SoW-2020-0002: Trace Hit Counters: Implement key-addressed counters in shared memory...
[deliverable/lttng-ust.git] / liblttng-ust / lttng-bytecode-validator.c
diff --git a/liblttng-ust/lttng-bytecode-validator.c b/liblttng-ust/lttng-bytecode-validator.c
new file mode 100644 (file)
index 0000000..f60c936
--- /dev/null
@@ -0,0 +1,2024 @@
+/*
+ * lttng-bytecode-validator.c
+ *
+ * LTTng UST bytecode validator.
+ *
+ * Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * 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:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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
+#include <stddef.h>
+#include <stdint.h>
+#include <time.h>
+
+#include <urcu-bp.h>
+#include <urcu/rculfhash.h>
+
+#include "lttng-bytecode.h"
+#include "lttng-hash-helper.h"
+#include "string-utils.h"
+#include "ust-events-internal.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 vstack stack;
+       unsigned long target_pc;
+};
+
+static unsigned long lttng_hash_seed;
+static unsigned int lttng_hash_seed_ready;
+
+static
+int lttng_hash_match(struct cds_lfht_node *node, const void *key)
+{
+       struct lfht_mp_node *mp_node =
+               caa_container_of(node, struct lfht_mp_node, node);
+       unsigned long key_pc = (unsigned long) key;
+
+       if (mp_node->target_pc == key_pc)
+               return 1;
+       else
+               return 0;
+}
+
+static
+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 char *) target_pc,
+                               sizeof(target_pc),
+                               lttng_hash_seed);
+       struct cds_lfht_node *ret;
+
+       dbg_printf("Bytecode: adding merge point at offset %lu, hash %lu\n",
+                       target_pc, hash);
+       node = zmalloc(sizeof(struct lfht_mp_node));
+       if (!node)
+               return -ENOMEM;
+       node->target_pc = target_pc;
+       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("Bytecode: 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;
+}
+
+/*
+ * 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.
+ */
+static
+int bin_op_compare_check(struct vstack *stack, bytecode_opcode_t opcode,
+               const char *str)
+{
+       if (unlikely(!vstack_ax(stack) || !vstack_bx(stack)))
+               goto error_empty;
+
+       switch (vstack_ax(stack)->type) {
+       default:
+               goto error_type;
+
+       case REG_UNKNOWN:
+               goto unknown;
+       case REG_STRING:
+               switch (vstack_bx(stack)->type) {
+               default:
+                       goto error_type;
+
+               case REG_UNKNOWN:
+                       goto unknown;
+               case REG_STRING:
+                       break;
+               case REG_STAR_GLOB_STRING:
+                       if (opcode != BYTECODE_OP_EQ && opcode != BYTECODE_OP_NE) {
+                               goto error_mismatch;
+                       }
+                       break;
+               case REG_S64:
+               case REG_U64:
+               case REG_DOUBLE:
+                       goto error_mismatch;
+               }
+               break;
+       case REG_STAR_GLOB_STRING:
+               switch (vstack_bx(stack)->type) {
+               default:
+                       goto error_type;
+
+               case REG_UNKNOWN:
+                       goto unknown;
+               case REG_STRING:
+                       if (opcode != BYTECODE_OP_EQ && opcode != BYTECODE_OP_NE) {
+                               goto error_mismatch;
+                       }
+                       break;
+               case REG_STAR_GLOB_STRING:
+               case REG_S64:
+               case REG_U64:
+               case REG_DOUBLE:
+                       goto error_mismatch;
+               }
+               break;
+       case REG_S64:
+       case REG_U64:
+       case REG_DOUBLE:
+               switch (vstack_bx(stack)->type) {
+               default:
+                       goto error_type;
+
+               case REG_UNKNOWN:
+                       goto unknown;
+               case REG_STRING:
+               case REG_STAR_GLOB_STRING:
+                       goto error_mismatch;
+               case REG_S64:
+               case REG_U64:
+               case REG_DOUBLE:
+                       break;
+               }
+               break;
+       }
+       return 0;
+
+unknown:
+       return 1;
+
+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;
+}
+
+/*
+ * Binary bitwise operators 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.
+ */
+static
+int bin_op_bitwise_check(struct vstack *stack, bytecode_opcode_t opcode,
+               const char *str)
+{
+       if (unlikely(!vstack_ax(stack) || !vstack_bx(stack)))
+               goto error_empty;
+
+       switch (vstack_ax(stack)->type) {
+       default:
+               goto error_type;
+
+       case REG_UNKNOWN:
+               goto unknown;
+       case REG_S64:
+       case REG_U64:
+               switch (vstack_bx(stack)->type) {
+               default:
+                       goto error_type;
+
+               case REG_UNKNOWN:
+                       goto unknown;
+               case REG_S64:
+               case REG_U64:
+                       break;
+               }
+               break;
+       }
+       return 0;
+
+unknown:
+       return 1;
+
+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;
+}
+
+static
+int validate_get_symbol(struct bytecode_runtime *bytecode,
+               const struct get_symbol *sym)
+{
+       const char *str, *str_limit;
+       size_t len_limit;
+
+       if (sym->offset >= bytecode->p.bc->bc.len - bytecode->p.bc->bc.reloc_offset)
+               return -EINVAL;
+
+       str = bytecode->p.bc->bc.data + bytecode->p.bc->bc.reloc_offset + sym->offset;
+       str_limit = bytecode->p.bc->bc.data + bytecode->p.bc->bc.len;
+       len_limit = str_limit - str;
+       if (strnlen(str, len_limit) == len_limit)
+               return -EINVAL;
+       return 0;
+}
+
+/*
+ * Validate bytecode range overflow within the validation pass.
