[DTrace-devel] [PATCH 05/10] Add disassembler annotations for register spills

[Kris Van Hees]

Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_dis.c                        | 20 +++++++++++++++++
 test/unittest/disasm/tst.ann-reg-spill.r  |  7 ++++++
 test/unittest/disasm/tst.ann-reg-spill.sh | 27 +++++++++++++++++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 test/unittest/disasm/tst.ann-reg-spill.r
 create mode 100755 test/unittest/disasm/tst.ann-reg-spill.sh

diff --git a/libdtrace/dt_dis.c b/libdtrace/dt_dis.c
index d911dbf5..e7d7194f 100644
--- a/libdtrace/dt_dis.c
+++ b/libdtrace/dt_dis.c
@@ -252,6 +252,16 @@ dt_dis_load(const dtrace_difo_t *dp, const char *name, uint_t addr,
 	n = fprintf(fp, "%-4s %s, [%s%+d]", name, reg(in->dst_reg),
 		    reg(in->src_reg), in->off);
 
+#if 1
+	if (in->code == (BPF_LDX | BPF_MEM | BPF_DW) &&
+	    in->src_reg == BPF_REG_FP &&
+	    in->off <= DT_STK_SPILL(0) &&
+	    in->off >= DT_STK_SPILL(DT_STK_NREGS) &&
+	    in->dst_reg == -(in->off - DT_STK_SPILL_BASE) / DT_STK_SLOT_SZ) {
+		fprintf(fp, "%*s! restore %s\n", DT_DIS_PAD(n), "",
+			reg(in->dst_reg));
+	} else
+#endif
 	dt_dis_refname(dp, in, addr, n, fp);
 
 	return 0;
@@ -288,6 +298,16 @@ dt_dis_store(const dtrace_difo_t *dp, const char *name, uint_t addr,
 	n = fprintf(fp, "%-4s [%s%+d], %s", name, reg(in->dst_reg), in->off,
 		    reg(in->src_reg));
 
+#if 1
+	if (in->code == (BPF_STX | BPF_MEM | BPF_DW) &&
+	    in->dst_reg == BPF_REG_FP &&
+	    in->off <= DT_STK_SPILL(0) &&
+	    in->off >= DT_STK_SPILL(DT_STK_NREGS - 1) &&
+	    in->src_reg == -(in->off - DT_STK_SPILL_BASE) / DT_STK_SLOT_SZ) {
+		fprintf(fp, "%*s! spill %s\n", DT_DIS_PAD(n), "",
+			reg(in->src_reg));
+	} else
+#endif
 	dt_dis_refname(dp, in, addr, n, fp);
 
 	return 0;
diff --git a/test/unittest/disasm/tst.ann-reg-spill.r b/test/unittest/disasm/tst.ann-reg-spill.r
new file mode 100644
index 00000000..2b71ca92
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-reg-spill.r
@@ -0,0 +1,7 @@
+7b a 8 ffa8 00000000    stdw [%fp-88], %r8            ! spill %r8
+79 8 a ffa8 00000000    lddw %r8, [%fp-88]            ! restore %r8
+7b a 8 ffa8 00000000    stdw [%fp-88], %r8            ! spill %r8
+7b a 7 ffb0 00000000    stdw [%fp-80], %r7            ! spill %r7
+79 7 a ffb0 00000000    lddw %r7, [%fp-80]            ! restore %r7
+79 8 a ffa8 00000000    lddw %r8, [%fp-88]            ! restore %r8
+123456798
diff --git a/test/unittest/disasm/tst.ann-reg-spill.sh b/test/unittest/disasm/tst.ann-reg-spill.sh
new file mode 100755
index 00000000..16786947
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-reg-spill.sh
@@ -0,0 +1,27 @@
+#!/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 -qSn '
+BEGIN
+{
+	a = 100000000;
+	b = 20000000;
+	c = 3000000;
+	d = 400000;
+	e = 50000;
+	f = 6000;
+	g = 700;
+	h = 80;
+	i = 9;
+	trace(++a + (++b + (++c + (++d + (++e + (++f + (++g + (++h + ++i))))))));
+	exit(0);
+}' 2>&1 | awk '/! (spill|restore)/ { sub(/^[^:]+: /, ""); print; next; }
+	       { s = $0; }
+	       END { print s; }'
-- 
2.34.1