1 MIPS: allow disabling the kernel FPU emulator
3 This patch allows turning off the in-kernel Algorithmics
4 FPU emulator support, which allows one to save a couple of
5 precious blocks on an embedded system.
7 Signed-off-by: Florian Fainelli <florian@openwrt.org>
9 --- a/arch/mips/Kconfig
10 +++ b/arch/mips/Kconfig
11 @@ -974,6 +974,17 @@ config I8259
16 + bool "Enable FPU emulation"
19 + This option allows building a kernel with or without the Algorithmics
20 + FPU emulator enabled. Turning off this option results in a kernel which
21 + does not catch floating operations exceptions. Make sure that your toolchain
22 + is configured to enable software floating point emulation in that case.
24 + If unsure say Y here.
29 --- a/arch/mips/math-emu/Makefile
30 +++ b/arch/mips/math-emu/Makefile
32 # Makefile for the Linux/MIPS kernel FPU emulation.
35 -obj-y := cp1emu.o ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \
36 +obj-y := kernel_linkage.o dsemul.o cp1emu.o
37 +obj-$(CONFIG_MIPS_FPU_EMU) += ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \
38 ieee754xcpt.o dp_frexp.o dp_modf.o dp_div.o dp_mul.o dp_sub.o \
39 dp_add.o dp_fsp.o dp_cmp.o dp_logb.o dp_scalb.o dp_simple.o \
40 dp_tint.o dp_fint.o dp_tlong.o dp_flong.o sp_frexp.o sp_modf.o \
41 sp_div.o sp_mul.o sp_sub.o sp_add.o sp_fdp.o sp_cmp.o sp_logb.o \
42 sp_scalb.o sp_simple.o sp_tint.o sp_fint.o sp_tlong.o sp_flong.o \
43 - dp_sqrt.o sp_sqrt.o kernel_linkage.o dsemul.o
45 --- a/arch/mips/math-emu/cp1emu.c
46 +++ b/arch/mips/math-emu/cp1emu.c
50 /* Function which emulates a floating point instruction. */
51 +#ifdef CONFIG_DEBUG_FS
52 +DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
55 +#ifdef CONFIG_MIPS_FPU_EMU
56 static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
59 @@ -69,10 +73,6 @@ static int fpux_emu(struct pt_regs *,
61 /* Further private data for which no space exists in mips_fpu_struct */
63 -#ifdef CONFIG_DEBUG_FS
64 -DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
67 /* Control registers */
69 #define FPCREG_RID 0 /* $0 = revision id */
70 @@ -1361,7 +1361,6 @@ int fpu_emulator_cop1Handler(struct pt_r
75 #ifdef CONFIG_DEBUG_FS
77 static int fpuemu_stat_get(void *data, u64 *val)
78 @@ -1410,4 +1409,11 @@ static int __init debugfs_fpuemu(void)
81 __initcall(debugfs_fpuemu);
83 +#endif /* CONFIG_DEBUGFS */
85 +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
90 +#endif /* CONFIG_MIPS_FPU_EMU */
91 --- a/arch/mips/math-emu/dsemul.c
92 +++ b/arch/mips/math-emu/dsemul.c
93 @@ -108,6 +108,7 @@ int mips_dsemul(struct pt_regs *regs, mi
94 return SIGILL; /* force out of emulation loop */
97 +#ifdef CONFIG_MIPS_FPU_EMU
98 int do_dsemulret(struct pt_regs *xcp)
100 struct emuframe __user *fr;
101 @@ -164,3 +165,9 @@ int do_dsemulret(struct pt_regs *xcp)
106 +int do_dsemulret(struct pt_regs *xcp)
110 +#endif /* CONFIG_MIPS_FPU_EMU */
111 --- a/arch/mips/math-emu/kernel_linkage.c
112 +++ b/arch/mips/math-emu/kernel_linkage.c
115 #define SIGNALLING_NAN 0x7ff800007ff80000LL
117 +#ifdef CONFIG_MIPS_FPU_EMU
118 void fpu_emulator_init_fpu(void)
120 static int first = 1;
121 @@ -112,4 +113,36 @@ int fpu_emulator_restore_context32(struc
126 +#endif /* CONFIG_64BIT */
129 +void fpu_emulator_init_fpu(void)
131 + printk(KERN_INFO "FPU emulator disabled, make sure your toolchain"
132 + "was compiled with software floating point support (soft-float)\n");
136 +int fpu_emulator_save_context(struct sigcontext __user *sc)
141 +int fpu_emulator_restore_context(struct sigcontext __user *sc)
146 +int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
151 +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
157 +#endif /* CONFIG_64BIT */
158 +#endif /* CONFIG_MIPS_FPU_EMU */