m68k: Handle fewer relocations for RTLD_BOOTSTRAP (#BZ29071)

m68k is a non-PI_STATIC_AND_HIDDEN arch which uses a GOT relocation when
loading the address of a jump table. The GOT load may be reordered
before processing R_68K_RELATIVE relocations, leading to an
unrelocated/incorrect jump table, which will cause a crash.

The foolproof approach is to add an optimization barrier (e.g. calling
an non-inlinable function after relative relocations are resolved). That
is non-trivial given the current code structure, so just use the simple
approach to avoid the jump table: handle only the essential reloctions
for RTLD_BOOTSTRAP code.

This is based on Andreas Schwab's patch and fixed ld.so crash on m68k.

Reviewed-by: Adheemrval Zanella  <adhemerval.zanella@linaro.org>

diff --git a/sysdeps/m68k/dl-machine.h b/sysdeps/m68k/dl-machine.h
index c44ab055aa0c77266dbe0cd4a48113466da72d25..bb51b4198c4a81ec143ad7b43806486263ff724a 100644 (file)
--- a/sysdeps/m68k/dl-machine.h
+++ b/sysdeps/m68k/dl-machine.h
@@ -234,6 +234,11 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
 
       switch (r_type)
        {
+       case R_68K_GLOB_DAT:
+       case R_68K_JMP_SLOT:
+         *reloc_addr = value;
+         break;
+#ifndef RTLD_BOOTSTRAP
        case R_68K_COPY:
          if (sym == NULL)
            /* This can happen in trace mode if an object could not be
@@ -252,10 +257,6 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
          memcpy (reloc_addr_arg, (void *) value,
                  MIN (sym->st_size, refsym->st_size));
          break;
-       case R_68K_GLOB_DAT:
-       case R_68K_JMP_SLOT:
-         *reloc_addr = value;
-         break;
        case R_68K_8:
          *(char *) reloc_addr = value + reloc->r_addend;
          break;
@@ -276,7 +277,6 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
        case R_68K_PC32:
          *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
          break;
-#ifndef RTLD_BOOTSTRAP
        case R_68K_TLS_DTPMOD32:
          /* Get the information from the link map returned by the
             resolv function.  */
@@ -294,9 +294,9 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
              *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
            }
          break;
-#endif /* !RTLD_BOOTSTRAP */
        case R_68K_NONE:                /* Alright, Wilbur.  */
          break;
+#endif /* !RTLD_BOOTSTRAP */
        default:
          _dl_reloc_bad_type (map, r_type, 0);
          break;