From: Ilya Leoshkevich Date: Mon, 12 May 2025 20:57:30 +0000 (+0200) Subject: bpf: Pass the same orig_call value to trampoline functions X-Git-Tag: v6.16-rc1~131^2~21^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=94bde253d3ae5d8a01cb958663b12daef1d06574;p=thirdparty%2Flinux.git bpf: Pass the same orig_call value to trampoline functions There is currently some confusion in the s390x JIT regarding whether orig_call can be NULL and what that means. Originally the NULL value was used to distinguish the struct_ops case, but this was superseded by BPF_TRAMP_F_INDIRECT (see commit 0c970ed2f87c ("s390/bpf: Fix indirect trampoline generation"). The remaining reason to have this check is that NULL can actually be passed to the arch_bpf_trampoline_size() call - but not to the respective arch_prepare_bpf_trampoline()! call - by bpf_struct_ops_prepare_trampoline(). Remove this asymmetry by passing stub_func to both functions, so that JITs may rely on orig_call never being NULL. Signed-off-by: Ilya Leoshkevich Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20250512221911.61314-2-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov --- diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c index db13ee70d94d5..96113633e391a 100644 --- a/kernel/bpf/bpf_struct_ops.c +++ b/kernel/bpf/bpf_struct_ops.c @@ -601,7 +601,7 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks, if (model->ret_size > 0) flags |= BPF_TRAMP_F_RET_FENTRY_RET; - size = arch_bpf_trampoline_size(model, flags, tlinks, NULL); + size = arch_bpf_trampoline_size(model, flags, tlinks, stub_func); if (size <= 0) return size ? : -EFAULT;