[PATCH] arm64: Unconditionally select CONFIG_JUMP_LABEL

[Marc Zyngier]

Aneesh reports that his kernel fails to boot in nVHE mode with
KVM's protected mode enabled. Further investigation by Mostafa
reveals that this fails because CONFIG_JUMP_LABEL=n and that
we have static keys shared between EL1 and EL2.

While this can be worked around, it is obvious that we have long
relied on having CONFIG_JUMP_LABEL enabled at all times, as all
supported compilers now have 'asm goto' (which is the basic block
for jump labels).

Let's simplify our lives once and for all by mandating jump labels.
It's not like anyone else is testing anything without them, and
we already rely on them for other things (kfence, xfs, preempt).

Link: https://lore.kernel.org/r/yq5ah60pkq03.fsf@kernel.org
Reported-by: "Aneesh Kumar K.V" <aneesh.kumar at kernel.org>
Reported-by: Mostafa Saleh <smostafa at google.com>
Signed-off-by: Marc Zyngier <maz at kernel.org>
Cc: Will Deacon <will at kernel.org>
Cc: Catalin marinas <catalin.marinas at arm.com>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm64/Kconfig         | 1 +
 arch/arm64/kernel/Makefile | 3 +--
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 55fc331af3371..393d71124f5d2 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -256,6 +256,7 @@ config ARM64
 	select HOTPLUG_SMT if HOTPLUG_CPU
 	select IRQ_DOMAIN
 	select IRQ_FORCED_THREADING
+	select JUMP_LABEL
 	select KASAN_VMALLOC if KASAN
 	select LOCK_MM_AND_FIND_VMA
 	select MODULES_USE_ELF_RELA
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 2920b0a514037..a2faf0049dab1 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -34,7 +34,7 @@ obj-y			:= debug-monitors.o entry.o irq.o fpsimd.o		\
 			   cpufeature.o alternative.o cacheinfo.o		\
 			   smp.o smp_spin_table.o topology.o smccc-call.o	\
 			   syscall.o proton-pack.o idle.o patching.o pi/	\
-			   rsi.o
+			   rsi.o jump_label.o
 
 obj-$(CONFIG_COMPAT)			+= sys32.o signal32.o			\
 					   sys_compat.o
@@ -47,7 +47,6 @@ obj-$(CONFIG_PERF_EVENTS)		+= perf_regs.o perf_callchain.o
 obj-$(CONFIG_HARDLOCKUP_DETECTOR_PERF)	+= watchdog_hld.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
 obj-$(CONFIG_CPU_PM)			+= sleep.o suspend.o
-obj-$(CONFIG_JUMP_LABEL)		+= jump_label.o
 obj-$(CONFIG_KGDB)			+= kgdb.o
 obj-$(CONFIG_EFI)			+= efi.o efi-rt-wrapper.o
 obj-$(CONFIG_PCI)			+= pci.o
-- 
2.39.2