compat.bpf.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
  4 * Copyright (c) 2024 Tejun Heo <tj@kernel.org>
  5 * Copyright (c) 2024 David Vernet <dvernet@meta.com>
  6 */
  7#ifndef __SCX_COMPAT_BPF_H
  8#define __SCX_COMPAT_BPF_H
  9
 10#define __COMPAT_ENUM_OR_ZERO(__type, __ent)					\
 11({										\
 12	__type __ret = 0;							\
 13	if (bpf_core_enum_value_exists(__type, __ent))				\
 14		__ret = __ent;							\
 15	__ret;									\
 16})
 17
 18/* v6.12: 819513666966 ("sched_ext: Add cgroup support") */
 19struct cgroup *scx_bpf_task_cgroup___new(struct task_struct *p) __ksym __weak;
 20
 21#define scx_bpf_task_cgroup(p)							\
 22	(bpf_ksym_exists(scx_bpf_task_cgroup___new) ?				\
 23	 scx_bpf_task_cgroup___new((p)) : NULL)
 24
 25/*
 26 * v6.13: The verb `dispatch` was too overloaded and confusing. kfuncs are
 27 * renamed to unload the verb.
 28 *
 29 * scx_bpf_dispatch_from_dsq() and friends were added during v6.12 by
 30 * 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()").
 31 */
 32bool scx_bpf_dsq_move_to_local___new(u64 dsq_id) __ksym __weak;
 33void scx_bpf_dsq_move_set_slice___new(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
 34void scx_bpf_dsq_move_set_vtime___new(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
 35bool scx_bpf_dsq_move___new(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
 36bool scx_bpf_dsq_move_vtime___new(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
 37
 38bool scx_bpf_consume___old(u64 dsq_id) __ksym __weak;
 39void scx_bpf_dispatch_from_dsq_set_slice___old(struct bpf_iter_scx_dsq *it__iter, u64 slice) __ksym __weak;
 40void scx_bpf_dispatch_from_dsq_set_vtime___old(struct bpf_iter_scx_dsq *it__iter, u64 vtime) __ksym __weak;
 41bool scx_bpf_dispatch_from_dsq___old(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
 42bool scx_bpf_dispatch_vtime_from_dsq___old(struct bpf_iter_scx_dsq *it__iter, struct task_struct *p, u64 dsq_id, u64 enq_flags) __ksym __weak;
 43
 44#define scx_bpf_dsq_move_to_local(dsq_id)					\
 45	(bpf_ksym_exists(scx_bpf_dsq_move_to_local___new) ?			\
 46	 scx_bpf_dsq_move_to_local___new((dsq_id)) :				\
 47	 scx_bpf_consume___old((dsq_id)))
 48
 49#define scx_bpf_dsq_move_set_slice(it__iter, slice)				\
 50	(bpf_ksym_exists(scx_bpf_dsq_move_set_slice___new) ?			\
 51	 scx_bpf_dsq_move_set_slice___new((it__iter), (slice)) :		\
 52	 (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_slice___old) ?		\
 53	  scx_bpf_dispatch_from_dsq_set_slice___old((it__iter), (slice)) :	\
 54	  (void)0))
 55
 56#define scx_bpf_dsq_move_set_vtime(it__iter, vtime)				\
 57	(bpf_ksym_exists(scx_bpf_dsq_move_set_vtime___new) ?			\
 58	 scx_bpf_dsq_move_set_vtime___new((it__iter), (vtime)) :		\
 59	 (bpf_ksym_exists(scx_bpf_dispatch_from_dsq_set_vtime___old) ?		\
 60	  scx_bpf_dispatch_from_dsq_set_vtime___old((it__iter), (vtime)) :	\
 61	  (void)0))
 62
 63#define scx_bpf_dsq_move(it__iter, p, dsq_id, enq_flags)			\
 64	(bpf_ksym_exists(scx_bpf_dsq_move___new) ?				\
 65	 scx_bpf_dsq_move___new((it__iter), (p), (dsq_id), (enq_flags)) :	\
 66	 (bpf_ksym_exists(scx_bpf_dispatch_from_dsq___old) ?			\
 67	  scx_bpf_dispatch_from_dsq___old((it__iter), (p), (dsq_id), (enq_flags)) : \
 68	  false))
 69
 70#define scx_bpf_dsq_move_vtime(it__iter, p, dsq_id, enq_flags)			\
 71	(bpf_ksym_exists(scx_bpf_dsq_move_vtime___new) ?			\
 72	 scx_bpf_dsq_move_vtime___new((it__iter), (p), (dsq_id), (enq_flags)) : \
 73	 (bpf_ksym_exists(scx_bpf_dispatch_vtime_from_dsq___old) ?		\
 74	  scx_bpf_dispatch_vtime_from_dsq___old((it__iter), (p), (dsq_id), (enq_flags)) : \
 75	  false))
 76
 77/*
 78 * v6.15: 950ad93df2fc ("bpf: add kfunc for populating cpumask bits")
 79 *
 80 * Compat macro will be dropped on v6.19 release.
