svn commit: r304044 - projects/powernv/powerpc/aim

[Nathan Whitehorn]

Author: nwhitehorn
Date: Sat Aug 13 15:49:46 2016
New Revision: 304044
URL: https://svnweb.freebsd.org/changeset/base/304044

Log:
  Don't rely on having mapped trap vectors. This allows the system to run with
  low memory unmapped, which can be useful during debugging to catch NULL
  pointer dereferences.

Modified:
  projects/powernv/powerpc/aim/trap_subr64.S

Modified: projects/powernv/powerpc/aim/trap_subr64.S
==============================================================================
--- projects/powernv/powerpc/aim/trap_subr64.S	Sat Aug 13 15:48:56 2016	(r304043)
+++ projects/powernv/powerpc/aim/trap_subr64.S	Sat Aug 13 15:49:46 2016	(r304044)
@@ -720,11 +720,13 @@ u_trap:
  * Now the common trap catching code.
  */
 k_trap:
+	GET_TOCBASE(%r31) /* Get TOC base while we can */
+	mtsprg2	%r31
 	FRAME_SETUP(PC_TEMPSAVE)
-/* Call C interrupt dispatcher: */
-trapagain:
-	GET_TOCBASE(%r2)
+
+	/* Call C interrupt dispatcher: */
 	addi	%r3,%r1,48
+	mfsprg2	%r2
 	bl	CNAME(powerpc_interrupt)
 	nop
 
@@ -750,7 +752,6 @@ CNAME(trapexit):
 	ori	%r3,%r3,PSL_EE at l
 	mtmsr	%r3
 	isync
-	GET_TOCBASE(%r2)
 	addi	%r3,%r1,48
 	bl	CNAME(ast)
 	nop
@@ -797,9 +798,11 @@ dbtrap:
 	ld	%r1,TOC_REF(tmpstk)(%r1)
 	addi	%r1,%r1,(TMPSTKSZ-48)
 
+	GET_TOCBASE(%r31)
+	mtsprg2	%r31
 	FRAME_SETUP(PC_DBSAVE)
 /* Call C trap code: */
-	GET_TOCBASE(%r2)
+	mfsprg2	%r2
 	addi	%r3,%r1,48
 	bl	CNAME(db_trap_glue)
 	nop