score: Add Thread_Control::is_fp

Store the floating-point unit property in the thread control block
regardless of the CPU_HARDWARE_FP and CPU_SOFTWARE_FP settings.  Make
sure the floating-point unit is only enabled for the corresponding
multilibs.  This helps targets which have a volatile only floating point
context like SPARC for example.

c/src/lib/libcpu/powerpc/new-exceptions/cpu.c

@@ -98,8 +98,6 @@ void _CPU_Context_Initialize(
   }
 
 #ifdef PPC_MULTILIB_FPU
-  msr_value |= MSR_FP;
-#else
   /*
    *  The FP bit of the MSR should only be enabled if this is a floating
    *  point task.  Unfortunately, the vfprintf_r routine in newlib
@@ -108,21 +106,7 @@ void _CPU_Context_Initialize(
    *  of vfprintf.c will be required to avoid this behavior.  At this
    *  time (7 July 1997), this restructuring is not being done.
    */
-
+  msr_value |= MSR_FP;
-  /* Make sure integer tasks have no FPU access in order to
-   * catch violations. Gcc may implicitely use the FPU and
-   * data corruption may happen.
-   * Since we set the_contex->msr using our current MSR,
-   * we must make sure MSR_FP is off if (!is_fp)...
-   * Unfortunately, this means that users of vfprintf_r have to use FP
-   * tasks or fix vfprintf. Furthermore, users of int-only tasks
-   * must prevent gcc from using the FPU (currently -msoft-float is the
-   * only way...)
-   */
-  if ( is_fp )
-    msr_value |= PPC_MSR_FP;
-  else
-    msr_value &= ~PPC_MSR_FP;
 #endif
 
 #ifdef PPC_MULTILIB_ALTIVEC

cpukit/posix/src/pthreadcreate.c

@@ -155,11 +155,7 @@ int pthread_create(
    *  Currently all POSIX threads are floating point if the hardware
    *  supports it.
    */
-  #if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
+  is_fp = true;
-    is_fp = true;
-  #else
-    is_fp = false;
-  #endif
 
   /*
    *  Allocate the thread control block.

cpukit/score/cpu/mips/cpu.c

@@ -179,6 +179,7 @@ void _CPU_Context_Initialize(
 {
   uintptr_t             stack_tmp;
   __MIPS_REGISTER_TYPE  intlvl = new_level & 0xff;
+  __MIPS_REGISTER_TYPE  c0_sr;
 
   stack_tmp  = (uintptr_t)stack_base;
   stack_tmp += ((size) - CPU_STACK_ALIGNMENT);
@@ -187,11 +188,18 @@ void _CPU_Context_Initialize(
   the_context->sp = (__MIPS_REGISTER_TYPE) stack_tmp;
   the_context->fp = (__MIPS_REGISTER_TYPE) stack_tmp;
   the_context->ra = (__MIPS_REGISTER_TYPE) (uintptr_t)entry_point;
-  the_context->c0_sr =
+
+  c0_sr =
     ((intlvl==0)? (mips_interrupt_mask() | 0x300 | _INTON):
       ( ((intlvl<<9) & mips_interrupt_mask()) | 0x300 |
       ((intlvl & 1)?_INTON:0)) ) |
-      SR_CU0 | ((is_fp)?SR_CU1:0) | _EXTRABITS;
+      SR_CU0 | _EXTRABITS;
+#if MIPS_HAS_FPU == 1
+  if ( is_fp ) {
+    c0_sr |= SR_CU1;
+  }
+#endif
+  the_context->c0_sr = c0_sr;
 }
 /*
  *  _CPU_Internal_threads_Idle_thread_body

cpukit/score/include/rtems/score/thread.h

@@ -750,6 +750,8 @@ struct Thread_Control_struct {
 #endif
   /** This field is true if the thread is preemptible. */
   bool                                  is_preemptible;
+  /** This field is true if the thread uses the floating point unit. */
+  bool                                  is_fp;
 
   /**
    * @brief Scheduler related control.

cpukit/score/src/threadinitialize.c

@@ -159,6 +159,7 @@ bool _Thread_Initialize(
    *  General initialization
    */
 
+  the_thread->is_fp                  = is_fp;
   the_thread->Start.isr_level        = isr_level;
   the_thread->Start.is_preemptible   = is_preemptible;
   the_thread->Start.budget_algorithm = budget_algorithm;

cpukit/score/src/threadloadenv.c

@@ -25,17 +25,14 @@ void _Thread_Load_environment(
   Thread_Control *the_thread
 )
 {
-  bool is_fp;
   uint32_t isr_level;
 
 #if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
   if ( the_thread->Start.fp_context ) {
     the_thread->fp_context = the_thread->Start.fp_context;
     _Context_Initialize_fp( &the_thread->fp_context );
-    is_fp = true;
+  }
-  } else
 #endif
-    is_fp = false;
 
   the_thread->is_preemptible   = the_thread->Start.is_preemptible;
   the_thread->budget_algorithm = the_thread->Start.budget_algorithm;
@@ -58,7 +55,7 @@ void _Thread_Load_environment(
     the_thread->Start.Initial_stack.size,
     isr_level,
     _Thread_Handler,
-    is_fp,
+    the_thread->is_fp,
     the_thread->Start.tls_area
   );