1 files changed, 133 insertions, 0 deletions

diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h
new file mode 100644
index 000000000000..d620fa43756c
--- /dev/null
+++ b/include/uapi/linux/rseq.h
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_RSEQ_H
+#define _UAPI_LINUX_RSEQ_H
+
+/*
+ * linux/rseq.h
+ *
+ * Restartable sequences system call API
+ *
+ * Copyright (c) 2015-2018 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#ifdef __KERNEL__
+# include <linux/types.h>
+#else
+# include <stdint.h>
+#endif
+
+#include <linux/types_32_64.h>
+
+enum rseq_cpu_id_state {
+        RSEQ_CPU_ID_UNINITIALIZED               = -1,
+        RSEQ_CPU_ID_REGISTRATION_FAILED         = -2,
+};
+
+enum rseq_flags {
+        RSEQ_FLAG_UNREGISTER = (1 << 0),
+};
+
+enum rseq_cs_flags_bit {
+        RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT  = 0,
+        RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT   = 1,
+        RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT  = 2,
+};
+
+enum rseq_cs_flags {
+        RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT      =
+                (1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
+        RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL       =
+                (1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
+        RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE      =
+                (1U << 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.
+ */
+struct rseq_cs {
+        /* Version of this structure. */
+        __u32 version;
+        /* enum rseq_cs_flags */
+        __u32 flags;
+        LINUX_FIELD_u32_u64(start_ip);
+        /* Offset from start_ip. */
+        LINUX_FIELD_u32_u64(post_commit_offset);
+        LINUX_FIELD_u32_u64(abort_ip);
+} __attribute__((aligned(4 * sizeof(__u64))));
+
+/*
+ * 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.
+ */
+struct rseq {
+        /*
+         * Restartable sequences cpu_id_start field. Updated by the
+         * kernel, and read by user-space with single-copy atomicity
+         * semantics. 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,
+         * and read by user-space with single-copy atomicity semantics.
+         * 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 with single-copy atomicity semantics.
+         * Set by user-space with single-copy atomicity semantics. Aligned
+         * on 64-bit.
+         */
+        LINUX_FIELD_u32_u64(rseq_cs);
+        /*
+         * - RSEQ_DISABLE flag:
+         *
+         * Fallback fast-track flag for single-stepping.
+         * Set by user-space if lack of progress is detected.
+         * Cleared by user-space after rseq finish.
+         * Read by the kernel.
+         * - RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
+         *     Inhibit instruction sequence block restart and event
+         *     counter increment on preemption for this thread.
+         * - RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
+         *     Inhibit instruction sequence block restart and event
+         *     counter increment on signal delivery for this thread.
+         * - RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
+         *     Inhibit instruction sequence block restart and event
+         *     counter increment on migration for this thread.
+         */
+        __u32 flags;
+} __attribute__((aligned(4 * sizeof(__u64))));
+
+#endif /* _UAPI_LINUX_RSEQ_H */