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, 354 insertions, 0 deletions

diff --git a/drivers/bcma/driver_mips.c b/drivers/bcma/driver_mips.c
new file mode 100644
index 000000000..9be0806eb
--- /dev/null
+++ b/drivers/bcma/driver_mips.c
@@ -0,0 +1,354 @@
+/*
+ * Broadcom specific AMBA
+ * Broadcom MIPS32 74K core driver
+ *
+ * Copyright 2009, Broadcom Corporation
+ * Copyright 2006, 2007, Michael Buesch <mb@bu3sch.de>
+ * Copyright 2010, Bernhard Loos <bernhardloos@googlemail.com>
+ * Copyright 2011, Hauke Mehrtens <hauke@hauke-m.de>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include "bcma_private.h"
+
+#include <linux/bcma/bcma.h>
+
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+#include <linux/time.h>
+#ifdef CONFIG_BCM47XX
+#include <linux/bcm47xx_nvram.h>
+#endif
+
+enum bcma_boot_dev {
+	BCMA_BOOT_DEV_UNK = 0,
+	BCMA_BOOT_DEV_ROM,
+	BCMA_BOOT_DEV_PARALLEL,
+	BCMA_BOOT_DEV_SERIAL,
+	BCMA_BOOT_DEV_NAND,
+};
+
+/* The 47162a0 hangs when reading MIPS DMP registers */
+static inline bool bcma_core_mips_bcm47162a0_quirk(struct bcma_device *dev)
+{
+	return dev->bus->chipinfo.id == BCMA_CHIP_ID_BCM47162 &&
+	       dev->bus->chipinfo.rev == 0 && dev->id.id == BCMA_CORE_MIPS_74K;
+}
+
+/* The 5357b0 hangs when reading USB20H DMP registers */
+static inline bool bcma_core_mips_bcm5357b0_quirk(struct bcma_device *dev)
+{
+	return (dev->bus->chipinfo.id == BCMA_CHIP_ID_BCM5357 ||
+		dev->bus->chipinfo.id == BCMA_CHIP_ID_BCM4749) &&
+	       dev->bus->chipinfo.pkg == 11 &&
+	       dev->id.id == BCMA_CORE_USB20_HOST;
+}
+
+static u32 bcma_core_mips_irqflag(struct bcma_device *dev)
+{
+	u32 flag;
+
+	if (bcma_core_mips_bcm47162a0_quirk(dev))
+		return dev->core_index;
+	if (bcma_core_mips_bcm5357b0_quirk(dev))
+		return dev->core_index;
+	flag = bcma_aread32(dev, BCMA_MIPS_OOBSELOUTA30);
+
+	if (flag)
+		return flag & 0x1F;
+	else
+		return 0x3f;
+}
+
+/* Get the MIPS IRQ assignment for a specified device.
+ * If unassigned, 0 is returned.
+ * If disabled, 5 is returned.
+ * If not supported, 6 is returned.
