Re: [Qemu-devel] [PATCH] target-i386: update fp status fix

[TeLeMan]

update_fp_status() should be used after all of env->fpuc changes :
helper_fldcw(), helper_fninit(), helper_fldenv()
,helper_fxrstor(), helper_fsave(), x86_cpu_reset(), cpu_post_load().

On Mon, Sep 15, 2014 at 7:17 PM, Pavel Dovgalyuk
<address@hidden> wrote:
> This patch adds calls to update_fp_status() function from several
> places where FPU state is changed. These calls update status of
> softfloat library and prevent bugs caused by non-coherent rounding
> settings of the FPU and softfloat.
>
> Signed-off-by: Pavel Dovgalyuk <address@hidden>
> ---
>  target-i386/cpu.c        |    1 +
>  target-i386/cpu.h        |    1 +
>  target-i386/fpu_helper.c |    5 ++++-
>  target-i386/machine.c    |    2 +-
>  4 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 217500c..0ebedb0 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -2573,6 +2573,7 @@ static void x86_cpu_reset(CPUState *s)
>          env->fptags[i] = 1;
>      }
>      env->fpuc = 0x37f;
> +    update_fp_status(env);
>
>      env->mxcsr = 0x1f80;
>      env->xstate_bv = XSTATE_FP | XSTATE_SSE;
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index e634d83..42bda46 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -1249,6 +1249,7 @@ void QEMU_NORETURN raise_interrupt(CPUX86State *nenv, 
> int intno, int is_int,
>  /* cc_helper.c */
>  extern const uint8_t parity_table[256];
>  uint32_t cpu_cc_compute_all(CPUX86State *env1, int op);
> +void update_fp_status(CPUX86State *env);
>
>  static inline uint32_t cpu_compute_eflags(CPUX86State *env)
>  {
> diff --git a/target-i386/fpu_helper.c b/target-i386/fpu_helper.c
> index 1b2900d..a8ffba9 100644
> --- a/target-i386/fpu_helper.c
> +++ b/target-i386/fpu_helper.c
> @@ -537,7 +537,7 @@ uint32_t helper_fnstcw(CPUX86State *env)
>      return env->fpuc;
>  }
>
> -static void update_fp_status(CPUX86State *env)
> +void update_fp_status(CPUX86State *env)
>  {
>      int rnd_type;
>
> @@ -1006,6 +1006,7 @@ void helper_fstenv(CPUX86State *env, target_ulong ptr, 
> int data32)
>          cpu_stw_data(env, ptr + 10, 0);
>          cpu_stw_data(env, ptr + 12, 0);
>      }
> +    update_fp_status(env);
>  }
>
>  void helper_fldenv(CPUX86State *env, target_ulong ptr, int data32)
> @@ -1055,6 +1056,7 @@ void helper_fsave(CPUX86State *env, target_ulong ptr, 
> int data32)
>      env->fptags[5] = 1;
>      env->fptags[6] = 1;
>      env->fptags[7] = 1;
> +    update_fp_status(env);
>  }
>
>  void helper_frstor(CPUX86State *env, target_ulong ptr, int data32)
> @@ -1158,6 +1160,7 @@ void helper_fxrstor(CPUX86State *env, target_ulong ptr, 
> int data64)
>      }
>
>      env->fpuc = cpu_lduw_data(env, ptr);
> +    update_fp_status(env);
>      fpus = cpu_lduw_data(env, ptr + 2);
>      fptag = cpu_lduw_data(env, ptr + 4);
>      env->fpstt = (fpus >> 11) & 7;
> diff --git a/target-i386/machine.c b/target-i386/machine.c
> index 16d2f6a..2922c97 100644
> --- a/target-i386/machine.c
> +++ b/target-i386/machine.c
> @@ -315,13 +315,13 @@ static int cpu_post_load(void *opaque, int version_id)
>      env->hflags &= ~HF_CPL_MASK;
>      env->hflags |= (env->segs[R_SS].flags >> DESC_DPL_SHIFT) & HF_CPL_MASK;
>
> -    /* XXX: restore FPU round state */
>      env->fpstt = (env->fpus_vmstate >> 11) & 7;
>      env->fpus = env->fpus_vmstate & ~0x3800;
>      env->fptag_vmstate ^= 0xff;
>      for(i = 0; i < 8; i++) {
>          env->fptags[i] = (env->fptag_vmstate >> i) & 1;
>      }
> +    update_fp_status(env);
>
>      cpu_breakpoint_remove_all(cs, BP_CPU);
>      cpu_watchpoint_remove_all(cs, BP_CPU);
>
>