X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-filter-validator.c;h=75cd98a5d134fe05b00ec432d8e559785e0b892e;hb=7e50015d099795fcce0602bdb670fd6ae0510026;hp=b164cbbfc421d3c555a3b61c08bb81c6692a9a29;hpb=bf956ec0051ba7f365693e194bc0aeaf4343a82c;p=lttng-ust.git

diff --git a/liblttng-ust/lttng-filter-validator.c b/liblttng-ust/lttng-filter-validator.c
index b164cbbf..75cd98a5 100644
--- a/liblttng-ust/lttng-filter-validator.c
+++ b/liblttng-ust/lttng-filter-validator.c
@@ -3,21 +3,25 @@
  *
  * LTTng UST filter bytecode validator.
  *
- * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
  *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
  *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
  */
 
 #define _LGPL_SOURCE
@@ -28,12 +32,22 @@
 #include <urcu/rculfhash.h>
 #include "lttng-hash-helper.h"
 
+/*
+ * Number of merge points for hash table size. Hash table initialized to
+ * that size, and we do not resize, because we do not want to trigger
+ * RCU worker thread execution: fall-back on linear traversal if number
+ * of merge points exceeds this value.
+ */
+#define DEFAULT_NR_MERGE_POINTS		128
+#define MIN_NR_BUCKETS			128
+#define MAX_NR_BUCKETS			128
+
 /* merge point table node */
 struct lfht_mp_node {
 	struct cds_lfht_node node;
 
 	/* Context at merge point */
-	struct vreg reg[NR_REG];
+	struct vstack stack;
 	unsigned long target_pc;
 };
 
@@ -54,13 +68,33 @@ int lttng_hash_match(struct cds_lfht_node *node, const void *key)
 }
 
 static
-int merge_point_add(struct cds_lfht *ht, unsigned long target_pc,
-		const struct vreg reg[NR_REG])
+int merge_points_compare(const struct vstack *stacka,
+			const struct vstack *stackb)
+{
+	int i, len;
+
+	if (stacka->top != stackb->top)
+		return 1;
+	len = stacka->top + 1;
+	assert(len >= 0);
+	for (i = 0; i < len; i++) {
+		if (stacka->e[i].type != REG_UNKNOWN
+				&& stackb->e[i].type != REG_UNKNOWN
+				&& stacka->e[i].type != stackb->e[i].type)
+			return 1;
+	}
+	return 0;
+}
+
+static
+int merge_point_add_check(struct cds_lfht *ht, unsigned long target_pc,
+		const struct vstack *stack)
 {
 	struct lfht_mp_node *node;
-	unsigned long hash = lttng_hash_mix((const void *) target_pc,
+	unsigned long hash = lttng_hash_mix((const char *) target_pc,
 				sizeof(target_pc),
 				lttng_hash_seed);
+	struct cds_lfht_node *ret;
 
 	dbg_printf("Filter: adding merge point at offset %lu, hash %lu\n",
 			target_pc, hash);
@@ -68,33 +102,50 @@ int merge_point_add(struct cds_lfht *ht, unsigned long target_pc,
 	if (!node)
 		return -ENOMEM;
 	node->target_pc = target_pc;
-	memcpy(node->reg, reg, sizeof(node->reg));
-	cds_lfht_add(ht, hash, &node->node);
+	memcpy(&node->stack, stack, sizeof(node->stack));
+	ret = cds_lfht_add_unique(ht, hash, lttng_hash_match,
+		(const char *) target_pc, &node->node);
+	if (ret != &node->node) {
+		struct lfht_mp_node *ret_mp =
+			caa_container_of(ret, struct lfht_mp_node, node);
+
+		/* Key already present */
+		dbg_printf("Filter: compare merge points for offset %lu, hash %lu\n",
+				target_pc, hash);
+		free(node);
+		if (merge_points_compare(stack, &ret_mp->stack)) {
+			ERR("Merge points differ for offset %lu\n",
+				target_pc);
+			return -EINVAL;
+		}
+	}
 	return 0;
 }
 
