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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@linux.dev>, <kernel-team@meta.com>,
	<iii@linux.ibm.com>, Song Liu <song@kernel.org>
Subject: [PATCH bpf 1/2] s390/bpf: Let arch_prepare_bpf_trampoline return program size
Date: Mon, 18 Sep 2023 23:02:57 -0700	[thread overview]
Message-ID: <20230919060258.3237176-2-song@kernel.org> (raw)
In-Reply-To: <20230919060258.3237176-1-song@kernel.org>

arch_prepare_bpf_trampoline() for s390 currently returns 0 on success. This
is not a problem for regular trampoline. However, struct_ops relies on the
return value to advance "image" pointer:

bpf_struct_ops_map_update_elem() {
    ...
    for_each_member(i, t, member) {
        ...
        err = bpf_struct_ops_prepare_trampoline();
        ...
        image += err;
    }
}

When arch_prepare_bpf_trampoline returns 0 on success, all members of the
struct_ops will point to the same trampoline (the last one).

Fix this by returning the program size in arch_prepare_bpf_trampoline (on
success). This is the same behavior as other architectures.

Signed-off-by: Song Liu <song@kernel.org>
---
 arch/s390/net/bpf_jit_comp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index de2fb12120d2..2861e3360aff 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -2513,7 +2513,7 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image,
 			return -E2BIG;
 	}
 
-	return ret;
+	return tjit.common.prg;
 }
 
 bool bpf_jit_supports_subprog_tailcalls(void)
-- 
2.34.1


  reply	other threads:[~2023-09-19  6:03 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-19  6:02 [PATCH bpf 0/2] s390/bpf: Fix arch_prepare_bpf_trampoline Song Liu
2023-09-19  6:02 ` Song Liu [this message]
2023-09-19  9:04   ` [PATCH bpf 1/2] s390/bpf: Let arch_prepare_bpf_trampoline return program size Ilya Leoshkevich
2023-09-19  6:02 ` [PATCH bpf 2/2] selftests/bpf: Check bpf_cubic_acked() is called via struct_ops Song Liu
2023-09-19  9:05   ` Ilya Leoshkevich
2023-09-19 10:10 ` [PATCH bpf 0/2] s390/bpf: Fix arch_prepare_bpf_trampoline patchwork-bot+netdevbpf

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