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 diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
  10 index 65d3b19..a467ee5 100644
  11 --- a/arch/mips/Kconfig
  12 +++ b/arch/mips/Kconfig
  13 @@ -811,6 +811,17 @@ config I8259
  14  config MIPS_BONITO64
  15         bool
  16
  17 +config MIPS_FPU_EMU
  18 +       bool
  19 +       default n
  20 +       help
  21 +          This option allows building a kernel with or without the Algorithmics
  22 +          FPU emulator enabled. Turning off this option results in a kernel which
  23 +          does not catch floating operations exceptions. Make sure that your toolchain
  24 +          is configured to enable software floating point emulation in that case.
  25 +
  26 +          If unsure say Y here.
  27 +
  28  config MIPS_MSC
  29         bool
  30
  31 diff --git a/arch/mips/math-emu/Makefile b/arch/mips/math-emu/Makefile
  32 index d547efd..7fdef24 100644
  33 --- a/arch/mips/math-emu/Makefile
  34 +++ b/arch/mips/math-emu/Makefile
  35 @@ -2,12 +2,14 @@
  36  # Makefile for the Linux/MIPS kernel FPU emulation.
  37  #
  38
  39 -obj-y  := cp1emu.o ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \
  40 +obj-y  :=      kernel_linkage.o dsemul.o cp1emu.o
  41 +
  42 +obj-$(CONFIG_MIPS_FPU_EMU)     += ieee754m.o ieee754d.o ieee754dp.o ieee754sp.o ieee754.o \
  43            ieee754xcpt.o dp_frexp.o dp_modf.o dp_div.o dp_mul.o dp_sub.o \
  44            dp_add.o dp_fsp.o dp_cmp.o dp_logb.o dp_scalb.o dp_simple.o \
  45            dp_tint.o dp_fint.o dp_tlong.o dp_flong.o sp_frexp.o sp_modf.o \
  46            sp_div.o sp_mul.o sp_sub.o sp_add.o sp_fdp.o sp_cmp.o sp_logb.o \
  47            sp_scalb.o sp_simple.o sp_tint.o sp_fint.o sp_tlong.o sp_flong.o \
  48 -          dp_sqrt.o sp_sqrt.o kernel_linkage.o dsemul.o
  49 +          dp_sqrt.o sp_sqrt.o
  50
  51  EXTRA_CFLAGS += -Werror
  52 diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
  53 index 890f779..9f4c767 100644
  54 --- a/arch/mips/math-emu/cp1emu.c
  55 +++ b/arch/mips/math-emu/cp1emu.c
  56 @@ -56,6 +56,12 @@
  57  #endif
  58  #define __mips 4
  59
  60 +/* Further private data for which no space exists in mips_fpu_struct */
  61 +
  62 +struct mips_fpu_emulator_stats fpuemustats;
  63 +
  64 +#ifdef CONFIG_MIPS_FPU_EMU
  65 +
  66  /* Function which emulates a floating point instruction. */
  67
  68  static int fpu_emu(struct pt_regs *, struct mips_fpu_struct *,
  69 @@ -66,10 +72,6 @@ static int fpux_emu(struct pt_regs *,
  70         struct mips_fpu_struct *, mips_instruction);
  71  #endif
  72
  73 -/* Further private data for which no space exists in mips_fpu_struct */
  74 -
  75 -struct mips_fpu_emulator_stats fpuemustats;
  76 -
  77  /* Control registers */
  78
  79  #define FPCREG_RID     0       /* $0  = revision id */
  80 @@ -1273,6 +1275,13 @@ int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
  81
  82         return sig;
  83  }
  84 +#else
  85 +int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
  86 +        int has_fpu)
  87 +{
  88 +       return 0;
  89 +}
  90 +#endif /* CONFIG_MIPS_FPU_EMU */
  91
  92  #ifdef CONFIG_DEBUG_FS
  93  extern struct dentry *mips_debugfs_dir;
  94 diff --git a/arch/mips/math-emu/dsemul.c b/arch/mips/math-emu/dsemul.c
  95 index df7b9d9..9b42bfd 100644
  96 --- a/arch/mips/math-emu/dsemul.c
  97 +++ b/arch/mips/math-emu/dsemul.c
  98 @@ -109,6 +109,7 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc)
  99         return SIGILL;          /* force out of emulation loop */
 100  }
 101
 102 +#ifdef CONFIG_MIPS_FPU_EMU
 103  int do_dsemulret(struct pt_regs *xcp)
 104  {
 105         struct emuframe __user *fr;
 106 @@ -165,3 +166,9 @@ int do_dsemulret(struct pt_regs *xcp)
 107
 108         return 1;
 109  }
 110 +#else
 111 +int do_dsemulret(struct pt_regs *xcp)
 112 +{
 113 +       return 0;
 114 +}
 115 +#endif /* CONFIG_MIPS_FPU_EMU */
 116 diff --git a/arch/mips/math-emu/kernel_linkage.c b/arch/mips/math-emu/kernel_linkage.c
 117 index 52e6c58..211a399 100644
 118 --- a/arch/mips/math-emu/kernel_linkage.c
 119 +++ b/arch/mips/math-emu/kernel_linkage.c
 120 @@ -29,6 +29,7 @@
 121
 122  #define SIGNALLING_NAN 0x7ff800007ff80000LL
 123
 124 +#ifdef CONFIG_MIPS_FPU_EMU
 125  void fpu_emulator_init_fpu(void)
 126  {
 127         static int first = 1;
 128 @@ -112,4 +113,34 @@ int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
 129
 130         return err;
 131  }
 132 -#endif
 133 +#endif /* CONFIG_64BIT */
 134 +#else
 135 +
 136 +void fpu_emulator_init_fpu(void)
 137 +{
 138 +       return;
 139 +}
 140 +
 141 +int fpu_emulator_save_context(struct sigcontext __user *sc)
 142 +{
 143 +       return 0;
 144 +}
 145 +
 146 +int fpu_emulator_restore_context(struct sigcontext __user *sc)
 147 +{
 148 +       return 0;
 149 +}
 150 +
 151 +int fpu_emulator_save_context32(struct sigcontext32 __user *sc)
 152 +{
 153 +       return 0;
 154 +}
 155 +
 156 +int fpu_emulator_restore_context32(struct sigcontext32 __user *sc)
 157 +{
 158 +       return 0;
 159 +}
 160 +
 161 +#ifdef CONFIG_64BIT
 162 +#endif /* CONFIG_64BIT */
 163 +#endif /* CONFIG_MIPS_FPU_EMU */