From 0cf76f7c2e69a098c9b2080902de4b40ae024ca3 Mon Sep 17 00:00:00 2001 From: Antoine Tenart Date: Mon, 24 Jun 2024 11:09:07 +0200 Subject: [PATCH] libbpf: Skip base btf sanity checks BugLink: https://bugs.launchpad.net/bugs/2083196 [ Upstream commit c73a9683cb21012b6c0f14217974837151c527a8 ] When upgrading to libbpf 1.3 we noticed a big performance hit while loading programs using CORE on non base-BTF symbols. This was tracked down to the new BTF sanity check logic. The issue is the base BTF definitions are checked first for the base BTF and then again for every module BTF. Loading 5 dummy programs (using libbpf-rs) that are using CORE on a non-base BTF symbol on my system: - Before this fix: 3s. - With this fix: 0.1s. Fix this by only checking the types starting at the BTF start id. This should ensure the base BTF is still checked as expected but only once (btf->start_id == 1 when creating the base BTF), and then only additional types are checked for each module BTF. Fixes: 3903802bb99a ("libbpf: Add basic BTF sanity validation") Signed-off-by: Antoine Tenart Signed-off-by: Andrii Nakryiko Reviewed-by: Alan Maguire Link: https://lore.kernel.org/bpf/20240624090908.171231-1-atenart@kernel.org Signed-off-by: Sasha Levin Signed-off-by: Portia Stephens Signed-off-by: Roxana Nicolescu --- tools/lib/bpf/btf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index ee95fd379d4d..8a5fbcf8b24d 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -598,7 +598,7 @@ static int btf_sanity_check(const struct btf *btf) __u32 i, n = btf__type_cnt(btf); int err; - for (i = 1; i < n; i++) { + for (i = btf->start_id; i < n; i++) { t = btf_type_by_id(btf, i); err = btf_validate_type(btf, t, i); if (err)