+ * Called for each instruction encountered.
+ */
+static
+int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
+               char *start_pc, char *pc)
+{
+       int ret = 0;
+
+       switch (*(bytecode_opcode_t *) pc) {
+       case BYTECODE_OP_UNKNOWN:
+       default:
+       {
+               ERR("unknown bytecode op %u\n",
+                       (unsigned int) *(bytecode_opcode_t *) pc);
+               ret = -EINVAL;
+               break;
+       }
+
+       case BYTECODE_OP_RETURN:
+       case BYTECODE_OP_RETURN_S64:
+       {
+               if (unlikely(pc + sizeof(struct return_op)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       /* binary */
+       case BYTECODE_OP_MUL:
+       case BYTECODE_OP_DIV:
+       case BYTECODE_OP_MOD:
+       case BYTECODE_OP_PLUS:
+       case BYTECODE_OP_MINUS:
+       {
+               ERR("unsupported bytecode op %u\n",
+                       (unsigned int) *(bytecode_opcode_t *) pc);
+               ret = -EINVAL;
+               break;
+       }
+
+       case BYTECODE_OP_EQ:
+       case BYTECODE_OP_NE:
+       case BYTECODE_OP_GT:
+       case BYTECODE_OP_LT:
+       case BYTECODE_OP_GE:
+       case BYTECODE_OP_LE:
+       case BYTECODE_OP_EQ_STRING:
+       case BYTECODE_OP_NE_STRING:
+       case BYTECODE_OP_GT_STRING:
+       case BYTECODE_OP_LT_STRING:
+       case BYTECODE_OP_GE_STRING:
+       case BYTECODE_OP_LE_STRING:
+       case BYTECODE_OP_EQ_STAR_GLOB_STRING:
+       case BYTECODE_OP_NE_STAR_GLOB_STRING:
+       case BYTECODE_OP_EQ_S64:
+       case BYTECODE_OP_NE_S64:
+       case BYTECODE_OP_GT_S64:
+       case BYTECODE_OP_LT_S64:
+       case BYTECODE_OP_GE_S64:
+       case BYTECODE_OP_LE_S64:
+       case BYTECODE_OP_EQ_DOUBLE:
+       case BYTECODE_OP_NE_DOUBLE:
+       case BYTECODE_OP_GT_DOUBLE:
+       case BYTECODE_OP_LT_DOUBLE:
+       case BYTECODE_OP_GE_DOUBLE:
+       case BYTECODE_OP_LE_DOUBLE:
+       case BYTECODE_OP_EQ_DOUBLE_S64:
+       case BYTECODE_OP_NE_DOUBLE_S64:
+       case BYTECODE_OP_GT_DOUBLE_S64:
+       case BYTECODE_OP_LT_DOUBLE_S64:
+       case BYTECODE_OP_GE_DOUBLE_S64:
+       case BYTECODE_OP_LE_DOUBLE_S64:
+       case BYTECODE_OP_EQ_S64_DOUBLE:
+       case BYTECODE_OP_NE_S64_DOUBLE:
+       case BYTECODE_OP_GT_S64_DOUBLE:
+       case BYTECODE_OP_LT_S64_DOUBLE:
+       case BYTECODE_OP_GE_S64_DOUBLE:
+       case BYTECODE_OP_LE_S64_DOUBLE:
+       case BYTECODE_OP_BIT_RSHIFT:
+       case BYTECODE_OP_BIT_LSHIFT:
+       case BYTECODE_OP_BIT_AND:
+       case BYTECODE_OP_BIT_OR:
+       case BYTECODE_OP_BIT_XOR:
+       {
+               if (unlikely(pc + sizeof(struct binary_op)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       /* unary */
+       case BYTECODE_OP_UNARY_PLUS:
+       case BYTECODE_OP_UNARY_MINUS:
+       case BYTECODE_OP_UNARY_NOT:
+       case BYTECODE_OP_UNARY_PLUS_S64:
+       case BYTECODE_OP_UNARY_MINUS_S64:
+       case BYTECODE_OP_UNARY_NOT_S64:
+       case BYTECODE_OP_UNARY_PLUS_DOUBLE:
+       case BYTECODE_OP_UNARY_MINUS_DOUBLE:
+       case BYTECODE_OP_UNARY_NOT_DOUBLE:
+       case BYTECODE_OP_UNARY_BIT_NOT:
+       {
+               if (unlikely(pc + sizeof(struct unary_op)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       /* logical */
+       case BYTECODE_OP_AND:
+       case BYTECODE_OP_OR:
+       {
+               if (unlikely(pc + sizeof(struct logical_op)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       /* load field ref */
+       case BYTECODE_OP_LOAD_FIELD_REF:
+       {
+               ERR("Unknown field ref type\n");
+               ret = -EINVAL;
+               break;
+       }
+
+       /* get context ref */
+       case BYTECODE_OP_GET_CONTEXT_REF:
+       case BYTECODE_OP_LOAD_FIELD_REF_STRING:
+       case BYTECODE_OP_LOAD_FIELD_REF_SEQUENCE:
+       case BYTECODE_OP_LOAD_FIELD_REF_S64:
+       case BYTECODE_OP_LOAD_FIELD_REF_DOUBLE:
+       case BYTECODE_OP_GET_CONTEXT_REF_STRING:
+       case BYTECODE_OP_GET_CONTEXT_REF_S64:
+       case BYTECODE_OP_GET_CONTEXT_REF_DOUBLE:
+       {
+               if (unlikely(pc + sizeof(struct load_op) + sizeof(struct field_ref)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       /* load from immediate operand */
+       case BYTECODE_OP_LOAD_STRING:
+       case BYTECODE_OP_LOAD_STAR_GLOB_STRING:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               uint32_t str_len, maxlen;
+
+               if (unlikely(pc + sizeof(struct load_op)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+                       break;
+               }
+
+               maxlen = start_pc + bytecode->len - pc - sizeof(struct load_op);
+               str_len = strnlen(insn->data, maxlen);
+               if (unlikely(str_len >= maxlen)) {
+                       /* Final '\0' not found within range */
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_S64:
+       {
+               if (unlikely(pc + sizeof(struct load_op) + sizeof(struct literal_numeric)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_DOUBLE:
+       {
+               if (unlikely(pc + sizeof(struct load_op) + sizeof(struct literal_double)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_CAST_TO_S64:
+       case BYTECODE_OP_CAST_DOUBLE_TO_S64:
+       case BYTECODE_OP_CAST_NOP:
+       {
+               if (unlikely(pc + sizeof(struct cast_op)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       /*
+        * Instructions for recursive traversal through composed types.