 /*
- * Number of merge points for hash table size. Hash table initialized to
- * that size, and we do not resize, because we do not want to trigger
- * RCU worker thread execution: fall-back on linear traversal if number
- * of merge points exceeds this value.
+ * Binary comparators use top of stack and top of stack -1.
+ * Return 0 if typing is known to match, 1 if typing is dynamic
+ * (unknown), negative error value on error.
  */
-#define DEFAULT_NR_MERGE_POINTS		128
-#define MIN_NR_BUCKETS			128
-#define MAX_NR_BUCKETS			128
-
 static
-int bin_op_compare_check(const struct vreg reg[NR_REG], const char *str)
+int bin_op_compare_check(struct vstack *stack, const char *str)
 {
-	switch (reg[REG_R0].type) {
+	if (unlikely(!vstack_ax(stack) || !vstack_bx(stack)))
+		goto error_empty;
+
+	switch (vstack_ax(stack)->type) {
 	default:
-		goto error_unknown;
+		goto error_type;
 
+	case REG_UNKNOWN:
+		goto unknown;
 	case REG_STRING:
-		switch (reg[REG_R1].type) {
+		switch (vstack_bx(stack)->type) {
 		default:
-			goto error_unknown;
+			goto error_type;
 
+		case REG_UNKNOWN:
+			goto unknown;
 		case REG_STRING:
 			break;
 		case REG_S64:
@@ -104,13 +155,14 @@ int bin_op_compare_check(const struct vreg reg[NR_REG], const char *str)
 		break;
 	case REG_S64:
 	case REG_DOUBLE:
-		switch (reg[REG_R1].type) {
+		switch (vstack_bx(stack)->type) {
 		default:
-			goto error_unknown;
+			goto error_type;
 
+		case REG_UNKNOWN:
+			goto unknown;
 		case REG_STRING:
 			goto error_mismatch;
-
 		case REG_S64:
 		case REG_DOUBLE:
 			break;
@@ -119,12 +171,20 @@ int bin_op_compare_check(const struct vreg reg[NR_REG], const char *str)
 	}
 	return 0;
 
-error_unknown:
+unknown:
+	return 1;
 
-	return -EINVAL;
 error_mismatch:
 	ERR("type mismatch for '%s' binary operator\n", str);
 	return -EINVAL;
+
+error_empty:
+	ERR("empty stack for '%s' binary operator\n", str);
+	return -EINVAL;
+
+error_type:
+	ERR("unknown type for '%s' binary operator\n", str);
+	return -EINVAL;
 }
 
 /*
@@ -133,7 +193,7 @@ error_mismatch:
  */
 static
 int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
-		void *start_pc, void *pc)
+		char *start_pc, char *pc)
 {
 	int ret = 0;
 
@@ -151,7 +211,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 	{
 		if (unlikely(pc + sizeof(struct return_op)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
@@ -198,10 +258,22 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 	case FILTER_OP_LT_DOUBLE:
 	case FILTER_OP_GE_DOUBLE:
 	case FILTER_OP_LE_DOUBLE:
+	case FILTER_OP_EQ_DOUBLE_S64:
+	case FILTER_OP_NE_DOUBLE_S64:
+	case FILTER_OP_GT_DOUBLE_S64:
+	case FILTER_OP_LT_DOUBLE_S64:
+	case FILTER_OP_GE_DOUBLE_S64:
+	case FILTER_OP_LE_DOUBLE_S64:
+	case FILTER_OP_EQ_S64_DOUBLE:
+	case FILTER_OP_NE_S64_DOUBLE:
+	case FILTER_OP_GT_S64_DOUBLE:
+	case FILTER_OP_LT_S64_DOUBLE:
+	case FILTER_OP_GE_S64_DOUBLE:
+	case FILTER_OP_LE_S64_DOUBLE:
 	{
 		if (unlikely(pc + sizeof(struct binary_op)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
@@ -219,7 +291,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 	{
 		if (unlikely(pc + sizeof(struct unary_op)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
@@ -230,30 +302,36 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 	{
 		if (unlikely(pc + sizeof(struct logical_op)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
 
-	/* load */
+	/* load field ref */
 	case FILTER_OP_LOAD_FIELD_REF:
 	{
 		ERR("Unknown field ref type\n");
 		ret = -EINVAL;
 		break;
 	}
+	/* get context ref */
+	case FILTER_OP_GET_CONTEXT_REF:
 	case FILTER_OP_LOAD_FIELD_REF_STRING:
 	case FILTER_OP_LOAD_FIELD_REF_SEQUENCE:
 	case FILTER_OP_LOAD_FIELD_REF_S64:
 	case FILTER_OP_LOAD_FIELD_REF_DOUBLE:
+	case FILTER_OP_GET_CONTEXT_REF_STRING:
+	case FILTER_OP_GET_CONTEXT_REF_S64:
+	case FILTER_OP_GET_CONTEXT_REF_DOUBLE:
 	{
 		if (unlikely(pc + sizeof(struct load_op) + sizeof(struct field_ref)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
 
