MIPS: Simplify FP context initialization

[mirror_ubuntu-focal-kernel.git] / arch / mips / include / asm / fpu.h

diff --git a/arch/mips/include/asm/fpu.h b/arch/mips/include/asm/fpu.h
index a2813fe381cf5442ca5a4fb2a3f22d619d7ef557..84de64606ccf16565244b57dfcc54f803bfa0c27 100644 (file)
--- a/arch/mips/include/asm/fpu.h
+++ b/arch/mips/include/asm/fpu.h
@@ -33,7 +33,6 @@
 struct sigcontext;
 struct sigcontext32;
 
-extern void _init_fpu(unsigned int);
 extern void _save_fp(struct task_struct *);
 extern void _restore_fp(struct task_struct *);
 
@@ -198,42 +197,36 @@ static inline void lose_fpu(int save)
        preempt_enable();
 }
 
-static inline int init_fpu(void)
+/**
+ * init_fp_ctx() - Initialize task FP context
+ * @target: The task whose FP context should be initialized.
+ *
+ * Initializes the FP context of the target task to sane default values if that
+ * target task does not already have valid FP context. Once the context has
+ * been initialized, the task will be marked as having used FP & thus having
+ * valid FP context.
+ *
+ * Returns: true if context is initialized, else false.
+ */
+static inline bool init_fp_ctx(struct task_struct *target)
 {
-       unsigned int fcr31 = current->thread.fpu.fcr31;
-       int ret = 0;
-
-       if (cpu_has_fpu) {
-               unsigned int config5;
-
-               ret = __own_fpu();
-               if (ret)
-                       return ret;
+       /* If FP has been used then the target already has context */
+       if (tsk_used_math(target))
+               return false;
 
-               if (!cpu_has_fre) {
-                       _init_fpu(fcr31);
+       /* Begin with data registers set to all 1s... */
+       memset(&target->thread.fpu.fpr, ~0, sizeof(target->thread.fpu.fpr));
 
-                       return 0;
-               }
-
-               /*
-                * Ensure FRE is clear whilst running _init_fpu, since
-                * single precision FP instructions are used. If FRE
-                * was set then we'll just end up initialising all 32
-                * 64b registers.
-                */
-               config5 = clear_c0_config5(MIPS_CONF5_FRE);
-               enable_fpu_hazard();
+       /* FCSR has been preset by `mips_set_personality_nan'.  */
 
-               _init_fpu(fcr31);
+       /*
+        * Record that the target has "used" math, such that the context
+        * just initialised, and any modifications made by the caller,
+        * aren't discarded.
+        */
+       set_stopped_child_used_math(target);
 
-               /* Restore FRE */
-               write_c0_config5(config5);
-               enable_fpu_hazard();
-       } else
-               fpu_emulator_init_fpu();
-
-       return ret;
+       return true;
 }
 
 static inline void save_fp(struct task_struct *tsk)