+        */
+       case BYTECODE_OP_GET_CONTEXT_ROOT:
+       case BYTECODE_OP_GET_APP_CONTEXT_ROOT:
+       case BYTECODE_OP_GET_PAYLOAD_ROOT:
+       case BYTECODE_OP_LOAD_FIELD:
+       case BYTECODE_OP_LOAD_FIELD_S8:
+       case BYTECODE_OP_LOAD_FIELD_S16:
+       case BYTECODE_OP_LOAD_FIELD_S32:
+       case BYTECODE_OP_LOAD_FIELD_S64:
+       case BYTECODE_OP_LOAD_FIELD_U8:
+       case BYTECODE_OP_LOAD_FIELD_U16:
+       case BYTECODE_OP_LOAD_FIELD_U32:
+       case BYTECODE_OP_LOAD_FIELD_U64:
+       case BYTECODE_OP_LOAD_FIELD_STRING:
+       case BYTECODE_OP_LOAD_FIELD_SEQUENCE:
+       case BYTECODE_OP_LOAD_FIELD_DOUBLE:
+               if (unlikely(pc + sizeof(struct load_op)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+
+       case BYTECODE_OP_GET_SYMBOL:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct get_symbol *sym = (struct get_symbol *) insn->data;
+
+               if (unlikely(pc + sizeof(struct load_op) + sizeof(struct get_symbol)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+                       break;
+               }
+               ret = validate_get_symbol(bytecode, sym);
+               break;
+       }
+
+       case BYTECODE_OP_GET_SYMBOL_FIELD:
+               ERR("Unexpected get symbol field");
+               ret = -EINVAL;
+               break;
+
+       case BYTECODE_OP_GET_INDEX_U16:
+               if (unlikely(pc + sizeof(struct load_op) + sizeof(struct get_index_u16)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+
+       case BYTECODE_OP_GET_INDEX_U64:
+               if (unlikely(pc + sizeof(struct load_op) + sizeof(struct get_index_u64)
+                               > start_pc + bytecode->len)) {
+                       ret = -ERANGE;
+               }
+               break;
+       }
+
+       return ret;
+}
+
+static
+unsigned long delete_all_nodes(struct cds_lfht *ht)
+{
+       struct cds_lfht_iter iter;
+       struct lfht_mp_node *node;
+       unsigned long nr_nodes = 0;
+
+       cds_lfht_for_each_entry(ht, &iter, node, node) {
+               int ret;
+
+               ret = cds_lfht_del(ht, cds_lfht_iter_get_node(&iter));
+               assert(!ret);
+               /* note: this hash table is never used concurrently */
+               free(node);
+               nr_nodes++;
+       }
+       return nr_nodes;
+}
+
+/*
+ * Return value:
+ * >=0: success
+ * <0: error
+ */
+static
+int validate_instruction_context(struct bytecode_runtime *bytecode,
+               struct vstack *stack,
+               char *start_pc,
+               char *pc)
+{
+       int ret = 0;
+       const bytecode_opcode_t opcode = *(bytecode_opcode_t *) pc;
+
+       switch (opcode) {
+       case BYTECODE_OP_UNKNOWN:
+       default:
+       {
+               ERR("unknown bytecode op %u\n",
+                       (unsigned int) *(bytecode_opcode_t *) pc);
+               ret = -EINVAL;
+               goto end;
+       }
+
+       case BYTECODE_OP_RETURN:
+       case BYTECODE_OP_RETURN_S64:
+       {
+               goto end;
+       }
+
+       /* binary */
+       case BYTECODE_OP_MUL:
+       case BYTECODE_OP_DIV:
+       case BYTECODE_OP_MOD:
+       case BYTECODE_OP_PLUS:
+       case BYTECODE_OP_MINUS:
+       {
+               ERR("unsupported bytecode op %u\n",
+                       (unsigned int) opcode);
+               ret = -EINVAL;
+               goto end;
+       }
+
+       case BYTECODE_OP_EQ:
+       {
+               ret = bin_op_compare_check(stack, opcode, "==");
+               if (ret < 0)
+                       goto end;
+               break;
+       }
+       case BYTECODE_OP_NE:
+       {
+               ret = bin_op_compare_check(stack, opcode, "!=");
+               if (ret < 0)
+                       goto end;
+               break;
+       }
+       case BYTECODE_OP_GT:
+       {
+               ret = bin_op_compare_check(stack, opcode, ">");
+               if (ret < 0)
+                       goto end;
+               break;
+       }
+       case BYTECODE_OP_LT:
+       {
+               ret = bin_op_compare_check(stack, opcode, "<");
+               if (ret < 0)
+                       goto end;
+               break;
+       }
+       case BYTECODE_OP_GE:
+       {
+               ret = bin_op_compare_check(stack, opcode, ">=");
+               if (ret < 0)
+                       goto end;
+               break;
+       }
+       case BYTECODE_OP_LE:
+       {
+               ret = bin_op_compare_check(stack, opcode, "<=");
+               if (ret < 0)
+                       goto end;
+               break;
+       }
+
+       case BYTECODE_OP_EQ_STRING:
+       case BYTECODE_OP_NE_STRING:
+       case BYTECODE_OP_GT_STRING:
+       case BYTECODE_OP_LT_STRING:
+       case BYTECODE_OP_GE_STRING:
+       case BYTECODE_OP_LE_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;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_EQ_STAR_GLOB_STRING:
+       case BYTECODE_OP_NE_STAR_GLOB_STRING:
+       {
+               if (!vstack_ax(stack) || !vstack_bx(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_STAR_GLOB_STRING
+                               && vstack_bx(stack)->type != REG_STAR_GLOB_STRING) {
+                       ERR("Unexpected register type for globbing pattern comparator\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_EQ_S64:
+       case BYTECODE_OP_NE_S64:
+       case BYTECODE_OP_GT_S64:
+       case BYTECODE_OP_LT_S64:
+       case BYTECODE_OP_GE_S64:
+       case BYTECODE_OP_LE_S64:
+       {
+               if (!vstack_ax(stack) || !vstack_bx(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("Unexpected register type for s64 comparator\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_bx(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("Unexpected register type for s64 comparator\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_EQ_DOUBLE:
+       case BYTECODE_OP_NE_DOUBLE:
+       case BYTECODE_OP_GT_DOUBLE:
+       case BYTECODE_OP_LT_DOUBLE:
+       case BYTECODE_OP_GE_DOUBLE:
+       case BYTECODE_OP_LE_DOUBLE:
+       {
+               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 BYTECODE_OP_EQ_DOUBLE_S64:
+       case BYTECODE_OP_NE_DOUBLE_S64:
+       case BYTECODE_OP_GT_DOUBLE_S64:
+       case BYTECODE_OP_LT_DOUBLE_S64:
+       case BYTECODE_OP_GE_DOUBLE_S64:
+       case BYTECODE_OP_LE_DOUBLE_S64:
+       {
+               if (!vstack_ax(stack) || !vstack_bx(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("Double-S64 operator has unexpected register types\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_bx(stack)->type) {
+               case REG_DOUBLE:
+                       break;
+               default:
+                       ERR("Double-S64 operator has unexpected register types\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_EQ_S64_DOUBLE:
+       case BYTECODE_OP_NE_S64_DOUBLE:
+       case BYTECODE_OP_GT_S64_DOUBLE:
+       case BYTECODE_OP_LT_S64_DOUBLE:
+       case BYTECODE_OP_GE_S64_DOUBLE:
+       case BYTECODE_OP_LE_S64_DOUBLE:
+       {
+               if (!vstack_ax(stack) || !vstack_bx(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_DOUBLE:
+                       break;
+               default:
+                       ERR("S64-Double operator has unexpected register types\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_bx(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("S64-Double operator has unexpected register types\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_BIT_RSHIFT:
+               ret = bin_op_bitwise_check(stack, opcode, ">>");
+               if (ret < 0)
+                       goto end;
+               break;
+       case BYTECODE_OP_BIT_LSHIFT:
+               ret = bin_op_bitwise_check(stack, opcode, "<<");
+               if (ret < 0)
+                       goto end;
+               break;
+       case BYTECODE_OP_BIT_AND:
+               ret = bin_op_bitwise_check(stack, opcode, "&");
+               if (ret < 0)
+                       goto end;
+               break;
+       case BYTECODE_OP_BIT_OR:
+               ret = bin_op_bitwise_check(stack, opcode, "|");
+               if (ret < 0)
+                       goto end;
+               break;
+       case BYTECODE_OP_BIT_XOR:
+               ret = bin_op_bitwise_check(stack, opcode, "^");
+               if (ret < 0)
+                       goto end;
+               break;
+
+       /* unary */
+       case BYTECODE_OP_UNARY_PLUS:
+       case BYTECODE_OP_UNARY_MINUS:
+       case BYTECODE_OP_UNARY_NOT:
+       {
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               default:
+                       ERR("unknown register type\n");
+                       ret = -EINVAL;
+                       goto end;
+
+               case REG_STRING:
+               case REG_STAR_GLOB_STRING:
+                       ERR("Unary op can only be applied to numeric or floating point registers\n");
+                       ret = -EINVAL;
+                       goto end;
+               case REG_S64:
+                       break;
+               case REG_U64:
+                       break;
+               case REG_DOUBLE:
+                       break;
+               case REG_UNKNOWN:
+                       break;
+               }
+               break;
+       }
+       case BYTECODE_OP_UNARY_BIT_NOT:
+       {
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               default:
+                       ERR("unknown register type\n");
+                       ret = -EINVAL;
+                       goto end;
+
+               case REG_STRING:
+               case REG_STAR_GLOB_STRING:
+               case REG_DOUBLE:
+                       ERR("Unary bitwise op can only be applied to numeric registers\n");
+                       ret = -EINVAL;
+                       goto end;
+               case REG_S64:
+                       break;
+               case REG_U64:
+                       break;
+               case REG_UNKNOWN:
+                       break;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_UNARY_PLUS_S64:
+       case BYTECODE_OP_UNARY_MINUS_S64:
+       case BYTECODE_OP_UNARY_NOT_S64:
+       {
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_S64 &&
+                               vstack_ax(stack)->type != REG_U64) {
