[DTrace-devel] [PATCH 06/14] Support strrchr() for addresses that are not DTrace pointers

[eugene.loh at oracle.com]

From: Eugene Loh <eugene.loh at oracle.com>

Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
 bpf/strrchr.S                            |  6 +++---
 test/unittest/funcs/tst.strchr_nonDPTR.d | 25 ++++++++++++++++++++++++
 test/unittest/funcs/tst.strchr_nonDPTR.r |  3 +++
 3 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 test/unittest/funcs/tst.strchr_nonDPTR.d
 create mode 100644 test/unittest/funcs/tst.strchr_nonDPTR.r

diff --git a/bpf/strrchr.S b/bpf/strrchr.S
index 8273b59c..05ccecb9 100644
--- a/bpf/strrchr.S
+++ b/bpf/strrchr.S
@@ -21,7 +21,7 @@
  *     r8 = r6;
  * Lloop:
  *     r8--;
- *     r3 = src[r8];
+ *     r3 = dst[r8];     // use copy in dst[] in case src[] is unsafe memory
  *     r3 <<= 56;
  *     if (r3 == c) goto Lfound;
  *     if (r8 > 0) goto Lloop;
@@ -65,9 +65,9 @@ dt_strrchr :
 .Lloop:
 	sub	%r8, 1			/* r8-- */
 	mov	%r4, %r8
-	ldxdw	%r3, [%fp+-8]
+	ldxdw	%r3, [%fp+-24]
 	add	%r3, %r4
-	ldxb	%r3, [%r3+0]		/* r3 = src[r8] */
+	ldxb	%r3, [%r3+0]		/* r3 = dst[r8] */
 	lsh	%r3, 56			/* r3 <<= 56 */
 	jeq	%r3, %r5, .Lfound	/* if (r3 == c) goto Lfound */
 	jgt	%r8, 0, .Lloop		/* if (r8 > 0) goto Lloop */
diff --git a/test/unittest/funcs/tst.strchr_nonDPTR.d b/test/unittest/funcs/tst.strchr_nonDPTR.d
new file mode 100644
index 00000000..95cb08c2
--- /dev/null
+++ b/test/unittest/funcs/tst.strchr_nonDPTR.d
@@ -0,0 +1,25 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Licensed under the Universal Permissive License v 1.0 as shown at
+ * http://oss.oracle.com/licenses/upl.
+ */
+
+#pragma D option quiet
+#pragma D option destructive
+
+BEGIN
+{
+	/* "abcdef" */
+	system("printf '\x61\x62\x63\x64\x65\x66' > /dev/null 2>&1");
+}
+
+syscall::write:entry
+/ppid == $pid/
+{
+	printf("|%s|\n", strchr((void *)arg1, 'b'));
+	printf("|%s|\n", strrchr((void *)arg1, 'b'));
+	exit(0);
+}
+
+ERROR { exit(1); }
diff --git a/test/unittest/funcs/tst.strchr_nonDPTR.r b/test/unittest/funcs/tst.strchr_nonDPTR.r
new file mode 100644
index 00000000..b1b10def
--- /dev/null
+++ b/test/unittest/funcs/tst.strchr_nonDPTR.r
@@ -0,0 +1,3 @@
+|bcdef|
+|bcdef|
+
-- 
2.18.4