+	/* load from immediate operand */
 	case FILTER_OP_LOAD_STRING:
 	{
 		struct load_op *insn = (struct load_op *) pc;
@@ -261,7 +339,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 
 		if (unlikely(pc + sizeof(struct load_op)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 			break;
 		}
 
@@ -269,7 +347,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 		str_len = strnlen(insn->data, maxlen);
 		if (unlikely(str_len >= maxlen)) {
 			/* Final '\0' not found within range */
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
@@ -278,7 +356,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 	{
 		if (unlikely(pc + sizeof(struct load_op) + sizeof(struct literal_numeric)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
@@ -287,7 +365,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 	{
 		if (unlikely(pc + sizeof(struct load_op) + sizeof(struct literal_double)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
@@ -298,10 +376,11 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
 	{
 		if (unlikely(pc + sizeof(struct cast_op)
 				> start_pc + bytecode->len)) {
-			ret = -EINVAL;
+			ret = -ERANGE;
 		}
 		break;
 	}
+
 	}
 
 	return ret;
@@ -328,14 +407,14 @@ unsigned long delete_all_nodes(struct cds_lfht *ht)
 
 /*
  * Return value:
- * 0: success
+ * >=0: success
  * <0: error
  */
 static
 int validate_instruction_context(struct bytecode_runtime *bytecode,
-		const struct vreg reg[NR_REG],
-		void *start_pc,
-		void *pc)
+		struct vstack *stack,
+		char *start_pc,
+		char *pc)
 {
 	int ret = 0;
 
