Handle ADD/SUB relocations

[platform/upstream/elfutils.git] / libdwfl / relocate.c

diff --git a/libdwfl/relocate.c b/libdwfl/relocate.c
index 9afcdeb..58c5678 100644 (file)
--- a/libdwfl/relocate.c
+++ b/libdwfl/relocate.c
@@ -338,7 +338,8 @@ relocate (Dwfl_Module * const mod,
         So we just pretend it's OK without further relocation.  */
       return DWFL_E_NOERROR;
 
-    Elf_Type type = ebl_reloc_simple_type (mod->ebl, rtype);
+    int addsub = 0;
+    Elf_Type type = ebl_reloc_simple_type (mod->ebl, rtype, &addsub);
     if (unlikely (type == ELF_T_NUM))
       return DWFL_E_BADRELTYPE;
 
@@ -383,6 +384,9 @@ relocate (Dwfl_Module * const mod,
       {
 #define DO_TYPE(NAME, Name)                    \
        case ELF_T_##NAME:                      \
+         if (addsub != 0 && addend == NULL)    \
+           /* These do not make sense with SHT_REL.  */ \
+           return DWFL_E_BADRELTYPE;           \
          size = sizeof (GElf_##Name);          \
        break
        TYPES;
@@ -417,11 +421,24 @@ relocate (Dwfl_Module * const mod,
       {
        /* For the addend form, we have the value already.  */
        value += *addend;
+       /* For ADD/SUB relocations we need to fetch the section
+          contents.  */
+       if (addsub != 0)
+         {
+           Elf_Data *d = gelf_xlatetom (relocated, &tmpdata, &rdata,
+                                        ehdr->e_ident[EI_DATA]);
+           if (d == NULL)
+             return DWFL_E_LIBELF;
+           assert (d == &tmpdata);
+         }
        switch (type)
          {
 #define DO_TYPE(NAME, Name)                    \
            case ELF_T_##NAME:                  \
-             tmpbuf.Name = value;              \
+             if (addsub != 0)                  \
+               tmpbuf.Name += value * addsub;  \
+             else                              \
+               tmpbuf.Name = value;            \
            break
            TYPES;
 #undef DO_TYPE