mm: expose arch_mmap_rnd when available

When an architecture fully supports randomizing the ELF load location,
a per-arch mmap_rnd() function is used to find a randomized mmap base.
In preparation for randomizing the location of ET_DYN binaries
separately from mmap, this renames and exports these functions as
arch_mmap_rnd(). Additionally introduces CONFIG_ARCH_HAS_ELF_RANDOMIZE
for describing this feature on architectures that support it
(which is a superset of ARCH_BINFMT_ELF_RANDOMIZE_PIE, since s390
already supports a separated ET_DYN ASLR from mmap ASLR without the
ARCH_BINFMT_ELF_RANDOMIZE_PIE logic).

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Hector Marco-Gisbert <hecmargi@upv.es>
Cc: Russell King <linux@arm.linux.org.uk>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: "David A. Long" <dave.long@linaro.org>
Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Arun Chandran <achandran@mvista.com>
Cc: Yann Droneaud <ydroneaud@opteya.com>
Cc: Min-Hua Chen <orca.chen@gmail.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Alex Smith <alex@alex-smith.me.uk>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Vineeth Vijayan <vvijayan@mvista.com>
Cc: Jeff Bailey <jeffbailey@google.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Behan Webster <behanw@converseincode.com>
Cc: Ismael Ripoll <iripoll@upv.es>
Cc: Jan-Simon Mller <dl9pf@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3f2fba996bc2..7c1dbeb73e8d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2,6 +2,7 @@ config ARM64
         def_bool y
         select ARCH_BINFMT_ELF_RANDOMIZE_PIE
         select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
+        select ARCH_HAS_ELF_RANDOMIZE
         select ARCH_HAS_GCOV_PROFILE_ALL
         select ARCH_HAS_SG_CHAIN
         select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST