sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 448 insertions, 0 deletions

diff --git a/drivers/android/binder_trace.h b/drivers/android/binder_trace.h
new file mode 100644
index 000000000..fa5eb61cf
--- /dev/null
+++ b/drivers/android/binder_trace.h
@@ -0,0 +1,448 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012 Google, Inc.
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM binder
+
+#if !defined(_BINDER_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _BINDER_TRACE_H
+
+#include <linux/tracepoint.h>
+
+struct binder_buffer;
+struct binder_node;
+struct binder_proc;
+struct binder_alloc;
+struct binder_ref_data;
+struct binder_thread;
+struct binder_transaction;
+
+TRACE_EVENT(binder_ioctl,
+	TP_PROTO(unsigned int cmd, unsigned long arg),
+	TP_ARGS(cmd, arg),
+
+	TP_STRUCT__entry(
+		__field(unsigned int, cmd)
+		__field(unsigned long, arg)
+	),
+	TP_fast_assign(
+		__entry->cmd = cmd;
+		__entry->arg = arg;
+	),
+	TP_printk("cmd=0x%x arg=0x%lx", __entry->cmd, __entry->arg)
+);
+
+DECLARE_EVENT_CLASS(binder_function_return_class,
+	TP_PROTO(int ret),
+	TP_ARGS(ret),
+	TP_STRUCT__entry(
+		__field(int, ret)
+	),
+	TP_fast_assign(
+		__entry->ret = ret;
+	),
+	TP_printk("ret=%d", __entry->ret)
+);
+
+#define DEFINE_BINDER_FUNCTION_RETURN_EVENT(name)	\
+DEFINE_EVENT(binder_function_return_class, name,	\
+	TP_PROTO(int ret), \
+	TP_ARGS(ret))
+
+DEFINE_BINDER_FUNCTION_RETURN_EVENT(binder_ioctl_done);
+DEFINE_BINDER_FUNCTION_RETURN_EVENT(binder_write_done);
+DEFINE_BINDER_FUNCTION_RETURN_EVENT(binder_read_done);
+
+TRACE_EVENT(binder_wait_for_work,
+	TP_PROTO(bool proc_work, bool transaction_stack, bool thread_todo),
+	TP_ARGS(proc_work, transaction_stack, thread_todo),
+
+	TP_STRUCT__entry(
+		__field(bool, proc_work)
+		__field(bool, transaction_stack)
+		__field(bool, thread_todo)
+	),
+	TP_fast_assign(
+		__entry->proc_work = proc_work;
+		__entry->transaction_stack = transaction_stack;
+		__entry->thread_todo = thread_todo;
+	),
+	TP_printk("proc_work=%d transaction_stack=%d thread_todo=%d",
+		  __entry->proc_work, __entry->transaction_stack,
+		  __entry->thread_todo)
+);
+
+TRACE_EVENT(binder_txn_latency_free,
+	TP_PROTO(struct binder_transaction *t,
+		 int from_proc, int from_thread,
+		 int to_proc, int to_thread),
+	TP_ARGS(t, from_proc, from_thread, to_proc, to_thread),
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(int, from_proc)
+		__field(int, from_thread)
+		__field(int, to_proc)
+		__field(int, to_thread)
+		__field(unsigned int, code)
+		__field(unsigned int, flags)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+		__entry->from_proc = from_proc;
+		__entry->from_thread = from_thread;
+		__entry->to_proc = to_proc;
+		__entry->to_thread = to_thread;
+		__entry->code = t->code;
+		__entry->flags = t->flags;
+	),
+	TP_printk("transaction=%d from %d:%d to %d:%d flags=0x%x code=0x%x",
+		  __entry->debug_id, __entry->from_proc, __entry->from_thread,
+		  __entry->to_proc, __entry->to_thread, __entry->code,
+		  __entry->flags)
+);
+
+TRACE_EVENT(binder_transaction,
+	TP_PROTO(bool reply, struct binder_transaction *t,
+		 struct binder_node *target_node),
