-linux-gnu and aarch64-linux-gnu. > >> --- > >> elf/Makefile | 5 --- > >> elf/dl-support.c | 1 + > >> elf/dl-symbol-hacks.h | 31 ++++++++++++++++ > >> elf/dl-tunables.c | 1 + > >> sysdeps/generic/dl-ifunc-generic.h | 37 +++++++++++++++++++ > >> .../sysv/linux/aarch64/dl-ifunc-generic.h | 24 ++++++++++++ > >> .../unix/sysv/linux/i386/dl-ifunc-generic.h | 26 +++++++++++++ > >> .../sysv/linux/powerpc/dl-ifunc-generic.h | 28 ++++++++++++++ > >> .../unix/sysv/linux/s390/dl-ifunc-generic.h | 31 ++++++++++++++++ > >> .../unix/sysv/linux/sparc/dl-ifunc-generic.h | 26 +++++++++++++ > >> .../unix/sysv/linux/x86_64/dl-ifunc-generic.h | 32 ++++++++++++++++ > >> 11 files changed, 237 insertions(+), 5 deletions(-) > >> create mode 100644 elf/dl-symbol-hacks.h > >> create mode 100644 sysdeps/generic/dl-ifunc-generic.h > >> create mode 100644 sysdeps/unix/sysv/linux/aarch64/dl-ifunc-generic.h > >> create mode 100644 sysdeps/unix/sysv/linux/i386/dl-ifunc-generic.h > >> create mode 100644 sysdeps/unix/sysv/linux/powerpc/dl-ifunc-generic.h > >> create mode 100644 sysdeps/unix/sysv/linux/s390/dl-ifunc-generic.h > >> create mode 100644 sysdeps/unix/sysv/linux/sparc/dl-ifunc-generic.h > >> create mode 100644 sysdeps/unix/sysv/linux/x86_64/dl-ifunc-generic.h > >> > >> diff --git a/elf/Makefile b/elf/Makefile > >> index 3386f0ce77..4b992bd348 100644 > >> --- a/elf/Makefile > >> +++ b/elf/Makefile > >> @@ -162,11 +162,6 @@ ifeq (yes,$(have-loop-to-function)) > >> CFLAGS-rtld.c += -fno-tree-loop-distribute-patterns > >> endif > >> > >> -ifeq (yes,$(have-loop-to-function)) > >> -# Likewise, during static library startup, memset is not yet available. > >> -CFLAGS-dl-support.c = -fno-tree-loop-distribute-patterns > >> -endif > >> - > >> # Compile rtld itself without stack protection. > >> # Also compile all routines in the static library that are elided from > >> # the shared libc because they are in libc.a in the same way. > >> diff --git a/elf/dl-support.c b/elf/dl-support.c > >> index 4af0b5b2ce..6d1996ae6e 100644 > >> --- a/elf/dl-support.c > >> +++ b/elf/dl-support.c > >> @@ -44,6 +44,7 @@ > >> #include > >> #include > >> #include > >> +#include > >> > >> extern char *__progname; > >> char **_dl_argv = &__progname; /* This is checked for some error messages. */ > >> diff --git a/elf/dl-symbol-hacks.h b/elf/dl-symbol-hacks.h > >> new file mode 100644 > >> index 0000000000..6b9d24ed03 > >> --- /dev/null > >> +++ b/elf/dl-symbol-hacks.h > >> @@ -0,0 +1,31 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_SYMBOL_HACKS_H > >> +#define _DL_SYMBOL_HACKS_H > >> + > >> +#include > >> + > >> +/* Some compiler optimizations may transform loops into memset/memmove > >> + calls and without proper redirection it might call PLT throught > >> + ifunc without relocations being processed. */ > >> +#if !IS_IN(rtld) && defined HAVE_MEMSET_IFUNC_GENERIC > >> +asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC); > >> +#endif > >> + > >> +#endif > >> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c > >> index 8e7ee9df10..c797484522 100644 > >> --- a/elf/dl-tunables.c > >> +++ b/elf/dl-tunables.c > >> @@ -32,6 +32,7 @@ > >> #include > >> #include > >> #include > >> +#include > >> > >> #define TUNABLES_INTERNAL 1 > >> #include "dl-tunables.h" > >> diff --git a/sysdeps/generic/dl-ifunc-generic.h b/sysdeps/generic/dl-ifunc-generic.h > >> new file mode 100644 > >> index 0000000000..5e1d5c1fd8 > >> --- /dev/null > >> +++ b/sysdeps/generic/dl-ifunc-generic.h > >> @@ -0,0 +1,37 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_IFUNC_GENERIC_H > >> +#define _DL_IFUNC_GENERIC_H > >> + > >> +/* The compiler might optimize loops or other constructs to library calls even > >> + in freestanding mode. Although it is safe in most scenarios, on program > >> + loading and static startup, iFUNC resolution might require other dynamic > >> + relocation that are not yet done. > >> + > >> + Instead of adding per-file compiler flags to avoid the libcall generation, > >> + this header defines generic symbols that will be routed instead of the > >> + default symbols name. > >> + > >> + Each port can then define the following macro to the expected generic > >> + implementation if the symbol is provided as iFUNC: > >> + > >> + HAVE_MEMSET_IFUNC_GENERIC - the generic memset call. > >> + */ > >> + > >> +#endif > >> diff --git