Fix compilation with -fno-common.

Making all other archs consistent with IA64 which should not have this problem.
Also move the FIXME to the correct place.

Also add some minimum comments about this...

15 files changed, 89 insertions, 80 deletions

diff --git a/src/aarch64/Ginit.c b/src/aarch64/Ginit.c
index dec235c8..35389762 100644
--- a/src/aarch64/Ginit.c
+++ b/src/aarch64/Ginit.c
@@ -61,13 +61,6 @@ tdep_uc_addr (unw_tdep_context_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -78,7 +71,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/arm/Ginit.c b/src/arm/Ginit.c
index 2720d063..0bac0d72 100644
--- a/src/arm/Ginit.c
+++ b/src/arm/Ginit.c
@@ -57,18 +57,17 @@ tdep_uc_addr (unw_tdep_context_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/coredump/_UPT_get_dyn_info_list_addr.c b/src/coredump/_UPT_get_dyn_info_list_addr.c
index 0d119055..739ed056 100644
--- a/src/coredump/_UPT_get_dyn_info_list_addr.c
+++ b/src/coredump/_UPT_get_dyn_info_list_addr.c
@@ -74,6 +74,11 @@ get_list_addr (unw_addr_space_t as, unw_word_t *dil_addr, void *arg,
 
 #else
 
+/* XXX fix me: there is currently no way to locate the dyn-info list
+       by a remote unwinder.  On ia64, this is done via a special
+       unwind-table entry.  Perhaps something similar can be done with
+       DWARF2 unwind info.  */
+
 static inline int
 get_list_addr (unw_addr_space_t as, unw_word_t *dil_addr, void *arg,
                int *countp)
diff --git a/src/hppa/Ginit.c b/src/hppa/Ginit.c
index 461e4b93..265455a6 100644
--- a/src/hppa/Ginit.c
+++ b/src/hppa/Ginit.c
@@ -64,13 +64,6 @@ _Uhppa_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -81,7 +74,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/ia64/Ginit.c b/src/ia64/Ginit.c
index b09a2ad5..8601bb3c 100644
--- a/src/ia64/Ginit.c
+++ b/src/ia64/Ginit.c
@@ -68,6 +68,7 @@ get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
   if (!_U_dyn_info_list_addr)
     return -UNW_ENOINFO;
 #endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
   *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
diff --git a/src/mi/Gfind_dynamic_proc_info.c b/src/mi/Gfind_dynamic_proc_info.c
index 98d35012..2e7c62e5 100644
--- a/src/mi/Gfind_dynamic_proc_info.c
+++ b/src/mi/Gfind_dynamic_proc_info.c
@@ -49,6 +49,7 @@ local_find_proc_info (unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
     return -UNW_ENOINFO;
 #endif
 
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
   list = (unw_dyn_info_list_t *) (uintptr_t) _U_dyn_info_list_addr ();
   for (di = list->first; di; di = di->next)
     if (ip >= di->start_ip && ip < di->end_ip)
diff --git a/src/mips/Ginit.c b/src/mips/Ginit.c
index 3df170c7..bf7a8f5a 100644
--- a/src/mips/Ginit.c
+++ b/src/mips/Ginit.c
@@ -69,13 +69,6 @@ tdep_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -86,7 +79,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) (intptr_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/ppc32/Ginit.c b/src/ppc32/Ginit.c
index ba302448..7b454558 100644
--- a/src/ppc32/Ginit.c
+++ b/src/ppc32/Ginit.c
@@ -91,9 +91,6 @@ tdep_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -104,7 +101,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/ppc64/Ginit.c b/src/ppc64/Ginit.c
index 4c88cd6e..7bfb395a 100644
--- a/src/ppc64/Ginit.c
+++ b/src/ppc64/Ginit.c
@@ -95,9 +95,6 @@ tdep_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -108,7 +105,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/ptrace/_UPT_get_dyn_info_list_addr.c b/src/ptrace/_UPT_get_dyn_info_list_addr.c
index cc5ed044..16671d45 100644
--- a/src/ptrace/_UPT_get_dyn_info_list_addr.c
+++ b/src/ptrace/_UPT_get_dyn_info_list_addr.c
@@ -71,6 +71,11 @@ get_list_addr (unw_addr_space_t as, unw_word_t *dil_addr, void *arg,
 
 #else
 
+/* XXX fix me: there is currently no way to locate the dyn-info list
+       by a remote unwinder.  On ia64, this is done via a special
+       unwind-table entry.  Perhaps something similar can be done with
+       DWARF2 unwind info.  */
+
 static inline int
 get_list_addr (unw_addr_space_t as, unw_word_t *dil_addr, void *arg,
                int *countp)
diff --git a/src/s390x/Ginit.c b/src/s390x/Ginit.c
index f0886ac9..db01743c 100644
--- a/src/s390x/Ginit.c
+++ b/src/s390x/Ginit.c
@@ -50,8 +50,6 @@ static struct unw_addr_space local_addr_space;
 
 unw_addr_space_t unw_local_addr_space = &local_addr_space;
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
 static inline void *
 uc_addr (ucontext_t *uc, int reg)
 {
@@ -75,11 +73,6 @@ tdep_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -90,7 +83,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/sh/Ginit.c b/src/sh/Ginit.c
index 52988a72..9fe96d2b 100644
--- a/src/sh/Ginit.c
+++ b/src/sh/Ginit.c
@@ -58,13 +58,6 @@ tdep_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -75,7 +68,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/tilegx/Ginit.c b/src/tilegx/Ginit.c
index 7564a558..925e6413 100644
--- a/src/tilegx/Ginit.c
+++ b/src/tilegx/Ginit.c
@@ -64,13 +64,6 @@ tdep_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -81,7 +74,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) (intptr_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/x86/Ginit.c b/src/x86/Ginit.c
index f6b8dc27..3cec74a2 100644
--- a/src/x86/Ginit.c
+++ b/src/x86/Ginit.c
@@ -54,13 +54,6 @@ tdep_uc_addr (ucontext_t *uc, int reg)
 
 # endif /* UNW_LOCAL_ONLY */
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -71,7 +64,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }
 
diff --git a/src/x86_64/Ginit.c b/src/x86_64/Ginit.c
index a865d338..fd8d418b 100644
--- a/src/x86_64/Ginit.c
+++ b/src/x86_64/Ginit.c
@@ -49,13 +49,6 @@ static struct unw_addr_space local_addr_space;
 
 unw_addr_space_t unw_local_addr_space = &local_addr_space;
 
-HIDDEN unw_dyn_info_list_t _U_dyn_info_list;
-
-/* XXX fix me: there is currently no way to locate the dyn-info list
-       by a remote unwinder.  On ia64, this is done via a special
-       unwind-table entry.  Perhaps something similar can be done with
-       DWARF2 unwind info.  */
-
 static void
 put_unwind_info (unw_addr_space_t as, unw_proc_info_t *proc_info, void *arg)
 {
@@ -66,7 +59,13 @@ static int
 get_dyn_info_list_addr (unw_addr_space_t as, unw_word_t *dyn_info_list_addr,
                         void *arg)
 {
-  *dyn_info_list_addr = (unw_word_t) &_U_dyn_info_list;
+#ifndef UNW_LOCAL_ONLY
+# pragma weak _U_dyn_info_list_addr
+  if (!_U_dyn_info_list_addr)
+    return -UNW_ENOINFO;
+#endif
+  // Access the `_U_dyn_info_list` from `LOCAL_ONLY` library, i.e. libunwind.so.
+  *dyn_info_list_addr = _U_dyn_info_list_addr ();
   return 0;
 }