fs: binfmt_elf: create Kconfig variable for PIE randomization

Randomization of PIE load address is hard coded in binfmt_elf.c for X86
and ARM.  Create a new Kconfig variable
(CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE) for this and use it instead.  Thus
architecture specific policy is pushed out of the generic binfmt_elf.c and
into the architecture Kconfig files.

X86 and ARM Kconfigs are modified to select the new variable so there is
no change in behavior.  A follow on patch will select it for MIPS too.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 9d66dfc33a5a..98a6459cd398 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -16,6 +16,7 @@ config ARM
         select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
         select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)
         select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
+        select ARCH_BINFMT_ELF_RANDOMIZE_PIE
         select HAVE_GENERIC_DMA_COHERENT
         select HAVE_KERNEL_GZIP
         select HAVE_KERNEL_LZO
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 1d2a69dd36d8..d6ddc0bfe36a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -62,6 +62,7 @@ config X86
         select ANON_INODES
         select HAVE_ARCH_KMEMCHECK
         select HAVE_USER_RETURN_NOTIFIER
+        select ARCH_BINFMT_ELF_RANDOMIZE_PIE
         select HAVE_ARCH_JUMP_LABEL
         select HAVE_TEXT_POKE_SMP
         select HAVE_GENERIC_HARDIRQS