Before updating certain subsystems to use place relative 32-bit
relocations in special sections, to save space and reduce the
number of absolute relocations that need to be processed at runtime
by relocatable kernels, introduce the Kconfig symbol and define it
for some architectures that should be able to support and benefit
from it.
Acked-by: Michael Ellerman <m...@ellerman.id.au>
Reviewed-by: Will Deacon <will.dea...@arm.com>
Acked-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
---
arch/Kconfig | 10 ++++++++++
arch/arm64/Kconfig | 1 +
arch/powerpc/Kconfig | 1 +
arch/x86/Kconfig | 1 +
4 files changed, 13 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index 1aa59063f1fd..2b8b70820002 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -971,4 +971,14 @@ config REFCOUNT_FULL
against various use-after-free conditions that can be used in
security flaw exploits.
+config HAVE_ARCH_PREL32_RELOCATIONS
+ bool
+ help
+ May be selected by an architecture if it supports place-relative
+ 32-bit relocations, both in the toolchain and in the module loader,
+ in which case relative references can be used in special sections
+ for PCI fixup, initcalls etc which are only half the size on 64 bit
+ architectures, and don't require runtime relocation on relocatable
+ kernels.
+
source "kernel/gcov/Kconfig"
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 42c090cf0292..1940c6405d04 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -95,6 +95,7 @@ config ARM64
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
+ select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9f2b75fe2c2d..e4fe19789b8b 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -177,6 +177,7 @@ config PPC
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
+ select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_CBPF_JIT if !PPC64
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f1dbb4ee19d7..e10a3542db7e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -123,6 +123,7 @@ config X86
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
+ select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
--
2.17.1