+                       ERR("Invalid register type\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               break;
+       }
+
+       case BYTECODE_OP_UNARY_PLUS_DOUBLE:
+       case BYTECODE_OP_UNARY_MINUS_DOUBLE:
+       case BYTECODE_OP_UNARY_NOT_DOUBLE:
+       {
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_DOUBLE) {
+                       ERR("Invalid register type\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               break;
+       }
+
+       /* logical */
+       case BYTECODE_OP_AND:
+       case BYTECODE_OP_OR:
+       {
+               struct logical_op *insn = (struct logical_op *) pc;
+
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_S64
+                               && vstack_ax(stack)->type != REG_U64
+                               && vstack_ax(stack)->type != REG_UNKNOWN) {
+                       ERR("Logical comparator expects S64, U64 or dynamic register\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               dbg_printf("Validate jumping to bytecode offset %u\n",
+                       (unsigned int) insn->skip_offset);
+               if (unlikely(start_pc + insn->skip_offset <= pc)) {
+                       ERR("Loops are not allowed in bytecode\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               break;
+       }
+
+       /* load field ref */
+       case BYTECODE_OP_LOAD_FIELD_REF:
+       {
+               ERR("Unknown field ref type\n");
+               ret = -EINVAL;
+               goto end;
+       }
+       case BYTECODE_OP_LOAD_FIELD_REF_STRING:
+       case BYTECODE_OP_LOAD_FIELD_REF_SEQUENCE:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct field_ref *ref = (struct field_ref *) insn->data;
+
+               dbg_printf("Validate load field ref offset %u type string\n",
+                       ref->offset);
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_REF_S64:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct field_ref *ref = (struct field_ref *) insn->data;
+
+               dbg_printf("Validate load field ref offset %u type s64\n",
+                       ref->offset);
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_REF_DOUBLE:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct field_ref *ref = (struct field_ref *) insn->data;
+
+               dbg_printf("Validate load field ref offset %u type double\n",
+                       ref->offset);
+               break;
+       }
+
+       /* load from immediate operand */
+       case BYTECODE_OP_LOAD_STRING:
+       case BYTECODE_OP_LOAD_STAR_GLOB_STRING:
+       {
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_S64:
+       {
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_DOUBLE:
+       {
+               break;
+       }
+
+       case BYTECODE_OP_CAST_TO_S64:
+       case BYTECODE_OP_CAST_DOUBLE_TO_S64:
+       {
+               struct cast_op *insn = (struct cast_op *) pc;
+
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               default:
+                       ERR("unknown register type\n");
+                       ret = -EINVAL;
+                       goto end;
+
+               case REG_STRING:
+               case REG_STAR_GLOB_STRING:
+                       ERR("Cast op can only be applied to numeric or floating point registers\n");
+                       ret = -EINVAL;
+                       goto end;
+               case REG_S64:
+                       break;
+               case REG_U64:
+                       break;
+               case REG_DOUBLE:
+                       break;
+               case REG_UNKNOWN:
+                       break;
+               }
+               if (insn->op == BYTECODE_OP_CAST_DOUBLE_TO_S64) {
+                       if (vstack_ax(stack)->type != REG_DOUBLE) {
+                               ERR("Cast expects double\n");
+                               ret = -EINVAL;
+                               goto end;
+                       }
+               }
+               break;
+       }
+       case BYTECODE_OP_CAST_NOP:
+       {
+               break;
+       }
+
+       /* get context ref */
+       case BYTECODE_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 BYTECODE_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 BYTECODE_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 BYTECODE_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;
+       }
+
+       /*
+        * Instructions for recursive traversal through composed types.
+        */
+       case BYTECODE_OP_GET_CONTEXT_ROOT:
+       {
+               dbg_printf("Validate get context root\n");
+               break;
+       }
+       case BYTECODE_OP_GET_APP_CONTEXT_ROOT:
+       {
+               dbg_printf("Validate get app context root\n");
+               break;
+       }
+       case BYTECODE_OP_GET_PAYLOAD_ROOT:
+       {
+               dbg_printf("Validate get payload root\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD:
+       {
+               /*
+                * We tolerate that field type is unknown at validation,
+                * because we are performing the load specialization in
+                * a phase after validation.
