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Currently kernel image relocation tables and other ELF
data are set to base zero. Since kernel virtual and
physical address spaces are uncoupled the kernel is
mapped at the top of the virtual address space, hence
making the information contained in vmlinux ELF tables
inconsistent.

That does not pose any issue with regard to the kernel
booting and operation, but makes it difficult to use a
generated vmlinux with some debugging tools (e.g. gdb).

Relocate vmlinux image base address from zero to a base
address in the virtual address space. It is the address
that kernel is mapped to in cases KASLR is disabled.

The vmlinux ELF header before and after this change looks
like this:

Elf file type is EXEC (Executable file)
Entry point 0x100000
There are 3 program headers, starting at offset 64

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  LOAD           0x0000000000001000 0x0000000000100000 0x0000000000100000
                 0x0000000001323378 0x0000000001323378  R E    0x1000
  LOAD           0x0000000001325000 0x0000000001424000 0x0000000001424000
                 0x00000000003a4200 0x000000000048fdb8  RWE    0x1000
  NOTE           0x00000000012a33b0 0x00000000013a23b0 0x00000000013a23b0
                 0x0000000000000054 0x0000000000000054         0x4

Elf file type is EXEC (Executable file)
Entry point 0x3ffe0000000
There are 3 program headers, starting at offset 64

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  LOAD           0x0000000000001000 0x000003ffe0000000 0x000003ffe0000000
                 0x0000000001323378 0x0000000001323378  R E    0x1000
  LOAD           0x0000000001325000 0x000003ffe1324000 0x000003ffe1324000
                 0x00000000003a4200 0x000000000048fdb8  RWE    0x1000
  NOTE           0x00000000012a33b0 0x000003ffe12a23b0 0x000003ffe12a23b0
                 0x0000000000000054 0x0000000000000054         0x4
Suggested-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>