 81 */
 82int bpf_cpumask_populate(struct cpumask *dst, void *src, size_t src__sz) __ksym __weak;
 83
 84#define __COMPAT_bpf_cpumask_populate(cpumask, src, size__sz)		\
 85	(bpf_ksym_exists(bpf_cpumask_populate) ?			\
 86	 (bpf_cpumask_populate(cpumask, src, size__sz)) : -EOPNOTSUPP)
 87
 88/*
 89 * v6.19: Introduce lockless peek API for user DSQs.
 90 *
 91 * Preserve the following macro until v6.21.
 92 */
 93static inline struct task_struct *__COMPAT_scx_bpf_dsq_peek(u64 dsq_id)
 94{
 95	struct task_struct *p = NULL;
 96	struct bpf_iter_scx_dsq it;
 97
 98	if (bpf_ksym_exists(scx_bpf_dsq_peek))
 99		return scx_bpf_dsq_peek(dsq_id);
100	if (!bpf_iter_scx_dsq_new(&it, dsq_id, 0))
101		p = bpf_iter_scx_dsq_next(&it);
102	bpf_iter_scx_dsq_destroy(&it);
103	return p;
104}
105
106/**
107 * __COMPAT_is_enq_cpu_selected - Test if SCX_ENQ_CPU_SELECTED is on
108 * in a compatible way. We will preserve this __COMPAT helper until v6.16.
109 *
110 * @enq_flags: enqueue flags from ops.enqueue()
111 *
112 * Return: True if SCX_ENQ_CPU_SELECTED is turned on in @enq_flags
113 */
114static inline bool __COMPAT_is_enq_cpu_selected(u64 enq_flags)
115{
116#ifdef HAVE_SCX_ENQ_CPU_SELECTED
117	/*
118	 * This is the case that a BPF code compiled against vmlinux.h
119	 * where the enum SCX_ENQ_CPU_SELECTED exists.
120	 */
121
122	/*
123	 * We should temporarily suspend the macro expansion of
124	 * 'SCX_ENQ_CPU_SELECTED'. This avoids 'SCX_ENQ_CPU_SELECTED' being
125	 * rewritten to '__SCX_ENQ_CPU_SELECTED' when 'SCX_ENQ_CPU_SELECTED'
126	 * is defined in 'scripts/gen_enums.py'.
127	 */
128#pragma push_macro("SCX_ENQ_CPU_SELECTED")
129#undef SCX_ENQ_CPU_SELECTED
130	u64 flag;
131
132	/*
133	 * When the kernel did not have SCX_ENQ_CPU_SELECTED,
134	 * select_task_rq_scx() has never been skipped. Thus, this case
135	 * should be considered that the CPU has already been selected.
136	 */
137	if (!bpf_core_enum_value_exists(enum scx_enq_flags,
138					SCX_ENQ_CPU_SELECTED))
139		return true;
140
141	flag = bpf_core_enum_value(enum scx_enq_flags, SCX_ENQ_CPU_SELECTED);
142	return enq_flags & flag;
143
144	/*
145	 * Once done, resume the macro expansion of 'SCX_ENQ_CPU_SELECTED'.
146	 */
147#pragma pop_macro("SCX_ENQ_CPU_SELECTED")
148#else
149	/*
150	 * This is the case that a BPF code compiled against vmlinux.h
151	 * where the enum SCX_ENQ_CPU_SELECTED does NOT exist.
152	 */
153	return true;
154#endif /* HAVE_SCX_ENQ_CPU_SELECTED */
155}
156
157
158#define scx_bpf_now()								\
159	(bpf_ksym_exists(scx_bpf_now) ?						\
160	 scx_bpf_now() :							\
161	 bpf_ktime_get_ns())
162
163/*
164 * v6.15: Introduce event counters.
165 *
166 * Preserve the following macro until v6.17.
167 */
168#define __COMPAT_scx_bpf_events(events, size)					\
169	(bpf_ksym_exists(scx_bpf_events) ?					\
170	 scx_bpf_events(events, size) : ({}))
171
172/*
173 * v6.15: Introduce NUMA-aware kfuncs to operate with per-node idle
174 * cpumasks.
175 *
176 * Preserve the following __COMPAT_scx_*_node macros until v6.17.
