On Wed, May 28, 2025 at 10:45:22AM -0400, Joe Lawrence wrote:
> > - if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
> > + if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ||
> > + is_enabled CONFIG_LIVEPATCH; then
> > # Use vmlinux.o instead of performing the slow LTO link again.
> > objs=vmlinux.o
> > libs=
>
> At this commit, I'm getting the following linker error on ppc64le:
>
> ld -EL -m elf64lppc -z noexecstack --no-warn-rwx-segments -pie -z notext
> --build-id=sha1 -X --orphan-handling=error
> --script=./arch/powerpc/kernel/vmlinux.lds -o .tmp_vmlinux1
> --whole-archive vmlinux.o .vmlinux.export.o init/version-timestamp.o
> --no-whole-archive --start-group --end-group .tmp_vmlinux0.kallsyms.o
> arch/powerpc/tools/vmlinux.arch.o
>
> vmlinux.o:(__ftr_alt_97+0x20): relocation truncated to fit:
> R_PPC64_REL14 against `.text'+4b54
> vmlinux.o:(__ftr_alt_97+0x270): relocation truncated to fit:
> R_PPC64_REL14 against `.text'+173ecc
Looks like objtool is causing the the __ftr_alt_* sections to get placed
far away from .text somehow.
I guess objtool-on-vmlinux isn't quite ready for primetime on powerpc.
Though my next TODO is to get all this working there.
Until then, here's the fix:
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 996d59e59e5d..23269e8ee906 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -265,6 +265,7 @@ config X86
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_KRETPROBES
select HAVE_RETHOOK
+ select HAVE_KLP_BUILD if X86_64
select HAVE_LIVEPATCH if X86_64
select HAVE_MIXED_BREAKPOINTS_REGS
select HAVE_MOD_ARCH_SPECIFIC
diff --git a/kernel/livepatch/Kconfig b/kernel/livepatch/Kconfig
index 53d51ed619a3..4c0a9c18d0b2 100644
--- a/kernel/livepatch/Kconfig
+++ b/kernel/livepatch/Kconfig
@@ -18,3 +18,15 @@ config LIVEPATCH
module uses the interface provided by this option to register
a patch, causing calls to patched functions to be redirected
to new function code contained in the patch module.
+
+config HAVE_KLP_BUILD
+ bool
+ help
+ Arch supports klp-build
+
+config KLP_BUILD
+ def_bool y
+ depends on LIVEPATCH && HAVE_KLP_BUILD
+ select OBJTOOL
+ help
+ Enable klp-build support
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index a68390ff5cd9..d9426fd4ab33 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -278,7 +278,7 @@ objtool-args = $(objtool-args-y)
\
$(if $(delay-objtool), --link) \
$(if $(part-of-module), --module)
-delay-objtool := $(or
$(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT),$(CONFIG_LIVEPATCH))
+delay-objtool := $(or
$(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT),$(CONFIG_KLP_BUILD))
cmd_objtool = $(if $(objtool-enabled), ; $(objtool) $(objtool-args) $@)
cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard
$(objtool))' ; } >> $(dot-target).cmd)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index acffa3c935f2..59f875236292 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -61,7 +61,7 @@ vmlinux_link()
shift
if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ||
- is_enabled CONFIG_LIVEPATCH; then
+ is_enabled CONFIG_KLP_BUILD; then
# Use vmlinux.o instead of performing the slow LTO link again.
objs=vmlinux.o
libs=
