* High level FPU state handling functions:
*/
extern void fpu__activate_curr(struct fpu *fpu);
+extern void fpu__activate_fpstate_read(struct fpu *fpu);
extern void fpu__activate_fpstate(struct fpu *fpu);
extern void fpu__save(struct fpu *fpu);
extern void fpu__restore(struct fpu *fpu);
EXPORT_SYMBOL_GPL(fpu__activate_curr);
/*
+ * This function must be called before we read a task's fpstate.
+ *
+ * If the task has not used the FPU before then initialize its
+ * fpstate.
+ *
+ * If the task has used the FPU before then save it.
+ */
+void fpu__activate_fpstate_read(struct fpu *fpu)
+{
+ /*
+ * If fpregs are active (in the current CPU), then
+ * copy them to the fpstate:
+ */
+ if (fpu->fpregs_active) {
+ fpu__save(fpu);
+ } else {
+ if (fpu->fpstate_active) {
+ /* Invalidate any lazy state: */
+ fpu->last_cpu = -1;
+ } else {
+ fpstate_init(&fpu->state);
+
+ /* Safe to do for current and for stopped child tasks: */
+ fpu->fpstate_active = 1;
+ }
+ }
+}
+
+/*
* This function must be called before we read or write a task's fpstate.
*
* If the task has not used the FPU before then initialize its
if (!cpu_has_fxsr)
return -ENODEV;
- fpu__activate_fpstate(fpu);
+ fpu__activate_fpstate_read(fpu);
fpstate_sanitize_xstate(fpu);
return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
if (!cpu_has_xsave)
return -ENODEV;
- fpu__activate_fpstate(fpu);
+ fpu__activate_fpstate_read(fpu);
xsave = &fpu->state.xsave;
struct fpu *fpu = &target->thread.fpu;
struct user_i387_ia32_struct env;
- fpu__activate_fpstate(fpu);
+ fpu__activate_fpstate_read(fpu);
if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);