ELF/MIPS build fix

CONFIG_MIPS32_N32=y but CONFIG_BINFMT_ELF disabled results in the
following linker errors:

  arch/mips/built-in.o: In function `elf_core_dump':
  binfmt_elfn32.c:(.text+0x23dbc): undefined reference to `elf_core_extra_phdrs'
  binfmt_elfn32.c:(.text+0x246e4): undefined reference to `elf_core_extra_data_size'
  binfmt_elfn32.c:(.text+0x248d0): undefined reference to `elf_core_write_extra_phdrs'
  binfmt_elfn32.c:(.text+0x24ac4): undefined reference to `elf_core_write_extra_data'

CONFIG_MIPS32_O32=y but CONFIG_BINFMT_ELF disabled results in the following
linker errors:

  arch/mips/built-in.o: In function `elf_core_dump':
  binfmt_elfo32.c:(.text+0x28a04): undefined reference to `elf_core_extra_phdrs'
  binfmt_elfo32.c:(.text+0x29330): undefined reference to `elf_core_extra_data_size'
  binfmt_elfo32.c:(.text+0x2951c): undefined reference to `elf_core_write_extra_phdrs'
  binfmt_elfo32.c:(.text+0x29710): undefined reference to `elf_core_write_extra_data'

This is because binfmt_elfn32 and binfmt_elfo32 are using symbols from
elfcore but for these configurations elfcore will not be built.

Fixed by making elfcore selectable by a separate config symbol which
unlike the current mechanism can also be used from other directories
than kernel/, then having each flavor of ELF that relies on elfcore.o,
select it in Kconfig, including CONFIG_MIPS32_N32 and CONFIG_MIPS32_O32
which fixes this issue.

Link: http://lkml.kernel.org/r/20160520141705.GA1913@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index 2d0cbbd14cfc..72c03354c14b 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -1,6 +1,7 @@
 config BINFMT_ELF
         bool "Kernel support for ELF binaries"
         depends on MMU && (BROKEN || !FRV)
+        select ELFCORE
         default y
         ---help---
           ELF (Executable and Linkable Format) is a format for libraries and
@@ -26,6 +27,7 @@ config BINFMT_ELF
 config COMPAT_BINFMT_ELF
         bool
         depends on COMPAT && BINFMT_ELF
+        select ELFCORE
 
 config ARCH_BINFMT_ELF_STATE
         bool
@@ -34,6 +36,7 @@ config BINFMT_ELF_FDPIC
         bool "Kernel support for FDPIC ELF binaries"
         default y
         depends on (FRV || BLACKFIN || (SUPERH32 && !MMU) || C6X)
+        select ELFCORE
         help
           ELF FDPIC binaries are based on ELF, but allow the individual load
           segments of a binary to be located in memory independently of each
@@ -43,6 +46,11 @@ config BINFMT_ELF_FDPIC
 
           It is also possible to run FDPIC ELF binaries on MMU linux also.
 
+config ELFCORE
+        bool
+        help
+          This option enables kernel/elfcore.o.
+
 config CORE_DUMP_DEFAULT_ELF_HEADERS
         bool "Write ELF core dumps with partial segments"
         default y