target/linux/generic-2.6/patches-2.6.33/025-mips_disable_fpu.patch

   1 MIPS: allow disabling the kernel FPU emulator
   2
   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.
   6
   7 Signed-off-by: Florian Fainelli <florian@openwrt.org>
   8 --
   9 --- a/arch/mips/Kconfig
  10 +++ b/arch/mips/Kconfig
  11 @@ -839,6 +839,17 @@ config I8259
  12  config MIPS_BONITO64
  13         bool
  14
  15 +config MIPS_FPU_EMU
  16 +       bool "Enable FPU emulation"
  17 +       default y
  18 +       help
  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.
  23 +
  24 +          If unsure say Y here.
  25 +
  26  config MIPS_MSC
  27         bool
  28
  29 --- a/arch/mips/math-emu/Makefile
  30 +++ b/arch/mips/math-emu/Makefile
  31 @@ -2,12 +2,14 @@
  32  # Makefile for the Linux/MIPS kernel FPU emulation.
  33  #
  34
  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 +
  38 +obj-$(CONFIG_MIPS_FPU_EMU)     += ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \
  39            ieee754xcpt.o dp_frexp.o dp_modf.o dp_div.o dp_mul.o dp_sub.o \
  40            dp_add.o dp_fsp.o dp_cmp.o dp_logb.o dp_scalb.o dp_simple.o \
  41            dp_tint.o dp_fint.o dp_tlong.o dp_flong.o sp_frexp.o sp_modf.o \
  42            sp_div.o sp_mul.o sp_sub.o sp_add.o sp_fdp.o sp_cmp.o sp_logb.o \
  43            sp_scalb.o sp_simple.o sp_tint.o sp_fint.o sp_tlong.o sp_flong.o \
  44 -          dp_sqrt.o sp_sqrt.o kernel_linkage.o dsemul.o
  45 +          dp_sqrt.o sp_sqrt.o
  46
  47  EXTRA_CFLAGS += -Werror
  48 --- a/arch/mips/math-emu/cp1emu.c
  49 +++ b/arch/mips/math-emu/cp1emu.c
  50 @@ -58,7 +58,11 @@
  51  #define __mips 4
  52
  53  /* Function which emulates a floating point instruction. */
  54 +#ifdef CONFIG_DEBUG_FS
  55 +DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
  56 +#endif
  57
  58 +#ifdef CONFIG_MIPS_FPU_EMU
  59  static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
  60         mips_instruction);
  61
  62 @@ -69,10 +73,6 @@ static int fpux_emu(struct pt_regs *,
  63
  64  /* Further private data for which no space exists in mips_fpu_struct */
  65
  66 -#ifdef CONFIG_DEBUG_FS
  67 -DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
  68 -#endif
  69 -
  70  /* Control registers */
  71
  72  #define FPCREG_RID     0       /* $0  = revision id */
  73 @@ -1277,7 +1277,6 @@ int fpu_emulator_cop1Handler(struct pt_r
  74
  75         return sig;
  76  }
  77 -
  78  #ifdef CONFIG_DEBUG_FS
  79
  80  static int fpuemu_stat_get(void *data, u64 *val)
  81 @@ -1326,4 +1325,11 @@ static int __init debugfs_fpuemu(void)
  82         return 0;
  83  }
  84  __initcall(debugfs_fpuemu);
  85 -#endif
  86 +#endif /* CONFIG_DEBUGFS */
  87 +#else
  88 +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
  89 +        int has_fpu)
  90 +{
  91 +       return 0;
  92 +}
  93 +#endif /* CONFIG_MIPS_FPU_EMU */
  94 --- a/arch/mips/math-emu/dsemul.c
  95 +++ b/arch/mips/math-emu/dsemul.c
  96 @@ -109,6 +109,7 @@ int mips_dsemul(struct pt_regs *regs, mi
  97         return SIGILL;          /* force out of emulation loop */
  98  }
  99
 100 +#ifdef CONFIG_MIPS_FPU_EMU
 101  int do_dsemulret(struct pt_regs *xcp)
 102  {
 103         struct emuframe __user *fr;
 104 @@ -165,3 +166,9 @@ int do_dsemulret(struct pt_regs *xcp)
 105
 106         return 1;
 107  }
 108 +#else
 109 +int do_dsemulret(struct pt_regs *xcp)
 110 +{
 111 +       return 0;
 112 +}
 113 +#endif /* CONFIG_MIPS_FPU_EMU */
 114 --- a/arch/mips/math-emu/kernel_linkage.c
 115 +++ b/arch/mips/math-emu/kernel_linkage.c
 116 @@ -29,6 +29,7 @@
 117
 118  #define SIGNALLING_NAN 0x7ff800007ff80000LL
 119
 120 +#ifdef CONFIG_MIPS_FPU_EMU
 121  void fpu_emulator_init_fpu(void)
 122  {
 123         static int first = 1;
 124 @@ -112,4 +113,36 @@ int fpu_emulator_restore_context32(struc
 125
 126         return err;
 127  }
 128 -#endif
 129 +#endif /* CONFIG_64BIT */
 130 +#else
 131 +
 132 +void fpu_emulator_init_fpu(void)
 133 +{
 134 +       printk(KERN_INFO "FPU emulator disabled, make sure your toolchain"
 135 +               "was compiled with software floating point support (soft-float)\n");
 136 +       return;
 137 +}
 138 +
 139 +int fpu_emulator_save_context(struct sigcontext __user *sc)
 140 +{
 141 +       return 0;
 142 +}
 143 +
 144 +int fpu_emulator_restore_context(struct sigcontext __user *sc)
 145 +{
 146 +       return 0;
 147 +}
 148 +
 149 +int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
 150 +{
 151 +       return 0;
 152 +}
 153 +
 154 +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
 155 +{
 156 +       return 0;
 157 +}
 158 +
 159 +#ifdef CONFIG_64BIT
 160 +#endif /* CONFIG_64BIT */
 161 +#endif /* CONFIG_MIPS_FPU_EMU */