[DTrace-devel] [PATCH 2/2 v4] Show signed values for signed immediate conditional branches

[Kris Van Hees]

The disassembler will now print negative values correctly in signed
conditional branch instructions with an immediate operand.

Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_dis.c                     | 29 +++++++++++++++++++-------
 test/unittest/disasm/tst.ann-js-neg.r  |  2 ++
 test/unittest/disasm/tst.ann-js-neg.sh | 24 +++++++++++++++++++++
 3 files changed, 47 insertions(+), 8 deletions(-)
 create mode 100644 test/unittest/disasm/tst.ann-js-neg.r
 create mode 100755 test/unittest/disasm/tst.ann-js-neg.sh

diff --git a/libdtrace/dt_dis.c b/libdtrace/dt_dis.c
index bfd639c6..b5a1f067 100644
--- a/libdtrace/dt_dis.c
+++ b/libdtrace/dt_dis.c
@@ -286,6 +286,19 @@ dt_dis_branch_imm(const dtrace_difo_t *dp, const char *name, uint_t addr,
 	return 0;
 }
 
+/*ARGSUSED*/
+static uint_t
+dt_dis_sbranch_imm(const dtrace_difo_t *dp, const char *name, uint_t addr,
+	      const struct bpf_insn *in, const char *rname, FILE *fp)
+{
+	int	n;
+
+	n = fprintf(fp, "%-4s %s, %d, %d", name, reg(in->dst_reg), in->imm,
+		    in->off);
+	fprintf(fp, "%*s! -> %03u\n", DT_DIS_PAD(n), "", addr + 1 + in->off);
+	return 0;
+}
+
 /*ARGSUSED*/
 static uint_t
 dt_dis_load(const dtrace_difo_t *dp, const char *name, uint_t addr,
@@ -720,10 +733,10 @@ dt_dis_difo(const dtrace_difo_t *dp, FILE *fp, const dt_ident_t *idp,
 		INSN3(JMP32, JLT, K)	= { "jlt", dt_dis_branch_imm },
 		INSN3(JMP32, JGE, K)	= { "jge", dt_dis_branch_imm },
 		INSN3(JMP32, JLE, K)	= { "jle", dt_dis_branch_imm },
-		INSN3(JMP32, JSGT, K)	= { "jsgt", dt_dis_branch_imm },
-		INSN3(JMP32, JSLT, K)	= { "jslt", dt_dis_branch_imm },
-		INSN3(JMP32, JSGE, K)	= { "jsge", dt_dis_branch_imm },
-		INSN3(JMP32, JSLE, K)	= { "jsle", dt_dis_branch_imm },
+		INSN3(JMP32, JSGT, K)	= { "jsgt", dt_dis_sbranch_imm },
+		INSN3(JMP32, JSLT, K)	= { "jslt", dt_dis_sbranch_imm },
+		INSN3(JMP32, JSGE, K)	= { "jsge", dt_dis_sbranch_imm },
+		INSN3(JMP32, JSLE, K)	= { "jsle", dt_dis_sbranch_imm },
 		INSN3(JMP32, JSET, K)	= { "jset", dt_dis_branch_imm },
 		/* 64-bit jump ops, op(dst, src) */
 		INSN3(JMP, JEQ, X)	= { "jeq", dt_dis_branch },
@@ -744,10 +757,10 @@ dt_dis_difo(const dtrace_difo_t *dp, FILE *fp, const dt_ident_t *idp,
 		INSN3(JMP, JLT, K)	= { "jlt", dt_dis_branch_imm },
 		INSN3(JMP, JGE, K)	= { "jge", dt_dis_branch_imm },
 		INSN3(JMP, JLE, K)	= { "jle", dt_dis_branch_imm },
-		INSN3(JMP, JSGT, K)	= { "jsgt", dt_dis_branch_imm },
-		INSN3(JMP, JSLT, K)	= { "jslt", dt_dis_branch_imm },
-		INSN3(JMP, JSGE, K)	= { "jsge", dt_dis_branch_imm },
-		INSN3(JMP, JSLE, K)	= { "jsle", dt_dis_branch_imm },
+		INSN3(JMP, JSGT, K)	= { "jsgt", dt_dis_sbranch_imm },
+		INSN3(JMP, JSLT, K)	= { "jslt", dt_dis_sbranch_imm },
+		INSN3(JMP, JSGE, K)	= { "jsge", dt_dis_sbranch_imm },
+		INSN3(JMP, JSLE, K)	= { "jsle", dt_dis_sbranch_imm },
 		INSN3(JMP, JSET, K)	= { "jset", dt_dis_branch_imm },
 		INSN2(JMP, JA)		= { "ja", dt_dis_jump },
 		/* Store instructions, [dst + off] = src */
diff --git a/test/unittest/disasm/tst.ann-js-neg.r b/test/unittest/disasm/tst.ann-js-neg.r
new file mode 100644
index 00000000..d70a02ff
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-js-neg.r
@@ -0,0 +1,2 @@
+75 0 0 XXXX 00000000    jsge %r0, 0, 3
+d5 0 0 XXXX fffff800    jsle %r0, -2048, 2
diff --git a/test/unittest/disasm/tst.ann-js-neg.sh b/test/unittest/disasm/tst.ann-js-neg.sh
new file mode 100755
index 00000000..0914d3fe
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-js-neg.sh
@@ -0,0 +1,24 @@
+#!/bin/bash
+#
+# 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.
+#
+
+dtrace=$1
+
+$dtrace $dt_flags -xdisasm=8 -Sn '
+BEGIN, syscall::write:return
+{
+	exit(0);
+}
+' 2>&1 | \
+	awk '/js[a-z]+/ {
+		sub(/^[^:]+: /, "");
+		sub(/ +!.*$/, "");
+		sub(/ [0-9a-f]{4} /, " XXXX ");
+		print;
+	     }'
+
+exit $?
-- 
2.34.1