elf: Remove -fno-tree-loop-distribute-patterns usage on dl-support

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.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>

diff --git a/elf/Makefile b/elf/Makefile
index 276343a47f2d30b5e6fe4c5b41f3a0a6d7799c46..7b50ccc07ad22bfffe2cec36cba13d6665540f48 100644 (file)
--- 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 4af0b5b2ce23a762bd78d29747f50b0e1210680d..614b5b3e0c9594b1e45186d8165941c79086340e 100644 (file)
--- 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>
 
 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 (file)
index 0000000..6ee6537
--- /dev/null
+++ b/sysdeps/aarch64/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_generic");
+
+#endif

diff --git a/sysdeps/generic/dl-symbol-redir-ifunc.h b/sysdeps/generic/dl-symbol-redir-ifunc.h
new file mode 100644 (file)
index 0000000..b4a087e
--- /dev/null
+++ b/sysdeps/generic/dl-symbol-redir-ifunc.h
@@ -0,0 +1,38 @@
+/* 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 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

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 (file)
index 0000000..a0c66f8
--- /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");
+
+#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 (file)
index 0000000..1883bc3
--- /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");
+
+#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 (file)
index 0000000..14cdd46
--- /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));
+
+#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 (file)
index 0000000..42c477b
--- /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");
+
+#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 (file)
index 0000000..42c477b
--- /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");
+
+#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 (file)
index 0000000..64f9996
--- /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);
+
+#endif