elf: Move vDSO setup to rtld (BZ#24967)

This patch moves the vDSO setup from libc to loader code, just after
the vDSO link_map setup.  For static case the initialization
is moved to _dl_non_dynamic_init instead.

Instead of using the mangled pointer, the vDSO data is set as
attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for
static).  It is read-only even with partial relro.

It fixes BZ#24967 now that the vDSO pointer is setup earlier than
malloc interposition is called.

Also, vDSO calls should not be a problem for static dlopen as
indicated by BZ#20802.  The vDSO pointer would be zero-initialized
and the syscall will be issued instead.

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu,
powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and
sparcv9-linux-gnu.  I also run some tests on mips.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

4 files changed, 2 insertions, 64 deletions

diff --git a/sysdeps/unix/sysv/linux/powerpc/Makefile b/sysdeps/unix/sysv/linux/powerpc/Makefile
index 1596238afa..cc2f804d86 100644
--- a/sysdeps/unix/sysv/linux/powerpc/Makefile
+++ b/sysdeps/unix/sysv/linux/powerpc/Makefile
@@ -13,7 +13,6 @@ gen-as-const-headers += ucontext_i.sym
 endif
 
 ifeq ($(subdir),elf)
-sysdep_routines += dl-vdso
 ifeq ($(build-shared),yes)
 # This is needed for DSO loading from static binaries.
 sysdep-dl-routines += dl-static
diff --git a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
index ebd0d2f880..81f7c73f38 100644
--- a/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
+++ b/sysdeps/unix/sysv/linux/powerpc/get_timebase_freq.c
@@ -21,7 +21,7 @@
 
 #include <libc-internal.h>
 #include <not-cancel.h>
-#include <libc-vdso.h>
+#include <sysdep-vdso.h>
 
 static uint64_t
 get_timebase_freq_fallback (void)
@@ -101,8 +101,7 @@ uint64_t
 __get_timebase_freq (void)
 {
   /* The vDSO does not have a fallback mechanism (such calling a syscall).  */
-  __typeof (VDSO_SYMBOL (get_tbfreq)) vdsop = VDSO_SYMBOL (get_tbfreq);
-  PTR_DEMANGLE (vdsop);
+  uint64_t (*vdsop)(void) = GLRO(dl_vdso_get_tbfreq);
   if (vdsop == NULL)
     return get_timebase_freq_fallback ();
 
diff --git a/sysdeps/unix/sysv/linux/powerpc/init-first.c b/sysdeps/unix/sysv/linux/powerpc/init-first.c
deleted file mode 100644
index d20938c1da..0000000000
--- a/sysdeps/unix/sysv/linux/powerpc/init-first.c
+++ /dev/null
@@ -1,50 +0,0 @@
-/* Initialization code run first thing by the ELF startup code.  Linux/PowerPC.
-   Copyright (C) 2007-2020 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 <dl-vdso.h>
-#include <libc-vdso.h>
-
-unsigned long long (*VDSO_SYMBOL(get_tbfreq)) (void) attribute_hidden;
-#if defined(__PPC64__) || defined(__powerpc64__)
-void *VDSO_SYMBOL(sigtramp_rt64) attribute_hidden;
-#else
-void *VDSO_SYMBOL(sigtramp32) attribute_hidden;
-void *VDSO_SYMBOL(sigtramp_rt32) attribute_hidden;
-#endif
-
-static inline void
-__libc_vdso_platform_setup_arch (void)
-{
-  VDSO_SYMBOL (get_tbfreq) = get_vdso_mangle_symbol (HAVE_GET_TBFREQ);
-
-  /* PPC64 uses only one signal trampoline symbol, while PPC32 will use
-     two depending if SA_SIGINFO is used (__kernel_sigtramp_rt32) or not
-     (__kernel_sigtramp32).
-     There is no need to pointer mangle these symbol because they will
-     used only for pointer comparison.  */
-#if defined(__PPC64__) || defined(__powerpc64__)
-  VDSO_SYMBOL(sigtramp_rt64) =  get_vdso_symbol (HAVE_SIGTRAMP_RT64);
-#else
-  VDSO_SYMBOL(sigtramp32) = get_vdso_symbol (HAVE_SIGTRAMP_32);
-  VDSO_SYMBOL(sigtramp_rt32) = get_vdso_symbol (HAVE_SIGTRAMP_RT32);
-#endif
-}
-
-#define VDSO_SETUP_ARCH __libc_vdso_platform_setup_arch
-
-#include <sysdeps/unix/sysv/linux/init-first.c>
diff --git a/sysdeps/unix/sysv/linux/powerpc/libc-vdso.h b/sysdeps/unix/sysv/linux/powerpc/libc-vdso.h
index 2f18a762d8..8dae14057c 100644
--- a/sysdeps/unix/sysv/linux/powerpc/libc-vdso.h
+++ b/sysdeps/unix/sysv/linux/powerpc/libc-vdso.h
@@ -54,14 +54,4 @@
 # define VDSO_IFUNC_RET(value)  ((void *) (value))
 #endif
 
-#include_next <libc-vdso.h>
-
-extern unsigned long long (*VDSO_SYMBOL(get_tbfreq)) (void);
-#if defined(__PPC64__) || defined(__powerpc64__)
-extern void *VDSO_SYMBOL(sigtramp_rt64);
-#else
-extern void *VDSO_SYMBOL(sigtramp32);
-extern void *VDSO_SYMBOL(sigtramp_rt32);
-#endif
-
 #endif /* _LIBC_VDSO_H */