Remove caching of emit_address for kernel modules and shared libraries.

Caching of the address is only safe for kernel addresses that can never
change. For kernel module or dynamic shared library addresses it isn't
safe to cache the address since they can be unloaded, reloaded or mapped
differently in separate executables.

* dwflpp.cxx (emit_address): Remove static from addr definition for
  kernel and dynamic modules.

1 files changed, 7 insertions, 4 deletions

diff --git a/dwflpp.cxx b/dwflpp.cxx
index 35637568..53f3d8eb 100644
--- a/dwflpp.cxx
+++ b/dwflpp.cxx
@@ -1484,8 +1484,8 @@ dwflpp::emit_address (struct obstack *pool, Dwarf_Addr address)
         {
           // This gives us the module name, and section name within the
           // module, for a kernel module (or other ET_REL module object).
-          obstack_printf (pool, "({ static unsigned long addr = 0; ");
-          obstack_printf (pool, "if (addr==0) addr = _stp_module_relocate (\"%s\",\"%s\",%#" PRIx64 "); ",
+          obstack_printf (pool, "({ unsigned long addr = 0; ");
+          obstack_printf (pool, "addr = _stp_module_relocate (\"%s\",\"%s\",%#" PRIx64 "); ",
                           modname, secname, reloc_address);
           obstack_printf (pool, "addr; })");
         }
@@ -1495,6 +1495,9 @@ dwflpp::emit_address (struct obstack *pool, Dwarf_Addr address)
           // need to treat the same way here as dwarf_query::add_probe_point does: _stext.
           address -= sess.sym_stext;
           secname = "_stext";
+          // Note we "cache" the result here through a static because the
+          // kernel will never move after being loaded (unlike modules and
+          // user-space dynamic share libraries).
           obstack_printf (pool, "({ static unsigned long addr = 0; ");
           obstack_printf (pool, "if (addr==0) addr = _stp_module_relocate (\"%s\",\"%s\",%#" PRIx64 "); ",
                           modname, secname, address); // PR10000 NB: not reloc_address
@@ -1503,8 +1506,8 @@ dwflpp::emit_address (struct obstack *pool, Dwarf_Addr address)
       else
         {
           enable_task_finder (sess);
-          obstack_printf (pool, "({ static unsigned long addr = 0; ");
-          obstack_printf (pool, "if (addr==0) addr = _stp_module_relocate (\"%s\",\"%s\",%#" PRIx64 "); ",
+          obstack_printf (pool, "({ unsigned long addr = 0; ");
+          obstack_printf (pool, "addr = _stp_module_relocate (\"%s\",\"%s\",%#" PRIx64 "); ",
                           modname, ".dynamic", reloc_address);
           obstack_printf (pool, "addr; })");
         }