When using some libthread, we need to update the value of __libc_stack_end
to what the libthread allocated. This requires making __libc_stack_end
non-relro to be able to modify it.
Samuel
2011-08-24 Samuel Thibault <samuel.thiba...@ens-lyon.org>
* sysdeps/generic/ldsodefs.h [LIBC_STACK_END_NOT_RELRO] (__libc_stack_end): Do
not use attribute_relro.
* sysdeps/mach/hurd/dl-sysdep.h (LIBC_STACK_END_NOT_RELRO): Define.
* sysdeps/mach/hurd/i386/init-first.c (init): Update __libc_stack_end to
libthread-provided value.
* sysdeps/mach/hurd/dl-sysdep.c (__libc_stack_end): Do not use attribute_relro.
---
generic/ldsodefs.h | 6 +++++-
mach/hurd/dl-sysdep.c | 2 +-
mach/hurd/dl-sysdep.h | 3 ++-
mach/hurd/i386/init-first.c | 2 ++
4 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index d040590..cb24ca7 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -723,7 +723,11 @@ rtld_hidden_proto (_dl_make_stack_executable)
might use the variable which results in copy relocations on some
platforms. But this does not matter, ld.so can always use the local
copy. */
-extern void *__libc_stack_end attribute_relro;
+extern void *__libc_stack_end
+#ifndef LIBC_STACK_END_NOT_RELRO
+ attribute_relro
+#endif
+ ;
rtld_hidden_proto (__libc_stack_end)
/* Parameters passed to the dynamic linker. */
diff --git a/sysdeps/mach/hurd/dl-sysdep.h b/sysdeps/mach/hurd/dl-sysdep.h
index 4b21b77..8f1c728 100644
--- a/sysdeps/mach/hurd/dl-sysdep.h
+++ b/sysdeps/mach/hurd/dl-sysdep.h
@@ -25,7 +25,8 @@
#define RTLD_PRIVATE_ERRNO 0
#ifdef SHARED
-/* _dl_argv cannot be attribute_relro, because the stack-switching
+/* _dl_argv and __libc_stack_end cannot be attribute_relro, because the
stack-switching
libc initializer for using cthreads might write into it. */
# define DL_ARGV_NOT_RELRO 1
+# define LIBC_STACK_END_NOT_RELRO 1
#endif
diff --git a/sysdeps/mach/hurd/i386/init-first.c
b/sysdeps/mach/hurd/i386/init-first.c
index e79af1d..7b2ea12 100644
--- a/sysdeps/mach/hurd/i386/init-first.c
+++ b/sysdeps/mach/hurd/i386/init-first.c
@@ -227,6 +224,8 @@ init (int *_data)
void switch_stacks (void);
+ __libc_stack_end = newsp;
+
/* Copy per-thread variables from that temporary
area onto the new cthread stack. */
memcpy (__hurd_threadvar_location_from_sp (0, newsp),
diff --git a/sysdeps/mach/hurd/dl-sysdep.c b/sysdeps/mach/hurd/dl-sysdep.c
index a63151f..a5df5c1 100644
--- a/sysdeps/mach/hurd/dl-sysdep.c
+++ b/sysdeps/mach/hurd/dl-sysdep.c
@@ -55,7 +55,7 @@ INTVARDEF(__libc_enable_secure)
int __libc_multiple_libcs = 0; /* Defining this here avoids the inclusion
of init-first. */
/* This variable containts the lowest stack address ever used. */
-void *__libc_stack_end attribute_relro = NULL;
+void *__libc_stack_end = NULL;
rtld_hidden_data_def(__libc_stack_end)
void *_dl_random attribute_relro = NULL; /* TODO */
