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[RFC,bpf-next,3/5] bpf: propagate poke descriptors to subprograms

Message ID 20200702134930.4717-4-maciej.fijalkowski@intel.com
State RFC
Delegated to: BPF Maintainers
Headers show
Series bpf: tailcalls in BPF subprograms | expand

Commit Message

Maciej Fijalkowski July 2, 2020, 1:49 p.m. UTC 
Previously, there was no need for poke descriptors being present in
subprogram's bpf_prog_aux struct since tailcalls were simply not allowed
in them. Each subprog is JITed independently so in order to enable
JITing such subprograms, simply copy poke descriptors from main program
to subprogram's poke tab.

Add also subprog's aux struct to the BPF map poke_progs list by calling
on it map_poke_track().

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
---
 kernel/bpf/verifier.c | 9 +++++++++
 1 file changed, 9 insertions(+)
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Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index e7b6b059e6e9..716538ada537 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9931,6 +9931,9 @@  static int jit_subprogs(struct bpf_verifier_env *env)
 		goto out_undo_insn;
 
 	for (i = 0; i < env->subprog_cnt; i++) {
+		struct bpf_map *map_ptr;
+		int j;
+
 		subprog_start = subprog_end;
 		subprog_end = env->subprog_info[i + 1].start;
 
@@ -9955,6 +9958,12 @@  static int jit_subprogs(struct bpf_verifier_env *env)
 		func[i]->aux->btf = prog->aux->btf;
 		func[i]->aux->func_info = prog->aux->func_info;
 
+		for (j = 0; j < prog->aux->size_poke_tab; j++) {
+			bpf_jit_add_poke_descriptor(func[i], &prog->aux->poke_tab[j]);
+			map_ptr = func[i]->aux->poke_tab[j].tail_call.map;
+			map_ptr->ops->map_poke_track(map_ptr, func[i]->aux);
+		}
+
 		/* Use bpf_prog_F_tag to indicate functions in stack traces.
 		 * Long term would need debug info to populate names
 		 */