The branch main has been updated by jhb:
URL:
https://cgit.FreeBSD.org/src/commit/?id=7314f78b240bdbf2bcec07e3d5a475e37941bb6b
commit 7314f78b240bdbf2bcec07e3d5a475e37941bb6b
Author: John Baldwin <j...@freebsd.org>
AuthorDate: 2025-09-16 11:21:39 +0000
Commit: John Baldwin <j...@freebsd.org>
CommitDate: 2025-09-16 11:21:39 +0000
aarch64: Clarify the initial adjustments to sp for kernel exception entry
The first store-pair instruction in save_registers_head decrements the
stack pointer to create room for most of the trapframe (and the
redzone area for nested exceptions). However, the expression was a
bit non-intuitive as it was using an expression without a leading
negative sign to adjust the stack pointer. Rewrite the expression so
that it is more clearly a negative adjustment to the stack pointer.
Suggested by: andrew
Reviewed by: andrew
Sponsored by: AFRL, DARPA
Differential Revision: https://reviews.freebsd.org/D52514
---
sys/arm64/arm64/exception.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sys/arm64/arm64/exception.S b/sys/arm64/arm64/exception.S
index 13095def8b00..6e673fbe5a43 100644
--- a/sys/arm64/arm64/exception.S
+++ b/sys/arm64/arm64/exception.S
@@ -43,9 +43,9 @@
.macro save_registers_head el
.if \el == 1
mov x18, sp
- stp x0, x1, [sp, #(TF_X - TF_SIZE - 128)]!
+ stp x0, x1, [sp, #-(TF_SIZE - TF_X + 128)]!
.else
- stp x0, x1, [sp, #(TF_X - TF_SIZE)]!
+ stp x0, x1, [sp, #-(TF_SIZE - TF_X)]!
.endif
stp x2, x3, [sp, #(2 * 8)]
stp x4, x5, [sp, #(4 * 8)]
