target/linux/generic-2.6/patches-2.6.28/024-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 @@ -751,6 +751,17 @@ 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 @@ -56,6 +56,12 @@
  51  #endif
  52  #define __mips 4
  53
  54 +/* Further private data for which no space exists in mips_fpu_struct */
  55 +
  56 +struct mips_fpu_emulator_stats fpuemustats;
  57 +
  58 +#ifdef CONFIG_MIPS_FPU_EMU
  59 +
  60  /* Function which emulates a floating point instruction. */
  61
  62  static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
  63 @@ -66,10 +72,6 @@ static int fpux_emu(struct pt_regs *,
  64         struct mips_fpu_struct *, mips_instruction);
  65  #endif
  66
  67 -/* Further private data for which no space exists in mips_fpu_struct */
  68 -
  69 -struct mips_fpu_emulator_stats fpuemustats;
  70 -
  71  /* Control registers */
  72
  73  #define FPCREG_RID     0       /* $0  = revision id */
  74 @@ -1273,6 +1275,13 @@ int fpu_emulator_cop1Handler(struct pt_r
  75
  76         return sig;
  77  }
  78 +#else
  79 +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
  80 +        int has_fpu)
  81 +{
  82 +       return 0;
  83 +}
  84 +#endif /* CONFIG_MIPS_FPU_EMU */
  85
  86  #ifdef CONFIG_DEBUG_FS
  87  extern struct dentry *mips_debugfs_dir;
  88 --- a/arch/mips/math-emu/dsemul.c
  89 +++ b/arch/mips/math-emu/dsemul.c
  90 @@ -109,6 +109,7 @@ int mips_dsemul(struct pt_regs *regs, mi
  91         return SIGILL;          /* force out of emulation loop */
  92  }
  93
  94 +#ifdef CONFIG_MIPS_FPU_EMU
  95  int do_dsemulret(struct pt_regs *xcp)
  96  {
  97         struct emuframe __user *fr;
  98 @@ -165,3 +166,9 @@ int do_dsemulret(struct pt_regs *xcp)
  99
 100         return 1;
 101  }
 102 +#else
 103 +int do_dsemulret(struct pt_regs *xcp)
 104 +{
 105 +       return 0;
 106 +}
 107 +#endif /* CONFIG_MIPS_FPU_EMU */
 108 --- a/arch/mips/math-emu/kernel_linkage.c
 109 +++ b/arch/mips/math-emu/kernel_linkage.c
 110 @@ -29,6 +29,7 @@
 111
 112  #define SIGNALLING_NAN 0x7ff800007ff80000LL
 113
 114 +#ifdef CONFIG_MIPS_FPU_EMU
 115  void fpu_emulator_init_fpu(void)
 116  {
 117         static int first = 1;
 118 @@ -112,4 +113,36 @@ int fpu_emulator_restore_context32(struc
 119
 120         return err;
 121  }
 122 -#endif
 123 +#endif /* CONFIG_64BIT */
 124 +#else
 125 +
 126 +void fpu_emulator_init_fpu(void)
 127 +{
 128 +       printk(KERN_INFO "FPU emulator disabled, make sure your toolchain"
 129 +               "was compiled with software floating point support (soft-float)\n");
 130 +       return;
 131 +}
 132 +
 133 +int fpu_emulator_save_context(struct sigcontext __user *sc)
 134 +{
 135 +       return 0;
 136 +}
 137 +
 138 +int fpu_emulator_restore_context(struct sigcontext __user *sc)
 139 +{
 140 +       return 0;
 141 +}
 142 +
 143 +int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
 144 +{
 145 +       return 0;
 146 +}
 147 +
 148 +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
 149 +{
 150 +       return 0;
 151 +}
 152 +
 153 +#ifdef CONFIG_64BIT
 154 +#endif /* CONFIG_64BIT */
 155 +#endif /* CONFIG_MIPS_FPU_EMU */