+ */
+unsigned int bcma_core_mips_irq(struct bcma_device *dev)
+{
+	struct bcma_device *mdev = dev->bus->drv_mips.core;
+	u32 irqflag;
+	unsigned int irq;
+
+	irqflag = bcma_core_mips_irqflag(dev);
+	if (irqflag == 0x3f)
+		return 6;
+
+	for (irq = 0; irq <= 4; irq++)
+		if (bcma_read32(mdev, BCMA_MIPS_MIPS74K_INTMASK(irq)) &
+		    (1 << irqflag))
+			return irq;
+
+	return 5;
+}
+
+static void bcma_core_mips_set_irq(struct bcma_device *dev, unsigned int irq)
+{
+	unsigned int oldirq = bcma_core_mips_irq(dev);
+	struct bcma_bus *bus = dev->bus;
+	struct bcma_device *mdev = bus->drv_mips.core;
+	u32 irqflag;
+
+	irqflag = bcma_core_mips_irqflag(dev);
+	BUG_ON(oldirq == 6);
+
+	dev->irq = irq + 2;
+
+	/* clear the old irq */
+	if (oldirq == 0)
+		bcma_write32(mdev, BCMA_MIPS_MIPS74K_INTMASK(0),
+			    bcma_read32(mdev, BCMA_MIPS_MIPS74K_INTMASK(0)) &
+			    ~(1 << irqflag));
+	else if (oldirq != 5)
+		bcma_write32(mdev, BCMA_MIPS_MIPS74K_INTMASK(oldirq), 0);
+
+	/* assign the new one */
+	if (irq == 0) {
+		bcma_write32(mdev, BCMA_MIPS_MIPS74K_INTMASK(0),
+			    bcma_read32(mdev, BCMA_MIPS_MIPS74K_INTMASK(0)) |
+			    (1 << irqflag));
+	} else {
+		u32 irqinitmask = bcma_read32(mdev,
+					      BCMA_MIPS_MIPS74K_INTMASK(irq));
+		if (irqinitmask) {
+			struct bcma_device *core;
+
+			/* backplane irq line is in use, find out who uses
+			 * it and set user to irq 0
+			 */
+			list_for_each_entry(core, &bus->cores, list) {
+				if ((1 << bcma_core_mips_irqflag(core)) ==
+				    irqinitmask) {
+					bcma_core_mips_set_irq(core, 0);
+					break;
+				}
+			}
+		}
+		bcma_write32(mdev, BCMA_MIPS_MIPS74K_INTMASK(irq),
+			     1 << irqflag);
+	}
+
+	bcma_debug(bus, "set_irq: core 0x%04x, irq %d => %d\n",
+		   dev->id.id, oldirq <= 4 ? oldirq + 2 : 0, irq + 2);
+}
+
+static void bcma_core_mips_set_irq_name(struct bcma_bus *bus, unsigned int irq,
+					u16 coreid, u8 unit)
+{
+	struct bcma_device *core;
+
+	core = bcma_find_core_unit(bus, coreid, unit);
+	if (!core) {
+		bcma_warn(bus,
+			  "Can not find core (id: 0x%x, unit %i) for IRQ configuration.\n",
+			  coreid, unit);
+		return;
+	}
+
+	bcma_core_mips_set_irq(core, irq);
+}
+
+static void bcma_core_mips_print_irq(struct bcma_device *dev, unsigned int irq)
+{
+	int i;
+	static const char *irq_name[] = {"2(S)", "3", "4", "5", "6", "D", "I"};
+	char interrupts[25];
+	char *ints = interrupts;
+
+	for (i = 0; i < ARRAY_SIZE(irq_name); i++)
+		ints += sprintf(ints, " %s%c",
+				irq_name[i], i == irq ? '*' : ' ');
+
+	bcma_debug(dev->bus, "core 0x%04x, irq:%s\n", dev->id.id, interrupts);
+}
+
+static void bcma_core_mips_dump_irq(struct bcma_bus *bus)
+{
+	struct bcma_device *core;
+
