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hurd: break relocation loop between libc.so and lib{mach,hurd}user.so

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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.
This commit is contained in:
Samuel Thibault 2020-11-13 15:56:51 +00:00
parent a24f414ba1
commit 56010b73e8
5 changed files with 44 additions and 15 deletions
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2
mach/Makefile
View File

@ -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 \

4
mach/Versions
View File

@ -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;
}
}

15
mach/mach/mig_support.h
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@ -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 */

26
mach/mig_memcpy.c Normal file
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@ -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);
}

12
sysdeps/mach/include/mach/mig_support.h
View File

@ -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