+                */
+               dbg_printf("Validate load field\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_S8:
+       {
+               dbg_printf("Validate load field s8\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_S16:
+       {
+               dbg_printf("Validate load field s16\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_S32:
+       {
+               dbg_printf("Validate load field s32\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_S64:
+       {
+               dbg_printf("Validate load field s64\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_U8:
+       {
+               dbg_printf("Validate load field u8\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_U16:
+       {
+               dbg_printf("Validate load field u16\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_U32:
+       {
+               dbg_printf("Validate load field u32\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_U64:
+       {
+               dbg_printf("Validate load field u64\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_STRING:
+       {
+               dbg_printf("Validate load field string\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_SEQUENCE:
+       {
+               dbg_printf("Validate load field sequence\n");
+               break;
+       }
+       case BYTECODE_OP_LOAD_FIELD_DOUBLE:
+       {
+               dbg_printf("Validate load field double\n");
+               break;
+       }
+
+       case BYTECODE_OP_GET_SYMBOL:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct get_symbol *sym = (struct get_symbol *) insn->data;
+
+               dbg_printf("Validate get symbol offset %u\n", sym->offset);
+               break;
+       }
+
+       case BYTECODE_OP_GET_SYMBOL_FIELD:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct get_symbol *sym = (struct get_symbol *) insn->data;
+
+               dbg_printf("Validate get symbol field offset %u\n", sym->offset);
+               break;
+       }
+
+       case BYTECODE_OP_GET_INDEX_U16:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct get_index_u16 *get_index = (struct get_index_u16 *) insn->data;
+
+               dbg_printf("Validate get index u16 index %u\n", get_index->index);
+               break;
+       }
+
+       case BYTECODE_OP_GET_INDEX_U64:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+               struct get_index_u64 *get_index = (struct get_index_u64 *) insn->data;
+
+               dbg_printf("Validate get index u64 index %" PRIu64 "\n", get_index->index);
+               break;
+       }
+       }
+end:
+       return ret;
+}
+
+/*
+ * Return value:
+ * 0: success
+ * <0: error
+ */
+static
+int validate_instruction_all_contexts(struct bytecode_runtime *bytecode,
+               struct cds_lfht *merge_points,
+               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, stack, start_pc, pc);
+       if (ret < 0)
+               return ret;
+
+       /* Validate merge points */
+       hash = lttng_hash_mix((const char *) target_pc, sizeof(target_pc),
+                       lttng_hash_seed);
+       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("Bytecode: validate merge point at offset %lu\n",
+                               target_pc);
+               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("Bytecode: remove merge point at offset %lu\n",
+                               target_pc);
+               ret = cds_lfht_del(merge_points, node);
+               assert(!ret);
+       }
+       return 0;
+}
+
+/*
+ * Return value:
+ * >0: going to next insn.
+ * 0: success, stop iteration.
+ * <0: error
+ */
+static
+int exec_insn(struct bytecode_runtime *bytecode,
+               struct cds_lfht *merge_points,
+               struct vstack *stack,
+               char **_next_pc,
+               char *pc)
+{
+       int ret = 1;
+       char *next_pc = *_next_pc;
+
+       switch (*(bytecode_opcode_t *) pc) {
+       case BYTECODE_OP_UNKNOWN:
+       default:
+       {
+               ERR("unknown bytecode op %u\n",
+                       (unsigned int) *(bytecode_opcode_t *) pc);
+               ret = -EINVAL;
+               goto end;
+       }
+
+       case BYTECODE_OP_RETURN:
+       {
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+               case REG_DOUBLE:
+               case REG_STRING:
+               case REG_PTR:
+               case REG_UNKNOWN:
+                       break;
+               default:
+                       ERR("Unexpected register type %d at end of bytecode\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               ret = 0;
+               goto end;
+       }
+       case BYTECODE_OP_RETURN_S64:
+       {
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+               case REG_UNKNOWN:
+                       ERR("Unexpected register type %d at end of bytecode\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               ret = 0;
+               goto end;
+       }
+
+       /* binary */
+       case BYTECODE_OP_MUL:
+       case BYTECODE_OP_DIV:
+       case BYTECODE_OP_MOD:
+       case BYTECODE_OP_PLUS:
+       case BYTECODE_OP_MINUS:
+       {
+               ERR("unsupported bytecode op %u\n",
+                       (unsigned int) *(bytecode_opcode_t *) pc);
+               ret = -EINVAL;
+               goto end;
+       }
+
+       case BYTECODE_OP_EQ:
+       case BYTECODE_OP_NE:
+       case BYTECODE_OP_GT:
+       case BYTECODE_OP_LT:
+       case BYTECODE_OP_GE:
+       case BYTECODE_OP_LE:
+       case BYTECODE_OP_EQ_STRING:
+       case BYTECODE_OP_NE_STRING:
+       case BYTECODE_OP_GT_STRING:
+       case BYTECODE_OP_LT_STRING:
+       case BYTECODE_OP_GE_STRING:
+       case BYTECODE_OP_LE_STRING:
+       case BYTECODE_OP_EQ_STAR_GLOB_STRING:
+       case BYTECODE_OP_NE_STAR_GLOB_STRING:
+       case BYTECODE_OP_EQ_S64:
+       case BYTECODE_OP_NE_S64:
+       case BYTECODE_OP_GT_S64:
+       case BYTECODE_OP_LT_S64:
+       case BYTECODE_OP_GE_S64:
+       case BYTECODE_OP_LE_S64:
+       case BYTECODE_OP_EQ_DOUBLE:
+       case BYTECODE_OP_NE_DOUBLE:
+       case BYTECODE_OP_GT_DOUBLE:
+       case BYTECODE_OP_LT_DOUBLE:
+       case BYTECODE_OP_GE_DOUBLE:
+       case BYTECODE_OP_LE_DOUBLE:
+       case BYTECODE_OP_EQ_DOUBLE_S64:
+       case BYTECODE_OP_NE_DOUBLE_S64:
+       case BYTECODE_OP_GT_DOUBLE_S64:
+       case BYTECODE_OP_LT_DOUBLE_S64:
+       case BYTECODE_OP_GE_DOUBLE_S64:
+       case BYTECODE_OP_LE_DOUBLE_S64:
+       case BYTECODE_OP_EQ_S64_DOUBLE:
+       case BYTECODE_OP_NE_S64_DOUBLE:
+       case BYTECODE_OP_GT_S64_DOUBLE:
+       case BYTECODE_OP_LT_S64_DOUBLE:
+       case BYTECODE_OP_GE_S64_DOUBLE:
+       case BYTECODE_OP_LE_S64_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;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+               case REG_DOUBLE:
