From: Carlos O'Donell <carlos@redhat.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>,
libc-alpha@sourceware.org
Subject: Re: [PATCH v5] elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support
Date: Mon, 10 Oct 2022 08:28:00 -0400 [thread overview]
Message-ID: <7bfa0e9f-393f-c5c7-92a3-c3b5937ff51a@redhat.com> (raw)
In-Reply-To: <20221006153535.1666521-1-adhemerval.zanella@linaro.org>
On 10/6/22 11:35, Adhemerval Zanella wrote:
> Besides the option being gcc specific, this approach is still fragile
> and not future proof since we do not know if this will be the only
> optimization option gcc will add that transforms loops to memset
> (or any libcall).
>
> This patch adds a new header, dl-symbol-redir-ifunc.h, that can b
> used to redirect the compiler generated libcalls to port the generic
> memset implementation if required.
>
> Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Thanks. In v5 you collapse this all to one header and that simplifies things.
LGTM.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
> ---
> elf/Makefile | 5 ---
> elf/dl-support.c | 1 +
> .../aarch64/multiarch/dl-symbol-redir-ifunc.h | 24 ++++++++++++
> sysdeps/generic/dl-symbol-redir-ifunc.h | 38 +++++++++++++++++++
> .../i686/multiarch/dl-symbol-redir-ifunc.h | 24 ++++++++++++
> .../le/multiarch/dl-symbol-redir-ifunc.h | 24 ++++++++++++
> .../s390/multiarch/dl-symbol-redir-ifunc.h | 29 ++++++++++++++
> .../sparcv9/multiarch/dl-symbol-redir-ifunc.h | 24 ++++++++++++
> .../sparc64/multiarch/dl-symbol-redir-ifunc.h | 24 ++++++++++++
> .../x86_64/multiarch/dl-symbol-redir-ifunc.h | 34 +++++++++++++++++
> 10 files changed, 222 insertions(+), 5 deletions(-)
> create mode 100644 sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
> create mode 100644 sysdeps/generic/dl-symbol-redir-ifunc.h
> create mode 100644 sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
> create mode 100644 sysdeps/powerpc/powerpc64/le/multiarch/dl-symbol-redir-ifunc.h
> create mode 100644 sysdeps/s390/multiarch/dl-symbol-redir-ifunc.h
> create mode 100644 sysdeps/sparc/sparc32/sparcv9/multiarch/dl-symbol-redir-ifunc.h
> create mode 100644 sysdeps/sparc/sparc64/multiarch/dl-symbol-redir-ifunc.h
> create mode 100644 sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
>
> diff --git a/elf/Makefile b/elf/Makefile
> index 276343a47f..7b50ccc07a 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
> -
OK.
> # 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..614b5b3e0c 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-redir-ifunc.h>
OK. Include the single header.
>
> extern char *__progname;
> char **_dl_argv = &__progname; /* This is checked for some error messages. */
> diff --git a/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..6ee6537181
> --- /dev/null
> +++ b/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
> @@ -0,0 +1,24 @@
> +/* Symbol rediretion for loader/static initialization code.
OK.
> + 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
> +
> +asm ("memset = __memset_generic");
> +
> +#endif
> diff --git a/sysdeps/generic/dl-symbol-redir-ifunc.h b/sysdeps/generic/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..b4a087e531
> --- /dev/null
> +++ b/sysdeps/generic/dl-symbol-redir-ifunc.h
> @@ -0,0 +1,38 @@
> +/* Symbol rediretion for loader/static initialization code.
OK.
> + 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 make the required redirection to the expected generic
> + implementation if the symbol is provided as iFUNC, with a global definition
> + such as:
> +
> + asm ("memset = __memset_generic");
> + */
> +
> +#endif
OK.
> diff --git a/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..a0c66f8892
> --- /dev/null
> +++ b/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.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
> +
> +asm ("memset = __memset_ia32");
OK.
> +
> +#endif
> diff --git a/sysdeps/powerpc/powerpc64/le/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/powerpc/powerpc64/le/multiarch/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..1883bc3a9d
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/le/multiarch/dl-symbol-redir-ifunc.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
> +
> +asm ("memset = __memset_power8");
OK. POWER8 is the minimum for ppc64le.
> +
> +#endif
> diff --git a/sysdeps/s390/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/s390/multiarch/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..14cdd46808
> --- /dev/null
> +++ b/sysdeps/s390/multiarch/dl-symbol-redir-ifunc.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)
> +
> +asm ("memset = " IFUNC_SYMBOL_STR(MEMSET_DEFAULT));
OK.
> +
> +#endif
> diff --git a/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..42c477b872
> --- /dev/null
> +++ b/sysdeps/sparc/sparc32/sparcv9/multiarch/dl-symbol-redir-ifunc.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
> +
> +asm ("memset = __memset_ultra1");
OK.
> +
> +#endif
> diff --git a/sysdeps/sparc/sparc64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/sparc/sparc64/multiarch/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..42c477b872
> --- /dev/null
> +++ b/sysdeps/sparc/sparc64/multiarch/dl-symbol-redir-ifunc.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
> +
> +asm ("memset = __memset_ultra1");
> +
OK.
> +#endif
> diff --git a/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
> new file mode 100644
> index 0000000000..64f9996854
> --- /dev/null
> +++ b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
> @@ -0,0 +1,34 @@
> +/* 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
> +
> +asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC);
OK.
> +
> +#endif
--
Cheers,
Carlos.
prev parent reply other threads:[~2022-10-10 12:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-06 15:35 Adhemerval Zanella
2022-10-10 12:28 ` Carlos O'Donell [this message]
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