fs, kernel: permit disabling the uselib syscall

uselib hasn't been used since libc5; glibc does not use it.  Support
turning it off.

When disabled, also omit the load_elf_library implementation from
binfmt_elf.c, which only uselib invokes.

bloat-o-meter:
add/remove: 0/4 grow/shrink: 0/1 up/down: 0/-785 (-785)
function                                     old     new   delta
padzero                                       39      36      -3
uselib_flags                                  20       -     -20
sys_uselib                                   168       -    -168
SyS_uselib                                   168       -    -168
load_elf_library                             426       -    -426

The new CONFIG_USELIB defaults to `y'.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/init/Kconfig b/init/Kconfig
index e45cc62904b3..8114a06117e3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -273,6 +273,16 @@ config FHANDLE
           get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2)
           syscalls.
 
+config USELIB
+        bool "uselib syscall"
+        default y
+        help
+          This option enables the uselib syscall, a system call used in the
+          dynamic linker from libc5 and earlier.  glibc does not use this
+          system call.  If you intend to run programs built on libc5 or
+          earlier, you may need to enable this syscall.  Current systems
+          running glibc can safely disable this.
+
 config AUDIT
         bool "Auditing support"
         depends on NET