[hurd,commited] hurd: break relocation loop between libc.so and lib{mach, hurd}user.so
Commit Message
See
https://sourceware.org/pipermail/libc-alpha/2020-November/119575.html
lib{mach,hurd}user.so gets relocated before libc.so, but its references
to strpcpy and memcpy would need an ifunc decision, which e.g. on
x86 relies on cpu_features, but libc.so's _rtld_global_ro is not
relocated yet.
We can however just make lib{mach,hurd}user.so only call non-ifunc
functions, which can be relocated before libc.so is relocated.
---
mach/Makefile | 2 +-
mach/Versions | 4 ++++
mach/mach/mig_support.h | 15 +-------------
mach/mig_memcpy.c | 26 +++++++++++++++++++++++++
sysdeps/mach/include/mach/mig_support.h | 12 ++++++++++++
5 files changed, 44 insertions(+), 15 deletions(-)
create mode 100644 mach/mig_memcpy.c
@@ -25,7 +25,7 @@ headers = mach_init.h mach.h mach_error.h mach-shortcuts.h mach/mach_traps.h \
lock = spin-solid spin-lock mutex-init mutex-solid
lock-headers = lock-intern.h spin-lock.h
routines = $(mach-syscalls) $(mach-shortcuts) \
- mach_init mig_strncpy msg \
+ mach_init mig_strncpy mig_memcpy msg \
mig-alloc mig-dealloc mig-reply \
msg-destroy msgserver \
mach_error errstring error_compat errsystems \
@@ -68,4 +68,8 @@ libc {
__spin_lock; __spin_lock_init; __spin_lock_solid; __spin_try_lock;
__spin_unlock;
}
+ GLIBC_PRIVATE {
+ # functions used by RPC stubs
+ __mig_memcpy;
+ }
}
@@ -54,19 +54,6 @@ extern void mig_reply_setup (const mach_msg_header_t *__request,
extern vm_size_t mig_strncpy (char *__dst, const char *__src, vm_size_t __len);
extern vm_size_t __mig_strncpy (char *__dst, const char *__src, vm_size_t);
-#if defined __USE_EXTERN_INLINES && defined _LIBC
-__extern_inline vm_size_t
-__mig_strncpy (char *__dst, const char *__src, vm_size_t __len)
-{
- return __stpncpy (__dst, __src, __len) - __dst;
-}
-__extern_inline vm_size_t
-mig_strncpy (char *__dst, const char *__src, vm_size_t __len)
-{
- return __mig_strncpy (__dst, __src, __len);
-}
-#endif
-
-
+extern void *__mig_memcpy (void *__dst, const void *__src, vm_size_t __len);
#endif /* mach/mig_support.h */
new file mode 100644
@@ -0,0 +1,26 @@
+/* memcpy stub for mig stubs in libmachuser and libhurduser.
+ Copyright (C) 2020 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 <mach.h>
+#include <string.h>
+
+void *
+__mig_memcpy (void *dst, const void *src, vm_size_t len)
+{
+ return memcpy (dst, src, len);
+}
@@ -4,5 +4,17 @@
libc_hidden_proto (__mig_get_reply_port)
libc_hidden_proto (__mig_dealloc_reply_port)
libc_hidden_proto (__mig_init)
+
+#ifdef _LIBC
+# include <libc-symbols.h>
+
+# if defined USE_MULTIARCH && (IS_IN (libmachuser) || IS_IN (libhurduser))
+/* Avoid directly calling ifunc-enabled memcpy or strpcpy,
+ because they would introduce a relocation loop between lib*user and
+ libc.so. */
+# define memcpy(dest, src, n) __mig_memcpy(dest, src, n)
+# endif
+#endif
+
#endif
#endif