* [PATCH AUTOSEL 6.6 5/6] ARM: 9434/1: cfi: Fix compilation corner case [not found] <20241120140647.1768984-1-sashal@kernel.org> @ 2024-11-20 14:06 ` Sasha Levin 2024-11-20 15:13 ` Nathan Chancellor 0 siblings, 1 reply; 3+ messages in thread From: Sasha Levin @ 2024-11-20 14:06 UTC (permalink / raw) To: linux-kernel, stable Cc: Linus Walleij, kernel test robot, Nathan Chancellor, Russell King, Sasha Levin, linux, arnd, samitolvanen, linux-arm-kernel, llvm From: Linus Walleij <linus.walleij@linaro.org> [ 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@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> Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/arm/mm/proc-v7.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index 193c7aeb67039..bea11f9bfe856 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -93,7 +93,7 @@ ENTRY(cpu_v7_dcache_clean_area) ret lr ENDPROC(cpu_v7_dcache_clean_area) -#ifdef CONFIG_ARM_PSCI +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) .arch_extension sec ENTRY(cpu_v7_smc_switch_mm) stmfd sp!, {r0 - r3} -- 2.43.0 ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH AUTOSEL 6.6 5/6] ARM: 9434/1: cfi: Fix compilation corner case 2024-11-20 14:06 ` [PATCH AUTOSEL 6.6 5/6] ARM: 9434/1: cfi: Fix compilation corner case Sasha Levin @ 2024-11-20 15:13 ` Nathan Chancellor 2024-11-22 15:21 ` Sasha Levin 0 siblings, 1 reply; 3+ messages in thread From: Nathan Chancellor @ 2024-11-20 15:13 UTC (permalink / raw) To: Sasha Levin Cc: linux-kernel, stable, Linus Walleij, kernel test robot, Russell King, linux, arnd, samitolvanen, linux-arm-kernel, llvm Hi Sasha, On Wed, Nov 20, 2024 at 09:06:35AM -0500, Sasha Levin wrote: > From: Linus Walleij <linus.walleij@linaro.org> > > [ 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@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> > Signed-off-by: Sasha Levin <sashal@kernel.org> > --- > arch/arm/mm/proc-v7.S | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S > index 193c7aeb67039..bea11f9bfe856 100644 > --- a/arch/arm/mm/proc-v7.S > +++ b/arch/arm/mm/proc-v7.S > @@ -93,7 +93,7 @@ ENTRY(cpu_v7_dcache_clean_area) > ret lr > ENDPROC(cpu_v7_dcache_clean_area) > > -#ifdef CONFIG_ARM_PSCI > +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) > .arch_extension sec > ENTRY(cpu_v7_smc_switch_mm) This patch is unnecessary in branches prior to 6.10 (when ARM started supporting kCFI) because SYM_TYPED_FUNC_START() is not used here. I would just drop it for 6.6 and earlier. > stmfd sp!, {r0 - r3} > -- > 2.43.0 > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH AUTOSEL 6.6 5/6] ARM: 9434/1: cfi: Fix compilation corner case 2024-11-20 15:13 ` Nathan Chancellor @ 2024-11-22 15:21 ` Sasha Levin 0 siblings, 0 replies; 3+ messages in thread From: Sasha Levin @ 2024-11-22 15:21 UTC (permalink / raw) To: Nathan Chancellor Cc: linux-kernel, stable, Linus Walleij, kernel test robot, Russell King, linux, arnd, samitolvanen, linux-arm-kernel, llvm On Wed, Nov 20, 2024 at 08:13:38AM -0700, Nathan Chancellor wrote: >Hi Sasha, > >On Wed, Nov 20, 2024 at 09:06:35AM -0500, Sasha Levin wrote: >> From: Linus Walleij <linus.walleij@linaro.org> >> >> [ 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@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> >> Signed-off-by: Sasha Levin <sashal@kernel.org> >> --- >> arch/arm/mm/proc-v7.S | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S >> index 193c7aeb67039..bea11f9bfe856 100644 >> --- a/arch/arm/mm/proc-v7.S >> +++ b/arch/arm/mm/proc-v7.S >> @@ -93,7 +93,7 @@ ENTRY(cpu_v7_dcache_clean_area) >> ret lr >> ENDPROC(cpu_v7_dcache_clean_area) >> >> -#ifdef CONFIG_ARM_PSCI >> +#if defined(CONFIG_ARM_PSCI) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) >> .arch_extension sec >> ENTRY(cpu_v7_smc_switch_mm) > >This patch is unnecessary in branches prior to 6.10 (when ARM started >supporting kCFI) because SYM_TYPED_FUNC_START() is not used here. I >would just drop it for 6.6 and earlier. Ack, will do. -- Thanks, Sasha ^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-11-20 14:06 ` [PATCH AUTOSEL 6.6 5/6] ARM: 9434/1: cfi: Fix compilation corner case Sasha Levin
2024-11-20 15:13 ` Nathan Chancellor
2024-11-22 15:21 ` Sasha Levin
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