On Thu, 2013-07-11 at 20:21 +0800, Kevin Hao wrote:
> Some cores (such as Freescale BookE) don't implement all floating
> point instructions in ISA. But some gcc versions do use these
> instructions. So we would have to enable the math emulation in this
> case. Add this to emulated instructions tracking statistics so that
> the user has a way to know that its toolcahin emit these unimplemented
> floating point instructions.
That patch is gross, it makes the function even more nasty than it
already is. Besides, CONFIG_PPC_FPU doesn't mean you have a HW FPU,
you need to check the CPU feature bits.
Also the caller already does PPC_WARN_EMULATED, so this patch makes
you call it twice or am I missing something ?
Cheers,
Ben.
> Signed-off-by: Kevin Hao <haoke...@gmail.com>
> ---
> arch/powerpc/math-emu/math.c | 50
> +++++++++++++++++++++++++++-----------------
> 1 file changed, 31 insertions(+), 19 deletions(-)
>
> diff --git a/arch/powerpc/math-emu/math.c b/arch/powerpc/math-emu/math.c
> index 18ce6a7..9a98b6c 100644
> --- a/arch/powerpc/math-emu/math.c
> +++ b/arch/powerpc/math-emu/math.c
> @@ -10,6 +10,7 @@
>
> #include <asm/sfp-machine.h>
> #include <math-emu/double.h>
> +#include <asm/emulated_ops.h>
>
> #define FLOATFUNC(x) extern int x(void *, void *, void *, void *)
>
> @@ -222,10 +223,17 @@ do_mathemu(struct pt_regs *regs)
> int idx = 0;
> int (*func)(void *, void *, void *, void *);
> int type = 0;
> - int eflag, trap;
> + int eflag, trap, ret = -ENOSYS;
> + int has_hw_fpu = 0;
>
> - if (get_user(insn, (u32 *)pc))
> - return -EFAULT;
> +#ifdef CONFIG_PPC_FPU
> + has_hw_fpu = 1;
> +#endif
> +
> + if (get_user(insn, (u32 *)pc)) {
> + ret = -EFAULT;
> + goto out;
> + }
>
> switch (insn >> 26) {
> case LFS: func = lfs; type = D; break;
> @@ -249,7 +257,7 @@ do_mathemu(struct pt_regs *regs)
> case STFDUX: func = stfd; type = XEU; break;
> case STFIWX: func = stfiwx; type = XE; break;
> default:
> - goto illegal;
> + goto out;
> }
> break;
>
> @@ -267,7 +275,7 @@ do_mathemu(struct pt_regs *regs)
> case FNMSUBS: func = fnmsubs; type = ABC; break;
> case FNMADDS: func = fnmadds; type = ABC; break;
> default:
> - goto illegal;
> + goto out;
> }
> break;
>
> @@ -287,7 +295,7 @@ do_mathemu(struct pt_regs *regs)
> case FNMSUB: func = fnmsub; type = ABC; break;
> case FNMADD: func = fnmadd; type = ABC; break;
> default:
> - goto illegal;
> + goto out;
> }
> break;
> }
> @@ -309,12 +317,12 @@ do_mathemu(struct pt_regs *regs)
> case MFFS: func = mffs; type = X; break;
> case MTFSF: func = mtfsf; type = XFLB; break;
> default:
> - goto illegal;
> + goto out;
> }
> break;
>
> default:
> - goto illegal;
> + goto out;
> }
>
> switch (type) {
> @@ -347,7 +355,7 @@ do_mathemu(struct pt_regs *regs)
> case DU:
> idx = (insn >> 16) & 0x1f;
> if (!idx)
> - goto illegal;
> + goto out;
>
> sdisp = (insn & 0xffff);
> op0 = (void *)¤t->thread.TS_FPR((insn >> 21) & 0x1f);
> @@ -375,7 +383,7 @@ do_mathemu(struct pt_regs *regs)
> if (((insn >> 1) & 0x3ff) == STFIWX)
> op1 = (void *)(regs->gpr[(insn >> 11) & 0x1f]);
> else
> - goto illegal;
> + goto out;
> } else {
> op1 = (void *)(regs->gpr[idx] + regs->gpr[(insn >> 11)
> & 0x1f]);
> }
> @@ -417,7 +425,7 @@ do_mathemu(struct pt_regs *regs)
> break;
>
> default:
> - goto illegal;
> + goto out;
> }
>
> /*
> @@ -425,9 +433,8 @@ do_mathemu(struct pt_regs *regs)
> * if flushed into the thread_struct before attempting
> * emulation
> */
> -#ifdef CONFIG_PPC_FPU
> - flush_fp_to_thread(current);
> -#endif
> + if (has_hw_fpu)
> + flush_fp_to_thread(current);
>
> eflag = func(op0, op1, op2, op3);
>
> @@ -437,8 +444,10 @@ do_mathemu(struct pt_regs *regs)
> }
>
> trap = record_exception(regs, eflag);
> - if (trap)
> - return 1;
> + if (trap) {
> + ret = 1;
> + goto out;
> + }
>
> switch (type) {
> case DU:
> @@ -451,8 +460,11 @@ do_mathemu(struct pt_regs *regs)
> }
>
> regs->nip += 4;
> - return 0;
> + ret = 0;
> +
> +out:
> + if (has_hw_fpu && ret >= 0)
> + PPC_WARN_EMULATED(math, regs);
>
> -illegal:
> - return -ENOSYS;
> + return ret;
> }
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