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From: Song Liu <song@kernel.org>
To: <bpf@vger.kernel.org>
Cc: <ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
	<martin.lau@kernel.org>, <kernel-team@meta.com>,
	<iii@linux.ibm.com>, <bjorn@kernel.org>,
	Song Liu <song@kernel.org>
Subject: [PATCH v3 bpf-next 5/8] bpf, x86: Adjust arch_prepare_bpf_trampoline return value
Date: Tue, 26 Sep 2023 12:00:17 -0700	[thread overview]
Message-ID: <20230926190020.1111575-6-song@kernel.org> (raw)
In-Reply-To: <20230926190020.1111575-1-song@kernel.org>

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>
---
 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


  parent reply	other threads:[~2023-09-26 19:00 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-26 19:00 [PATCH v3 bpf-next 0/8] Allocate bpf trampoline on bpf_prog_pack Song Liu
2023-09-26 19:00 ` [PATCH v3 bpf-next 1/8] s390/bpf: Let arch_prepare_bpf_trampoline return program size Song Liu
2023-09-26 19:00 ` [PATCH v3 bpf-next 2/8] bpf: Let bpf_prog_pack_free handle any pointer Song Liu
2023-09-27 18:29   ` Björn Töpel
2023-09-26 19:00 ` [PATCH v3 bpf-next 3/8] bpf: Adjust argument names of arch_prepare_bpf_trampoline() Song Liu
2023-09-26 19:00 ` [PATCH v3 bpf-next 4/8] bpf: Add helpers for trampoline image management Song Liu
2023-09-26 19:00 ` Song Liu [this message]
2023-09-26 19:00 ` [PATCH v3 bpf-next 6/8] bpf: Add arch_bpf_trampoline_size() Song Liu
2023-09-26 19:00 ` [PATCH v3 bpf-next 7/8] bpf: Use arch_bpf_trampoline_size Song Liu
2023-09-26 19:00 ` [PATCH v3 bpf-next 8/8] x86, bpf: Use bpf_prog_pack for bpf trampoline Song Liu
2023-09-27 13:16   ` Jiri Olsa
2023-09-27 15:47     ` Song Liu
2023-10-04 15:40 ` [PATCH v3 bpf-next 0/8] Allocate bpf trampoline on bpf_prog_pack patchwork-bot+netdevbpf
2023-10-04 15:50   ` Alexei Starovoitov

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