diff mbox series

[bpf-next,2/2] bpf, verifier: Check trampoline target is tail_call_reachable subprog

Message ID 20241028134041.94098-3-leon.hwang@linux.dev (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf, x64: Introduce two tailcall enhancements | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 204 this patch: 204
netdev/build_tools fail Errors and warnings before: 96 (+0) this patch: 135 (+0)
netdev/cc_maintainers warning 6 maintainers not CCed: sdf@fomichev.me song@kernel.org kpsingh@kernel.org haoluo@google.com john.fastabend@gmail.com martin.lau@linux.dev
netdev/build_clang success Errors and warnings before: 253 this patch: 253
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 6962 this patch: 6962
netdev/checkpatch warning WARNING: line length of 97 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 6 this patch: 6
netdev/source_inline success Was 0 now: 0

Commit Message

Leon Hwang Oct. 28, 2024, 1:40 p.m. UTC 
In the x86_64 JIT, tailcall info is propagated through the trampoline when
the target program is tail_call_reachable. However, this propagation is
unnecessary if the target is a main prog, or a subprog that is not
tail_call_reachable.

Since the verifier can determine if a subprog is tail_call_reachable, it
should only propagate tailcall info when the target is subprog and the
subprog is actually tail_call_reachable.

Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
 include/linux/bpf.h   | 1 +
 kernel/bpf/verifier.c | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index c3ba4d4751747..0c3b147c84af9 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1253,6 +1253,7 @@  struct bpf_attach_target_info {
 	struct module *tgt_mod;
 	const char *tgt_name;
 	const struct btf_type *tgt_type;
+	bool tgt_tail_call_reachable;
 };
 
 #define BPF_DISPATCHER_MAX 48 /* Fits in 2048B */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 797cf3ed32e0f..2e2f027b86375 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -21946,6 +21946,8 @@  int bpf_check_attach_target(struct bpf_verifier_log *log,
 			bpf_log(log, "Subprog %s doesn't exist\n", tname);
 			return -EINVAL;
 		}
+		tgt_info->tgt_tail_call_reachable = subprog &&
+						    aux->func[subprog]->aux->tail_call_reachable;
 		if (aux->func && aux->func[subprog]->aux->exception_cb) {
 			bpf_log(log,
 				"%s programs cannot attach to exception callback\n",
@@ -22315,7 +22317,7 @@  static int check_attach_btf_id(struct bpf_verifier_env *env)
 	if (!tr)
 		return -ENOMEM;
 
-	if (tgt_prog && tgt_prog->aux->tail_call_reachable)
+	if (tgt_prog && tgt_info.tgt_tail_call_reachable)
 		tr->flags = BPF_TRAMP_F_TAIL_CALL_CTX;
 
 	prog->aux->dst_trampoline = tr;