+	TP_ARGS(reply, t, target_node),
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(int, target_node)
+		__field(int, to_proc)
+		__field(int, to_thread)
+		__field(int, reply)
+		__field(unsigned int, code)
+		__field(unsigned int, flags)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+		__entry->target_node = target_node ? target_node->debug_id : 0;
+		__entry->to_proc = t->to_proc->pid;
+		__entry->to_thread = t->to_thread ? t->to_thread->pid : 0;
+		__entry->reply = reply;
+		__entry->code = t->code;
+		__entry->flags = t->flags;
+	),
+	TP_printk("transaction=%d dest_node=%d dest_proc=%d dest_thread=%d reply=%d flags=0x%x code=0x%x",
+		  __entry->debug_id, __entry->target_node,
+		  __entry->to_proc, __entry->to_thread,
+		  __entry->reply, __entry->flags, __entry->code)
+);
+
+TRACE_EVENT(binder_transaction_received,
+	TP_PROTO(struct binder_transaction *t),
+	TP_ARGS(t),
+
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+	),
+	TP_printk("transaction=%d", __entry->debug_id)
+);
+
+TRACE_EVENT(binder_transaction_node_to_ref,
+	TP_PROTO(struct binder_transaction *t, struct binder_node *node,
+		 struct binder_ref_data *rdata),
+	TP_ARGS(t, node, rdata),
+
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(int, node_debug_id)
+		__field(binder_uintptr_t, node_ptr)
+		__field(int, ref_debug_id)
+		__field(uint32_t, ref_desc)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+		__entry->node_debug_id = node->debug_id;
+		__entry->node_ptr = node->ptr;
+		__entry->ref_debug_id = rdata->debug_id;
+		__entry->ref_desc = rdata->desc;
+	),
+	TP_printk("transaction=%d node=%d src_ptr=0x%016llx ==> dest_ref=%d dest_desc=%d",
+		  __entry->debug_id, __entry->node_debug_id,
+		  (u64)__entry->node_ptr,
+		  __entry->ref_debug_id, __entry->ref_desc)
+);
+
+TRACE_EVENT(binder_transaction_ref_to_node,
+	TP_PROTO(struct binder_transaction *t, struct binder_node *node,
+		 struct binder_ref_data *rdata),
+	TP_ARGS(t, node, rdata),
+
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(int, ref_debug_id)
+		__field(uint32_t, ref_desc)
+		__field(int, node_debug_id)
+		__field(binder_uintptr_t, node_ptr)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+		__entry->ref_debug_id = rdata->debug_id;
+		__entry->ref_desc = rdata->desc;
+		__entry->node_debug_id = node->debug_id;
+		__entry->node_ptr = node->ptr;
+	),
+	TP_printk("transaction=%d node=%d src_ref=%d src_desc=%d ==> dest_ptr=0x%016llx",
+		  __entry->debug_id, __entry->node_debug_id,
+		  __entry->ref_debug_id, __entry->ref_desc,
+		  (u64)__entry->node_ptr)
+);
+
+TRACE_EVENT(binder_transaction_ref_to_ref,
+	TP_PROTO(struct binder_transaction *t, struct binder_node *node,
+		 struct binder_ref_data *src_ref,
+		 struct binder_ref_data *dest_ref),
+	TP_ARGS(t, node, src_ref, dest_ref),
+
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(int, node_debug_id)
+		__field(int, src_ref_debug_id)
+		__field(uint32_t, src_ref_desc)
+		__field(int, dest_ref_debug_id)
+		__field(uint32_t, dest_ref_desc)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+		__entry->node_debug_id = node->debug_id;
+		__entry->src_ref_debug_id = src_ref->debug_id;