177 */
178#define __COMPAT_scx_bpf_nr_node_ids()						\
179	(bpf_ksym_exists(scx_bpf_nr_node_ids) ?					\
180	 scx_bpf_nr_node_ids() : 1U)
181
182#define __COMPAT_scx_bpf_cpu_node(cpu)						\
183	(bpf_ksym_exists(scx_bpf_cpu_node) ?					\
184	 scx_bpf_cpu_node(cpu) : 0)
185
186#define __COMPAT_scx_bpf_get_idle_cpumask_node(node)				\
187	(bpf_ksym_exists(scx_bpf_get_idle_cpumask_node) ?			\
188	 scx_bpf_get_idle_cpumask_node(node) :					\
189	 scx_bpf_get_idle_cpumask())						\
190
191#define __COMPAT_scx_bpf_get_idle_smtmask_node(node)				\
192	(bpf_ksym_exists(scx_bpf_get_idle_smtmask_node) ?			\
193	 scx_bpf_get_idle_smtmask_node(node) :					\
194	 scx_bpf_get_idle_smtmask())
195
196#define __COMPAT_scx_bpf_pick_idle_cpu_node(cpus_allowed, node, flags)		\
197	(bpf_ksym_exists(scx_bpf_pick_idle_cpu_node) ?				\
198	 scx_bpf_pick_idle_cpu_node(cpus_allowed, node, flags) :		\
199	 scx_bpf_pick_idle_cpu(cpus_allowed, flags))
200
201#define __COMPAT_scx_bpf_pick_any_cpu_node(cpus_allowed, node, flags)		\
202	(bpf_ksym_exists(scx_bpf_pick_any_cpu_node) ?				\
203	 scx_bpf_pick_any_cpu_node(cpus_allowed, node, flags) :			\
204	 scx_bpf_pick_any_cpu(cpus_allowed, flags))
205
206/*
207 * v6.18: Add a helper to retrieve the current task running on a CPU.
208 *
209 * Keep this helper available until v6.20 for compatibility.
210 */
211static inline struct task_struct *__COMPAT_scx_bpf_cpu_curr(int cpu)
212{
213	struct rq *rq;
214
215	if (bpf_ksym_exists(scx_bpf_cpu_curr))
216		return scx_bpf_cpu_curr(cpu);
217
218	rq = scx_bpf_cpu_rq(cpu);
219
220	return rq ? rq->curr : NULL;
221}
222
223/*
224 * v6.19: To work around BPF maximum parameter limit, the following kfuncs are
225 * replaced with variants that pack scalar arguments in a struct. Wrappers are
226 * provided to maintain source compatibility.
227 *
228 * v6.13: scx_bpf_dsq_insert_vtime() renaming is also handled here. See the
229 * block on dispatch renaming above for more details.
230 *
231 * The kernel will carry the compat variants until v6.23 to maintain binary
232 * compatibility. After v6.23 release, remove the compat handling and move the
233 * wrappers to common.bpf.h.
234 */
235s32 scx_bpf_select_cpu_and___compat(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
236				    const struct cpumask *cpus_allowed, u64 flags) __ksym __weak;
237void scx_bpf_dispatch_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
238void scx_bpf_dsq_insert_vtime___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime, u64 enq_flags) __ksym __weak;
239
240/**
241 * scx_bpf_select_cpu_and - Pick an idle CPU usable by task @p
242 * @p: task_struct to select a CPU for
243 * @prev_cpu: CPU @p was on previously
244 * @wake_flags: %SCX_WAKE_* flags
245 * @cpus_allowed: cpumask of allowed CPUs
246 * @flags: %SCX_PICK_IDLE* flags
247 *
248 * Inline wrapper that packs scalar arguments into a struct and calls
249 * __scx_bpf_select_cpu_and(). See __scx_bpf_select_cpu_and() for details.
250 */
251static inline s32
252scx_bpf_select_cpu_and(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
253		       const struct cpumask *cpus_allowed, u64 flags)
254{
255	if (bpf_core_type_exists(struct scx_bpf_select_cpu_and_args)) {
256		struct scx_bpf_select_cpu_and_args args = {
257			.prev_cpu = prev_cpu,
258			.wake_flags = wake_flags,
259			.flags = flags,
260		};
261
262		return __scx_bpf_select_cpu_and(p, cpus_allowed, &args);
263	} else {
264		return scx_bpf_select_cpu_and___compat(p, prev_cpu, wake_flags,
265						       cpus_allowed, flags);
266	}
267}
268
269/**
270 * scx_bpf_dsq_insert_vtime - Insert a task into the vtime priority queue of a DSQ
271 * @p: task_struct to insert
272 * @dsq_id: DSQ to insert into
273 * @slice: duration @p can run for in nsecs, 0 to keep the current value
274 * @vtime: @p's ordering inside the vtime-sorted queue of the target DSQ
275 * @enq_flags: SCX_ENQ_*
276 *
277 * Inline wrapper that packs scalar arguments into a struct and calls
278 * __scx_bpf_dsq_insert_vtime(). See __scx_bpf_dsq_insert_vtime() for details.
