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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 <florian@openwrt.org>
--
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -945,6 +945,17 @@ 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
@@ -694,6 +694,7 @@ asmlinkage void do_ov(struct pt_regs *re
exception_exit(prev_state);
}
+#ifdef CONFIG_MIPS_FPU_EMU
int process_fpemu_return(int sig, void __user *fault_addr)
{
if (sig == SIGSEGV || sig == SIGBUS) {
@@ -717,6 +718,7 @@ 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
|