+		__entry->src_ref_desc = src_ref->desc;
+		__entry->dest_ref_debug_id = dest_ref->debug_id;
+		__entry->dest_ref_desc = dest_ref->desc;
+	),
+	TP_printk("transaction=%d node=%d src_ref=%d src_desc=%d ==> dest_ref=%d dest_desc=%d",
+		  __entry->debug_id, __entry->node_debug_id,
+		  __entry->src_ref_debug_id, __entry->src_ref_desc,
+		  __entry->dest_ref_debug_id, __entry->dest_ref_desc)
+);
+
+TRACE_EVENT(binder_transaction_fd_send,
+	TP_PROTO(struct binder_transaction *t, int fd, size_t offset),
+	TP_ARGS(t, fd, offset),
+
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(int, fd)
+		__field(size_t, offset)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+		__entry->fd = fd;
+		__entry->offset = offset;
+	),
+	TP_printk("transaction=%d src_fd=%d offset=%zu",
+		  __entry->debug_id, __entry->fd, __entry->offset)
+);
+
+TRACE_EVENT(binder_transaction_fd_recv,
+	TP_PROTO(struct binder_transaction *t, int fd, size_t offset),
+	TP_ARGS(t, fd, offset),
+
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(int, fd)
+		__field(size_t, offset)
+	),
+	TP_fast_assign(
+		__entry->debug_id = t->debug_id;
+		__entry->fd = fd;
+		__entry->offset = offset;
+	),
+	TP_printk("transaction=%d dest_fd=%d offset=%zu",
+		  __entry->debug_id, __entry->fd, __entry->offset)
+);
+
+DECLARE_EVENT_CLASS(binder_buffer_class,
+	TP_PROTO(struct binder_buffer *buf),
+	TP_ARGS(buf),
+	TP_STRUCT__entry(
+		__field(int, debug_id)
+		__field(size_t, data_size)
+		__field(size_t, offsets_size)
+		__field(size_t, extra_buffers_size)
+	),
+	TP_fast_assign(
+		__entry->debug_id = buf->debug_id;
+		__entry->data_size = buf->data_size;
+		__entry->offsets_size = buf->offsets_size;
+		__entry->extra_buffers_size = buf->extra_buffers_size;
+	),
+	TP_printk("transaction=%d data_size=%zd offsets_size=%zd extra_buffers_size=%zd",
+		  __entry->debug_id, __entry->data_size, __entry->offsets_size,
+		  __entry->extra_buffers_size)
+);
+
+DEFINE_EVENT(binder_buffer_class, binder_transaction_alloc_buf,
+	TP_PROTO(struct binder_buffer *buffer),
+	TP_ARGS(buffer));
+
+DEFINE_EVENT(binder_buffer_class, binder_transaction_buffer_release,
+	TP_PROTO(struct binder_buffer *buffer),
+	TP_ARGS(buffer));
+
+DEFINE_EVENT(binder_buffer_class, binder_transaction_failed_buffer_release,
+	TP_PROTO(struct binder_buffer *buffer),
+	TP_ARGS(buffer));
+
+DEFINE_EVENT(binder_buffer_class, binder_transaction_update_buffer_release,
+	     TP_PROTO(struct binder_buffer *buffer),
+	     TP_ARGS(buffer));
+
+TRACE_EVENT(binder_update_page_range,
+	TP_PROTO(struct binder_alloc *alloc, bool allocate,
+		 unsigned long start, unsigned long end),
+	TP_ARGS(alloc, allocate, start, end),
+	TP_STRUCT__entry(
+		__field(int, proc)
+		__field(bool, allocate)
+		__field(size_t, offset)
+		__field(size_t, size)
+	),
+	TP_fast_assign(
+		__entry->proc = alloc->pid;
+		__entry->allocate = allocate;
+		__entry->offset = start - alloc->vm_start;
+		__entry->size = end - start;
+	),
+	TP_printk("proc=%d allocate=%d offset=%zu size=%zu",
+		  __entry->proc, __entry->allocate,
+		  __entry->offset, __entry->size)
+);
+
+DECLARE_EVENT_CLASS(binder_lru_page_class,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index),
