target/linux/generic/patches-3.19/304-mips_disable_fpu.patch

   1 --- a/arch/mips/Kconfig
   2 +++ b/arch/mips/Kconfig
   3 @@ -2521,6 +2521,20 @@ config MIPS_O32_FP64_SUPPORT
   4
   5           If unsure, say N.
   6
   7 +config MIPS_FPU_EMULATOR
   8 +       bool "MIPS FPU Emulator"
   9 +       default y
  10 +       help
  11 +         This option lets you disable the built-in MIPS FPU (Coprocessor 1)
  12 +         emulator, which handles floating-point instructions on processors
  13 +         without a hardware FPU.  It is generally a good idea to keep the
  14 +         emulator built-in, unless you are perfectly sure you have a
  15 +         complete soft-float environment.  With the emulator disabled, all
  16 +         users of float operations will be killed with an illegal instr-
  17 +         uction exception.
  18 +
  19 +         Say Y, please.
  20 +
  21  config USE_OF
  22         bool
  23         select OF
  24 --- a/arch/mips/Makefile
  25 +++ b/arch/mips/Makefile
  26 @@ -275,7 +275,7 @@ OBJCOPYFLAGS                += --remove-section=.regin
  27  head-y := arch/mips/kernel/head.o
  28
  29  libs-y                 += arch/mips/lib/
  30 -libs-y                 += arch/mips/math-emu/
  31 +libs-$(CONFIG_MIPS_FPU_EMULATOR)       += arch/mips/math-emu/
  32
  33  # See arch/mips/Kbuild for content of core part of the kernel
  34  core-y += arch/mips/
  35 --- a/arch/mips/include/asm/fpu.h
  36 +++ b/arch/mips/include/asm/fpu.h
  37 @@ -210,8 +210,10 @@ static inline int init_fpu(void)
  38                 /* Restore FRE */
  39                 write_c0_config5(config5);
  40                 enable_fpu_hazard();
  41 -       } else
  42 +       } else (IS_ENABLED(CONFIG_MIPS_FPU_EMULATOR))
  43                 fpu_emulator_init_fpu();
  44 +       else
  45 +               ret = SIGILL;
  46
  47         return ret;
  48  }
  49 --- a/arch/mips/include/asm/fpu_emulator.h
  50 +++ b/arch/mips/include/asm/fpu_emulator.h
  51 @@ -30,6 +30,7 @@
  52  #include <asm/local.h>
  53  #include <asm/processor.h>
  54
  55 +#ifdef CONFIG_MIPS_FPU_EMULATOR
  56  #ifdef CONFIG_DEBUG_FS
  57
  58  struct mips_fpu_emulator_stats {
  59 @@ -65,6 +66,20 @@ extern int do_dsemulret(struct pt_regs *
  60  extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
  61                                     struct mips_fpu_struct *ctx, int has_fpu,
  62                                     void *__user *fault_addr);
  63 +#else  /* no CONFIG_MIPS_FPU_EMULATOR */
  64 +static inline int do_dsemulret(struct pt_regs *xcp)
  65 +{
  66 +       return 0;       /* 0 means error, should never get here anyway */
  67 +}
  68 +
  69 +static inline int fpu_emulator_cop1Handler(struct pt_regs *xcp,
  70 +                               struct mips_fpu_struct *ctx, int has_fpu,
  71 +                               void *__user *fault_addr)
  72 +{
  73 +       return SIGILL;  /* we don't speak MIPS FPU */
  74 +}
  75 +#endif /* CONFIG_MIPS_FPU_EMULATOR */
  76 +
  77  int process_fpemu_return(int sig, void __user *fault_addr);
  78  int mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
  79                      unsigned long *contpc);