Patch for RELATIVE relocation for an non-loaded section

[Ken Block USG <block at zk3 dot dec dot com>]

Problem description:

Here is the new bug that's been fixed:  The DWARF-2 sections .debug_info
and
.debug_line are never actually loaded into virtual memory.  They do
contain
addresses and offsets of other things in the object file and therefore
the
compiler emits the appropriate REFLONG and REFQUAD relocations.  If the
resulting object file is linked into an executable image, the linker
fully
resolves the REFLONG and REFQUAD relocations and all is well.  However,
if the
object file is linked into a shared object, the linker cannot fully
resolve the
relocations.  It determines the shared-object-relative offsets of the
items in
question, then it puts RELATIVE relocations in the shared object so that
the
run-time loader can change the relative offsets into virtual addresses
once the
shared object's base virtual address is known.  But this run-time
operation
cannot, and should not, be done for sections that are never actually
loaded
into virtual memory.  The run-time loader gets a segmentation fault
trying to
process a RELATIVE relocation for an non-loaded section.  The fix is for
the
linker not to emit RELATIVE relocations for REFLONGs and REFQUADs in
sections
that aren't loaded.

--PSW


Test case:

catch.zko.dec.com> ccc -c -g foo.c
catch.zko.dec.com> ccc foo.o -shared -o libfoo.so
catch.zko.dec.com> ccc -o main main.c ./libfoo.so
catch.zko.dec.com> ./main
foo


Relink using the old RH5.2 ld.

catch.zko.dec.com> $DECC_STABLE/ld -o libfoo.so -O1 -m elf64alpha -G 8
-shared -
L/usr/lib/compaq/ccc-6.2.9.002-2/alpha-linux/lib -L/usr/local/lib
-L/usr/alpha-r
edhat-linux/lib -L/usr/lib/gcc-lib/alpha-redhat-linux/egcs-2.90.29
/usr/lib/comp
aq/ccc-6.2.9.002-2/alpha-linux/bin/crti.o
/usr/lib/compaq/ccc-6.2.9.002-2/alpha-
linux/bin/crtbegin.o foo.o -lgcc -lc -lgcc -lots
/usr/lib/compaq/ccc-6.2.9.002-2
/alpha-linux/bin/crtend.o
/usr/lib/compaq/ccc-6.2.9.002-2/alpha-linux/bin/crtn.o
catch.zko.dec.com> ccc -o main main.c ./libfoo.so
catch.zko.dec.com> ./main
Segmentation fault (core dumped)


catch.zko.dec.com> cat foo.c
#include <stdio.h>

void foo(void)
{
        printf("foo\n");
}


catch.zko.dec.com> cat main.c
int main(int argc, char *argv[])
{
        foo();
}




*** ../../binutils-2.9.1.0.15/bfd/elf64-alpha.c Thu Oct  1 11:33:50 1998

--- elf64-alpha.c       Tue Sep 28 18:26:11 1999
***************
*** 1922,1934 ****
                  h->reloc_entries = rent;
                }
              else
                rent->count++;
            }
!         else if (info->shared)
            {
!             /* If this is a shared library, we need a RELATIVE reloc.
*/
              sreloc->_raw_size += sizeof (Elf64_External_Rela);
            }
          break;
        }
      }
--- 1922,1935 ----
                  h->reloc_entries = rent;
                }
              else
                rent->count++;
            }
!         else if (info->shared && (sec->flags & SEC_ALLOC))
            {
!             /* If this is a shared library, and the section is to be
loaded
!                into memory, we need a RELATIVE reloc.  */
              sreloc->_raw_size += sizeof (Elf64_External_Rela);
            }
          break;
        }
      }
***************
*** 3002,3012 ****
                BFD_ASSERT(h->root.dynindx != -1);
                outrel.r_info = ELF64_R_INFO(h->root.dynindx, r_type);
                outrel.r_addend = addend;
                addend = 0, relocation = 0;
              }
!           else if (info->shared)
              {
                outrel.r_info = ELF64_R_INFO(0, R_ALPHA_RELATIVE);
                outrel.r_addend = 0;
              }
            else
--- 3003,3015 ----
                BFD_ASSERT(h->root.dynindx != -1);
                outrel.r_info = ELF64_R_INFO(h->root.dynindx, r_type);
                outrel.r_addend = addend;
                addend = 0, relocation = 0;
              }
!           /* A RELATIVE relocation makes no sense if this section
isn't
!              to be loaded into memory */
!           else if (info->shared && (input_section->flags & SEC_ALLOC))

              {
                outrel.r_info = ELF64_R_INFO(0, R_ALPHA_RELATIVE);
                outrel.r_addend = 0;
              }
            else

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