git: 4eec584d79c1 - main - arm64: Clear td_frame when returning to userspace

The branch main has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=4eec584d79c1e8375d863c7eec7229ac7ec3f13b

commit 4eec584d79c1e8375d863c7eec7229ac7ec3f13b
Author:     Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2024-06-12 13:08:13 +0000
Commit:     Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2024-06-12 13:08:13 +0000

    arm64: Clear td_frame when returning to userspace
    
    When returning from an exception to userspace clear the saved td_frame.
    On the next exception this should point to the frame, however this is
    not guaranteed.
    
    To ensure the trap frame pointer is either valid or NULL clear it
    before returning to userspace in the EL0 synchronous exception handler.
    
    Reviewed by:    kib, markj
    Sponsored by:   Arm Ltd
    Differential Revision:  https://reviews.freebsd.org/D44807
---
 sys/arm64/arm64/exception.S | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/arm64/arm64/exception.S b/sys/arm64/arm64/exception.S
index 662684588e0c..3dff834e27a2 100644
--- a/sys/arm64/arm64/exception.S
+++ b/sys/arm64/arm64/exception.S
@@ -252,9 +252,11 @@ ENTRY(handle_el0_sync)
 	KMSAN_ENTER
 	ldr	x0, [x18, #PC_CURTHREAD]
 	mov	x1, sp
+	mov	x22, x0
 	str	x1, [x0, #TD_FRAME]
 	bl	do_el0_sync
 	do_ast
+	str	xzr, [x22, #TD_FRAME]
 	KMSAN_LEAVE
 	restore_registers 0
 	ERET