[PATCH] pipeline: add check against loops

[Cristian Dumitrescu <cristian.dumitrescu@intel.com>]

Detect when a jump instruction, either conditional or unconditional,
is jumping to itself, thus creating a loop, which is not allowed in
data plane code.

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Signed-off-by: Harshad Narayane <harshad.suresh.narayane@intel.com>
---
 lib/pipeline/rte_swx_pipeline.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/lib/pipeline/rte_swx_pipeline.c b/lib/pipeline/rte_swx_pipeline.c
index c332d44bd1..1a50c4bb72 100644
--- a/lib/pipeline/rte_swx_pipeline.c
+++ b/lib/pipeline/rte_swx_pipeline.c
@@ -6000,6 +6000,19 @@ instr_label_check(struct instruction_data *instruction_data,
 			CHECK(strcmp(label, instruction_data[j].label), EINVAL);
 	}
 
+	/* Check that no jump instruction (either conditional or not) can jump to itself (loop). */
+	for (i = 0; i < n_instructions; i++) {
+		struct instruction_data *data = &instruction_data[i];
+		char *label = data->label;
+		char *jmp_label = data->jmp_label;
+
+		/* Continue if this instruction does not have a label or it is not a jump. */
+		if (!label[0] || !jmp_label[0])
+			continue;
+
+		CHECK(strcmp(label, jmp_label), EINVAL);
+	}
+
 	/* Get users for each instruction label. */
 	for (i = 0; i < n_instructions; i++) {
 		struct instruction_data *data = &instruction_data[i];
-- 
2.17.1