1 files changed, 74 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/malloc-hugepages.c b/sysdeps/unix/sysv/linux/malloc-hugepages.c
new file mode 100644
index 0000000000..7497e07260
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/malloc-hugepages.c
@@ -0,0 +1,74 @@
+/* Huge Page support.  Linux implementation.
+   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; see the file COPYING.LIB.  If
+   not, see <https://www.gnu.org/licenses/>.  */
+
+#include <intprops.h>
+#include <malloc-hugepages.h>
+#include <not-cancel.h>
+
+unsigned long int
+__malloc_default_thp_pagesize (void)
+{
+  int fd = __open64_nocancel (
+    "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", O_RDONLY);
+  if (fd == -1)
+    return 0;
+
+  char str[INT_BUFSIZE_BOUND (unsigned long int)];
+  ssize_t s = __read_nocancel (fd, str, sizeof (str));
+  __close_nocancel (fd);
+  if (s < 0)
+    return 0;
+
+  unsigned long int r = 0;
+  for (ssize_t i = 0; i < s; i++)
+    {
+      if (str[i] == '\n')
+	break;
+      r *= 10;
+      r += str[i] - '0';
+    }
+  return r;
+}
+
+enum malloc_thp_mode_t
+__malloc_thp_mode (void)
+{
+  int fd = __open64_nocancel ("/sys/kernel/mm/transparent_hugepage/enabled",
+			      O_RDONLY);
+  if (fd == -1)
+    return malloc_thp_mode_not_supported;
+
+  static const char mode_always[]  = "[always] madvise never\n";
+  static const char mode_madvise[] = "always [madvise] never\n";
+  static const char mode_never[]   = "always madvise [never]\n";
+
+  char str[sizeof(mode_always)];
+  ssize_t s = __read_nocancel (fd, str, sizeof (str));
+  __close_nocancel (fd);
+
+  if (s == sizeof (mode_always) - 1)
+    {
+      if (strcmp (str, mode_always) == 0)
+	return malloc_thp_mode_always;
+      else if (strcmp (str, mode_madvise) == 0)
+	return malloc_thp_mode_madvise;
+      else if (strcmp (str, mode_never) == 0)
+	return malloc_thp_mode_never;
+    }
+  return malloc_thp_mode_not_supported;
+}