[PATCH v3 bpf-next 5/8] 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@xxxxxxxxxx>
Acked-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
 arch/x86/net/bpf_jit_comp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 8c10d9abc239..5f7528cac344 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -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);
-- 
2.34.1






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