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[bpf-next,v3,06/16] bpf: Reuse bpf_dynptr for userspace application use case

Message ID 20250327083455.848708-7-houtao@huaweicloud.com (mailing list archive)
State New
Delegated to: BPF
Headers show
Series Support dynptr key for hash map | expand

Checks

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Commit Message

Hou Tao March 27, 2025, 8:34 a.m. UTC 
From: Hou Tao <houtao1@huawei.com>

For bpf map with dynptr key support, the userspace application will use
bpf_dynptr to represent the variable-sized part in the map key and pass
it to bpf syscall. The bpf syscall will copy from bpf_dynptr to
construct a corresponding bpf_dynptr_kern object when the map key is an
input argument, and copy to bpf_dynptr from a bpf_dynptr_kern object
when the map key is an output argument.

Instead of adding a new uapi struct (e.g., bpf_dynptr_user) for
userspace application, reuse bpf_dynptr to unify the API for both bpf
program and userspace application. For the userspace application case,
the last 4-bytes of bpf_dynptr are not used, so make it a reserved
field.

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 include/uapi/linux/bpf.h       | 11 ++++++++++-
 tools/include/uapi/linux/bpf.h | 11 ++++++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 28705ae677849..560289f0f560b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -7370,7 +7370,16 @@  struct bpf_wq {
 } __attribute__((aligned(8)));
 
 struct bpf_dynptr {
-	__u64 __opaque[2];
+	union {
+		/* For bpf program */
+		__u64 __opaque[2];
+		/* For userspace application only */
+		struct {
+			__bpf_md_ptr(void *, data);
+			__u32 size;
+			__u32 reserved;
+		};
+	};
 } __attribute__((aligned(8)));
 
 struct bpf_list_head {
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 28705ae677849..560289f0f560b 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -7370,7 +7370,16 @@  struct bpf_wq {
 } __attribute__((aligned(8)));
 
 struct bpf_dynptr {
-	__u64 __opaque[2];
+	union {
+		/* For bpf program */
+		__u64 __opaque[2];
+		/* For userspace application only */
+		struct {
+			__bpf_md_ptr(void *, data);
+			__u32 size;
+			__u32 reserved;
+		};
+	};
 } __attribute__((aligned(8)));
 
 struct bpf_list_head {