+               case REG_STRING:
+               case REG_STAR_GLOB_STRING:
+               case REG_UNKNOWN:
+                       break;
+               default:
+                       ERR("Unexpected register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               vstack_ax(stack)->type = REG_S64;
+               next_pc += sizeof(struct binary_op);
+               break;
+       }
+
+       case BYTECODE_OP_BIT_RSHIFT:
+       case BYTECODE_OP_BIT_LSHIFT:
+       case BYTECODE_OP_BIT_AND:
+       case BYTECODE_OP_BIT_OR:
+       case BYTECODE_OP_BIT_XOR:
+       {
+               /* Pop 2, push 1 */
+               if (vstack_pop(stack)) {
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+               case REG_DOUBLE:
+               case REG_STRING:
+               case REG_STAR_GLOB_STRING:
+               case REG_UNKNOWN:
+                       break;
+               default:
+                       ERR("Unexpected register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               vstack_ax(stack)->type = REG_U64;
+               next_pc += sizeof(struct binary_op);
+               break;
+       }
+
+       /* unary */
+       case BYTECODE_OP_UNARY_PLUS:
+       case BYTECODE_OP_UNARY_MINUS:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_UNKNOWN:
+               case REG_DOUBLE:
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("Unexpected register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_UNKNOWN;
+               next_pc += sizeof(struct unary_op);
+               break;
+       }
+
+       case BYTECODE_OP_UNARY_PLUS_S64:
+       case BYTECODE_OP_UNARY_MINUS_S64:
+       case BYTECODE_OP_UNARY_NOT_S64:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("Unexpected register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               next_pc += sizeof(struct unary_op);
+               break;
+       }
+
+       case BYTECODE_OP_UNARY_NOT:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_UNKNOWN:
+               case REG_DOUBLE:
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("Unexpected register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               next_pc += sizeof(struct unary_op);
+               break;
+       }
+
+       case BYTECODE_OP_UNARY_BIT_NOT:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_UNKNOWN:
+               case REG_S64:
+               case REG_U64:
+                       break;
+               case REG_DOUBLE:
+               default:
+                       ERR("Unexpected register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               vstack_ax(stack)->type = REG_U64;
+               next_pc += sizeof(struct unary_op);
+               break;
+       }
+
+       case BYTECODE_OP_UNARY_NOT_DOUBLE:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_DOUBLE:
+                       break;
+               default:
+                       ERR("Incorrect register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               vstack_ax(stack)->type = REG_S64;
+               next_pc += sizeof(struct unary_op);
+               break;
+       }
+
+       case BYTECODE_OP_UNARY_PLUS_DOUBLE:
+       case BYTECODE_OP_UNARY_MINUS_DOUBLE:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_DOUBLE:
+                       break;
+               default:
+                       ERR("Incorrect register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               vstack_ax(stack)->type = REG_DOUBLE;
+               next_pc += sizeof(struct unary_op);
+               break;
+       }
+
+       /* logical */
+       case BYTECODE_OP_AND:
+       case BYTECODE_OP_OR:
+       {
+               struct logical_op *insn = (struct logical_op *) pc;
+               int merge_ret;
+
+               /* Add merge point to table */
+               merge_ret = merge_point_add_check(merge_points,
+                                       insn->skip_offset, stack);
+               if (merge_ret) {
+                       ret = merge_ret;
+                       goto end;
+               }
+
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               /* There is always a cast-to-s64 operation before a or/and op. */
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+                       break;
+               default:
+                       ERR("Incorrect register type %d for operation\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       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 field ref */
+       case BYTECODE_OP_LOAD_FIELD_REF:
+       {
+               ERR("Unknown field ref type\n");
+               ret = -EINVAL;
+               goto end;
+       }
+       /* get context ref */
+       case BYTECODE_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 BYTECODE_OP_LOAD_FIELD_REF_STRING:
+       case BYTECODE_OP_LOAD_FIELD_REF_SEQUENCE:
+       case BYTECODE_OP_GET_CONTEXT_REF_STRING:
+       {
+               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 BYTECODE_OP_LOAD_FIELD_REF_S64:
+       case BYTECODE_OP_GET_CONTEXT_REF_S64:
+       {
+               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 BYTECODE_OP_LOAD_FIELD_REF_DOUBLE:
+       case BYTECODE_OP_GET_CONTEXT_REF_DOUBLE:
+       {
+               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 BYTECODE_OP_LOAD_STRING:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+
+               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 BYTECODE_OP_LOAD_STAR_GLOB_STRING:
+       {
+               struct load_op *insn = (struct load_op *) pc;
+
+               if (vstack_push(stack)) {
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_STAR_GLOB_STRING;
+               next_pc += sizeof(struct load_op) + strlen(insn->data) + 1;
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_S64:
+       {
+               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;
+       }
+
+       case BYTECODE_OP_LOAD_DOUBLE:
+       {
+               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;
+       }
+
+       case BYTECODE_OP_CAST_TO_S64:
+       case BYTECODE_OP_CAST_DOUBLE_TO_S64:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+               case REG_U64:
+               case REG_DOUBLE:
+               case REG_UNKNOWN:
+                       break;
+               default:
+                       ERR("Incorrect register type %d for cast\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_S64;
+               next_pc += sizeof(struct cast_op);
+               break;
+       }
+       case BYTECODE_OP_CAST_NOP:
+       {
+               next_pc += sizeof(struct cast_op);
+               break;
+       }
+
+       /*
+        * Instructions for recursive traversal through composed types.