+	list_for_each_entry(core, &bus->cores, list) {
+		bcma_core_mips_print_irq(core, bcma_core_mips_irq(core));
+	}
+}
+
+u32 bcma_cpu_clock(struct bcma_drv_mips *mcore)
+{
+	struct bcma_bus *bus = mcore->core->bus;
+
+	if (bus->drv_cc.capabilities & BCMA_CC_CAP_PMU)
+		return bcma_pmu_get_cpu_clock(&bus->drv_cc);
+
+	bcma_err(bus, "No PMU available, need this to get the cpu clock\n");
+	return 0;
+}
+EXPORT_SYMBOL(bcma_cpu_clock);
+
+static enum bcma_boot_dev bcma_boot_dev(struct bcma_bus *bus)
+{
+	struct bcma_drv_cc *cc = &bus->drv_cc;
+	u8 cc_rev = cc->core->id.rev;
+
+	if (cc_rev == 42) {
+		struct bcma_device *core;
+
+		core = bcma_find_core(bus, BCMA_CORE_NS_ROM);
+		if (core) {
+			switch (bcma_aread32(core, BCMA_IOST) &
+				BCMA_NS_ROM_IOST_BOOT_DEV_MASK) {
+			case BCMA_NS_ROM_IOST_BOOT_DEV_NOR:
+				return BCMA_BOOT_DEV_SERIAL;
+			case BCMA_NS_ROM_IOST_BOOT_DEV_NAND:
+				return BCMA_BOOT_DEV_NAND;
+			case BCMA_NS_ROM_IOST_BOOT_DEV_ROM:
+			default:
+				return BCMA_BOOT_DEV_ROM;
+			}
+		}
+	} else {
+		if (cc_rev == 38) {
+			if (cc->status & BCMA_CC_CHIPST_5357_NAND_BOOT)
+				return BCMA_BOOT_DEV_NAND;
+			else if (cc->status & BIT(5))
+				return BCMA_BOOT_DEV_ROM;
+		}
+
+		if ((cc->capabilities & BCMA_CC_CAP_FLASHT) ==
+		    BCMA_CC_FLASHT_PARA)
+			return BCMA_BOOT_DEV_PARALLEL;
+		else
+			return BCMA_BOOT_DEV_SERIAL;
+	}
+
+	return BCMA_BOOT_DEV_SERIAL;
+}
+
+static void bcma_core_mips_nvram_init(struct bcma_drv_mips *mcore)
+{
+	struct bcma_bus *bus = mcore->core->bus;
+	enum bcma_boot_dev boot_dev;
+
+	/* Determine flash type this SoC boots from */
+	boot_dev = bcma_boot_dev(bus);
+	switch (boot_dev) {
+	case BCMA_BOOT_DEV_PARALLEL:
+	case BCMA_BOOT_DEV_SERIAL:
+#ifdef CONFIG_BCM47XX
+		bcm47xx_nvram_init_from_mem(BCMA_SOC_FLASH2,
+					    BCMA_SOC_FLASH2_SZ);
+#endif
+		break;
+	case BCMA_BOOT_DEV_NAND:
+#ifdef CONFIG_BCM47XX
+		bcm47xx_nvram_init_from_mem(BCMA_SOC_FLASH1,
+					    BCMA_SOC_FLASH1_SZ);
+#endif
+		break;
+	default:
+		break;
+	}
+}
+
+void bcma_core_mips_early_init(struct bcma_drv_mips *mcore)
+{
+	struct bcma_bus *bus = mcore->core->bus;
+
+	if (mcore->early_setup_done)
+		return;
+
+	bcma_chipco_serial_init(&bus->drv_cc);
+	bcma_core_mips_nvram_init(mcore);
+
+	mcore->early_setup_done = true;
+}
+
+static void bcma_fix_i2s_irqflag(struct bcma_bus *bus)
+{
+	struct bcma_device *cpu, *pcie, *i2s;
+
+	/* Fixup the interrupts in 4716/4748 for i2s core (2010 Broadcom SDK)
+	 * (IRQ flags > 7 are ignored when setting the interrupt masks)
+	 */
+	if (bus->chipinfo.id != BCMA_CHIP_ID_BCM4716 &&
+	    bus->chipinfo.id != BCMA_CHIP_ID_BCM4748)
+		return;
+
+	cpu = bcma_find_core(bus, BCMA_CORE_MIPS_74K);
