git: 281402e0a563 - main - arm64: Shave off two instructions in exceptions

The branch main has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=281402e0a5638108ead2529c63e34f3d1771d05e

commit 281402e0a5638108ead2529c63e34f3d1771d05e
Author:     Dapeng Gao <dg612@cam.ac.uk>
AuthorDate: 2023-03-01 14:28:53 +0000
Commit:     Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2023-03-01 14:43:43 +0000

    arm64: Shave off two instructions in exceptions
    
    This patch shaves off up to two three instructions in
    save_registers_head in exception.S for arm64, which would make more
    space for instructions that could be added in CheriBSD.
    
    This is done by:
     1. Combining pointer arithmetic with pre-incrementing STP instructions
     2. Removing the instruction that sets the frame pointer (x29) as its
        content is unused
    
    Differential Revision:  https://reviews.freebsd.org/D34631
---
 sys/arm64/arm64/exception.S | 43 +++++++++++++++++++++----------------------
 1 file changed, 21 insertions(+), 22 deletions(-)

diff --git a/sys/arm64/arm64/exception.S b/sys/arm64/arm64/exception.S
index 55bac5e5228a..fd55e1f39b58 100644
--- a/sys/arm64/arm64/exception.S
+++ b/sys/arm64/arm64/exception.S
@@ -41,35 +41,34 @@ __FBSDID("$FreeBSD$");
 .macro	save_registers_head el
 .if \el == 1
 	mov	x18, sp
-	sub	sp, sp, #128
+	stp	x0,  x1,  [sp, #(TF_X - TF_SIZE - 128)]!
+.else
+	stp	x0,  x1,  [sp, #(TF_X - TF_SIZE)]!
 .endif
-	sub	sp, sp, #(TF_SIZE)
-	stp	x28, x29, [sp, #(TF_X + 28 * 8)]
-	stp	x26, x27, [sp, #(TF_X + 26 * 8)]
-	stp	x24, x25, [sp, #(TF_X + 24 * 8)]
-	stp	x22, x23, [sp, #(TF_X + 22 * 8)]
-	stp	x20, x21, [sp, #(TF_X + 20 * 8)]
-	stp	x18, x19, [sp, #(TF_X + 18 * 8)]
-	stp	x16, x17, [sp, #(TF_X + 16 * 8)]
-	stp	x14, x15, [sp, #(TF_X + 14 * 8)]
-	stp	x12, x13, [sp, #(TF_X + 12 * 8)]
-	stp	x10, x11, [sp, #(TF_X + 10 * 8)]
-	stp	x8,  x9,  [sp, #(TF_X + 8  * 8)]
-	stp	x6,  x7,  [sp, #(TF_X + 6  * 8)]
-	stp	x4,  x5,  [sp, #(TF_X + 4  * 8)]
-	stp	x2,  x3,  [sp, #(TF_X + 2  * 8)]
-	stp	x0,  x1,  [sp, #(TF_X + 0  * 8)]
-	mrs	x10, elr_el1
-	mrs	x11, spsr_el1
-	mrs	x12, esr_el1
+	stp	x2,  x3,  [sp, #(2  * 8)]
+	stp	x4,  x5,  [sp, #(4  * 8)]
+	stp	x6,  x7,  [sp, #(6  * 8)]
+	stp	x8,  x9,  [sp, #(8  * 8)]
+	stp	x10, x11, [sp, #(10 * 8)]
+	stp	x12, x13, [sp, #(12 * 8)]
+	stp	x14, x15, [sp, #(14 * 8)]
+	stp	x16, x17, [sp, #(16 * 8)]
+	stp	x18, x19, [sp, #(18 * 8)]
+	stp	x20, x21, [sp, #(20 * 8)]
+	stp	x22, x23, [sp, #(22 * 8)]
+	stp	x24, x25, [sp, #(24 * 8)]
+	stp	x26, x27, [sp, #(26 * 8)]
+	stp	x28, x29, [sp, #(28 * 8)]
 .if \el == 0
 	mrs	x18, sp_el0
 .endif
+	mrs	x10, elr_el1
+	mrs	x11, spsr_el1
+	mrs	x12, esr_el1
+	stp	x18,  lr, [sp, #(TF_SP - TF_X)]!
 	str	x10, [sp, #(TF_ELR)]
 	stp	w11, w12, [sp, #(TF_SPSR)]
-	stp	x18,  lr, [sp, #(TF_SP)]
 	mrs	x18, tpidr_el1
-	add	x29, sp, #(TF_SIZE)
 .endm
 
 .macro	save_registers el