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- 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 <[email protected]>
- --
- --- a/arch/mips/Kconfig
- +++ b/arch/mips/Kconfig
- @@ -981,6 +981,17 @@ 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 +2,12 @@
- # 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
- +
- +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 dsemul.o cp1emu.o
- --- 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;
- @@ -113,3 +114,36 @@ int fpu_emulator_restore_context32(struc
- return err;
- }
- #endif
- +
- +#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;
- +}
- +
- +#ifdef CONFIG_64BIT
- +int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
- +{
- + return 0;
- +}
- +
- +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
- +{
- + return 0;
- +}
- +#endif /* CONFIG_64BIT */
- +
- +#endif /* CONFIG_MIPS_FPU_EMU */
- --- a/arch/mips/include/asm/fpu_emulator.h
- +++ b/arch/mips/include/asm/fpu_emulator.h
- @@ -27,6 +27,8 @@
- #include <asm/inst.h>
- #include <asm/local.h>
-
- +#ifdef CONFIG_MIPS_FPU_EMU
- +
- #ifdef CONFIG_DEBUG_FS
-
- struct mips_fpu_emulator_stats {
- @@ -60,6 +62,38 @@ extern int fpu_emulator_cop1Handler(stru
- int process_fpemu_return(int sig, void __user *fault_addr);
- int mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
- unsigned long *contpc);
- +#else
- +static inline int mips_dsemul(struct pt_regs *regs, mips_instruction ir,
- + unsigned long cpc)
- +{
- + return 0;
- +}
- +
- +static inline int do_dsemulret(struct pt_regs *xcp)
- +{
- + return 0;
- +}
- +
- +static inline int fpu_emulator_cop1Handler(struct pt_regs *xcp,
- + struct mips_fpu_struct *ctx,
- + int has_fpu,
- + void *__user *fault_addr)
- +{
- + return 0;
- +}
- +
- +static inline int process_fpemu_return(int sig, void __user *fault_addr)
- +{
- + return -EINVAL;
- +}
- +
- +static inline int mm_isBranchInstr(struct pt_regs *regs,
- + struct mm_decoded_insn dec_insn,
- + unsigned long *contpc)
- +{
- + return 0;
- +}
- +#endif /* CONFIG_MIPS_FPU_EMU */
-
- /*
- * Instruction inserted following the badinst to further tag the sequence
- --- a/arch/mips/kernel/traps.c
- +++ b/arch/mips/kernel/traps.c
- @@ -684,6 +684,7 @@ asmlinkage void do_ov(struct pt_regs *re
- force_sig_info(SIGFPE, &info, current);
- }
-
- +#ifdef CONFIG_MIPS_FPU_EMU
- int process_fpemu_return(int sig, void __user *fault_addr)
- {
- if (sig == SIGSEGV || sig == SIGBUS) {
- @@ -707,6 +708,7 @@ int process_fpemu_return(int sig, void _
- return 0;
- }
- }
- +#endif /* CONFIG_MIPS_FPU_EMU */
-
- /*
- * XXX Delayed fp exceptions when doing a lazy ctx switch XXX
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