include/uapi/linux/rseq.h

Source file repositories/reference/linux-study-clean/include/uapi/linux/rseq.h

File Facts

System
Linux kernel
Corpus path
include/uapi/linux/rseq.h
Extension
.h
Size
7153 bytes
Lines
211
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct rseq_cs {
	/* Version of this structure. */
	__u32 version;
	/* enum rseq_cs_flags */
	__u32 flags;
	__u64 start_ip;
	/* Offset from start_ip. */
	__u64 post_commit_offset;
	__u64 abort_ip;
} __attribute__((aligned(4 * sizeof(__u64))));

/**
 * rseq_slice_ctrl - Time slice extension control structure
 * @all:	Compound value
 * @request:	Request for a time slice extension
 * @granted:	Granted time slice extension
 *
 * @request is set by user space and can be cleared by user space or kernel
 * space.  @granted is set and cleared by the kernel and must only be read
 * by user space.
 */
struct rseq_slice_ctrl {
	union {
		__u32		all;
		struct {
			__u8	request;
			__u8	granted;
			__u16	__reserved;
		};
	};
};

/*
 * The original size and alignment of the allocation for struct rseq is
 * 32 bytes.
 *
 * The allocation size needs to be greater or equal to
 * max(getauxval(AT_RSEQ_FEATURE_SIZE), 32), and the allocation needs to
 * be aligned on max(getauxval(AT_RSEQ_ALIGN), 32).
 *
 * As an alternative, userspace is allowed to use both the original size
 * and alignment of 32 bytes for backward compatibility.
 *
 * A single active struct rseq registration per thread is allowed.
 */
struct rseq {
	/*
	 * Restartable sequences cpu_id_start field. Updated by the
	 * kernel. Read by user-space with single-copy atomicity
	 * semantics. This field should only be read by the thread which
	 * registered this data structure. Aligned on 32-bit. Always
	 * contains a value in the range of possible CPUs, although the
	 * value may not be the actual current CPU (e.g. if rseq is not
	 * initialized). This CPU number value should always be compared
	 * against the value of the cpu_id field before performing a rseq
	 * commit or returning a value read from a data structure indexed
	 * using the cpu_id_start value.
	 */
	__u32 cpu_id_start;
	/*
	 * Restartable sequences cpu_id field. Updated by the kernel.
	 * Read by user-space with single-copy atomicity semantics. This
	 * field should only be read by the thread which registered this
	 * data structure. Aligned on 32-bit. Values
	 * RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED
	 * have a special semantic: the former means "rseq uninitialized",
	 * and latter means "rseq initialization failed". This value is
	 * meant to be read within rseq critical sections and compared
	 * with the cpu_id_start value previously read, before performing
	 * the commit instruction, or read and compared with the
	 * cpu_id_start value before returning a value loaded from a data
	 * structure indexed using the cpu_id_start value.
	 */
	__u32 cpu_id;
	/*
	 * Restartable sequences rseq_cs field.
	 *
	 * Contains NULL when no critical section is active for the current
	 * thread, or holds a pointer to the currently active struct rseq_cs.
	 *
	 * Updated by user-space, which sets the address of the currently
	 * active rseq_cs at the beginning of assembly instruction sequence
	 * block, and set to NULL by the kernel when it restarts an assembly
	 * instruction sequence block, as well as when the kernel detects that
	 * it is preempting or delivering a signal outside of the range
	 * targeted by the rseq_cs. Also needs to be set to NULL by user-space
	 * before reclaiming memory that contains the targeted struct rseq_cs.
	 *
	 * Read and set by the kernel. Set by user-space with single-copy
	 * atomicity semantics. This field should only be updated by the

Annotation

Implementation Notes