a/sysdeps/unix/sysv/linux/aarch64/dl-ifunc-generic.h b/sysdeps/unix/sysv/linux/aarch64/dl-ifunc-generic.h > >> new file mode 100644 > >> index 0000000000..1278a06ff0 > >> --- /dev/null > >> +++ b/sysdeps/unix/sysv/linux/aarch64/dl-ifunc-generic.h > >> @@ -0,0 +1,24 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_IFUNC_GENERIC_H > >> +#define _DL_IFUNC_GENERIC_H > >> + > >> +#define HAVE_MEMSET_IFUNC_GENERIC "__memset_generic" > >> + > >> +#endif > >> diff --git a/sysdeps/unix/sysv/linux/i386/dl-ifunc-generic.h b/sysdeps/unix/sysv/linux/i386/dl-ifunc-generic.h > >> new file mode 100644 > >> index 0000000000..c8e294b3c9 > >> --- /dev/null > >> +++ b/sysdeps/unix/sysv/linux/i386/dl-ifunc-generic.h > >> @@ -0,0 +1,26 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_IFUNC_GENERIC_H > >> +#define _DL_IFUNC_GENERIC_H > >> + > >> +#ifdef USE_MULTIARCH > >> +# define HAVE_MEMSET_IFUNC_GENERIC "__memset_ia32" > >> +#endif > >> + > >> +#endif > > > > This file should be in sysdeps/i386/i686/multiarch. > > > > My understanding is we only support iFUNC for Linux, but it seems that multiarch > directory is not Linux specific. I will change it. > > >> diff --git a/sysdeps/unix/sysv/linux/powerpc/dl-ifunc-generic.h b/sysdeps/unix/sysv/linux/powerpc/dl-ifunc-generic.h > >> new file mode 100644 > >> index 0000000000..b0f9401670 > >> --- /dev/null > >> +++ b/sysdeps/unix/sysv/linux/powerpc/dl-ifunc-generic.h > >> @@ -0,0 +1,28 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_IFUNC_GENERIC_H > >> +#define _DL_IFUNC_GENERIC_H > >> + > >> +/* powerpc and powerpc64 provides the default memset as 'memset', so > >> + no need to redirect it. */ > >> +#if defined USE_MULTIARCH && defined __powerpc64__ && _CALL_ELF != 2 > >> +# define HAVE_MEMSET_IFUNC_GENERIC "__memset_power8" > >> +#endif > >> + > >> +#endif > >> diff --git a/sysdeps/unix/sysv/linux/s390/dl-ifunc-generic.h b/sysdeps/unix/sysv/linux/s390/dl-ifunc-generic.h > >> new file mode 100644 > >> index 0000000000..f664ac07a7 > >> --- /dev/null > >> +++ b/sysdeps/unix/sysv/linux/s390/dl-ifunc-generic.h > >> @@ -0,0 +1,31 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_IFUNC_GENERIC_H > >> +#define _DL_IFUNC_GENERIC_H > >> + > >> +#ifdef USE_MULTIARCH > >> +# include > >> + > >> +# define IFUNC_SYMBOL_STR1(s) #s > >> +# define IFUNC_SYMBOL_STR(s) IFUNC_SYMBOL_STR1(s) > >> + > >> +# define HAVE_MEMSET_IFUNC_GENERIC IFUNC_SYMBOL_STR(MEMSET_DEFAULT) > >> +#endif > >> + > >> +#endif > >> diff --git a/sysdeps/unix/sysv/linux/sparc/dl-ifunc-generic.h b/sysdeps/unix/sysv/linux/sparc/dl-ifunc-generic.h > >> new file mode 100644 > >> index 0000000000..86815317a9 > >> --- /dev/null > >> +++ b/sysdeps/unix/sysv/linux/sparc/dl-ifunc-generic.h > >> @@ -0,0 +1,26 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_IFUNC_GENERIC_H > >> +#define _DL_IFUNC_GENERIC_H > >> + > >> +#ifdef USE_MULTIARCH > >> +# define HAVE_MEMSET_IFUNC_GENERIC "__memset_ultra1" > >> +#endif > >> + > >> +#endif > >> diff --git a/sysdeps/unix/sysv/linux/x86_64/dl-ifunc-generic.h b/sysdeps/unix/sysv/linux/x86_64/dl-ifunc-generic.h > >> new file mode 100644 > >> index 0000000000..7b7cf1c3d6 > >> --- /dev/null > >> +++ b/sysdeps/unix/sysv/linux/x86_64/dl-ifunc-generic.h > >> @@ -0,0 +1,32 @@ > >> +/* Symbol rediretion for loader/static initialization code. > >> + Copyright (C) 2022 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 _DL_IFUNC_GENERIC_H > >> +#define _DL_IFUNC_GENERIC_H > >> + > >> +#include > >> + > >> +#if MINIMUM_X86_ISA_LEVEL >= 4 > >> +# define HAVE_MEMSET_IFUNC_GENERIC "__memset_evex_unaligned" > >> +#elif MINIMUM_X86_ISA_LEVEL == 3 > >> +# define HAVE_MEMSET_IFUNC_GENERIC "__memset_avx2_unaligned" > >> +#else > >> +# define HAVE_MEMSET_IFUNC_GENERIC "__memset_sse2_unaligned" > >> +#endif > >> + > >> +#endif > >> -- > >> 2.34.1 > >> > > > > This file should be in sysdeps/x86_64/multiarch and the generic > > memset should follow sysdeps/x86_64/memset.S: > > > > #define DEFAULT_IMPL_V1 "multiarch/memset-sse2-unaligned-erms.S" > > #define DEFAULT_IMPL_V3 "multiarch/memset-avx2-unaligned-erms.S" > > #define DEFAULT_IMPL_V4 "multiarch/memset-evex-unaligned-erms.S" > > Right, my understading it does follow the provided implementation based > on the MINIMUM_X86_ISA_LEVEL. What I am missing here? You are right. The file content is OK. But it should be in sysdeps/x86_64/multiarch. -- H.J.