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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
@@ -938,6 +938,17 @@ config LIMITED_DMA
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
@@ -1,11 +1,12 @@
#
# Makefile for the Linux/MIPS kernel FPU emulation.
#
+obj-y := kernel_linkage.o dsemul.o cp1emu.o
-obj-y := cp1emu.o ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.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
@@ -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 @@ static int fpux_emu(struct pt_regs *,
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 */
@@ -1277,3 +1279,10 @@ int fpu_emulator_cop1Handler(struct pt_r
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 */
--- a/arch/mips/math-emu/dsemul.c
+++ b/arch/mips/math-emu/dsemul.c
@@ -112,6 +112,7 @@ 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 *fr;
@@ -167,3 +168,9 @@ 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
@@ -28,6 +28,7 @@
#define SIGNALLING_NAN 0x7ff800007ff80000LL
+#ifdef CONFIG_MIPS_FPU_EMU
void fpu_emulator_init_fpu(void)
{
static int first = 1;
@@ -111,4 +112,36 @@ 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;
+}
+
+#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 */
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