SMP - lazy FPU

- when a process is migrated to a different CPU it may have an active
  FPU context in the processor registers. We must save it and migrate
  it together with the process.

kernel/system/do_clear.c

@@ -54,6 +54,9 @@ PUBLIC int do_clear(struct proc * caller, message * m_ptr)
    * and mark slot as FREE. Also mark saved fpu contents as not significant.
    */
   RTS_SETFLAGS(rc, RTS_SLOT_FREE);
+  
+  /* release FPU */
+  release_fpu(rc);
   rc->p_misc_flags &= ~MF_FPU_INITIALIZED;
 
   /* Release the process table slot. If this is a system process, also
@@ -70,10 +73,6 @@ PUBLIC int do_clear(struct proc * caller, message * m_ptr)
   }
 #endif
 
-  /* release FPU */
-  if (fpu_owner == rc)
-	  release_fpu();
-
   return OK;
 }
 

kernel/system/do_exec.c

@@ -46,8 +46,7 @@ PUBLIC int do_exec(struct proc * caller, message * m_ptr)
    * will be initialized, when it's used next time. */
   rp->p_misc_flags &= ~MF_FPU_INITIALIZED;
   /* force reloading FPU if the current process is the owner */
-  if (rp == fpu_owner)
-	  release_fpu();
+  release_fpu(rp);
   return(OK);
 }
 #endif /* USE_EXEC */

kernel/system/do_fork.c

@@ -53,10 +53,7 @@ PUBLIC int do_fork(struct proc * caller, message * m_ptr)
   map_ptr= (struct mem_map *) m_ptr->PR_MEM_PTR;
 
   /* make sure that the FPU context is saved in parent before copy */
-  if (fpu_owner == rpp) {
-	  disable_fpu_exception();
-	  save_fpu(rpp);
-  }
+  save_fpu(rpp);
   /* Copy parent 'proc' struct to child. And reinitialize some fields. */
   gen = _ENDPOINT_G(rpc->p_endpoint);
 #if (_MINIX_CHIP == _CHIP_INTEL)

kernel/system/do_mcontext.c

@@ -43,10 +43,7 @@ PUBLIC int do_getmcontext(struct proc * caller, message * m_ptr)
   mc.mc_fpu_flags = 0;
   if (proc_used_fpu(rp)) {
 	/* make sure that the FPU context is saved into proc structure first */
-	if (fpu_owner == rp) {
-		disable_fpu_exception();
-		save_fpu(rp);
-	}
+	save_fpu(rp);
 	mc.mc_fpu_flags = 0 | rp->p_misc_flags & MF_FPU_INITIALIZED;
 	memcpy(&(mc.mc_fpu_state), rp->p_fpu_state.fpu_save_area_p,
 							FPU_XFP_SIZE);
@@ -92,8 +89,7 @@ PUBLIC int do_setmcontext(struct proc * caller, message * m_ptr)
   } else
 	rp->p_misc_flags &= ~MF_FPU_INITIALIZED;
   /* force reloading FPU in either case */
-  if (fpu_owner == rp)
-	  release_fpu();
+  release_fpu(rp);
 #endif
 
   return(OK);

kernel/system/do_sigreturn.c

@@ -60,8 +60,7 @@ PUBLIC int do_sigreturn(struct proc * caller, message * m_ptr)
 		FPU_XFP_SIZE);
 	rp->p_misc_flags |=  MF_FPU_INITIALIZED; /* Restore math usage flag. */
 	/* force reloading FPU */
-	if (fpu_owner == rp)
-		release_fpu();
+	release_fpu(rp);
   }
 #endif
 

kernel/system/do_sigsend.c

@@ -46,10 +46,7 @@ PUBLIC int do_sigsend(struct proc * caller, message * m_ptr)
   #if (_MINIX_CHIP == _CHIP_INTEL)
     if(proc_used_fpu(rp)) {
 	    /* save the FPU context before saving it to the sig context */
-	    if (fpu_owner == rp) {
-		    disable_fpu_exception();
-		    save_fpu(rp);
-	    }
+	    save_fpu(rp);
 	    memcpy(&sc.sc_fpu_state, rp->p_fpu_state.fpu_save_area_p,
 	   	 FPU_XFP_SIZE);
     }