@@ -374,43 +453,43 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 
 	case FILTER_OP_EQ:
 	{
-		ret = bin_op_compare_check(reg, "==");
-		if (ret)
+		ret = bin_op_compare_check(stack, "==");
+		if (ret < 0)
 			goto end;
 		break;
 	}
 	case FILTER_OP_NE:
 	{
-		ret = bin_op_compare_check(reg, "!=");
-		if (ret)
+		ret = bin_op_compare_check(stack, "!=");
+		if (ret < 0)
 			goto end;
 		break;
 	}
 	case FILTER_OP_GT:
 	{
-		ret = bin_op_compare_check(reg, ">");
-		if (ret)
+		ret = bin_op_compare_check(stack, ">");
+		if (ret < 0)
 			goto end;
 		break;
 	}
 	case FILTER_OP_LT:
 	{
-		ret = bin_op_compare_check(reg, "<");
-		if (ret)
+		ret = bin_op_compare_check(stack, "<");
+		if (ret < 0)
 			goto end;
 		break;
 	}
 	case FILTER_OP_GE:
 	{
-		ret = bin_op_compare_check(reg, ">=");
-		if (ret)
+		ret = bin_op_compare_check(stack, ">=");
+		if (ret < 0)
 			goto end;
 		break;
 	}
 	case FILTER_OP_LE:
 	{
-		ret = bin_op_compare_check(reg, "<=");
-		if (ret)
+		ret = bin_op_compare_check(stack, "<=");
+		if (ret < 0)
 			goto end;
 		break;
 	}
@@ -422,8 +501,13 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	case FILTER_OP_GE_STRING:
 	case FILTER_OP_LE_STRING:
 	{
-		if (reg[REG_R0].type != REG_STRING
-				|| reg[REG_R1].type != REG_STRING) {
+		if (!vstack_ax(stack) || !vstack_bx(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		if (vstack_ax(stack)->type != REG_STRING
+				|| vstack_bx(stack)->type != REG_STRING) {
 			ERR("Unexpected register type for string comparator\n");
 			ret = -EINVAL;
 			goto end;
@@ -438,8 +522,13 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	case FILTER_OP_GE_S64:
 	case FILTER_OP_LE_S64:
 	{
-		if (reg[REG_R0].type != REG_S64
-				|| reg[REG_R1].type != REG_S64) {
+		if (!vstack_ax(stack) || !vstack_bx(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		if (vstack_ax(stack)->type != REG_S64
+				|| vstack_bx(stack)->type != REG_S64) {
 			ERR("Unexpected register type for s64 comparator\n");
 			ret = -EINVAL;
 			goto end;
@@ -454,14 +543,53 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	case FILTER_OP_GE_DOUBLE:
 	case FILTER_OP_LE_DOUBLE:
 	{
-		if ((reg[REG_R0].type != REG_DOUBLE && reg[REG_R0].type != REG_S64)
-				|| (reg[REG_R1].type != REG_DOUBLE && reg[REG_R1].type != REG_S64)) {
-			ERR("Unexpected register type for double comparator\n");
+		if (!vstack_ax(stack) || !vstack_bx(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		if (vstack_ax(stack)->type != REG_DOUBLE && vstack_bx(stack)->type != REG_DOUBLE) {
+			ERR("Double operator should have two double registers\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		break;
+	}
+
+	case FILTER_OP_EQ_DOUBLE_S64:
+	case FILTER_OP_NE_DOUBLE_S64:
+	case FILTER_OP_GT_DOUBLE_S64:
+	case FILTER_OP_LT_DOUBLE_S64:
+	case FILTER_OP_GE_DOUBLE_S64:
+	case FILTER_OP_LE_DOUBLE_S64:
+	{
+		if (!vstack_ax(stack) || !vstack_bx(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		if (vstack_ax(stack)->type != REG_S64 && vstack_bx(stack)->type != REG_DOUBLE) {
+			ERR("Double-S64 operator has unexpected register types\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		break;
+	}
+
+	case FILTER_OP_EQ_S64_DOUBLE:
+	case FILTER_OP_NE_S64_DOUBLE:
+	case FILTER_OP_GT_S64_DOUBLE:
+	case FILTER_OP_LT_S64_DOUBLE:
+	case FILTER_OP_GE_S64_DOUBLE:
+	case FILTER_OP_LE_S64_DOUBLE:
+	{
+		if (!vstack_ax(stack) || !vstack_bx(stack)) {
+			ERR("Empty stack\n");
 			ret = -EINVAL;
 			goto end;
 		}
-		if (reg[REG_R0].type != REG_DOUBLE && reg[REG_R1].type != REG_DOUBLE) {
-			ERR("Double operator should have at least one double register\n");
+		if (vstack_ax(stack)->type != REG_DOUBLE && vstack_bx(stack)->type != REG_S64) {
+			ERR("S64-Double operator has unexpected register types\n");
 			ret = -EINVAL;
 			goto end;
 		}
@@ -473,15 +601,12 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	case FILTER_OP_UNARY_MINUS:
 	case FILTER_OP_UNARY_NOT:
 	{
-		struct unary_op *insn = (struct unary_op *) pc;
-
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
 			ret = -EINVAL;
 			goto end;
 		}
-		switch (reg[insn->reg].type) {
+		switch (vstack_ax(stack)->type) {
 		default:
 			ERR("unknown register type\n");
 			ret = -EINVAL;
@@ -495,6 +620,8 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 			break;
 		case REG_DOUBLE:
 			break;
+		case REG_UNKNOWN:
+			break;
 		}
 		break;
 	}
@@ -503,15 +630,12 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	case FILTER_OP_UNARY_MINUS_S64:
 	case FILTER_OP_UNARY_NOT_S64:
 	{
-		struct unary_op *insn = (struct unary_op *) pc;
-
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
 			ret = -EINVAL;
 			goto end;
 		}
-		if (reg[insn->reg].type != REG_S64) {
+		if (vstack_ax(stack)->type != REG_S64) {
 			ERR("Invalid register type\n");
 			ret = -EINVAL;
 			goto end;
@@ -523,15 +647,12 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	case FILTER_OP_UNARY_MINUS_DOUBLE:
 	case FILTER_OP_UNARY_NOT_DOUBLE:
 	{
-		struct unary_op *insn = (struct unary_op *) pc;
-
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
 			ret = -EINVAL;
 			goto end;
 		}
-		if (reg[insn->reg].type != REG_DOUBLE) {
+		if (vstack_ax(stack)->type != REG_DOUBLE) {
 			ERR("Invalid register type\n");
 			ret = -EINVAL;
 			goto end;
@@ -545,8 +666,14 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	{
 		struct logical_op *insn = (struct logical_op *) pc;
 
