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>

2 files changed, 12 insertions, 12 deletions

diff --git a/sysdeps/powerpc/powerpc32/backtrace.c b/sysdeps/powerpc/powerpc32/backtrace.c
index 4a35588671..7c2d4726f8 100644
--- a/sysdeps/powerpc/powerpc32/backtrace.c
+++ b/sysdeps/powerpc/powerpc32/backtrace.c
@@ -51,14 +51,14 @@ struct signal_frame_32 {
   /* We don't care about the rest, since IP value is at 'mctx' field.  */
 };
 
-static inline int
+static inline bool
 is_sigtramp_address (void *nip)
 {
 #ifdef HAVE_SIGTRAMP_RT32
-  if (nip == VDSO_SYMBOL (sigtramp32))
-    return 1;
+  if (nip == GLRO (dl_vdso_sigtramp_32))
+    return true;
 #endif
-  return 0;
+  return false;
 }
 
 struct rt_signal_frame_32 {
@@ -68,14 +68,14 @@ struct rt_signal_frame_32 {
   /* We don't care about the rest, since IP value is at 'uc' field.  */
 };
 
-static inline int
+static inline bool
 is_sigtramp_address_rt (void * nip)
 {
 #ifdef HAVE_SIGTRAMP_32
-  if (nip == VDSO_SYMBOL (sigtramp_rt32))
-    return 1;
+  if (nip == GLRO (dl_vdso_sigtramp_rt32))
+    return true;
 #endif
-  return 0;
+  return false;
 }
 
 int
diff --git a/sysdeps/powerpc/powerpc64/backtrace.c b/sysdeps/powerpc/powerpc64/backtrace.c
index ee8ba21f27..65c260ab76 100644
--- a/sysdeps/powerpc/powerpc64/backtrace.c
+++ b/sysdeps/powerpc/powerpc64/backtrace.c
@@ -54,14 +54,14 @@ struct signal_frame_64 {
   /* We don't care about the rest, since the IP value is at 'uc' field.  */
 };
 
-static inline int
+static inline bool
 is_sigtramp_address (void *nip)
 {
 #ifdef HAVE_SIGTRAMP_RT64
-  if (nip == VDSO_SYMBOL (sigtramp_rt64))
-    return 1;
+  if (nip == GLRO (dl_vdso_sigtramp_rt64))
+    return true;
 #endif
-  return 0;
+  return false;
 }
 
 int