This is a note to let you know that I've just added the patch titled
ARM: 9434/1: cfi: Fix compilation corner case
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-9434-1-cfi-fix-compilation-corner-case.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit df95e936756de1af86649eb568f549ba38b52a37
Author: Linus Walleij <linus.walleij@xxxxxxxxxx>
Date: Mon Nov 11 00:17:03 2024 +0100
ARM: 9434/1: cfi: Fix compilation corner case
[ Upstream commit 4aea16b7cfb76bd3361858ceee6893ef5c9b5570 ]
When enabling expert mode CONFIG_EXPERT and using that power
user mode to disable the branch prediction hardening
!CONFIG_HARDEN_BRANCH_PREDICTOR, the assembly linker
in CLANG notices that some assembly in proc-v7.S does
not have corresponding C call sites, i.e. the prototypes
in proc-v7-bugs.c are enclosed in ifdef
CONFIG_HARDEN_BRANCH_PREDICTOR so this assembly:
SYM_TYPED_FUNC_START(cpu_v7_smc_switch_mm)
SYM_TYPED_FUNC_START(cpu_v7_hvc_switch_mm)
Results in:
ld.lld: error: undefined symbol: __kcfi_typeid_cpu_v7_smc_switch_mm
>>> referenced by proc-v7.S:94 (.../arch/arm/mm/proc-v7.S:94)
>>> arch/arm/mm/proc-v7.o:(.text+0x108) in archive vmlinux.a
ld.lld: error: undefined symbol: __kcfi_typeid_cpu_v7_hvc_switch_mm
>>> referenced by proc-v7.S:105 (.../arch/arm/mm/proc-v7.S:105)
>>> arch/arm/mm/proc-v7.o:(.text+0x124) in archive vmlinux.a
Fix this by adding an additional requirement that
CONFIG_HARDEN_BRANCH_PREDICTOR has to be enabled to compile
these assembly calls.
Closes: https://lore.kernel.org/oe-kbuild-all/202411041456.ZsoEiD7T-lkp@xxxxxxxxx/
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 5fb9a6aecb001..2cd9333426794 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -94,7 +94,7 @@ SYM_TYPED_FUNC_START(cpu_v7_dcache_clean_area)
ret lr
SYM_FUNC_END(cpu_v7_dcache_clean_area)
-#ifdef CONFIG_ARM_PSCI
+#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
.arch_extension sec
SYM_TYPED_FUNC_START(cpu_v7_smc_switch_mm)
stmfd sp!, {r0 - r3}
