tests/misc: Add a store/dcbz test

We have a bug where an store near a dcbz can cause the dcbz to only zero
8 bytes. Add a test case for this.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>

tests/misc/head.S

@@ -215,3 +215,45 @@ test_icbi:
 	nop
 	addi	%r3,%r3,1
 	blr
+
+	.global test_dcbz_near_store
+test_dcbz_near_store:
+	li	%r0,-1
+	addi	%r10,%r1,-64
+	# cacheline align stack pointer
+	srdi	%r10,%r10,6
+	sldi	%r10,%r10,6
+
+	std	%r0,0(%r10)
+	std	%r0,8(%r10)
+	std	%r0,16(%r10)
+	std	%r0,24(%r10)
+	std	%r0,32(%r10)
+	std	%r0,40(%r10)
+	std	%r0,48(%r10)
+	std	%r0,56(%r10)
+
+	li	%r3,0xa5
+	# Store to same cacheline as dcbz, although it doesn't seem
+	# necessary to hit the issue.
+	std	%r3,0(%r10)
+	dcbz	0,%r10
+
+	ld	%r0,0(%r10)
+	ld	%r3,8(%r10)
+	ld	%r4,16(%r10)
+	ld	%r5,24(%r10)
+	ld	%r6,32(%r10)
+	ld	%r7,40(%r10)
+	ld	%r8,48(%r10)
+	ld	%r9,56(%r10)
+
+	or	%r3,%r3,%r0
+	or	%r3,%r3,%r4
+	or	%r3,%r3,%r5
+	or	%r3,%r3,%r6
+	or	%r3,%r3,%r7
+	or	%r3,%r3,%r8
+	or	%r3,%r3,%r9
+
+	blr

tests/misc/misc.c

@@ -17,6 +17,7 @@ extern long test_mtpvr(void);
 extern long test_bdnzl(void);
 extern long test_loadhitstore(void);
 extern long test_icbi(void);
+extern long test_dcbz_near_store(void);
 
 // i < 100
 void print_test_number(int i)
@@ -82,5 +83,12 @@ int main(void)
 	} else
 		puts(PASS);
 
+	print_test_number(8);
+	if (test_dcbz_near_store() != 0) {
+		fail = 1;
+		puts(FAIL);
+	} else
+		puts(PASS);
+
 	return fail;
 }

tests/test_misc.console_out

@@ -5,3 +5,4 @@ Test 04:PASS
 Test 05:PASS
 Test 06:PASS
 Test 07:PASS
+Test 08:PASS