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

[Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>]

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 <pavel.dovgaluk@ispras.ru>
---
 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);