Author: andrew
Date: Wed Jul 1 17:27:44 2015
New Revision: 285014
URL: https://svnweb.freebsd.org/changeset/base/285014
Log:
Fix the logic for when to restore the VFP registers. It should restore
them when a different thread last used them, or when the thread was last
run on a different cpu.
Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/arm64/arm64/vfp.c
Modified: head/sys/arm64/arm64/vfp.c
==============================================================================
--- head/sys/arm64/arm64/vfp.c Wed Jul 1 17:19:51 2015 (r285013)
+++ head/sys/arm64/arm64/vfp.c Wed Jul 1 17:27:44 2015 (r285014)
@@ -95,6 +95,9 @@ vfp_save_state(struct thread *td)
*/
cpacr = READ_SPECIALREG(cpacr_el1);
if ((cpacr & CPACR_FPEN_MASK) == CPACR_FPEN_TRAP_NONE) {
+ KASSERT(PCPU_GET(fpcurthread) == td,
+ ("Storing an invalid VFP state"));
+
vfp_state = td->td_pcb->pcb_vfp;
__asm __volatile(
"mrs %0, fpcr \n"
@@ -142,7 +145,12 @@ vfp_restore_state(void)
vfp_enable();
- if (PCPU_GET(fpcurthread) != curthread && cpu != curpcb->pcb_vfpcpu) {
+ /*
+ * If the previous thread on this cpu to use the VFP was not the
+ * current threas, or the current thread last used it on a different
+ * cpu we need to restore the old state.
+ */
+ if (PCPU_GET(fpcurthread) != curthread || cpu != curpcb->pcb_vfpcpu) {
vfp_state = curthread->td_pcb->pcb_vfp;
fpcr = curthread->td_pcb->pcb_fpcr;
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