-		if (reg[REG_R0].type != REG_S64) {
-			ERR("Logical comparator expects S64 register\n");
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		if (vstack_ax(stack)->type != REG_S64
+				&& vstack_ax(stack)->type != REG_UNKNOWN) {
+			ERR("Logical comparator expects S64 or dynamic register\n");
 			ret = -EINVAL;
 			goto end;
 		}
@@ -561,7 +688,7 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 		break;
 	}
 
-	/* load */
+	/* load field ref */
 	case FILTER_OP_LOAD_FIELD_REF:
 	{
 		ERR("Unknown field ref type\n");
@@ -574,12 +701,6 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 		struct load_op *insn = (struct load_op *) pc;
 		struct field_ref *ref = (struct field_ref *) insn->data;
 
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
-			ret = -EINVAL;
-			goto end;
-		}
 		dbg_printf("Validate load field ref offset %u type string\n",
 			ref->offset);
 		break;
@@ -589,12 +710,6 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 		struct load_op *insn = (struct load_op *) pc;
 		struct field_ref *ref = (struct field_ref *) insn->data;
 
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
-			ret = -EINVAL;
-			goto end;
-		}
 		dbg_printf("Validate load field ref offset %u type s64\n",
 			ref->offset);
 		break;
@@ -604,53 +719,24 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 		struct load_op *insn = (struct load_op *) pc;
 		struct field_ref *ref = (struct field_ref *) insn->data;
 
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
-			ret = -EINVAL;
-			goto end;
-		}
 		dbg_printf("Validate load field ref offset %u type double\n",
 			ref->offset);
 		break;
 	}
 
+	/* load from immediate operand */
 	case FILTER_OP_LOAD_STRING:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
-			ret = -EINVAL;
-			goto end;
-		}
 		break;
 	}
 
 	case FILTER_OP_LOAD_S64:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
-			ret = -EINVAL;
-			goto end;
-		}
 		break;
 	}
 
 	case FILTER_OP_LOAD_DOUBLE:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
-			ret = -EINVAL;
-			goto end;
-		}
 		break;
 	}
 
@@ -659,13 +745,12 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 	{
 		struct cast_op *insn = (struct cast_op *) pc;
 
-		if (unlikely(insn->reg >= REG_ERROR)) {
-			ERR("invalid register %u\n",
-				(unsigned int) insn->reg);
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
 			ret = -EINVAL;
 			goto end;
 		}
-		switch (reg[insn->reg].type) {
+		switch (vstack_ax(stack)->type) {
 		default:
 			ERR("unknown register type\n");
 			ret = -EINVAL;
@@ -679,9 +764,11 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 			break;
 		case REG_DOUBLE:
 			break;
+		case REG_UNKNOWN:
+			break;
 		}
 		if (insn->op == FILTER_OP_CAST_DOUBLE_TO_S64) {
-			if (reg[insn->reg].type != REG_DOUBLE) {
+			if (vstack_ax(stack)->type != REG_DOUBLE) {
 				ERR("Cast expects double\n");
 				ret = -EINVAL;
 				goto end;
@@ -694,6 +781,44 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
 		break;
 	}
 
+	/* get context ref */
+	case FILTER_OP_GET_CONTEXT_REF:
+	{
+		struct load_op *insn = (struct load_op *) pc;
+		struct field_ref *ref = (struct field_ref *) insn->data;
+
+		dbg_printf("Validate get context ref offset %u type dynamic\n",
+			ref->offset);
+		break;
+	}
+	case FILTER_OP_GET_CONTEXT_REF_STRING:
+	{
+		struct load_op *insn = (struct load_op *) pc;
+		struct field_ref *ref = (struct field_ref *) insn->data;
+
+		dbg_printf("Validate get context ref offset %u type string\n",
+			ref->offset);
+		break;
+	}
+	case FILTER_OP_GET_CONTEXT_REF_S64:
+	{
+		struct load_op *insn = (struct load_op *) pc;
+		struct field_ref *ref = (struct field_ref *) insn->data;
+
+		dbg_printf("Validate get context ref offset %u type s64\n",
+			ref->offset);
+		break;
+	}
+	case FILTER_OP_GET_CONTEXT_REF_DOUBLE:
+	{
+		struct load_op *insn = (struct load_op *) pc;
+		struct field_ref *ref = (struct field_ref *) insn->data;
+
+		dbg_printf("Validate get context ref offset %u type double\n",
+			ref->offset);
+		break;
+	}
+
 	}
 end:
 	return ret;
@@ -707,37 +832,40 @@ end:
 static
 int validate_instruction_all_contexts(struct bytecode_runtime *bytecode,
 		struct cds_lfht *merge_points,
-		const struct vreg reg[NR_REG],
-		void *start_pc,
-		void *pc)
+		struct vstack *stack,
+		char *start_pc,
+		char *pc)
 {
 	int ret;
 	unsigned long target_pc = pc - start_pc;
 	struct cds_lfht_iter iter;
 	struct cds_lfht_node *node;
+	struct lfht_mp_node *mp_node;
 	unsigned long hash;
 
