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 -- Index: linux-2.6.30.7/arch/mips/Kconfig =================================================================== --- linux-2.6.30.7.orig/arch/mips/Kconfig 2009-09-28 08:21:26.000000000 +0200 +++ linux-2.6.30.7/arch/mips/Kconfig 2009-09-28 08:21:31.000000000 +0200 @@ -791,6 +791,17 @@ config MIPS_BONITO64 bool +config MIPS_FPU_EMU + bool + default n + 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 Index: linux-2.6.30.7/arch/mips/math-emu/Makefile =================================================================== --- linux-2.6.30.7.orig/arch/mips/math-emu/Makefile 2009-09-28 08:21:26.000000000 +0200 +++ linux-2.6.30.7/arch/mips/math-emu/Makefile 2009-09-28 08:21:31.000000000 +0200 @@ -2,12 +2,14 @@ # 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 EXTRA_CFLAGS += -Werror Index: linux-2.6.30.7/arch/mips/math-emu/cp1emu.c =================================================================== --- linux-2.6.30.7.orig/arch/mips/math-emu/cp1emu.c 2009-09-28 08:21:26.000000000 +0200 +++ linux-2.6.30.7/arch/mips/math-emu/cp1emu.c 2009-09-28 08:21:31.000000000 +0200 @@ -56,6 +56,12 @@ #endif #define __mips 4 +/* Further private data for which no space exists in mips_fpu_struct */ + +struct mips_fpu_emulator_stats fpuemustats; + +#ifdef CONFIG_MIPS_FPU_EMU + /* Function which emulates a floating point instruction. */ static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *, @@ -66,10 +72,6 @@ struct mips_fpu_struct *, mips_instruction); #endif -/* Further private data for which no space exists in mips_fpu_struct */ - -struct mips_fpu_emulator_stats fpuemustats; - /* Control registers */ #define FPCREG_RID 0 /* $0 = revision id */ @@ -1273,6 +1275,13 @@ return sig; } +#else +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx, + int has_fpu) +{ + return 0; +} +#endif /* CONFIG_MIPS_FPU_EMU */ #ifdef CONFIG_DEBUG_FS extern struct dentry *mips_debugfs_dir; Index: linux-2.6.30.7/arch/mips/math-emu/dsemul.c =================================================================== --- linux-2.6.30.7.orig/arch/mips/math-emu/dsemul.c 2009-09-28 08:21:26.000000000 +0200 +++ linux-2.6.30.7/arch/mips/math-emu/dsemul.c 2009-09-28 08:21:31.000000000 +0200 @@ -109,6 +109,7 @@ return SIGILL; /* force out of emulation loop */ } +#ifdef CONFIG_MIPS_FPU_EMU int do_dsemulret(struct pt_regs *xcp) { struct emuframe __user *fr; @@ -165,3 +166,9 @@ return 1; } +#else +int do_dsemulret(struct pt_regs *xcp) +{ + return 0; +} +#endif /* CONFIG_MIPS_FPU_EMU */ Index: linux-2.6.30.7/arch/mips/math-emu/kernel_linkage.c =================================================================== --- linux-2.6.30.7.orig/arch/mips/math-emu/kernel_linkage.c 2009-09-28 08:21:26.000000000 +0200 +++ linux-2.6.30.7/arch/mips/math-emu/kernel_linkage.c 2009-09-28 08:22:36.000000000 +0200 @@ -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 @@ 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 */