On 11/15/21 9:42 PM, Kumar Kartikeya Dwivedi wrote:
In CRIU, we need to be able to determine whether the page pinned by
io_uring is still present in the same range in the process VMA.
/proc/<pid>/pagemap gives us the PFN, hence using this helper we can
establish this mapping easily from the iterator side.
It is a simple wrapper over the in-kernel page_to_pfn helper, and
ensures the passed in pointer is a struct page PTR_TO_BTF_ID. This is
obtained from the bvec of io_uring_ubuf for the CRIU usecase.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
---
fs/io_uring.c | 17 +++++++++++++++++
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 9 +++++++++
kernel/trace/bpf_trace.c | 2 ++
scripts/bpf_doc.py | 2 ++
tools/include/uapi/linux/bpf.h | 9 +++++++++
6 files changed, 40 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 46a110989155..9e9df6767e29 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -11295,6 +11295,23 @@ static struct bpf_iter_reg io_uring_buf_reg_info = {
.seq_info = &bpf_io_uring_buf_seq_info,
};
+BPF_CALL_1(bpf_page_to_pfn, struct page *, page)
+{
+ /* PTR_TO_BTF_ID can be NULL */
+ if (!page)
+ return U64_MAX;
+ return page_to_pfn(page);
+}
+
+BTF_ID_LIST_SINGLE(btf_page_to_pfn_ids, struct, page)
+
+const struct bpf_func_proto bpf_page_to_pfn_proto = {
+ .func = bpf_page_to_pfn,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_BTF_ID,
+ .arg1_btf_id = &btf_page_to_pfn_ids[0],
Does this helper need to be gpl_only?
+};
+
static int __init io_uring_iter_init(void)
{
io_uring_buf_reg_info.ctx_arg_info[0].btf_id = btf_io_uring_ids[0];
[...]
