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/// linux/rseq.h /// /// Restartable sequences system call API /// pub const RSEQ_CPU_ID_UNINITIALIZED: i32 = -1; pub const RSEQ_CPU_ID_REGISTRATION_FAILED: i32 = -2; pub const RSEQ_FLAG_UNREGISTER: i32 = 1 << 0; pub const RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT: i32 = 0; pub const RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT: i32 = 1; pub const RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT: i32 = 2; pub const RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT: u32 = 1 << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT; pub const RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL: u32 = 1 << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT; pub const RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE: u32 = 1 << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT; /// struct rseq_cs is aligned on 4 * 8 bytes to ensure it is always /// contained within a single cache-line. It is usually declared as /// link-time constant data. #[repr(C)] // TODO(Shaohua): alignment __attribute__((aligned(4 * sizeof(__u64)))); pub struct rseq_cs_t { /// Version of this structure. pub version: u32, /// enum rseq_cs_flags pub flags: u32, pub start_ip: u64, /// Offset from start_ip. pub post_commit_offset: u64, pub abort_ip: u64, } #[cfg(target_endian = "big")] #[repr(C)] #[derive(Clone, Copy)] pub struct rseq_cs_ptr_t { /// Initialized to zero. pub padding: u32, pub ptr32: u32, } #[cfg(target_endian = "little")] #[repr(C)] #[derive(Clone, Copy)] pub struct rseq_cs_ptr_t { pub ptr32: u32, /// Initialized to zero. pub padding: u32, } #[repr(C)] pub union rseq_cs_union_t { pub ptr64: u64, pub ptr: rseq_cs_ptr_t, //#ifdef __LP64__ //__u64 ptr; //#else } /// struct rseq is aligned on 4 * 8 bytes to ensure it is always /// contained within a single cache-line. /// /// A single struct rseq per thread is allowed. #[repr(C)] // TODO(Shaohua): alignment __attribute__((aligned(4 * sizeof(__u64)))); pub struct rseq_t { /// 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. pub cpu_id_start: u32, /// 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. pub cpu_id: u32, /// 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 /// thread which registered this data structure. Aligned on 64-bit. pub rseq_cs: rseq_cs_union_t, /// Restartable sequences flags field. /// /// This field should only be updated by the thread which /// registered this data structure. Read by the kernel. /// Mainly used for single-stepping through rseq critical sections /// with debuggers. /// /// - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT /// Inhibit instruction sequence block restart on preemption /// for this thread. /// - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL /// Inhibit instruction sequence block restart on signal /// delivery for this thread. /// - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE /// Inhibit instruction sequence block restart on migration for /// this thread. pub flags: u32, }