Define PTHREAD_STACK_MIN to sysconf(_SC_THREAD_STACK_MIN)

The constant PTHREAD_STACK_MIN may be too small for some processors.
Rename _SC_SIGSTKSZ_SOURCE to _DYNAMIC_STACK_SIZE_SOURCE.  When
_DYNAMIC_STACK_SIZE_SOURCE or _GNU_SOURCE are defined, define
PTHREAD_STACK_MIN to sysconf(_SC_THREAD_STACK_MIN) which is changed
to MIN (PTHREAD_STACK_MIN, sysconf(_SC_MINSIGSTKSZ)).

Consolidate <bits/local_lim.h> with <bits/pthread_stack_min.h> to
provide a constant target specific PTHREAD_STACK_MIN value.

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

1 files changed, 39 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/sysconf-pthread_stack_min.h b/sysdeps/unix/sysv/linux/sysconf-pthread_stack_min.h
new file mode 100644
index 0000000000..9e0eb0f7fc
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sysconf-pthread_stack_min.h
@@ -0,0 +1,39 @@
+/* __get_pthread_stack_min ().  Linux version.
+   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/>.  */
+
+/* Return sysconf (_SC_THREAD_STACK_MIN).  */
+
+static inline long int
+__get_pthread_stack_min (void)
+{
+  /* sysconf (_SC_THREAD_STACK_MIN) >= sysconf (_SC_MINSIGSTKSZ).  */
+  long int pthread_stack_min = GLRO(dl_minsigstacksize);
+  assert (pthread_stack_min != 0);
+  _Static_assert (__builtin_constant_p (PTHREAD_STACK_MIN),
+		  "PTHREAD_STACK_MIN is constant");
+  /* Return MAX (PTHREAD_STACK_MIN, pthread_stack_min).  */
+  if (pthread_stack_min < PTHREAD_STACK_MIN)
+    pthread_stack_min = PTHREAD_STACK_MIN;
+  /* We have a private interface, __pthread_get_minstack@GLIBC_PRIVATE
+     which returns a larger size that includes the required TLS variable
+     space which has been determined at startup.  For sysconf here we are
+     conservative and don't include the space required for TLS access.
+     Eventually the TLS variable space will not be part of the stack
+     (Bug 11787).  */
+  return pthread_stack_min;
+}