From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, "H . J . Lu" <hjl.tools@gmail.com>
Subject: Re: [PATCH v4] elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support
Date: Tue, 20 Sep 2022 16:06:05 -0300 [thread overview]
Message-ID: <ce37c411-6545-339b-243b-7700422ec1c4@linaro.org> (raw)
In-Reply-To: <a497384b-8953-966a-c4c6-f10012941001@linaro.org>
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 <dl-auxv.h>
>> #include <dl-find_object.h>
>> #include <array_length.h>
>> +#include <dl-symbol-hacks.h>
>>
>> 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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#ifndef _DL_SYMBOL_HACKS_H
>> +#define _DL_SYMBOL_HACKS_H
>> +
>> +#include <dl-ifunc-generic.h>
>> +
>> +/* 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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#ifndef _DL_IFUNC_GENERIC_H
>> +#define _DL_IFUNC_GENERIC_H
>> +
>> +#include <ifunc-memset.h>
>> +
>> +#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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#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
>> + <https://www.gnu.org/licenses/>. */
>> +
>> +#ifndef _DL_IFUNC_GENERIC_H
>> +#define _DL_IFUNC_GENERIC_H
>> +
>> +#include <isa-level.h>
>> +
>> +#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
next prev parent reply other threads:[~2022-09-20 19:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-11 12:19 Adhemerval Zanella
2022-08-11 14:32 ` Andreas Schwab
2022-08-11 15:48 ` Adhemerval Zanella Netto
2022-08-11 14:33 ` Andreas Schwab
2022-08-22 13:55 ` Adhemerval Zanella Netto
2022-09-20 19:06 ` Adhemerval Zanella Netto [this message]
2022-10-04 16:13 ` Carlos O'Donell
2022-10-06 15:25 ` Adhemerval Zanella Netto
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