netdev - [PATCH bpf-next 1/3] bpf: Use precise image size for struct

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Date: Tue, 23 Jan 2024 10:32:39 +0000
From: Pu Lehui <pulehui@...weicloud.com>
To: bpf@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	netdev@...r.kernel.org
Cc: Björn Töpel <bjorn@...nel.org>,
	Song Liu <song@...nel.org>,
	Puranjay Mohan <puranjay12@...il.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Yonghong Song <yhs@...com>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Luke Nelson <luke.r.nels@...il.com>,
	Pu Lehui <pulehui@...wei.com>,
	Pu Lehui <pulehui@...weicloud.com>
Subject: [PATCH bpf-next 1/3] bpf: Use precise image size for struct_ops trampoline

From: Pu Lehui <pulehui@...wei.com>

For trampoline using bpf_prog_pack, we need to generate a rw_image
buffer with size of (image_end - image). For regular trampoline, we use
the precise image size generated by arch_bpf_trampoline_size to allocate
rw_image. But for struct_ops trampoline, we allocate rw_image directly
using close to PAGE_SIZE size. We do not need to allocate for that much,
as the patch size is usually much smaller than PAGE_SIZE. Let's use
precise image size for it too.

Signed-off-by: Pu Lehui <pulehui@...wei.com>
---
 kernel/bpf/bpf_struct_ops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 02068bd0e4d9..e2e1bf3c69a3 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -368,7 +368,7 @@ int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks,
 		return size;
 	if (size > (unsigned long)image_end - (unsigned long)image)
 		return -E2BIG;
-	return arch_prepare_bpf_trampoline(NULL, image, image_end,
+	return arch_prepare_bpf_trampoline(NULL, image, image + size,
 					   model, flags, tlinks, stub_func);
 }
 
-- 
2.34.1