[bpf-next,v2,1/3] bpf: Use precise image size for struct_ops trampoline

Commit Message

Pu Lehui May 18, 2024, 9:29 a.m. UTC

From: Pu Lehui <[e-mail]>

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 <[e-mail]>
Acked-by: Song Liu <[e-mail]>
Tested-by: Björn Töpel <[e-mail]> #riscv
---
 kernel/bpf/bpf_struct_ops.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 86c7884abaf8..8aee184622af 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -571,7 +571,7 @@  int bpf_struct_ops_prepare_trampoline(struct bpf_tramp_links *tlinks,
 	}
 
 	size = arch_prepare_bpf_trampoline(NULL, image + image_off,
-					   image + PAGE_SIZE,
+					   image + image_off + size,
 					   model, flags, tlinks, stub_func);
 	if (size <= 0) {
 		if (image != *_image)