From 87d6021b814353d7b353afcc3698ffe49de7d4ec Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 1 Oct 2019 16:23:35 +0200 Subject: [PATCH] x86/math-emu: Limit MATH_EMULATION to 486SX compatibles MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 some of the embedded versions remained available much longer. Signed-off-by: Arnd Bergmann Signed-off-by: Borislav Petkov Reviewed-by: Kees Cook Cc: "H. Peter Anvin" Cc: Andrew Morton Cc: Bill Metzenthen Cc: Ingo Molnar Cc: Masahiro Yamada Cc: Thomas Gleixner Cc: x86-ml Link: https://lkml.kernel.org/r/20191001142344.1274185-2-arnd@arndb.de --- 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 d6e1faa28c58..91c22ee6bc9a 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 8e29c991ba3e..af9c967782f6 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" @@ -312,20 +319,20 @@ 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 @@ -378,7 +385,7 @@ 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 @@ -402,7 +409,7 @@ 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 @@ -470,7 +477,7 @@ 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 -- 2.11.0