[DTrace-devel] [PATCH 6/6] Add disassembler annotations for assoc arrays
Kris Van Hees
kris.van.hees at oracle.com
Mon Mar 7 19:51:49 UTC 2022
Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
libdtrace/dt_dis.c | 44 ++++++++++++++++++++++
test/unittest/disasm/tst.ann-gvar-assoc.r | 1 +
test/unittest/disasm/tst.ann-gvar-assoc.sh | 19 ++++++++++
test/unittest/disasm/tst.ann-tvar-assoc.r | 1 +
test/unittest/disasm/tst.ann-tvar-assoc.sh | 19 ++++++++++
5 files changed, 84 insertions(+)
create mode 100644 test/unittest/disasm/tst.ann-gvar-assoc.r
create mode 100755 test/unittest/disasm/tst.ann-gvar-assoc.sh
create mode 100644 test/unittest/disasm/tst.ann-tvar-assoc.r
create mode 100755 test/unittest/disasm/tst.ann-tvar-assoc.sh
diff --git a/libdtrace/dt_dis.c b/libdtrace/dt_dis.c
index d911dbf5..37c5059e 100644
--- a/libdtrace/dt_dis.c
+++ b/libdtrace/dt_dis.c
@@ -337,6 +337,50 @@ dt_dis_bpf_args(const dtrace_difo_t *dp, const char *fn,
dt_dis_varname_id(dp, in->imm + DIF_VAR_OTHER_UBASE,
DIFV_SCOPE_THREAD, addr));
return buf;
+ } else if (strcmp(fn, "dt_get_assoc") == 0) {
+ uint_t varid;
+ dof_relodesc_t *rp = dp->dtdo_breltab;
+ int cnt = dp->dtdo_brelen;
+ const char *rname = NULL;
+
+ /*
+ * We know that the previous four instructions exist and
+ * move the variable id to a register in the first instruction
+ * of that seqeuence (because we wrote the code generator to
+ * emit the instructions in this exact order.)
+ */
+ in -= 4;
+ varid = in->imm + DIF_VAR_OTHER_UBASE;
+
+ /*
+ * We need to determine whether this is a associative TLS array
+ * or a global array. We know that for a TLS assoc, a call to
+ * dt_tlskey must be present 5 instructions earlier (actually
+ * 9 instructions before the call to dt_get_assoc).
+ */
+ if (addr < 9 || in[-5].code != (BPF_JMP | BPF_CALL) ||
+ in[-5].src_reg != BPF_PSEUDO_CALL)
+ goto gvar_assoc;
+
+ addr -= 9;
+ for (; cnt; cnt--, rp++) {
+ if (rp->dofr_offset > addr * sizeof(uint64_t))
+ break;
+ if (rp->dofr_offset == addr * sizeof(uint64_t))
+ rname = dt_difo_getstr(dp, rp->dofr_name);
+ }
+
+ if (strcmp(rname, "dt_tlskey") != 0)
+ goto gvar_assoc;
+
+ snprintf(buf, len, "self->%s[]",
+ dt_dis_varname_id(dp, varid, DIFV_SCOPE_THREAD, addr));
+ return buf;
+
+gvar_assoc:
+ snprintf(buf, len, "%s[]",
+ dt_dis_varname_id(dp, varid, DIFV_SCOPE_GLOBAL, addr));
+ return buf;
}
return NULL;
diff --git a/test/unittest/disasm/tst.ann-gvar-assoc.r b/test/unittest/disasm/tst.ann-gvar-assoc.r
new file mode 100644
index 00000000..522ba6f6
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-gvar-assoc.r
@@ -0,0 +1 @@
+85 0 1 0000 ffffffff call dt_get_assoc ! var[]
diff --git a/test/unittest/disasm/tst.ann-gvar-assoc.sh b/test/unittest/disasm/tst.ann-gvar-assoc.sh
new file mode 100755
index 00000000..c0fc4bf2
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-gvar-assoc.sh
@@ -0,0 +1,19 @@
+#!/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 -Sen '
+BEGIN
+{
+ var["foo"] = 42;
+ exit(0);
+}
+' 2>&1 | awk '/ call dt_get_assoc/ { sub(/^[^:]+: /, ""); print; }'
+
+exit $?
diff --git a/test/unittest/disasm/tst.ann-tvar-assoc.r b/test/unittest/disasm/tst.ann-tvar-assoc.r
new file mode 100644
index 00000000..2ae89edb
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-tvar-assoc.r
@@ -0,0 +1 @@
+85 0 1 0000 ffffffff call dt_get_assoc ! self->var[]
diff --git a/test/unittest/disasm/tst.ann-tvar-assoc.sh b/test/unittest/disasm/tst.ann-tvar-assoc.sh
new file mode 100755
index 00000000..e4690a28
--- /dev/null
+++ b/test/unittest/disasm/tst.ann-tvar-assoc.sh
@@ -0,0 +1,19 @@
+#!/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 -Sen '
+BEGIN
+{
+ self->var["foo"] = 42;
+ exit(0);
+}
+' 2>&1 | awk '/ call dt_get_assoc/ { sub(/^[^:]+: /, ""); print; }'
+
+exit $?
--
2.34.1
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