-/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) */
-#include <lib/ringbuffer/frontend_internal.h>
+/* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
+ *
+ * linux/ringbuffer/frontend_internal.h
+ *
+ * Ring Buffer Library Synchronization Header (internal helpers).
+ *
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * See ring_buffer_frontend.c for more information on wait-free algorithms.
+ */
+
+#ifndef _LIB_RING_BUFFER_FRONTEND_INTERNAL_H
+#define _LIB_RING_BUFFER_FRONTEND_INTERNAL_H
+
+#include <ringbuffer/config.h>
+#include <ringbuffer/backend_types.h>
+#include <ringbuffer/frontend_types.h>
+#include <lttng/lttng_prio_heap.h> /* For per-CPU read-side iterator */
+
+/* Buffer offset macros */
+
+/* buf_trunc mask selects only the buffer number. */
+static inline
+unsigned long buf_trunc(unsigned long offset, struct channel *chan)
+{
+ return offset & ~(chan->backend.buf_size - 1);
+
+}
+
+/* Select the buffer number value (counter). */
+static inline
+unsigned long buf_trunc_val(unsigned long offset, struct channel *chan)
+{
+ return buf_trunc(offset, chan) >> chan->backend.buf_size_order;
+}
+
+/* buf_offset mask selects only the offset within the current buffer. */
+static inline
+unsigned long buf_offset(unsigned long offset, struct channel *chan)
+{
+ return offset & (chan->backend.buf_size - 1);
+}
+
+/* subbuf_offset mask selects the offset within the current subbuffer. */
+static inline
+unsigned long subbuf_offset(unsigned long offset, struct channel *chan)
+{
+ return offset & (chan->backend.subbuf_size - 1);
+}
+
+/* subbuf_trunc mask selects the subbuffer number. */
+static inline
+unsigned long subbuf_trunc(unsigned long offset, struct channel *chan)
+{
+ return offset & ~(chan->backend.subbuf_size - 1);
+}
+
+/* subbuf_align aligns the offset to the next subbuffer. */
+static inline
+unsigned long subbuf_align(unsigned long offset, struct channel *chan)
+{
+ return (offset + chan->backend.subbuf_size)
+ & ~(chan->backend.subbuf_size - 1);
+}
+
+/* subbuf_index returns the index of the current subbuffer within the buffer. */
+static inline
+unsigned long subbuf_index(unsigned long offset, struct channel *chan)
+{
+ return buf_offset(offset, chan) >> chan->backend.subbuf_size_order;
+}
+
+/*
+ * Last TSC comparison functions. Check if the current TSC overflows tsc_bits
+ * bits from the last TSC read. When overflows are detected, the full 64-bit
+ * timestamp counter should be written in the record header. Reads and writes
+ * last_tsc atomically.
+ */
+
+#if (BITS_PER_LONG == 32)
+static inline
+void save_last_tsc(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return;
+
+ /*
+ * Ensure the compiler performs this update in a single instruction.
+ */
+ v_set(config, &buf->last_tsc, (unsigned long)(tsc >> config->tsc_bits));
+}
+
+static inline
+int last_tsc_overflow(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ unsigned long tsc_shifted;
+
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return 0;
+
+ tsc_shifted = (unsigned long)(tsc >> config->tsc_bits);
+ if (unlikely(tsc_shifted
+ - (unsigned long)v_read(config, &buf->last_tsc)))
+ return 1;
+ else
+ return 0;
+}
+#else
+static inline
+void save_last_tsc(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return;
+
+ v_set(config, &buf->last_tsc, (unsigned long)tsc);
+}
+
+static inline
+int last_tsc_overflow(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf, u64 tsc)
+{
+ if (config->tsc_bits == 0 || config->tsc_bits == 64)
+ return 0;
+
+ if (unlikely((tsc - v_read(config, &buf->last_tsc))
+ >> config->tsc_bits))
+ return 1;
+ else
+ return 0;
+}
+#endif
+
+extern
+int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx,
+ void *client_ctx);
+
+extern
+void lib_ring_buffer_switch_slow(struct lib_ring_buffer *buf,
+ enum switch_mode mode);
+
+extern
+void lib_ring_buffer_check_deliver_slow(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan,
+ unsigned long offset,
+ unsigned long commit_count,
+ unsigned long idx,
+ u64 tsc);
+
+extern
+void lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf);
+extern
+void lib_ring_buffer_switch_remote_empty(struct lib_ring_buffer *buf);
+extern
+void lib_ring_buffer_clear(struct lib_ring_buffer *buf);
+
+/* Buffer write helpers */
+
+static inline
+void lib_ring_buffer_reserve_push_reader(struct lib_ring_buffer *buf,
+ struct channel *chan,
+ unsigned long offset)
+{
+ unsigned long consumed_old, consumed_new;
+
+ do {
+ consumed_old = atomic_long_read(&buf->consumed);
+ /*
+ * If buffer is in overwrite mode, push the reader consumed
+ * count if the write position has reached it and we are not
+ * at the first iteration (don't push the reader farther than
+ * the writer). This operation can be done concurrently by many
+ * writers in the same buffer, the writer being at the farthest
+ * write position sub-buffer index in the buffer being the one
+ * which will win this loop.
