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From: Andrew Turner <andrew@FreeBSD.org>
Date: Sat, 6 Jun 2015 21:52:47 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r284103 - head/sys/arm64/arm64
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Author: andrew
Date: Sat Jun  6 21:52:46 2015
New Revision: 284103
URL: https://svnweb.freebsd.org/changeset/base/284103

Log:
  Rework exception entry to help with DTrace. We now store the stack pointer
  before adjusting it to store any registers. This is needed as DTrace may
  need to adjust the kernel stack pointer, and previously the new stack
  pointer would have needed to be checked incase it was changed.

Modified:
  head/sys/arm64/arm64/exception.S

Modified: head/sys/arm64/arm64/exception.S
==============================================================================
--- head/sys/arm64/arm64/exception.S	Sat Jun  6 21:11:17 2015	(r284102)
+++ head/sys/arm64/arm64/exception.S	Sat Jun  6 21:52:46 2015	(r284103)
@@ -33,6 +33,9 @@ __FBSDID("$FreeBSD$");
 	.text
 
 .macro	save_registers el
+.if \el == 1
+	mov	x18, sp
+.endif
 	stp	x28, x29, [sp, #-16]!
 	stp	x26, x27, [sp, #-16]!
 	stp	x24, x25, [sp, #-16]!
@@ -51,22 +54,20 @@ __FBSDID("$FreeBSD$");
 	mrs	x10, elr_el1
 	mrs	x11, spsr_el1
 .if \el == 0
-	mrs	x12, sp_el0
-.else
-	mov	x12, sp
+	mrs	x18, sp_el0
 .endif
 	stp	x10, x11, [sp, #-16]!
-	stp	x12, lr, [sp, #-16]!
+	stp	x18, lr, [sp, #-16]!
 	mrs	x18, tpidr_el1
 .endm
 
 .macro	restore_registers el
-	ldp	x12, lr, [sp], #16
+	msr	daifset, #2		/* Disable interrupts, x18 may change
+					 * in the interrupt exception handler */
+	ldp	x18, lr, [sp], #16
 	ldp	x10, x11, [sp], #16
 .if \el == 0
-	msr	sp_el0, x12
-.else
-	mov	sp, x12
+	msr	sp_el0, x18
 .endif
 	msr	spsr_el1, x11
 	msr	elr_el1, x10
@@ -89,6 +90,10 @@ __FBSDID("$FreeBSD$");
 	ldp	x24, x25, [sp], #16
 	ldp	x26, x27, [sp], #16
 	ldp	x28, x29, [sp], #16
+.if \el == 1
+	mov	sp, x18
+	mrs	x18, tpidr_el1
+.endif
 .endm
 
 .macro	do_ast