+	pcie = bcma_find_core(bus, BCMA_CORE_PCIE);
+	i2s = bcma_find_core(bus, BCMA_CORE_I2S);
+	if (cpu && pcie && i2s &&
+	    bcma_aread32(cpu, BCMA_MIPS_OOBSELINA74) == 0x08060504 &&
+	    bcma_aread32(pcie, BCMA_MIPS_OOBSELINA74) == 0x08060504 &&
+	    bcma_aread32(i2s, BCMA_MIPS_OOBSELOUTA30) == 0x88) {
+		bcma_awrite32(cpu, BCMA_MIPS_OOBSELINA74, 0x07060504);
+		bcma_awrite32(pcie, BCMA_MIPS_OOBSELINA74, 0x07060504);
+		bcma_awrite32(i2s, BCMA_MIPS_OOBSELOUTA30, 0x87);
+		bcma_debug(bus,
+			   "Moved i2s interrupt to oob line 7 instead of 8\n");
+	}
+}
+
+void bcma_core_mips_init(struct bcma_drv_mips *mcore)
+{
+	struct bcma_bus *bus;
+	struct bcma_device *core;
+	bus = mcore->core->bus;
+
+	if (mcore->setup_done)
+		return;
+
+	bcma_debug(bus, "Initializing MIPS core...\n");
+
+	bcma_core_mips_early_init(mcore);
+
+	bcma_fix_i2s_irqflag(bus);
+
+	switch (bus->chipinfo.id) {
+	case BCMA_CHIP_ID_BCM4716:
+	case BCMA_CHIP_ID_BCM4748:
+		bcma_core_mips_set_irq_name(bus, 1, BCMA_CORE_80211, 0);
+		bcma_core_mips_set_irq_name(bus, 2, BCMA_CORE_MAC_GBIT, 0);
+		bcma_core_mips_set_irq_name(bus, 3, BCMA_CORE_USB20_HOST, 0);
+		bcma_core_mips_set_irq_name(bus, 4, BCMA_CORE_PCIE, 0);
+		bcma_core_mips_set_irq_name(bus, 0, BCMA_CORE_CHIPCOMMON, 0);
+		bcma_core_mips_set_irq_name(bus, 0, BCMA_CORE_I2S, 0);
+		break;
+	case BCMA_CHIP_ID_BCM5356:
+	case BCMA_CHIP_ID_BCM47162:
+	case BCMA_CHIP_ID_BCM53572:
+		bcma_core_mips_set_irq_name(bus, 1, BCMA_CORE_80211, 0);
+		bcma_core_mips_set_irq_name(bus, 2, BCMA_CORE_MAC_GBIT, 0);
+		bcma_core_mips_set_irq_name(bus, 0, BCMA_CORE_CHIPCOMMON, 0);
+		break;
+	case BCMA_CHIP_ID_BCM5357:
+	case BCMA_CHIP_ID_BCM4749:
+		bcma_core_mips_set_irq_name(bus, 1, BCMA_CORE_80211, 0);
+		bcma_core_mips_set_irq_name(bus, 2, BCMA_CORE_MAC_GBIT, 0);
+		bcma_core_mips_set_irq_name(bus, 3, BCMA_CORE_USB20_HOST, 0);
+		bcma_core_mips_set_irq_name(bus, 0, BCMA_CORE_CHIPCOMMON, 0);
+		bcma_core_mips_set_irq_name(bus, 0, BCMA_CORE_I2S, 0);
+		break;
+	case BCMA_CHIP_ID_BCM4706:
+		bcma_core_mips_set_irq_name(bus, 1, BCMA_CORE_PCIE, 0);
+		bcma_core_mips_set_irq_name(bus, 2, BCMA_CORE_4706_MAC_GBIT,
+					    0);
+		bcma_core_mips_set_irq_name(bus, 3, BCMA_CORE_PCIE, 1);
+		bcma_core_mips_set_irq_name(bus, 4, BCMA_CORE_USB20_HOST, 0);
+		bcma_core_mips_set_irq_name(bus, 0, BCMA_CORE_4706_CHIPCOMMON,
+					    0);
+		break;
+	default:
+		list_for_each_entry(core, &bus->cores, list) {
+			core->irq = bcma_core_irq(core, 0);
+		}
+		bcma_err(bus,
+			 "Unknown device (0x%x) found, can not configure IRQs\n",
+			 bus->chipinfo.id);
+	}
+	bcma_debug(bus, "IRQ reconfiguration done\n");
+	bcma_core_mips_dump_irq(bus);
+
+	mcore->setup_done = true;
+}