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([2804:1b3:a7c0:5805:4e9:d353:8061:acad]) by smtp.gmail.com with ESMTPSA id f16-20020a1f1f10000000b00383bebb17bdsm9485389vkf.16.2022.08.22.06.55.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 22 Aug 2022 06:55:11 -0700 (PDT) Message-ID: Date: Mon, 22 Aug 2022 10:55:09 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.1.2 Subject: Re: [PATCH v4] elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support From: Adhemerval Zanella Netto To: libc-alpha@sourceware.org, "H . J . Lu" References: <20220811121909.4110665-1-adhemerval.zanella@linaro.org> Content-Language: en-US Organization: Linaro In-Reply-To: <20220811121909.4110665-1-adhemerval.zanella@linaro.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-11.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, KAM_STOCKGEN, NICE_REPLY_A, 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: Mon, 22 Aug 2022 13:55:16 -0000 Ping. On 11/08/22 09:19, 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 ++++++++++++++++ > sysdeps/aarch64/multiarch/dl-ifunc-generic.h | 24 ++++++++++++ > sysdeps/generic/dl-ifunc-generic.h | 37 +++++++++++++++++++ > .../i386/i686/multiarch/dl-ifunc-generic.h | 24 ++++++++++++ > .../powerpc64/le/multiarch/dl-ifunc-generic.h | 24 ++++++++++++ > sysdeps/s390/multiarch/dl-ifunc-generic.h | 29 +++++++++++++++ > .../sparcv9/multiarch/dl-ifunc-generic.h | 24 ++++++++++++ > .../sparc64/multiarch/dl-ifunc-generic.h | 24 ++++++++++++ > sysdeps/x86_64/multiarch/dl-ifunc-generic.h | 32 ++++++++++++++++ > 11 files changed, 250 insertions(+), 5 deletions(-) > create mode 100644 elf/dl-symbol-hacks.h > create mode 100644 sysdeps/aarch64/multiarch/dl-ifunc-generic.h > create mode 100644 sysdeps/generic/dl-ifunc-generic.h > create mode 100644 sysdeps/i386/i686/multiarch/dl-ifunc-generic.h > create mode 100644 sysdeps/powerpc/powerpc64/le/multiarch/dl-ifunc-generic.h > create mode 100644 sysdeps/s390/multiarch/dl-ifunc-generic.h > create mode 100644 sysdeps/sparc/sparc32/sparcv9/multiarch/dl-ifunc-generic.h > create mode 100644 sysdeps/sparc/sparc64/multiarch/dl-ifunc-generic.h > create mode 100644 sysdeps/x86_64/multiarch/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..1b83b284dd > --- /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. */ > +#ifdef HAVE_MEMSET_IFUNC_GENERIC > +asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC); > +#endif > + > +#endif > diff --git a/sysdeps/aarch64/multiarch/dl-ifunc-generic.h b/sysdeps/aarch64/multiarch/dl-ifunc-generic.h > new file mode 100644 > index 0000000000..1278a06ff0 > --- /dev/null > +++ b/sysdeps/aarch64/multiarch/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/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/i386/i686/multiarch/dl-ifunc-generic.h b/sysdeps/i386/i686/multiarch/dl-ifunc-generic.h > new file mode 100644 > index 0000000000..a538931c03 > --- /dev/null > +++ b/sysdeps/i386/i686/multiarch/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_ia32" > + > +#endif > diff --git a/sysdeps/powerpc/powerpc64/le/multiarch/dl-ifunc-generic.h b/sysdeps/powerpc/powerpc64/le/multiarch/dl-ifunc-generic.h > new file mode 100644 > index 0000000000..1bf516494d > --- /dev/null > +++ b/sysdeps/powerpc/powerpc64/le/multiarch/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_power8" > + > +#endif > diff --git a/sysdeps/s390/multiarch/dl-ifunc-generic.h b/sysdeps/s390/multiarch/dl-ifunc-generic.h > new file mode 100644 > index 0000000000..b0e5ed23aa > --- /dev/null > +++ b/sysdeps/s390/multiarch/dl-ifunc-generic.h > @@ -0,0 +1,29 @@ > +/* 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 > + > +#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 > diff --git a/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-ifunc-generic.h b/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-ifunc-generic.h > new file mode 100644 > index 0000000000..417b24d2c1 > --- /dev/null > +++ b/sysdeps/sparc/sparc32/sparcv9/multiarch/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_ultra1" > + > +#endif > diff --git a/sysdeps/sparc/sparc64/multiarch/dl-ifunc-generic.h b/sysdeps/sparc/sparc64/multiarch/dl-ifunc-generic.h > new file mode 100644 > index 0000000000..417b24d2c1 > --- /dev/null > +++ b/sysdeps/sparc/sparc64/multiarch/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_ultra1" > + > +#endif > diff --git a/sysdeps/x86_64/multiarch/dl-ifunc-generic.h b/sysdeps/x86_64/multiarch/dl-ifunc-generic.h > new file mode 100644 > index 0000000000..7b7cf1c3d6 > --- /dev/null > +++ b/sysdeps/x86_64/multiarch/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