Merge "Make static ifunc resolvers optional."ndk-r20bndk-r20-beta3ndk-r20-beta2ndk-r20-beta1ndk-r20ndk-release-r20

1 files changed, 24 insertions, 2 deletions

diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index 3219239b7..41f100dbb 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -67,9 +67,20 @@ static void call_array(void(**list)()) {
 }
 
 #if defined(__aarch64__) || defined(__x86_64__)
-extern __LIBC_HIDDEN__ ElfW(Rela) __rela_iplt_start[], __rela_iplt_end[];
+extern __LIBC_HIDDEN__ __attribute__((weak)) ElfW(Rela) __rela_iplt_start[], __rela_iplt_end[];
 
 static void call_ifunc_resolvers() {
+  if (__rela_iplt_start == nullptr || __rela_iplt_end == nullptr) {
+    // These symbols are not emitted by gold. Gold has code to do so, but for
+    // whatever reason it is not being run. In these cases ifuncs cannot be
+    // resolved, so we do not support using ifuncs in static executables linked
+    // with gold.
+    //
+    // Since they are weak, they will be non-null when linked with bfd/lld and
+    // null when linked with gold.
+    return;
+  }
+
   typedef ElfW(Addr) (*ifunc_resolver_t)(void);
   for (ElfW(Rela) *r = __rela_iplt_start; r != __rela_iplt_end; ++r) {
     ElfW(Addr)* offset = reinterpret_cast<ElfW(Addr)*>(r->r_offset);
@@ -78,9 +89,20 @@ static void call_ifunc_resolvers() {
   }
 }
 #else
-extern __LIBC_HIDDEN__ ElfW(Rel) __rel_iplt_start[], __rel_iplt_end[];
+extern __LIBC_HIDDEN__ __attribute__((weak)) ElfW(Rel) __rel_iplt_start[], __rel_iplt_end[];
 
 static void call_ifunc_resolvers() {
+  if (__rel_iplt_start == nullptr || __rel_iplt_end == nullptr) {
+    // These symbols are not emitted by gold. Gold has code to do so, but for
+    // whatever reason it is not being run. In these cases ifuncs cannot be
+    // resolved, so we do not support using ifuncs in static executables linked
+    // with gold.
+    //
+    // Since they are weak, they will be non-null when linked with bfd/lld and
+    // null when linked with gold.
+    return;
+  }
+
   typedef ElfW(Addr) (*ifunc_resolver_t)(void);
   for (ElfW(Rel) *r = __rel_iplt_start; r != __rel_iplt_end; ++r) {
     ElfW(Addr)* offset = reinterpret_cast<ElfW(Addr)*>(r->r_offset);