 	/* Validate the context resulting from the previous instruction */
-	ret = validate_instruction_context(bytecode, reg, start_pc, pc);
-	if (ret)
+	ret = validate_instruction_context(bytecode, stack, start_pc, pc);
+	if (ret < 0)
 		return ret;
 
 	/* Validate merge points */
-	hash = lttng_hash_mix((const void *) target_pc, sizeof(target_pc),
+	hash = lttng_hash_mix((const char *) target_pc, sizeof(target_pc),
 			lttng_hash_seed);
-	cds_lfht_for_each_duplicate(merge_points, hash, lttng_hash_match,
-			(const void *) target_pc, &iter, node) {
-		struct lfht_mp_node *mp_node =
-			caa_container_of(node, struct lfht_mp_node, node);
+	cds_lfht_lookup(merge_points, hash, lttng_hash_match,
+			(const char *) target_pc, &iter);
+	node = cds_lfht_iter_get_node(&iter);
+	if (node) {
+		mp_node = caa_container_of(node, struct lfht_mp_node, node);
 		
 		dbg_printf("Filter: validate merge point at offset %lu\n",
 				target_pc);
-		ret = validate_instruction_context(bytecode, mp_node->reg,
-				start_pc, pc);
-		if (ret)
-			return ret;
+		if (merge_points_compare(stack, &mp_node->stack)) {
+			ERR("Merge points differ for offset %lu\n",
+				target_pc);
+			return -EINVAL;
+		}
 		/* Once validated, we can remove the merge point */
-		dbg_printf("Filter: remove one merge point at offset %lu\n",
+		dbg_printf("Filter: remove merge point at offset %lu\n",
 				target_pc);
 		ret = cds_lfht_del(merge_points, node);
 		assert(!ret);
@@ -754,12 +882,12 @@ int validate_instruction_all_contexts(struct bytecode_runtime *bytecode,
 static
 int exec_insn(struct bytecode_runtime *bytecode,
 		struct cds_lfht *merge_points,
-		struct vreg reg[NR_REG],
-		void **_next_pc,
-		void *pc)
+		struct vstack *stack,
+		char **_next_pc,
+		char *pc)
 {
 	int ret = 1;
-	void *next_pc = *_next_pc;
+	char *next_pc = *_next_pc;
 
 	switch (*(filter_opcode_t *) pc) {
 	case FILTER_OP_UNKNOWN:
@@ -773,6 +901,11 @@ int exec_insn(struct bytecode_runtime *bytecode,
 
