MIPS: allow disabling the kernel FPU emulator This patch allows turning off the in-kernel Algorithmics FPU emulator support, which allows one to save a couple of precious blocks on an embedded system. Signed-off-by: Florian Fainelli <florian@openwrt.org> -- --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -974,6 +974,17 @@ config I8259 config MIPS_BONITO64 bool +config MIPS_FPU_EMU + bool "Enable FPU emulation" + default y + help + This option allows building a kernel with or without the Algorithmics + FPU emulator enabled. Turning off this option results in a kernel which + does not catch floating operations exceptions. Make sure that your toolchain + is configured to enable software floating point emulation in that case. + + If unsure say Y here. + config MIPS_MSC bool --- a/arch/mips/math-emu/Makefile +++ b/arch/mips/math-emu/Makefile @@ -2,10 +2,11 @@ # Makefile for the Linux/MIPS kernel FPU emulation. # -obj-y := cp1emu.o ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \ +obj-y := kernel_linkage.o dsemul.o cp1emu.o +obj-$(CONFIG_MIPS_FPU_EMU) += ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \ ieee754xcpt.o dp_frexp.o dp_modf.o dp_div.o dp_mul.o dp_sub.o \ dp_add.o dp_fsp.o dp_cmp.o dp_logb.o dp_scalb.o dp_simple.o \ dp_tint.o dp_fint.o dp_tlong.o dp_flong.o sp_frexp.o sp_modf.o \ sp_div.o sp_mul.o sp_sub.o sp_add.o sp_fdp.o sp_cmp.o sp_logb.o \ sp_scalb.o sp_simple.o sp_tint.o sp_fint.o sp_tlong.o sp_flong.o \ - dp_sqrt.o sp_sqrt.o kernel_linkage.o dsemul.o + dp_sqrt.o sp_sqrt.o --- a/arch/mips/math-emu/cp1emu.c +++ b/arch/mips/math-emu/cp1emu.c @@ -58,7 +58,11 @@ #define __mips 4 /* Function which emulates a floating point instruction. */ +#ifdef CONFIG_DEBUG_FS +DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats); +#endif +#ifdef CONFIG_MIPS_FPU_EMU static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *, mips_instruction); @@ -69,10 +73,6 @@ static int fpux_emu(struct pt_regs *, /* Further private data for which no space exists in mips_fpu_struct */ -#ifdef CONFIG_DEBUG_FS -DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats); -#endif - /* Control registers */ #define FPCREG_RID 0 /* $0 = revision id */ @@ -1361,7 +1361,6 @@ int fpu_emulator_cop1Handler(struct pt_r return sig; } - #ifdef CONFIG_DEBUG_FS static int fpuemu_stat_get(void *data, u64 *val) @@ -1410,4 +1409,11 @@ static int __init debugfs_fpuemu(void) return 0; } __initcall(debugfs_fpuemu); -#endif +#endif /* CONFIG_DEBUGFS */ +#else +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx, + int has_fpu) +{ + return 0; +} +#endif /* CONFIG_MIPS_FPU_EMU */ --- a/arch/mips/math-emu/dsemul.c +++ b/arch/mips/math-emu/dsemul.c @@ -108,6 +108,7 @@ int mips_dsemul(struct pt_regs *regs, mi return SIGILL; /* force out of emulation loop */ } +#ifdef CONFIG_MIPS_FPU_EMU int do_dsemulret(struct pt_regs *xcp) { struct emuframe __user *fr; @@ -164,3 +165,9 @@ int do_dsemulret(struct pt_regs *xcp) return 1; } +#else +int do_dsemulret(struct pt_regs *xcp) +{ + return 0; +} +#endif /* CONFIG_MIPS_FPU_EMU */ --- a/arch/mips/math-emu/kernel_linkage.c +++ b/arch/mips/math-emu/kernel_linkage.c @@ -29,6 +29,7 @@ #define SIGNALLING_NAN 0x7ff800007ff80000LL +#ifdef CONFIG_MIPS_FPU_EMU void fpu_emulator_init_fpu(void) { static int first = 1; @@ -112,4 +113,36 @@ int fpu_emulator_restore_context32(struc return err; } -#endif +#endif /* CONFIG_64BIT */ +#else + +void fpu_emulator_init_fpu(void) +{ + printk(KERN_INFO "FPU emulator disabled, make sure your toolchain" + "was compiled with software floating point support (soft-float)\n"); + return; +} + +int fpu_emulator_save_context(struct sigcontext __user *sc) +{ + return 0; +} + +int fpu_emulator_restore_context(struct sigcontext __user *sc) +{ + return 0; +} + +int fpu_emulator_save_context32(struct sigcontext32 __user *sc) +{ + return 0; +} + +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc) +{ + return 0; +} + +#ifdef CONFIG_64BIT +#endif /* CONFIG_64BIT */ +#endif /* CONFIG_MIPS_FPU_EMU */