+	TP_STRUCT__entry(
+		__field(int, proc)
+		__field(size_t, page_index)
+	),
+	TP_fast_assign(
+		__entry->proc = alloc->pid;
+		__entry->page_index = page_index;
+	),
+	TP_printk("proc=%d page_index=%zu",
+		  __entry->proc, __entry->page_index)
+);
+
+DEFINE_EVENT(binder_lru_page_class, binder_alloc_lru_start,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_alloc_lru_end,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_free_lru_start,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_free_lru_end,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_alloc_page_start,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_alloc_page_end,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_unmap_user_start,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_unmap_user_end,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_unmap_kernel_start,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+DEFINE_EVENT(binder_lru_page_class, binder_unmap_kernel_end,
+	TP_PROTO(const struct binder_alloc *alloc, size_t page_index),
+	TP_ARGS(alloc, page_index));
+
+TRACE_EVENT(binder_command,
+	TP_PROTO(uint32_t cmd),
+	TP_ARGS(cmd),
+	TP_STRUCT__entry(
+		__field(uint32_t, cmd)
+	),
+	TP_fast_assign(
+		__entry->cmd = cmd;
+	),
+	TP_printk("cmd=0x%x %s",
+		  __entry->cmd,
+		  _IOC_NR(__entry->cmd) < ARRAY_SIZE(binder_command_strings) ?
+			  binder_command_strings[_IOC_NR(__entry->cmd)] :
+			  "unknown")
+);
+
+TRACE_EVENT(binder_return,
+	TP_PROTO(uint32_t cmd),
+	TP_ARGS(cmd),
+	TP_STRUCT__entry(
+		__field(uint32_t, cmd)
+	),
+	TP_fast_assign(
+		__entry->cmd = cmd;
+	),
+	TP_printk("cmd=0x%x %s",
+		  __entry->cmd,
+		  _IOC_NR(__entry->cmd) < ARRAY_SIZE(binder_return_strings) ?
+			  binder_return_strings[_IOC_NR(__entry->cmd)] :
+			  "unknown")
+);
+
+TRACE_EVENT(binder_netlink_report,
+	TP_PROTO(const char *context,
+		 struct binder_transaction *t,
+		 u32 data_size,
+		 u32 error),
+	TP_ARGS(context, t, data_size, error),
+	TP_STRUCT__entry(
+		__field(const char *, context)
+		__field(u32, error)
+		__field(int, from_pid)
+		__field(int, from_tid)
+		__field(int, to_pid)
+		__field(int, to_tid)
+		__field(bool, is_reply)
+		__field(unsigned int, flags)
+		__field(unsigned int, code)
+		__field(size_t, data_size)
+	),
+	TP_fast_assign(
+		__entry->context = context;
+		__entry->error = error;
+		__entry->from_pid = t->from_pid;
+		__entry->from_tid = t->from_tid;
+		__entry->to_pid = t->to_proc ? t->to_proc->pid : 0;
+		__entry->to_tid = t->to_thread ? t->to_thread->pid : 0;
+		__entry->is_reply = t->is_reply;
+		__entry->flags = t->flags;
+		__entry->code = t->code;
+		__entry->data_size = data_size;
+	),
+	TP_printk("from %d:%d to %d:%d context=%s error=%d is_reply=%d flags=0x%x code=0x%x size=%zu",
+		  __entry->from_pid, __entry->from_tid,
+		  __entry->to_pid, __entry->to_tid,
+		  __entry->context, __entry->error, __entry->is_reply,
+		  __entry->flags, __entry->code, __entry->data_size)
+);
+
+#endif /* _BINDER_TRACE_H */
+
+#undef TRACE_INCLUDE_PATH
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE binder_trace
+#include <trace/define_trace.h>