6.15-stable review patch. If anyone has any objections, please let me know.
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From: Ilya Leoshkevich iii@linux.ibm.com
[ Upstream commit 94bde253d3ae5d8a01cb958663b12daef1d06574 ]
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 Originally the NULL value was used to distinguish the struct_ops case, but this was superseded by BPF_TRAMP_F_INDIRECT (see commit 0c970ed2f87c ("s390/bpf: Fix indirect trampoline generation").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 iii@linux.ibm.com Acked-by: Martin KaFai Lau martin.lau@kernel.org Link: https://lore.kernel.org/r/20250512221911.61314-2-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/bpf_struct_ops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
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;