 	case FILTER_OP_RETURN:
 	{
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
 		ret = 0;
 		goto end;
 	}
@@ -813,20 +946,36 @@ int exec_insn(struct bytecode_runtime *bytecode,
 	case FILTER_OP_LT_S64:
 	case FILTER_OP_GE_S64:
 	case FILTER_OP_LE_S64:
-	{
-		reg[REG_R0].type = REG_S64;
-		next_pc += sizeof(struct binary_op);
-		break;
-	}
-
 	case FILTER_OP_EQ_DOUBLE:
 	case FILTER_OP_NE_DOUBLE:
 	case FILTER_OP_GT_DOUBLE:
 	case FILTER_OP_LT_DOUBLE:
 	case FILTER_OP_GE_DOUBLE:
 	case FILTER_OP_LE_DOUBLE:
+	case FILTER_OP_EQ_DOUBLE_S64:
+	case FILTER_OP_NE_DOUBLE_S64:
+	case FILTER_OP_GT_DOUBLE_S64:
+	case FILTER_OP_LT_DOUBLE_S64:
+	case FILTER_OP_GE_DOUBLE_S64:
+	case FILTER_OP_LE_DOUBLE_S64:
+	case FILTER_OP_EQ_S64_DOUBLE:
+	case FILTER_OP_NE_S64_DOUBLE:
+	case FILTER_OP_GT_S64_DOUBLE:
+	case FILTER_OP_LT_S64_DOUBLE:
+	case FILTER_OP_GE_S64_DOUBLE:
+	case FILTER_OP_LE_S64_DOUBLE:
 	{
-		reg[REG_R0].type = REG_DOUBLE;
+		/* Pop 2, push 1 */
+		if (vstack_pop(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_S64;
 		next_pc += sizeof(struct binary_op);
 		break;
 	}
@@ -834,21 +983,45 @@ int exec_insn(struct bytecode_runtime *bytecode,
 	/* unary */
 	case FILTER_OP_UNARY_PLUS:
 	case FILTER_OP_UNARY_MINUS:
-	case FILTER_OP_UNARY_NOT:
+	{
+		/* Pop 1, push 1 */
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_UNKNOWN;
+		next_pc += sizeof(struct unary_op);
+		break;
+	}
+
 	case FILTER_OP_UNARY_PLUS_S64:
 	case FILTER_OP_UNARY_MINUS_S64:
+	case FILTER_OP_UNARY_NOT:
 	case FILTER_OP_UNARY_NOT_S64:
+	case FILTER_OP_UNARY_NOT_DOUBLE:
 	{
-		reg[REG_R0].type = REG_S64;
+		/* Pop 1, push 1 */
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_S64;
 		next_pc += sizeof(struct unary_op);
 		break;
 	}
 
 	case FILTER_OP_UNARY_PLUS_DOUBLE:
 	case FILTER_OP_UNARY_MINUS_DOUBLE:
-	case FILTER_OP_UNARY_NOT_DOUBLE:
 	{
-		reg[REG_R0].type = REG_DOUBLE;
+		/* Pop 1, push 1 */
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_DOUBLE;
 		next_pc += sizeof(struct unary_op);
 		break;
 	}
@@ -861,68 +1034,96 @@ int exec_insn(struct bytecode_runtime *bytecode,
 		int merge_ret;
 
 		/* Add merge point to table */
-		merge_ret = merge_point_add(merge_points, insn->skip_offset, reg);
+		merge_ret = merge_point_add_check(merge_points,
+					insn->skip_offset, stack);
 		if (merge_ret) {
 			ret = merge_ret;
 			goto end;
 		}
 		/* Continue to next instruction */
+		/* Pop 1 when jump not taken */
+		if (vstack_pop(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
 		next_pc += sizeof(struct logical_op);
 		break;
 	}
 
-	/* load */
+	/* load field ref */
 	case FILTER_OP_LOAD_FIELD_REF:
 	{
 		ERR("Unknown field ref type\n");
 		ret = -EINVAL;
 		goto end;
 	}
+	/* get context ref */
+	case FILTER_OP_GET_CONTEXT_REF:
+	{
+		if (vstack_push(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_UNKNOWN;
+		next_pc += sizeof(struct load_op) + sizeof(struct field_ref);
+		break;
+	}
 	case FILTER_OP_LOAD_FIELD_REF_STRING:
 	case FILTER_OP_LOAD_FIELD_REF_SEQUENCE:
+	case FILTER_OP_GET_CONTEXT_REF_STRING:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		reg[insn->reg].type = REG_STRING;
-		reg[insn->reg].literal = 0;
+		if (vstack_push(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_STRING;
 		next_pc += sizeof(struct load_op) + sizeof(struct field_ref);
 		break;
 	}
 	case FILTER_OP_LOAD_FIELD_REF_S64:
+	case FILTER_OP_GET_CONTEXT_REF_S64:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		reg[insn->reg].type = REG_S64;
-		reg[insn->reg].literal = 0;
+		if (vstack_push(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_S64;
 		next_pc += sizeof(struct load_op) + sizeof(struct field_ref);
 		break;
 	}
 	case FILTER_OP_LOAD_FIELD_REF_DOUBLE:
+	case FILTER_OP_GET_CONTEXT_REF_DOUBLE:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		reg[insn->reg].type = REG_DOUBLE;
-		reg[insn->reg].literal = 0;
+		if (vstack_push(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_DOUBLE;
 		next_pc += sizeof(struct load_op) + sizeof(struct field_ref);
 		break;
 	}
 
