tools: sync coredump.h header

Sync the headers for the selftests.

Link: https://patch.msgid.link/20260820-work-coredump-sparse-v2-15-ba32dd718c51@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

1 files changed, 77 insertions, 2 deletions

diff --git a/tools/include/uapi/linux/coredump.h b/tools/include/uapi/linux/coredump.h
index dc3789b78af0..f3771861ca48 100644
--- a/tools/include/uapi/linux/coredump.h
+++ b/tools/include/uapi/linux/coredump.h
@@ -11,12 +11,19 @@
  * @COREDUMP_USERSPACE: userspace writes coredump
  * @COREDUMP_REJECT: don't generate coredump
  * @COREDUMP_WAIT: wait for coredump server
+ * @COREDUMP_RECORDS: send the coredump as a sequence of records instead of
+ *                    as a plain byte stream, see struct coredump_record_header;
+ *                    requires COREDUMP_KERNEL
+ * @COREDUMP_SPARSE: describe the holes in the coredump as zero records
+ *                   instead of transferring them; requires COREDUMP_RECORDS
  */
 enum {
 	COREDUMP_KERNEL		= (1ULL << 0),
 	COREDUMP_USERSPACE	= (1ULL << 1),
 	COREDUMP_REJECT		= (1ULL << 2),
 	COREDUMP_WAIT		= (1ULL << 3),
+	COREDUMP_RECORDS	= (1ULL << 4),
+	COREDUMP_SPARSE		= (1ULL << 5),
 };
 
 /**
@@ -30,11 +37,11 @@ enum {
  * member is set to the size of struct coredump_req and provides a hint
  * to userspace how much data can be read. Userspace may use MSG_PEEK to
  * peek the size of struct coredump_req and then choose to consume it in
- * one go. Userspace may also simply read a COREDUMP_ACK_SIZE_VER0
+ * one go. Userspace may also simply read a COREDUMP_REQ_SIZE_VER0
  * request. If the size the kernel sends is larger userspace simply
  * discards any remaining data.
  *
- * The coredump_req->mask member is set to the currently know features.
+ * The coredump_req->mask member is set to the currently known features.
  * Userspace may only set coredump_ack->mask to the bits raised by the
  * kernel in coredump_req->mask.
  *
@@ -101,4 +108,72 @@ enum coredump_mark {
 	__COREDUMP_MARK_MAX		= (1U << 31),
 };
 
+/**
+ * enum coredump_record_type - Type of a coredump record
+ *
+ * @COREDUMP_RECORD_DATA: the header is followed by ->len bytes of data
+ * @COREDUMP_RECORD_END: the coredump ends here, the header is not followed
+ *                       by any data and no further record is sent
+ * @COREDUMP_RECORD_ZERO: the header stands for ->len zero bytes and is not
+ *                        followed by any data
+ * @__COREDUMP_RECORD_TYPE_MAX: the maximum coredump record type value
+ */
+enum coredump_record_type {
+	COREDUMP_RECORD_DATA		= 0U,
+	COREDUMP_RECORD_END		= 1U,
+	COREDUMP_RECORD_ZERO		= 2U,
+	__COREDUMP_RECORD_TYPE_MAX	= (1U << 31),
+};
+
+/**
+ * struct coredump_record_header - header of a coredump record
+ * @size: size of struct coredump_record_header
+ * @type: one of enum coredump_record_type
+ * @flags: modifiers for this record
+ * @offset: offset in the coredump this record starts at
+ * @len: number of coredump bytes this record accounts for
+ *
+ * If the coredump server raises COREDUMP_RECORDS in coredump_ack->mask
+ * the kernel doesn't send the coredump as a plain byte stream. It sends
+ * a sequence of records instead. A COREDUMP_RECORD_DATA record is
+ * followed by @len bytes of actual coredump data. A
+ * COREDUMP_RECORD_ZERO record is followed by nothing and stands for
+ * @len zero bytes. A server that didn't raise COREDUMP_SPARSE never
+ * sees a zero record. Records arrive in order and leave no gaps. So
+ * @offset is the sum of the @len of all records before it.
+ *
+ * The last record is a COREDUMP_RECORD_END record. It is followed by
+ * nothing. Its @len is zero. Its @offset is the size of the coredump.
+ * The kernel only sends it once it has written the whole coredump. A
+ * server that hits end-of-file without having seen an end record must
+ * treat the coredump as incomplete.
+ *
+ * The @size member is set to the size of struct coredump_record_header
+ * the kernel knows and lets the header grow later. It comes first so it
+ * can be peeked. Userspace must consume @size bytes and discard
+ * anything beyond what it knows. It must refuse a @size smaller than
+ * COREDUMP_RECORD_HEADER_SIZE_VER0. @size covers the header alone.
+ * @offset and @len count coredump bytes.
+ *
+ * The @flags member carries modifiers that change how the record is to
+ * be interpreted. No flag is defined yet. Userspace must refuse a
+ * record carrying a flag or a type it doesn't know. Every new record
+ * type is raised in coredump_req->mask as a feature of its own. A
+ * server only ever sees the types it asked for.
+ *
+ * COREDUMP_RECORDS must be combined with COREDUMP_KERNEL, and
+ * COREDUMP_SPARSE with COREDUMP_RECORDS.
+ */
+struct coredump_record_header {
+	__u32 size;
+	__u32 type;
+	__u64 flags;
+	__u64 offset;
+	__u64 len;
+};
+
+enum {
+	COREDUMP_RECORD_HEADER_SIZE_VER0 = 32U, /* size of first published struct */
+};
+
 #endif /* _UAPI_LINUX_COREDUMP_H */