elf: Use the minimal malloc on tunables_strdup

The rtld_malloc functions are moved to its own file so it can be
used on csu code.  Also, the functiosn are renamed to __minimal_*
(since there are now used not only on loader code).

Using the __minimal_malloc on tunables_strdup() avoids potential
issues with sbrk() calls while processing the tunables (I see
sporadic elf/tst-dso-ordering9 on powerpc64le with different
tests failing due ASLR).

Also, using __minimal_malloc over plain mmap optimizes the memory
allocation on both static and dynamic case (since it will any unused
space in either the last page of data segments, avoiding mmap() call,
or from the previous mmap() call).

Checked on x86_64-linux-gnu, i686-linux-gnu, and powerpc64le-linux-gnu.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

1 files changed, 28 insertions, 0 deletions

diff --git a/sysdeps/generic/dl-minimal-malloc.h b/sysdeps/generic/dl-minimal-malloc.h
new file mode 100644
index 0000000000..7f50e52df5
--- /dev/null
+++ b/sysdeps/generic/dl-minimal-malloc.h
@@ -0,0 +1,28 @@
+/* Minimal malloc implementation for dynamic linker and static
+   initialization.
+   Copyright (C) 2021 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_MINIMAL_MALLOC_H
+#define _DL_MINIMAL_MALLOC_H
+
+extern void *__minimal_malloc (size_t n) attribute_hidden;
+extern void *__minimal_calloc (size_t nmemb, size_t size) attribute_hidden;
+extern void __minimal_free (void *ptr) attribute_hidden;
+extern void *__minimal_realloc (void *ptr, size_t n) attribute_hidden;
+
+#endif