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([2804:1b3:a7c1:c266:cc93:9f8:1eba:d2e8]) by smtp.gmail.com with ESMTPSA id 30-20020a9d02a1000000b0063b24357269sm309658otl.13.2022.09.20.12.06.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Sep 2022 12:06:07 -0700 (PDT) Message-ID: Date: Tue, 20 Sep 2022 16:06:05 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH v4] elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support Content-Language: en-US From: Adhemerval Zanella Netto To: libc-alpha@sourceware.org, "H . J . Lu" References: <20220811121909.4110665-1-adhemerval.zanella@linaro.org> Organization: Linaro In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-13.3 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 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: Ping (x2). On 22/08/22 10:55, Adhemerval Zanella Netto wrote: > 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