csu: Implement and use _dl_early_allocate during static startup

This implements mmap fallback for a brk failure during TLS
allocation.

scripts/tls-elf-edit.py is updated to support the new patching method.
The script no longer requires that in the input object is of ET_DYN
type.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

3 files changed, 80 insertions, 0 deletions

diff --git a/elf/Makefile b/elf/Makefile
index fc9860edee..ce3345ed92 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -33,6 +33,7 @@ routines = \
   $(all-dl-routines) \
   dl-addr \
   dl-addr-obj \
+  dl-early_allocate \
   dl-error \
   dl-iteratephdr \
   dl-libc \
@@ -108,6 +109,7 @@ all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
 # But they are absent from the shared libc, because that code is in ld.so.
 elide-routines.os = \
   $(all-dl-routines) \
+  dl-early_allocate \
   dl-exception \
   dl-origin \
   dl-reloc-static-pie \
@@ -276,6 +278,7 @@ tests-static-normal := \
   tst-linkall-static \
   tst-single_threaded-pthread-static \
   tst-single_threaded-static \
+  tst-tls-allocation-failure-static \
   tst-tlsalign-extern-static \
   tst-tlsalign-static \
   # tests-static-normal
@@ -1213,6 +1216,10 @@ $(objpfx)tst-glibcelf.out: tst-glibcelf.py elf.h $(..)/scripts/glibcelf.py \
           --cc="$(CC) $(patsubst -DMODULE_NAME=%,-DMODULE_NAME=testsuite,$(CPPFLAGS))" \
 	  < /dev/null > $@ 2>&1; $(evaluate-test)
 
+ifeq ($(run-built-tests),yes)
+tests-special += $(objpfx)tst-tls-allocation-failure-static-patched.out
+endif
+
 # The test requires shared _and_ PIE because the executable
 # unit test driver must be able to link with the shared object
 # that is going to eventually go into an installed DSO.
@@ -2937,3 +2944,15 @@ $(eval $(call tst-trace-skeleton,4,\
 	$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4))
 $(eval $(call tst-trace-skeleton,5,\
 	$(objpfx)libtracemod2:$(objpfx)libtracemod3:$(objpfx)libtracemod4:$(objpfx)libtracemod5))
+
+$(objpfx)tst-tls-allocation-failure-static-patched: \
+  $(objpfx)tst-tls-allocation-failure-static $(..)scripts/tst-elf-edit.py
+	cp $< $@
+	$(PYTHON) $(..)scripts/tst-elf-edit.py --maximize-tls-size $@
+
+$(objpfx)tst-tls-allocation-failure-static-patched.out: \
+  $(objpfx)tst-tls-allocation-failure-static-patched
+	$< > $@ 2>&1; echo "status: $$?" >> $@
+	grep -q '^Fatal glibc error: Cannot allocate TLS block$$' $@ \
+	  && grep -q '^status: 127$$' $@; \
+	  $(evaluate-test)
diff --git a/elf/dl-early_allocate.c b/elf/dl-early_allocate.c
new file mode 100644
index 0000000000..61677aaa03
--- /dev/null
+++ b/elf/dl-early_allocate.c
@@ -0,0 +1,30 @@
+/* Early memory allocation for the dynamic loader.  Generic version.
+   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/>.  */
+
+#include <ldsodefs.h>
+#include <stddef.h>
+#include <unistd.h>
+
+void *
+_dl_early_allocate (size_t size)
+{
+  void *result = __sbrk (size);
+  if (result == (void *) -1)
+    result = NULL;
+  return result;
+}
diff --git a/elf/tst-tls-allocation-failure-static.c b/elf/tst-tls-allocation-failure-static.c
new file mode 100644
index 0000000000..8de831b246
--- /dev/null
+++ b/elf/tst-tls-allocation-failure-static.c
@@ -0,0 +1,31 @@
+/* Base for test program with impossiblyh large PT_TLS segment.
+   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/>.  */
+
+/* The test actual binary is patched using scripts/tst-elf-edit.py
+   --maximize-tls-size, and this introduces the expected test
+   allocation failure due to an excessive PT_LS p_memsz value.
+
+   Patching the binary is required because on some 64-bit targets, TLS
+   relocations can only cover a 32-bit range, and glibc-internal TLS
+   variables such as errno end up outside that range.  */
+
+int
+main (void)
+{
+  return 0;
+}