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bpf, x86: Adjust arch_prepare_bpf_trampoline return value

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x86's implementation of arch_prepare_bpf_trampoline() requires
BPF_INSN_SAFETY buffer space between end of program and image_end. OTOH,
the return value does not include BPF_INSN_SAFETY. This doesn't cause any
real issue at the moment. However, "image" of size retval is not enough for
arch_prepare_bpf_trampoline(). This will cause confusion when we introduce
a new helper arch_bpf_trampoline_size(). To avoid future confusion, adjust
the return value to include BPF_INSN_SAFETY.

Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20231206224054.492250-5-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Song Liu 2023-12-06 14:40:51 -08:00 committed by Alexei Starovoitov
parent 82583daa2e
commit 38b8b58ae7
1 changed files with 1 additions and 1 deletions
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2
arch/x86/net/bpf_jit_comp.c
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@ -2671,7 +2671,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
ret = -EFAULT;
goto cleanup;
}
ret = prog - (u8 *)image;
ret = prog - (u8 *)image + BPF_INSN_SAFETY;
cleanup:
kfree(branches);