+	/* load from immediate operand */
 	case FILTER_OP_LOAD_STRING:
 	{
 		struct load_op *insn = (struct load_op *) pc;
 
-		reg[insn->reg].type = REG_STRING;
-		reg[insn->reg].literal = 1;
+		if (vstack_push(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_STRING;
 		next_pc += sizeof(struct load_op) + strlen(insn->data) + 1;
 		break;
 	}
 
 	case FILTER_OP_LOAD_S64:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		reg[insn->reg].type = REG_S64;
-		reg[insn->reg].literal = 1;
+		if (vstack_push(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_S64;
 		next_pc += sizeof(struct load_op)
 				+ sizeof(struct literal_numeric);
 		break;
@@ -930,10 +1131,11 @@ int exec_insn(struct bytecode_runtime *bytecode,
 
 	case FILTER_OP_LOAD_DOUBLE:
 	{
-		struct load_op *insn = (struct load_op *) pc;
-
-		reg[insn->reg].type = REG_DOUBLE;
-		reg[insn->reg].literal = 1;
+		if (vstack_push(stack)) {
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_DOUBLE;
 		next_pc += sizeof(struct load_op)
 				+ sizeof(struct literal_double);
 		break;
@@ -942,9 +1144,13 @@ int exec_insn(struct bytecode_runtime *bytecode,
 	case FILTER_OP_CAST_TO_S64:
 	case FILTER_OP_CAST_DOUBLE_TO_S64:
 	{
-		struct cast_op *insn = (struct cast_op *) pc;
-
-		reg[insn->reg].type = REG_S64;
+		/* Pop 1, push 1 */
+		if (!vstack_ax(stack)) {
+			ERR("Empty stack\n");
+			ret = -EINVAL;
+			goto end;
+		}
+		vstack_ax(stack)->type = REG_S64;
 		next_pc += sizeof(struct cast_op);
 		break;
 	}
@@ -966,15 +1172,11 @@ end:
 int lttng_filter_validate_bytecode(struct bytecode_runtime *bytecode)
 {
 	struct cds_lfht *merge_points;
-	void *pc, *next_pc, *start_pc;
+	char *pc, *next_pc, *start_pc;
 	int ret = -EINVAL;
-	struct vreg reg[NR_REG];
-	int i;
+	struct vstack stack;
 
-	for (i = 0; i < NR_REG; i++) {
-		reg[i].type = REG_TYPE_UNKNOWN;
-		reg[i].literal = 0;
-	}
+	vstack_init(&stack);
 
 	if (!lttng_hash_seed_ready) {
 		lttng_hash_seed = time(NULL);
@@ -996,9 +1198,10 @@ int lttng_filter_validate_bytecode(struct bytecode_runtime *bytecode)
 	start_pc = &bytecode->data[0];
 	for (pc = next_pc = start_pc; pc - start_pc < bytecode->len;
 			pc = next_pc) {
-		if (bytecode_validate_overflow(bytecode, start_pc, pc) != 0) {
-			ERR("filter bytecode overflow\n");
-			ret = -EINVAL;
+		ret = bytecode_validate_overflow(bytecode, start_pc, pc);
+		if (ret != 0) {
+			if (ret == -ERANGE)
+				ERR("filter bytecode overflow\n");
 			goto end;
 		}
 		dbg_printf("Validating op %s (%u)\n",
@@ -1008,13 +1211,13 @@ int lttng_filter_validate_bytecode(struct bytecode_runtime *bytecode)
 		/*
 		 * For each instruction, validate the current context
 		 * (traversal of entire execution flow), and validate
-		 * all 	merge points targeting this instruction.
+		 * all merge points targeting this instruction.
 		 */
 		ret = validate_instruction_all_contexts(bytecode, merge_points,
-					reg, start_pc, pc);
+					&stack, start_pc, pc);
 		if (ret)
 			goto end;
-		ret = exec_insn(bytecode, merge_points, reg, &next_pc, pc);
+		ret = exec_insn(bytecode, merge_points, &stack, &next_pc, pc);
 		if (ret <= 0)
 			goto end;
 	}