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bpf: Pass the same orig_call value to trampoline functions

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[ 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was used to distinguish the struct_ops case, but this was superseded by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 0c970ed2f8 ("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>
This commit is contained in:
Ilya Leoshkevich
2025-05-12 22:57:30 +02:00
committed by Greg Kroah-Hartman
parent aefe45843e
commit 8fdf2f79eb
1 changed files with 1 additions and 1 deletions
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2
kernel/bpf/bpf_struct_ops.c
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@@ -577,7 +577,7 @@ 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;