--- /dev/null
+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
+@@ -976,6 +976,17 @@ 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 +2,11 @@
+ # 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
+--- a/arch/mips/math-emu/cp1emu.c
++++ b/arch/mips/math-emu/cp1emu.c
+@@ -59,7 +59,11 @@
+ #define __mips 4
+
+ /* Function which emulates a floating point instruction. */
++#ifdef CONFIG_DEBUG_FS
++DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
++#endif
+
++#ifdef CONFIG_MIPS_FPU_EMU
+ static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
+ mips_instruction);
+
+@@ -70,10 +74,6 @@ static int fpux_emu(struct pt_regs *,
+
+ /* Further private data for which no space exists in mips_fpu_struct */
+
+-#ifdef CONFIG_DEBUG_FS
+-DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
+-#endif
+-
+ /* Control registers */
+
+ #define FPCREG_RID 0 /* $0 = revision id */
+@@ -82,11 +82,15 @@ DEFINE_PER_CPU(struct mips_fpu_emulator_
+ /* Determine rounding mode from the RM bits of the FCSR */
+ #define modeindex(v) ((v) & FPU_CSR_RM)
+
++#endif /* CONFIG_MIPS_FPU_EMU */
++
+ /* microMIPS bitfields */
+ #define MM_POOL32A_MINOR_MASK 0x3f
+ #define MM_POOL32A_MINOR_SHIFT 0x6
+ #define MM_MIPS32_COND_FC 0x30
+
++#ifdef CONFIG_MIPS_FPU_EMU
++
+ /* Convert Mips rounding mode (0..3) to IEEE library modes. */
+ static const unsigned char ieee_rm[4] = {
+ [FPU_CSR_RN] = IEEE754_RN,
+@@ -116,9 +120,13 @@ static const unsigned int fpucondbit[8]
+ };
+ #endif
+
++#endif /* CONFIG_MIPS_FPU_EMU */
++
+ /* (microMIPS) Convert 16-bit register encoding to 32-bit register encoding. */
+ static const unsigned int reg16to32map[8] = {16, 17, 2, 3, 4, 5, 6, 7};
+
++#ifdef CONFIG_MIPS_FPU_EMU
++
+ /* (microMIPS) Convert certain microMIPS instructions to MIPS32 format. */
+ static const int sd_format[] = {16, 17, 0, 0, 0, 0, 0, 0};
+ static const int sdps_format[] = {16, 17, 22, 0, 0, 0, 0, 0};
+@@ -463,6 +471,8 @@ static int microMIPS32_to_MIPS32(union m
+ return 0;
+ }
+
++#endif /* CONFIG_MIPS_FPU_EMU */
++
+ int mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
+ unsigned long *contpc)
+ {
+@@ -667,6 +677,8 @@ int mm_isBranchInstr(struct pt_regs *reg
+ return 0;
+ }
+
++#ifdef CONFIG_MIPS_FPU_EMU
++
+ /*
+ * Redundant with logic already in kernel/branch.c,
+ * embedded in compute_return_epc. At some point,
+@@ -2102,7 +2114,6 @@ int fpu_emulator_cop1Handler(struct pt_r
+
+ return sig;
+ }
+-
+ #ifdef CONFIG_DEBUG_FS
+
+ static int fpuemu_stat_get(void *data, u64 *val)
+@@ -2151,4 +2162,11 @@ static int __init debugfs_fpuemu(void)
+ return 0;
+ }
+ __initcall(debugfs_fpuemu);
+-#endif
++#endif /* CONFIG_DEBUGFS */
++#else
++int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
++ int has_fpu, void *__user *fault_addr)
++{
++ return 0;
++}
++#endif /* CONFIG_MIPS_FPU_EMU */
+--- a/arch/mips/math-emu/dsemul.c
++++ b/arch/mips/math-emu/dsemul.c
+@@ -119,6 +119,7 @@ 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 __user *fr;
+@@ -182,3 +183,9 @@ 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
+@@ -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 @@ 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;
++}
++
++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 */
projects / openwrt.git / blobdiff