279 */
280static inline bool
281scx_bpf_dsq_insert_vtime(struct task_struct *p, u64 dsq_id, u64 slice, u64 vtime,
282			 u64 enq_flags)
283{
284	if (bpf_core_type_exists(struct scx_bpf_dsq_insert_vtime_args)) {
285		struct scx_bpf_dsq_insert_vtime_args args = {
286			.dsq_id = dsq_id,
287			.slice = slice,
288			.vtime = vtime,
289			.enq_flags = enq_flags,
290		};
291
292		return __scx_bpf_dsq_insert_vtime(p, &args);
293	} else if (bpf_ksym_exists(scx_bpf_dsq_insert_vtime___compat)) {
294		scx_bpf_dsq_insert_vtime___compat(p, dsq_id, slice, vtime,
295						  enq_flags);
296		return true;
297	} else {
298		scx_bpf_dispatch_vtime___compat(p, dsq_id, slice, vtime,
299						enq_flags);
300		return true;
301	}
302}
303
304/*
305 * v6.19: scx_bpf_dsq_insert() now returns bool instead of void. Move
306 * scx_bpf_dsq_insert() decl to common.bpf.h and drop compat helper after v6.22.
307 * The extra ___compat suffix is to work around libbpf not ignoring __SUFFIX on
308 * kernel side. The entire suffix can be dropped later.
309 *
310 * v6.13: scx_bpf_dsq_insert() renaming is also handled here. See the block on
311 * dispatch renaming above for more details.
312 */
313bool scx_bpf_dsq_insert___v2___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
314void scx_bpf_dsq_insert___v1(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
315void scx_bpf_dispatch___compat(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym __weak;
316
317static inline bool
318scx_bpf_dsq_insert(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags)
319{
320	if (bpf_ksym_exists(scx_bpf_dsq_insert___v2___compat)) {
321		return scx_bpf_dsq_insert___v2___compat(p, dsq_id, slice, enq_flags);
322	} else if (bpf_ksym_exists(scx_bpf_dsq_insert___v1)) {
323		scx_bpf_dsq_insert___v1(p, dsq_id, slice, enq_flags);
324		return true;
325	} else {
326		scx_bpf_dispatch___compat(p, dsq_id, slice, enq_flags);
327		return true;
328	}
329}
330
331/*
332 * v6.19: scx_bpf_task_set_slice() and scx_bpf_task_set_dsq_vtime() added to for
333 * sub-sched authority checks. Drop the wrappers and move the decls to
334 * common.bpf.h after v6.22.
335 */
336bool scx_bpf_task_set_slice___new(struct task_struct *p, u64 slice) __ksym __weak;
337bool scx_bpf_task_set_dsq_vtime___new(struct task_struct *p, u64 vtime) __ksym __weak;
338
339static inline void scx_bpf_task_set_slice(struct task_struct *p, u64 slice)
340{
341	if (bpf_ksym_exists(scx_bpf_task_set_slice___new))
342		scx_bpf_task_set_slice___new(p, slice);
343	else
344		p->scx.slice = slice;
345}
346
347static inline void scx_bpf_task_set_dsq_vtime(struct task_struct *p, u64 vtime)
348{
349	if (bpf_ksym_exists(scx_bpf_task_set_dsq_vtime___new))
350		scx_bpf_task_set_dsq_vtime___new(p, vtime);
351	else
352		p->scx.dsq_vtime = vtime;
353}
354
355/*
356 * v6.19: The new void variant can be called from anywhere while the older v1
357 * variant can only be called from ops.cpu_release(). The double ___ prefixes on
358 * the v2 variant need to be removed once libbpf is updated to ignore ___ prefix
359 * on kernel side. Drop the wrapper and move the decl to common.bpf.h after
360 * v6.22.
361 */
362u32 scx_bpf_reenqueue_local___v1(void) __ksym __weak;
363void scx_bpf_reenqueue_local___v2___compat(void) __ksym __weak;
364
365static inline bool __COMPAT_scx_bpf_reenqueue_local_from_anywhere(void)
366{
367	return bpf_ksym_exists(scx_bpf_reenqueue_local___v2___compat);
368}
369
370static inline void scx_bpf_reenqueue_local(void)
371{
372	if (__COMPAT_scx_bpf_reenqueue_local_from_anywhere())
373		scx_bpf_reenqueue_local___v2___compat();
374	else
375		scx_bpf_reenqueue_local___v1();
376}
377
378/*
379 * Define sched_ext_ops. This may be expanded to define multiple variants for
380 * backward compatibility. See compat.h::SCX_OPS_LOAD/ATTACH().
381 */
382#define SCX_OPS_DEFINE(__name, ...)						\
383	SEC(".struct_ops.link")							\
384	struct sched_ext_ops __name = {						\
385		__VA_ARGS__,							\
386	};
387
388#endif	/* __SCX_COMPAT_BPF_H */