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

[TeLeMan]

On Tue, Sep 16, 2014 at 1:42 PM, TeLeMan <address@hidden> wrote:
> 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().

missing one: x86_cpu_gdb_write_register().

>
> 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);
>>
>>