+        */
+       case BYTECODE_OP_GET_CONTEXT_ROOT:
+       case BYTECODE_OP_GET_APP_CONTEXT_ROOT:
+       case BYTECODE_OP_GET_PAYLOAD_ROOT:
+       {
+               if (vstack_push(stack)) {
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_PTR;
+               next_pc += sizeof(struct load_op);
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_FIELD:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_UNKNOWN;
+               next_pc += sizeof(struct load_op);
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_FIELD_S8:
+       case BYTECODE_OP_LOAD_FIELD_S16:
+       case BYTECODE_OP_LOAD_FIELD_S32:
+       case BYTECODE_OP_LOAD_FIELD_S64:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_S64;
+               next_pc += sizeof(struct load_op);
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_FIELD_U8:
+       case BYTECODE_OP_LOAD_FIELD_U16:
+       case BYTECODE_OP_LOAD_FIELD_U32:
+       case BYTECODE_OP_LOAD_FIELD_U64:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_U64;
+               next_pc += sizeof(struct load_op);
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_FIELD_STRING:
+       case BYTECODE_OP_LOAD_FIELD_SEQUENCE:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_STRING;
+               next_pc += sizeof(struct load_op);
+               break;
+       }
+
+       case BYTECODE_OP_LOAD_FIELD_DOUBLE:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               vstack_ax(stack)->type = REG_DOUBLE;
+               next_pc += sizeof(struct load_op);
+               break;
+       }
+
+       case BYTECODE_OP_GET_SYMBOL:
+       case BYTECODE_OP_GET_SYMBOL_FIELD:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               next_pc += sizeof(struct load_op) + sizeof(struct get_symbol);
+               break;
+       }
+
+       case BYTECODE_OP_GET_INDEX_U16:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               next_pc += sizeof(struct load_op) + sizeof(struct get_index_u16);
+               break;
+       }
+
+       case BYTECODE_OP_GET_INDEX_U64:
+       {
+               /* Pop 1, push 1 */
+               if (!vstack_ax(stack)) {
+                       ERR("Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               if (vstack_ax(stack)->type != REG_PTR) {
+                       ERR("Expecting pointer on top of stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               next_pc += sizeof(struct load_op) + sizeof(struct get_index_u64);
+               break;
+       }
+
+       }
+end:
+       *_next_pc = next_pc;
+       return ret;
+}
+
+/*
+ * Never called concurrently (hash seed is shared).
+ */
+int lttng_bytecode_validate(struct bytecode_runtime *bytecode)
+{
+       struct cds_lfht *merge_points;
+       char *pc, *next_pc, *start_pc;
+       int ret = -EINVAL;
+       struct vstack stack;
+
+       vstack_init(&stack);
+
+       if (!lttng_hash_seed_ready) {
+               lttng_hash_seed = time(NULL);
+               lttng_hash_seed_ready = 1;
+       }
+       /*
+        * Note: merge_points hash table used by single thread, and
+        * never concurrently resized. Therefore, we can use it without
+        * holding RCU read-side lock and free nodes without using
+        * call_rcu.
+        */
+       merge_points = cds_lfht_new(DEFAULT_NR_MERGE_POINTS,
+                       MIN_NR_BUCKETS, MAX_NR_BUCKETS,
+                       0, NULL);
+       if (!merge_points) {
+               ERR("Error allocating hash table for bytecode validation\n");
+               return -ENOMEM;
+       }
+       start_pc = &bytecode->code[0];
+       for (pc = next_pc = start_pc; pc - start_pc < bytecode->len;
+                       pc = next_pc) {
+               ret = bytecode_validate_overflow(bytecode, start_pc, pc);
+               if (ret != 0) {
+                       if (ret == -ERANGE)
+                               ERR("Bytecode overflow\n");
+                       goto end;
+               }
+               dbg_printf("Validating op %s (%u)\n",
+                       print_op((unsigned int) *(bytecode_opcode_t *) pc),
+                       (unsigned int) *(bytecode_opcode_t *) pc);
+
+               /*
+                * For each instruction, validate the current context
+                * (traversal of entire execution flow), and validate
+                * all merge points targeting this instruction.
+                */
+               ret = validate_instruction_all_contexts(bytecode, merge_points,
+                                       &stack, start_pc, pc);
+               if (ret)
+                       goto end;
+               ret = exec_insn(bytecode, merge_points, &stack, &next_pc, pc);
+               if (ret <= 0)
+                       goto end;
+       }
+end:
+       if (delete_all_nodes(merge_points)) {
+               if (!ret) {
+                       ERR("Unexpected merge points\n");
+                       ret = -EINVAL;
+               }
+       }
+       if (cds_lfht_destroy(merge_points, NULL)) {
+               ERR("Error destroying hash table\n");
+       }
+       return ret;
+}
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