From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena 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 Reviewed-by: Andrea Righi --- drivers/clocksource/timer-integrator-ap.c | 225 ++++++++++++++++++++++++++++++ 1 file changed, 225 insertions(+) create mode 100644 drivers/clocksource/timer-integrator-ap.c (limited to 'drivers/clocksource/timer-integrator-ap.c') diff --git a/drivers/clocksource/timer-integrator-ap.c b/drivers/clocksource/timer-integrator-ap.c new file mode 100644 index 000000000..a4c700b11 --- /dev/null +++ b/drivers/clocksource/timer-integrator-ap.c @@ -0,0 +1,225 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Integrator/AP timer driver + * Copyright (C) 2000-2003 Deep Blue Solutions Ltd + * Copyright (c) 2014, Linaro Limited + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +#include "timer-sp.h" + +static void __iomem * sched_clk_base; + +static u64 notrace integrator_read_sched_clock(void) +{ + return -readl(sched_clk_base + TIMER_VALUE); +} + +static int __init integrator_clocksource_init(unsigned long inrate, + void __iomem *base) +{ + u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC; + unsigned long rate = inrate; + int ret; + + if (rate >= 1500000) { + rate /= 16; + ctrl |= TIMER_CTRL_DIV16; + } + + writel(0xffff, base + TIMER_LOAD); + writel(ctrl, base + TIMER_CTRL); + + ret = clocksource_mmio_init(base + TIMER_VALUE, "timer2", + rate, 200, 16, clocksource_mmio_readl_down); + if (ret) + return ret; + + sched_clk_base = base; + sched_clock_register(integrator_read_sched_clock, 16, rate); + + return 0; +} + +static unsigned long timer_reload; +static void __iomem * clkevt_base; + +/* + * IRQ handler for the timer + */ +static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + + /* clear the interrupt */ + writel(1, clkevt_base + TIMER_INTCLR); + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static int clkevt_shutdown(struct clock_event_device *evt) +{ + u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE; + + /* Disable timer */ + writel(ctrl, clkevt_base + TIMER_CTRL); + return 0; +} + +static int clkevt_set_oneshot(struct clock_event_device *evt) +{ + u32 ctrl = readl(clkevt_base + TIMER_CTRL) & + ~(TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC); + + /* Leave the timer disabled, .set_next_event will enable it */ + writel(ctrl, clkevt_base + TIMER_CTRL); + return 0; +} + +static int clkevt_set_periodic(struct clock_event_device *evt) +{ + u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE; + + /* Disable timer */ + writel(ctrl, clkevt_base + TIMER_CTRL); + + /* Enable the timer and start the periodic tick */ + writel(timer_reload, clkevt_base + TIMER_LOAD); + ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE; + writel(ctrl, clkevt_base + TIMER_CTRL); + return 0; +} + +static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt) +{ + unsigned long ctrl = readl(clkevt_base + TIMER_CTRL); + + writel(ctrl & ~TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL); + writel(next, clkevt_base + TIMER_LOAD); + writel(ctrl | TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL); + + return 0; +} + +static struct clock_event_device integrator_clockevent = { + .name = "timer1", + .features = CLOCK_EVT_FEAT_PERIODIC | + CLOCK_EVT_FEAT_ONESHOT, + .set_state_shutdown = clkevt_shutdown, + .set_state_periodic = clkevt_set_periodic, + .set_state_oneshot = clkevt_set_oneshot, + .tick_resume = clkevt_shutdown, + .set_next_event = clkevt_set_next_event, + .rating = 300, +}; + +static int integrator_clockevent_init(unsigned long inrate, + void __iomem *base, int irq) +{ + unsigned long rate = inrate; + unsigned int ctrl = 0; + int ret; + + clkevt_base = base; + /* Calculate and program a divisor */ + if (rate > 0x100000 * HZ) { + rate /= 256; + ctrl |= TIMER_CTRL_DIV256; + } else if (rate > 0x10000 * HZ) { + rate /= 16; + ctrl |= TIMER_CTRL_DIV16; + } + timer_reload = rate / HZ; + writel(ctrl, clkevt_base + TIMER_CTRL); + + ret = request_irq(irq, integrator_timer_interrupt, + IRQF_TIMER | IRQF_IRQPOLL, "timer", + &integrator_clockevent); + if (ret) + return ret; + + clockevents_config_and_register(&integrator_clockevent, + rate, + 1, + 0xffffU); + return 0; +} + +static int __init integrator_ap_timer_init_of(struct device_node *node) +{ + const char *path; + void __iomem *base; + int err; + int irq; + struct clk *clk; + unsigned long rate; + struct device_node *alias_node; + + base = of_io_request_and_map(node, 0, "integrator-timer"); + if (IS_ERR(base)) + return PTR_ERR(base); + + clk = of_clk_get(node, 0); + if (IS_ERR(clk)) { + pr_err("No clock for %pOFn\n", node); + return PTR_ERR(clk); + } + clk_prepare_enable(clk); + rate = clk_get_rate(clk); + writel(0, base + TIMER_CTRL); + + err = of_property_read_string(of_aliases, + "arm,timer-primary", &path); + if (err) { + pr_warn("Failed to read property\n"); + return err; + } + + alias_node = of_find_node_by_path(path); + + /* + * The pointer is used as an identifier not as a pointer, we + * can drop the refcount on the of__node immediately after + * getting it. + */ + of_node_put(alias_node); + + if (node == alias_node) + /* The primary timer lacks IRQ, use as clocksource */ + return integrator_clocksource_init(rate, base); + + err = of_property_read_string(of_aliases, + "arm,timer-secondary", &path); + if (err) { + pr_warn("Failed to read property\n"); + return err; + } + + alias_node = of_find_node_by_path(path); + + of_node_put(alias_node); + + if (node == alias_node) { + /* The secondary timer will drive the clock event */ + irq = irq_of_parse_and_map(node, 0); + return integrator_clockevent_init(rate, base, irq); + } + + pr_info("Timer @%p unused\n", base); + clk_disable_unprepare(clk); + + return 0; +} + +TIMER_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer", + integrator_ap_timer_init_of); -- cgit v1.3.1