On Tue, Oct 01, 2019 at 04:23:35PM +0200, Arnd Bergmann wrote:
> The fpu emulation code is old and fragile in places, try to limit its
> use to builds for CPUs that actually use it. As far as I can tell,
> this is only true for i486sx compatibles, including the Cyrix 486SLC,
> AMD Am486SX and ÉLAN SC410, UMC U5S amd DM&P VortexSX86, all of which
> were relatively short-lived and got replaced with i486DX compatible
> processors soon after introduction, though the some of the embedded
> versions remained available much longer.
>
> Signed-off-by: Arnd Bergmann <a...@arndb.de>
Nice, I like carving out CONFIG space for 486SX; this makes sense to me.
Reviewed-by: Kees Cook <keesc...@chromium.org>
-Kees
> ---
> arch/x86/Kconfig | 2 +-
> arch/x86/Kconfig.cpu | 25 ++++++++++++++++---------
> arch/x86/Makefile_32.cpu | 1 +
> arch/x86/include/asm/module.h | 2 ++
> 4 files changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index f4d9d1e55e5c..77b02387bd0c 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1751,7 +1751,7 @@ config X86_RESERVE_LOW
> config MATH_EMULATION
> bool
> depends on MODIFY_LDT_SYSCALL
> - prompt "Math emulation" if X86_32
> + prompt "Math emulation" if X86_32 && (M486SX || MELAN)
> ---help---
> Linux can emulate a math coprocessor (used for floating point
> operations) if you don't have one. 486DX and Pentium processors have
> diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
> index 228705a1232a..5f7bff9885a1 100644
> --- a/arch/x86/Kconfig.cpu
> +++ b/arch/x86/Kconfig.cpu
> @@ -50,12 +50,19 @@ choice
> See each option's help text for additional details. If you don't know
> what to do, choose "486".
>
> +config M486SX
> + bool "486SX"
> + depends on X86_32
> + ---help---
> + Select this for an 486-class CPU without an FPU such as
> + AMD/Cyrix/IBM/Intel SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5S.
> +
> config M486
> - bool "486"
> + bool "486DX"
> depends on X86_32
> ---help---
> Select this for an 486-class CPU such as AMD/Cyrix/IBM/Intel
> - 486DX/DX2/DX4 or SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
> + 486DX/DX2/DX4 and UMC U5D.
>
> config M586
> bool "586/K5/5x86/6x86/6x86MX"
> @@ -313,20 +320,20 @@ config X86_L1_CACHE_SHIFT
> int
> default "7" if MPENTIUM4 || MPSC
> default "6" if MK7 || MK8 || MPENTIUMM || MCORE2 || MATOM || MVIAC7 ||
> X86_GENERIC || GENERIC_CPU
> - default "4" if MELAN || M486 || MGEODEGX1
> + default "4" if MELAN || M486SX || M486 || MGEODEGX1
> default "5" if MWINCHIP3D || MWINCHIPC6 || MCRUSOE || MEFFICEON ||
> MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC
> || M586 || MVIAC3_2 || MGEODE_LX
>
> config X86_F00F_BUG
> def_bool y
> - depends on M586MMX || M586TSC || M586 || M486
> + depends on M586MMX || M586TSC || M586 || M486SX || M486
>
> config X86_INVD_BUG
> def_bool y
> - depends on M486
> + depends on M486SX || M486
>
> config X86_ALIGNMENT_16
> def_bool y
> - depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || MELAN || MK6 ||
> M586MMX || M586TSC || M586 || M486 || MVIAC3_2 || MGEODEGX1
> + depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || MELAN || MK6 ||
> M586MMX || M586TSC || M586 || M486SX || M486 || MVIAC3_2 || MGEODEGX1
>
> config X86_INTEL_USERCOPY
> def_bool y
> @@ -379,7 +386,7 @@ config X86_MINIMUM_CPU_FAMILY
>
> config X86_DEBUGCTLMSR
> def_bool y
> - depends on !(MK6 || MWINCHIPC6 || MWINCHIP3D || MCYRIXIII || M586MMX ||
> M586TSC || M586 || M486) && !UML
> + depends on !(MK6 || MWINCHIPC6 || MWINCHIP3D || MCYRIXIII || M586MMX ||
> M586TSC || M586 || M486SX || M486) && !UML
>
> menuconfig PROCESSOR_SELECT
> bool "Supported processor vendors" if EXPERT
> @@ -403,7 +410,7 @@ config CPU_SUP_INTEL
> config CPU_SUP_CYRIX_32
> default y
> bool "Support Cyrix processors" if PROCESSOR_SELECT
> - depends on M486 || M586 || M586TSC || M586MMX || (EXPERT && !64BIT)
> + depends on M486SX || M486 || M586 || M586TSC || M586MMX || (EXPERT &&
> !64BIT)
> ---help---
> This enables detection, tunings and quirks for Cyrix processors
>
> @@ -471,7 +478,7 @@ config CPU_SUP_TRANSMETA_32
> config CPU_SUP_UMC_32
> default y
> bool "Support UMC processors" if PROCESSOR_SELECT
> - depends on M486 || (EXPERT && !64BIT)
> + depends on M486SX || M486 || (EXPERT && !64BIT)
> ---help---
> This enables detection, tunings and quirks for UMC processors
>
> diff --git a/arch/x86/Makefile_32.cpu b/arch/x86/Makefile_32.cpu
> index 1f5faf8606b4..cd3056759880 100644
> --- a/arch/x86/Makefile_32.cpu
> +++ b/arch/x86/Makefile_32.cpu
> @@ -10,6 +10,7 @@ else
> tune = $(call cc-option,-mcpu=$(1),$(2))
> endif
>
> +cflags-$(CONFIG_M486SX) += -march=i486
> cflags-$(CONFIG_M486) += -march=i486
> cflags-$(CONFIG_M586) += -march=i586
> cflags-$(CONFIG_M586TSC) += -march=i586
> diff --git a/arch/x86/include/asm/module.h b/arch/x86/include/asm/module.h
> index 7948a17febb4..c215d2762488 100644
> --- a/arch/x86/include/asm/module.h
> +++ b/arch/x86/include/asm/module.h
> @@ -15,6 +15,8 @@ struct mod_arch_specific {
>
> #ifdef CONFIG_X86_64
> /* X86_64 does not define MODULE_PROC_FAMILY */
> +#elif defined CONFIG_M486SX
> +#define MODULE_PROC_FAMILY "486SX "
> #elif defined CONFIG_M486
> #define MODULE_PROC_FAMILY "486 "
> #elif defined CONFIG_M586
> --
> 2.20.0
>
--
Kees Cook
