git: c6e27f5697c2 - main - arm64: Clear FPU flags in the pcb in cpu_copy_thread().

[John Baldwin]

The branch main has been updated by jhb:

URL: https://cgit.FreeBSD.org/src/commit/?id=c6e27f5697c28e188739ea1b4994dc8869dfb6c2

commit c6e27f5697c28e188739ea1b4994dc8869dfb6c2
Author:     John Baldwin <jhb at FreeBSD.org>
AuthorDate: 2021-01-08 22:56:54 +0000
Commit:     John Baldwin <jhb at FreeBSD.org>
CommitDate: 2021-01-19 19:05:48 +0000

    arm64: Clear FPU flags in the pcb in cpu_copy_thread().
    
    New threads start off with clean FPU state instead of inheriting state
    from the parent thread.
    
    PR:             247945
    Sponsored by:   Netflix
---
 sys/arm64/arm64/vm_machdep.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/arm64/arm64/vm_machdep.c b/sys/arm64/arm64/vm_machdep.c
index 37fcf0224521..90d628a7d6ee 100644
--- a/sys/arm64/arm64/vm_machdep.c
+++ b/sys/arm64/arm64/vm_machdep.c
@@ -175,6 +175,7 @@ cpu_copy_thread(struct thread *td, struct thread *td0)
 	td->td_pcb->pcb_x[9] = (uintptr_t)td;
 	td->td_pcb->pcb_lr = (uintptr_t)fork_trampoline;
 	td->td_pcb->pcb_sp = (uintptr_t)td->td_frame;
+	td->td_pcb->pcb_fpflags &= ~(PCB_FP_STARTED | PCB_FP_KERN | PCB_FP_NOSAVE);
 	td->td_pcb->pcb_fpusaved = &td->td_pcb->pcb_fpustate;
 	td->td_pcb->pcb_vfpcpu = UINT_MAX;