target/linux/generic-2.6/patches-2.6.21/024-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 @@ -938,6 +938,17 @@ config LIMITED_DMA
  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 @@ -1,11 +1,12 @@
  32  #
  33  # Makefile for the Linux/MIPS kernel FPU emulation.
  34  #
  35 +obj-y  :=      kernel_linkage.o dsemul.o cp1emu.o
  36
  37 -obj-y  := cp1emu.o ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \
  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 --- a/arch/mips/math-emu/cp1emu.c
  47 +++ b/arch/mips/math-emu/cp1emu.c
  48 @@ -56,6 +56,12 @@
  49  #endif
  50  #define __mips 4
  51
  52 +/* Further private data for which no space exists in mips_fpu_struct */
  53 +
  54 +struct mips_fpu_emulator_stats fpuemustats;
  55 +
  56 +#ifdef CONFIG_MIPS_FPU_EMU
  57 +
  58  /* Function which emulates a floating point instruction. */
  59
  60  static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
  61 @@ -66,10 +72,6 @@ static int fpux_emu(struct pt_regs *,
  62         struct mips_fpu_struct *, mips_instruction);
  63  #endif
  64
  65 -/* Further private data for which no space exists in mips_fpu_struct */
  66 -
  67 -struct mips_fpu_emulator_stats fpuemustats;
  68 -
  69  /* Control registers */
  70
  71  #define FPCREG_RID     0       /* $0  = revision id */
  72 @@ -1277,3 +1279,10 @@ int fpu_emulator_cop1Handler(struct pt_r
  73
  74         return sig;
  75  }
  76 +#else
  77 +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
  78 +        int has_fpu)
  79 +{
  80 +       return 0;
  81 +}
  82 +#endif /* CONFIG_MIPS_FPU_EMU */
  83 --- a/arch/mips/math-emu/dsemul.c
  84 +++ b/arch/mips/math-emu/dsemul.c
  85 @@ -112,6 +112,7 @@ int mips_dsemul(struct pt_regs *regs, mi
  86         return SIGILL;          /* force out of emulation loop */
  87  }
  88
  89 +#ifdef CONFIG_MIPS_FPU_EMU
  90  int do_dsemulret(struct pt_regs *xcp)
  91  {
  92         struct emuframe *fr;
  93 @@ -167,3 +168,9 @@ int do_dsemulret(struct pt_regs *xcp)
  94
  95         return 1;
  96  }
  97 +#else
  98 +int do_dsemulret(struct pt_regs *xcp)
  99 +{
 100 +       return 0;
 101 +}
 102 +#endif /* CONFIG_MIPS_FPU_EMU */
 103 --- a/arch/mips/math-emu/kernel_linkage.c
 104 +++ b/arch/mips/math-emu/kernel_linkage.c
 105 @@ -28,6 +28,7 @@
 106
 107  #define SIGNALLING_NAN 0x7ff800007ff80000LL
 108
 109 +#ifdef CONFIG_MIPS_FPU_EMU
 110  void fpu_emulator_init_fpu(void)
 111  {
 112         static int first = 1;
 113 @@ -111,4 +112,36 @@ int fpu_emulator_restore_context32(struc
 114
 115         return err;
 116  }
 117 -#endif
 118 +#endif /* CONFIG_64BIT */
 119 +#else
 120 +
 121 +void fpu_emulator_init_fpu(void)
 122 +{
 123 +       printk(KERN_INFO "FPU emulator disabled, make sure your toolchain"
 124 +               "was compiled with software floating point support (soft-float)\n");
 125 +       return;
 126 +}
 127 +
 128 +int fpu_emulator_save_context(struct sigcontext __user *sc)
 129 +{
 130 +       return 0;
 131 +}
 132 +
 133 +int fpu_emulator_restore_context(struct sigcontext __user *sc)
 134 +{
 135 +       return 0;
 136 +}
 137 +
 138 +#ifdef CONFIG_64BIT
 139 +int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
 140 +{
 141 +       return 0;
 142 +}
 143 +
 144 +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
 145 +{
 146 +       return 0;
 147 +}
 148 +
 149 +#endif /* CONFIG_64BIT */
 150 +#endif /* CONFIG_MIPS_FPU_EMU */