+ */
+ if (unlikely(subbuf_trunc(offset, chan)
+ - subbuf_trunc(consumed_old, chan)
+ >= chan->backend.buf_size))
+ consumed_new = subbuf_align(consumed_old, chan);
+ else
+ return;
+ } while (unlikely(atomic_long_cmpxchg(&buf->consumed, consumed_old,
+ consumed_new) != consumed_old));
+}
+
+/*
+ * Move consumed position to the beginning of subbuffer in which the
+ * write offset is. Should only be used on ring buffers that are not
+ * actively being written into, because clear_reader does not take into
+ * account the commit counters when moving the consumed position, which
+ * can make concurrent trace producers or consumers observe consumed
+ * position further than the write offset, which breaks ring buffer
+ * algorithm guarantees.
+ */
+static inline
+void lib_ring_buffer_clear_reader(struct lib_ring_buffer *buf,
+ struct channel *chan)
+{
+ const struct lib_ring_buffer_config *config = &chan->backend.config;
+ unsigned long offset, consumed_old, consumed_new;
+
+ do {
+ offset = v_read(config, &buf->offset);
+ consumed_old = atomic_long_read(&buf->consumed);
+ CHAN_WARN_ON(chan, (long) (subbuf_trunc(offset, chan)
+ - subbuf_trunc(consumed_old, chan))
+ < 0);
+ consumed_new = subbuf_trunc(offset, chan);
+ } while (unlikely(atomic_long_cmpxchg(&buf->consumed, consumed_old,
+ consumed_new) != consumed_old));
+}
+
+static inline
+int lib_ring_buffer_pending_data(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan)
+{
+ return !!subbuf_offset(v_read(config, &buf->offset), chan);
+}
+
+static inline
+unsigned long lib_ring_buffer_get_data_size(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ unsigned long idx)
+{
+ return subbuffer_get_data_size(config, &buf->backend, idx);
+}
+
+/*
+ * Check if all space reservation in a buffer have been committed. This helps
+ * knowing if an execution context is nested (for per-cpu buffers only).
+ * This is a very specific ftrace use-case, so we keep this as "internal" API.
+ */
+static inline
+int lib_ring_buffer_reserve_committed(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan)
+{
+ unsigned long offset, idx, commit_count;
+
+ CHAN_WARN_ON(chan, config->alloc != RING_BUFFER_ALLOC_PER_CPU);
+ CHAN_WARN_ON(chan, config->sync != RING_BUFFER_SYNC_PER_CPU);
+
+ /*
+ * Read offset and commit count in a loop so they are both read
+ * atomically wrt interrupts. By deal with interrupt concurrency by
+ * restarting both reads if the offset has been pushed. Note that given
+ * we only have to deal with interrupt concurrency here, an interrupt
+ * modifying the commit count will also modify "offset", so it is safe
+ * to only check for offset modifications.
+ */
+ do {
+ offset = v_read(config, &buf->offset);
+ idx = subbuf_index(offset, chan);
+ commit_count = v_read(config, &buf->commit_hot[idx].cc);
+ } while (offset != v_read(config, &buf->offset));
+
+ return ((buf_trunc(offset, chan) >> chan->backend.num_subbuf_order)
+ - (commit_count & chan->commit_count_mask) == 0);
+}
+
+/*
+ * Receive end of subbuffer TSC as parameter. It has been read in the
+ * space reservation loop of either reserve or switch, which ensures it
+ * progresses monotonically with event records in the buffer. Therefore,
+ * it ensures that the end timestamp of a subbuffer is <= begin
+ * timestamp of the following subbuffers.
+ */
+static inline
+void lib_ring_buffer_check_deliver(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan,
+ unsigned long offset,
+ unsigned long commit_count,
+ unsigned long idx,
+ u64 tsc)
+{
+ unsigned long old_commit_count = commit_count
+ - chan->backend.subbuf_size;
+
+ /* Check if all commits have been done */
+ if (unlikely((buf_trunc(offset, chan) >> chan->backend.num_subbuf_order)
+ - (old_commit_count & chan->commit_count_mask) == 0))
+ lib_ring_buffer_check_deliver_slow(config, buf, chan, offset,
+ commit_count, idx, tsc);
+}
+
+/*
+ * lib_ring_buffer_write_commit_counter
+ *
+ * For flight recording. must be called after commit.
+ * This function increments the subbuffer's commit_seq counter each time the
+ * commit count reaches back the reserve offset (modulo subbuffer size). It is
+ * useful for crash dump.
+ */
+static inline
+void lib_ring_buffer_write_commit_counter(const struct lib_ring_buffer_config *config,
+ struct lib_ring_buffer *buf,
+ struct channel *chan,
+ unsigned long buf_offset,
+ unsigned long commit_count,
+ struct commit_counters_hot *cc_hot)
+{
+ unsigned long commit_seq_old;
+
+ if (config->oops != RING_BUFFER_OOPS_CONSISTENCY)
+ return;
+
+ /*
+ * subbuf_offset includes commit_count_mask. We can simply
+ * compare the offsets within the subbuffer without caring about
+ * buffer full/empty mismatch because offset is never zero here
+ * (subbuffer header and record headers have non-zero length).
+ */
+ if (unlikely(subbuf_offset(buf_offset - commit_count, chan)))
+ return;
+
+ commit_seq_old = v_read(config, &cc_hot->seq);
+ if (likely((long) (commit_seq_old - commit_count) < 0))
+ v_set(config, &cc_hot->seq, commit_count);
+}
+
+extern int lib_ring_buffer_create(struct lib_ring_buffer *buf,
+ struct channel_backend *chanb, int cpu);
+extern void lib_ring_buffer_free(struct lib_ring_buffer *buf);
+
+/* Keep track of trap nesting inside ring buffer code */
+DECLARE_PER_CPU(unsigned int, lib_ring_buffer_nesting);
+
+#endif /* _LIB_RING_BUFFER_FRONTEND_INTERNAL_H */
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