git: d6a53211a716 - main - Discard the arm64 VFP state before resetting it

[Andrew Turner]

The branch main has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=d6a53211a716c987de76294cff32b652fe38bb09

commit d6a53211a716c987de76294cff32b652fe38bb09
Author:     Andrew Turner <andrew at FreeBSD.org>
AuthorDate: 2021-03-23 18:23:47 +0000
Commit:     Andrew Turner <andrew at FreeBSD.org>
CommitDate: 2021-04-08 07:51:26 +0000

    Discard the arm64 VFP state before resetting it
    
    When resetting the VFP state we need to discard any old state so we don't
    try to save it on a context switch. Move this first so resetting the pcb
    is safe to perform outside a critical section.
    
    Reviewed by:    arichardson
    Sponsored by:   Innovate UK
    Differential Revision:  https://reviews.freebsd.org/D29401
---
 sys/arm64/arm64/vfp.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sys/arm64/arm64/vfp.c b/sys/arm64/arm64/vfp.c
index 4935946d2430..9de27349fb8d 100644
--- a/sys/arm64/arm64/vfp.c
+++ b/sys/arm64/arm64/vfp.c
@@ -208,7 +208,15 @@ vfp_save_state(struct thread *td, struct pcb *pcb)
 void
 vfp_reset_state(struct thread *td, struct pcb *pcb)
 {
+	/* Discard the threads VFP state before resetting it */
 	critical_enter();
+	vfp_discard(td);
+	critical_exit();
+
+	/*
+	 * Clear the thread state. The VFP is disabled and is not the current
+	 * VFP thread so we won't change any of these on context switch.
+	 */
 	bzero(&pcb->pcb_fpustate.vfp_regs, sizeof(pcb->pcb_fpustate.vfp_regs));
 	KASSERT(pcb->pcb_fpusaved == &pcb->pcb_fpustate,
 	    ("pcb_fpusaved should point to pcb_fpustate."));
@@ -216,8 +224,6 @@ vfp_reset_state(struct thread *td, struct pcb *pcb)
 	pcb->pcb_fpustate.vfp_fpsr = 0;
 	pcb->pcb_vfpcpu = UINT_MAX;
 	pcb->pcb_fpflags = 0;
-	vfp_discard(td);
-	critical_exit();
 }
 
 void