target/linux/generic/patches-3.3/304-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 @@ -961,6 +961,17 @@ 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 @@ -2,11 +2,13 @@
  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 --- a/arch/mips/math-emu/cp1emu.c
  48 +++ b/arch/mips/math-emu/cp1emu.c
  49 @@ -58,7 +58,11 @@
  50  #define __mips 4
  51
  52  /* Function which emulates a floating point instruction. */
  53 +#ifdef CONFIG_DEBUG_FS
  54 +DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
  55 +#endif
  56
  57 +#ifdef CONFIG_MIPS_FPU_EMU
  58  static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
  59         mips_instruction);
  60
  61 @@ -69,10 +73,6 @@ static int fpux_emu(struct pt_regs *,
  62
  63  /* Further private data for which no space exists in mips_fpu_struct */
  64
  65 -#ifdef CONFIG_DEBUG_FS
  66 -DEFINE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);
  67 -#endif
  68 -
  69  /* Control registers */
  70
  71  #define FPCREG_RID     0       /* $0  = revision id */
  72 @@ -1360,7 +1360,6 @@ int fpu_emulator_cop1Handler(struct pt_r
  73
  74         return sig;
  75  }
  76 -
  77  #ifdef CONFIG_DEBUG_FS
  78
  79  static int fpuemu_stat_get(void *data, u64 *val)
  80 @@ -1409,4 +1408,11 @@ static int __init debugfs_fpuemu(void)
  81         return 0;
  82  }
  83  __initcall(debugfs_fpuemu);
  84 -#endif
  85 +#endif /* CONFIG_DEBUGFS */
  86 +#else
  87 +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
  88 +        int has_fpu)
  89 +{
  90 +       return 0;
  91 +}
  92 +#endif /* CONFIG_MIPS_FPU_EMU */
  93 --- a/arch/mips/math-emu/dsemul.c
  94 +++ b/arch/mips/math-emu/dsemul.c
  95 @@ -109,6 +109,7 @@ int mips_dsemul(struct pt_regs *regs, mi
  96         return SIGILL;          /* force out of emulation loop */
  97  }
  98
  99 +#ifdef CONFIG_MIPS_FPU_EMU
 100  int do_dsemulret(struct pt_regs *xcp)
 101  {
 102         struct emuframe __user *fr;
 103 @@ -165,3 +166,9 @@ int do_dsemulret(struct pt_regs *xcp)
 104
 105         return 1;
 106  }
 107 +#else
 108 +int do_dsemulret(struct pt_regs *xcp)
 109 +{
 110 +       return 0;
 111 +}
 112 +#endif /* CONFIG_MIPS_FPU_EMU */
 113 --- a/arch/mips/math-emu/kernel_linkage.c
 114 +++ b/arch/mips/math-emu/kernel_linkage.c
 115 @@ -29,6 +29,7 @@
 116
 117  #define SIGNALLING_NAN 0x7ff800007ff80000LL
 118
 119 +#ifdef CONFIG_MIPS_FPU_EMU
 120  void fpu_emulator_init_fpu(void)
 121  {
 122         static int first = 1;
 123 @@ -112,4 +113,36 @@ int fpu_emulator_restore_context32(struc
 124
 125         return err;
 126  }
 127 -#endif
 128 +#endif /* CONFIG_64BIT */
 129 +#else
 130 +
 131 +void fpu_emulator_init_fpu(void)
 132 +{
 133 +       printk(KERN_INFO "FPU emulator disabled, make sure your toolchain"
 134 +               "was compiled with software floating point support (soft-float)\n");
 135 +       return;
 136 +}
 137 +
 138 +int fpu_emulator_save_context(struct sigcontext __user *sc)
 139 +{
 140 +       return 0;
 141 +}
 142 +
 143 +int fpu_emulator_restore_context(struct sigcontext __user *sc)
 144 +{
 145 +       return 0;
 146 +}
 147 +
 148 +int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
 149 +{
 150 +       return 0;
 151 +}
 152 +
 153 +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
 154 +{
 155 +       return 0;
 156 +}
 157 +
 158 +#ifdef CONFIG_64BIT
 159 +#endif /* CONFIG_64BIT */
 160 +#endif /* CONFIG_MIPS_FPU_EMU */