git: 3822a970ff3c - stable/13 - Move instructions into the arm64 exception vectors

The branch stable/13 has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=3822a970ff3c48848e1074a81819fbd57de76bbd

commit 3822a970ff3c48848e1074a81819fbd57de76bbd
Author:     Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2022-01-05 15:12:01 +0000
Commit:     Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2022-01-31 10:05:47 +0000

    Move instructions into the arm64 exception vectors
    
    We have 32 instructions in each exception vector on arm64. Previously
    only one was used to branch to the handler function. We can split the
    start of these functions and move some of the instructions into the
    vectors.
    
    Reviewed by:    kib, markj
    Sponsored by:   The FreeBSD Foundation
    Differential Revision: https://reviews.freebsd.org/D33751
    
    (cherry picked from commit 77402d2834e64a3530fbaa47d57eccce23c58603)
---
 sys/arm64/arm64/exception.S | 56 +++++++++++++++++++++++++++------------------
 1 file changed, 34 insertions(+), 22 deletions(-)

diff --git a/sys/arm64/arm64/exception.S b/sys/arm64/arm64/exception.S
index 629385c659be..8dd39048226f 100644
--- a/sys/arm64/arm64/exception.S
+++ b/sys/arm64/arm64/exception.S
@@ -33,7 +33,12 @@ __FBSDID("$FreeBSD$");
 
 	.text
 
-.macro	save_registers el
+/*
+ * This is limited to 28 instructions as it's placed in the exception vector
+ * slot that is 32 instructions long. We need one for the branch, and three
+ * for the prolog.
+ */
+.macro	save_registers_head el
 .if \el == 1
 	mov	x18, sp
 	sub	sp, sp, #128
@@ -66,6 +71,9 @@ __FBSDID("$FreeBSD$");
 	stp	x18,  lr, [sp, #(TF_SP)]
 	mrs	x18, tpidr_el1
 	add	x29, sp, #(TF_SIZE)
+.endm
+
+.macro	save_registers el
 .if \el == 0
 #if defined(PERTHREAD_SSP)
 	/* Load the SSP canary to sp_el0 */
@@ -235,36 +243,40 @@ ENTRY(handle_empty_exception)
 	b	1b
 END(handle_unhandled_exception)
 
-.macro	vempty
+.macro	vector	name, el
 	.align 7
-	b	handle_empty_exception
+	save_registers_head \el
+	b	handle_\name
+	dsb	sy
+	isb
+	/* Break instruction to ensure we aren't executing code here. */
+	brk	0x42
 .endm
 
-.macro	vector	name
-	.align 7
-	b	handle_\name
+.macro	vempty el
+	vector	empty_exception \el
 .endm
 
 	.align 11
 	.globl exception_vectors
 exception_vectors:
-	vempty			/* Synchronous EL1t */
-	vempty			/* IRQ EL1t */
-	vempty			/* FIQ EL1t */
-	vempty			/* Error EL1t */
+	vempty 1		/* Synchronous EL1t */
+	vempty 1		/* IRQ EL1t */
+	vempty 1		/* FIQ EL1t */
+	vempty 1		/* Error EL1t */
 
-	vector el1h_sync	/* Synchronous EL1h */
-	vector el1h_irq		/* IRQ EL1h */
-	vempty			/* FIQ EL1h */
-	vector serror		/* Error EL1h */
+	vector el1h_sync 1	/* Synchronous EL1h */
+	vector el1h_irq 1	/* IRQ EL1h */
+	vempty 1		/* FIQ EL1h */
+	vector serror 1		/* Error EL1h */
 
-	vector el0_sync		/* Synchronous 64-bit EL0 */
-	vector el0_irq		/* IRQ 64-bit EL0 */
-	vempty			/* FIQ 64-bit EL0 */
-	vector serror		/* Error 64-bit EL0 */
+	vector el0_sync 0	/* Synchronous 64-bit EL0 */
+	vector el0_irq 0	/* IRQ 64-bit EL0 */
+	vempty 0		/* FIQ 64-bit EL0 */
+	vector serror 0		/* Error 64-bit EL0 */
 
-	vector el0_sync		/* Synchronous 32-bit EL0 */
-	vector el0_irq		/* IRQ 32-bit EL0 */
-	vempty			/* FIQ 32-bit EL0 */
-	vector serror		/* Error 32-bit EL0 */
+	vector el0_sync 0	/* Synchronous 32-bit EL0 */
+	vector el0_irq 0	/* IRQ 32-bit EL0 */
+	vempty 0		/* FIQ 32-bit EL0 */
+	vector serror 0		/* Error 32-bit EL0 */