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ARM: 9434/1: cfi: Fix compilation corner case

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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@intel.com/

Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Linus Walleij 2024-11-11 00:17:03 +01:00 committed by Russell King (Oracle)
parent 9e9b0cf931
commit 4aea16b7cf
1 changed files with 1 additions and 1 deletions
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arch/arm/mm/proc-v7.S
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@ -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}