[DTrace-devel] [PATCH 7/8] Add support for strstr() subroutine

[eugene.loh at oracle.com]

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

Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
 libdtrace/dt_cg.c                | 91 +++++++++++++++++++++++++++++++-
 test/unittest/dif/strstr.d       |  1 -
 test/unittest/funcs/tst.strstr.d |  5 +-
 3 files changed, 93 insertions(+), 4 deletions(-)

diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index 5b6ec4a9..6aac64ae 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -3492,6 +3492,95 @@ dt_cg_subr_strjoin(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
 	TRACE_REGSET("    subr-strjoin:End  ");
 }
 
+static void
+dt_cg_subr_strstr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
+{
+	dt_node_t	*s = dnp->dn_args;
+	dt_node_t	*t = s->dn_list;
+	dt_ident_t	*idp;
+	uint64_t	off1, off2;
+	uint_t		Ldone = dt_irlist_label(dlp);
+
+	TRACE_REGSET("    subr-strstr:Begin");
+
+	/* get args */
+	dt_cg_node(s, dlp, drp);
+	dt_cg_check_notnull(dlp, drp, s->dn_reg);
+	dt_cg_node(t, dlp, drp);
+	dt_cg_check_notnull(dlp, drp, t->dn_reg);
+
+	/* call dt_index() call */
+	if (dt_regset_xalloc_args(drp) == -1)
+		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+
+	emit(dlp,  BPF_MOV_REG(BPF_REG_1, s->dn_reg));
+	emit(dlp,  BPF_MOV_REG(BPF_REG_2, t->dn_reg));
+	dt_regset_free(drp, t->dn_reg);
+	if (t->dn_tstring)
+		dt_cg_tstring_free(yypcb, t);
+	emit(dlp,  BPF_MOV_IMM(BPF_REG_3, 0));
+
+	off1 = dt_cg_tstring_xalloc(yypcb);
+	off2 = dt_cg_tstring_xalloc(yypcb);
+
+	emit(dlp,  BPF_LOAD(BPF_DW, BPF_REG_4, BPF_REG_FP, DT_STK_DCTX));
+	emit(dlp,  BPF_LOAD(BPF_DW, BPF_REG_4, BPF_REG_4, DCTX_MEM));
+	emit(dlp,  BPF_MOV_REG(BPF_REG_5, BPF_REG_4));
+	emit(dlp,  BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, off1));
+	emit(dlp,  BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, off2));
+
+	dt_regset_xalloc(drp, BPF_REG_0);
+	idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_index");
+	assert(idp != NULL);
+	emite(dlp, BPF_CALL_FUNC(idp->di_id), idp);
+	dt_regset_free_args(drp);
+
+	dt_cg_tstring_xfree(yypcb, off1);
+	dt_cg_tstring_xfree(yypcb, off2);
+
+	/*
+	 * Allocate the result register and associate it with a temporary
+	 * string slot.
+	 */
+	dnp->dn_reg = dt_regset_alloc(drp);
+	if (dnp->dn_reg == -1)
+		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+	dt_cg_tstring_alloc(yypcb, dnp);
+
+	/* account for not finding the substring */
+
+	emit(dlp,  BPF_MOV_IMM(dnp->dn_reg, 0));
+	emit(dlp,  BPF_BRANCH_IMM(BPF_JSLT, BPF_REG_0, 0, Ldone));
+
+	emit(dlp,  BPF_LOAD(BPF_DW, dnp->dn_reg, BPF_REG_FP, DT_STK_DCTX));
+	emit(dlp,  BPF_LOAD(BPF_DW, dnp->dn_reg, dnp->dn_reg, DCTX_MEM));
+	emit(dlp,  BPF_ALU64_IMM(BPF_ADD, dnp->dn_reg, dnp->dn_tstring->dn_value));
+
+	/* call dt_substr() using the index we already found */
+
+	if (dt_regset_xalloc_args(drp) == -1)
+		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+
+	emit(dlp, BPF_MOV_REG(BPF_REG_1, dnp->dn_reg));
+	emit(dlp, BPF_MOV_REG(BPF_REG_2, s->dn_reg));
+	dt_regset_free(drp, s->dn_reg);
+	if (s->dn_tstring)
+		dt_cg_tstring_free(yypcb, s);
+	emit(dlp, BPF_MOV_REG(BPF_REG_3, BPF_REG_0));
+	emit(dlp, BPF_MOV_IMM(BPF_REG_5, 2));
+	idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_substr");
+	assert(idp != NULL);
+	emite(dlp,  BPF_CALL_FUNC(idp->di_id), idp);
+	dt_regset_free_args(drp);
+
+	emitl(dlp, Ldone,
+		   BPF_NOP());
+
+	dt_regset_free(drp, BPF_REG_0);
+
+	TRACE_REGSET("    subr-strstr:End  ");
+}
+
 static void
 dt_cg_subr_substr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
 {
@@ -3606,7 +3695,7 @@ static dt_cg_subr_f *_dt_cg_subr[DIF_SUBR_MAX + 1] = {
 	[DIF_SUBR_CLEANPATH]		= NULL,
 	[DIF_SUBR_STRCHR]		= &dt_cg_subr_strchr,
 	[DIF_SUBR_STRRCHR]		= &dt_cg_subr_strrchr,
-	[DIF_SUBR_STRSTR]		= NULL,
+	[DIF_SUBR_STRSTR]		= &dt_cg_subr_strstr,
 	[DIF_SUBR_STRTOK]		= NULL,
 	[DIF_SUBR_SUBSTR]		= &dt_cg_subr_substr,
 	[DIF_SUBR_INDEX]		= &dt_cg_subr_index,
diff --git a/test/unittest/dif/strstr.d b/test/unittest/dif/strstr.d
index 8d1349e4..d5be34aa 100644
--- a/test/unittest/dif/strstr.d
+++ b/test/unittest/dif/strstr.d
@@ -1,4 +1,3 @@
-/* @@xfail: dtv2 */
 BEGIN
 {
 	trace(strstr(probename, "GIN"));
diff --git a/test/unittest/funcs/tst.strstr.d b/test/unittest/funcs/tst.strstr.d
index 279e3ae6..de96cd28 100644
--- a/test/unittest/funcs/tst.strstr.d
+++ b/test/unittest/funcs/tst.strstr.d
@@ -1,12 +1,13 @@
 /*
  * Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, 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.
  */
-/* @@xfail: dtv2 */
 
+/* limit the string size to relieve pressure on the BPF verifier */
 #pragma D option quiet
+#pragma D option strsize=184
 
 BEGIN
 {
-- 
2.18.4