#
# commit 76a9b9986141b1a7d9fd290c349d27fcee780c7a
# Author: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
# Date:   Thu Nov 7 05:34:22 2013 -0600
# 
#     PowerPC: Fix vDSO missing ODP entries
#    
#     This patch fixes the vDSO symbol used directed in IFUNC resolver where
#     they do not have an associated ODP entry leading to undefined behavior
#     in some cases. It adds an artificial OPD static entry to such cases
#     and set its TOC to non 0 to avoid triggering lazy resolutions.
#
diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h	2015-01-15 16:05:08.853681325 -0500
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h	2015-01-15 16:06:11.451747716 -0500
@@ -34,12 +34,32 @@
 
 extern void *__vdso_time;
 
-/* This macro is needed for PPC64 to return a skeleton OPD entry of a vDSO
-   symbol.  This works because _dl_vdso_vsym always return the function
-   address, and no vDSO symbols use the TOC or chain pointers from the OPD
-   so we can allow them to be garbage.  */
-#if defined(__PPC64__) || defined(__powerpc64__)
-#define VDSO_IFUNC_RET(value)  ((void *) &(value))
+/* The correct solution is for _dl_vdso_vsym to return the address of the OPD
+   for the kernel VDSO function.  That address would then be stored in the
+   __vdso_* variables and returned as the result of the IFUNC resolver function.
+   Yet, the kernel does not contain any OPD entries for the VDSO functions
+   (incomplete implementation).  However, PLT relocations for IFUNCs still expect
+   the address of an OPD to be returned from the IFUNC resolver function (since
+   PLT entries on PPC64 are just copies of OPDs).  The solution for now is to
+   create an artificial static OPD for each VDSO function returned by a resolver
+   function.  The TOC value is set to a non-zero value to avoid triggering lazy
+   symbol resolution via .glink0/.plt0 for a zero TOC (requires thread-safe PLT
+   sequences) when the dynamic linker isn't prepared for it e.g. RTLD_NOW.  None
+   of the kernel VDSO routines use the TOC or AUX values so any non-zero value
+   will work.  Note that function pointer comparisons will not use this artificial
+   static OPD since those are resolved via ADDR64 relocations and will point at
+   the non-IFUNC default OPD for the symbol.  Lastly, because the IFUNC relocations
+   are processed immediately at startup the resolver functions and this code need
+   not be thread-safe, but if the caller writes to a PLT slot it must do so in a
+   thread-safe manner with all the required barriers.  */
+#if (defined(__PPC64__) || defined(__powerpc64__)) && _CALL_ELF != 2
+#define VDSO_IFUNC_RET(value)                            \
+  ({                                                     \
+    static Elf64_FuncDesc vdso_opd = { .fd_toc = ~0x0 }; \
+    vdso_opd.fd_func = (Elf64_Addr)value;                \
+    &vdso_opd;                                           \
+  })
+
 #else
 #define VDSO_IFUNC_RET(value)  ((void *) (value))
 #endif
diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c	2015-01-15 16:05:08.912679502 -0500
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c	2015-01-15 16:06:11.451747716 -0500
@@ -21,6 +21,7 @@
 
 # include <dl-vdso.h>
 # include <bits/libc-vdso.h>
+# include <dl-machine.h>
 
 void *gettimeofday_ifunc (void) __asm__ ("__gettimeofday");
 
diff -urN glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/time.c glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/time.c
--- glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/time.c	2015-01-15 16:05:08.912679502 -0500
+++ glibc-2.17-c758a686/sysdeps/unix/sysv/linux/powerpc/time.c	2015-01-15 16:06:11.451747716 -0500
@@ -20,7 +20,9 @@
 
 # include <time.h>
 # include <sysdep.h>
+# include <dl-vdso.h>
 # include <bits/libc-vdso.h>
+# include <dl-machine.h>
 
 void *time_ifunc (void) asm ("time");