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, 530 insertions, 0 deletions

diff --git a/drivers/video/fbdev/tcx.c b/drivers/video/fbdev/tcx.c
new file mode 100644
index 000000000..ca9e84e8d
--- /dev/null
+++ b/drivers/video/fbdev/tcx.c
@@ -0,0 +1,530 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* tcx.c: TCX frame buffer driver
+ *
+ * Copyright (C) 2003, 2006 David S. Miller (davem@davemloft.net)
+ * Copyright (C) 1996,1998 Jakub Jelinek (jj@ultra.linux.cz)
+ * Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
+ * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
+ *
+ * Driver layout based loosely on tgafb.c, see that file for credits.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/fb.h>
+#include <linux/mm.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+#include <asm/io.h>
+#include <asm/fbio.h>
+
+#include "sbuslib.h"
+
+/*
+ * Local functions.
+ */
+
+static int tcx_setcolreg(unsigned, unsigned, unsigned, unsigned,
+			 unsigned, struct fb_info *);
+static int tcx_blank(int, struct fb_info *);
+static int tcx_pan_display(struct fb_var_screeninfo *, struct fb_info *);
+
+static int tcx_sbusfb_mmap(struct fb_info *info, struct vm_area_struct *vma);
+static int tcx_sbusfb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg);
+
+/*
+ *  Frame buffer operations
+ */
+
+static const struct fb_ops tcx_ops = {
+	.owner			= THIS_MODULE,
+	FB_DEFAULT_SBUS_OPS(tcx),
+	.fb_setcolreg		= tcx_setcolreg,
+	.fb_blank		= tcx_blank,
+	.fb_pan_display		= tcx_pan_display,
+};
+
+/* THC definitions */
+#define TCX_THC_MISC_REV_SHIFT       16
+#define TCX_THC_MISC_REV_MASK        15
+#define TCX_THC_MISC_VSYNC_DIS       (1 << 25)
+#define TCX_THC_MISC_HSYNC_DIS       (1 << 24)
+#define TCX_THC_MISC_RESET           (1 << 12)
+#define TCX_THC_MISC_VIDEO           (1 << 10)
+#define TCX_THC_MISC_SYNC            (1 << 9)
+#define TCX_THC_MISC_VSYNC           (1 << 8)
+#define TCX_THC_MISC_SYNC_ENAB       (1 << 7)
+#define TCX_THC_MISC_CURS_RES        (1 << 6)
+#define TCX_THC_MISC_INT_ENAB        (1 << 5)
+#define TCX_THC_MISC_INT             (1 << 4)
+#define TCX_THC_MISC_INIT            0x9f
+#define TCX_THC_REV_REV_SHIFT        20
+#define TCX_THC_REV_REV_MASK         15
+#define TCX_THC_REV_MINREV_SHIFT     28
+#define TCX_THC_REV_MINREV_MASK      15
+
+/* The contents are unknown */
+struct tcx_tec {
+	u32 tec_matrix;
+	u32 tec_clip;
+	u32 tec_vdc;
+};
+
+struct tcx_thc {
+	u32 thc_rev;
+	u32 thc_pad0[511];
+	u32 thc_hs;		/* hsync timing */
+	u32 thc_hsdvs;
+	u32 thc_hd;
+	u32 thc_vs;		/* vsync timing */
+	u32 thc_vd;
+	u32 thc_refresh;
+	u32 thc_misc;
+	u32 thc_pad1[56];
+	u32 thc_cursxy;	/* cursor x,y position (16 bits each) */
+	u32 thc_cursmask[32];	/* cursor mask bits */
+	u32 thc_cursbits[32];	/* what to show where mask enabled */
+};
+
+struct bt_regs {
+	u32 addr;
+	u32 color_map;
+	u32 control;
+	u32 cursor;
+};
+
+#define TCX_MMAP_ENTRIES 14
+
+struct tcx_par {
+	spinlock_t		lock;
+	struct bt_regs		__iomem *bt;
+	struct tcx_thc		__iomem *thc;
+	struct tcx_tec		__iomem *tec;
+	u32			__iomem *cplane;
+
+	u32			flags;
+#define TCX_FLAG_BLANKED	0x00000001
+
+	unsigned long		which_io;
+
+	struct sbus_mmap_map	mmap_map[TCX_MMAP_ENTRIES];
+	int			lowdepth;
+};
+
+/* Reset control plane so that WID is 8-bit plane. */
+static void __tcx_set_control_plane(struct fb_info *info)
+{
+	struct tcx_par *par = info->par;
+	u32 __iomem *p, *pend;
+
+	if (par->lowdepth)
+		return;
+
+	p = par->cplane;
+	if (p == NULL)
+		return;
+	for (pend = p + info->fix.smem_len; p < pend; p++) {
+		u32 tmp = sbus_readl(p);
+
+		tmp &= 0xffffff;
+		sbus_writel(tmp, p);
+	}
+}
+
+static void tcx_reset(struct fb_info *info)
+{
+	struct tcx_par *par = (struct tcx_par *) info->par;
+	unsigned long flags;
+
+	spin_lock_irqsave(&par->lock, flags);
+	__tcx_set_control_plane(info);
+	spin_unlock_irqrestore(&par->lock, flags);
+}
+
+static int tcx_pan_display(struct fb_var_screeninfo *var, struct fb_info *info)
+{
+	tcx_reset(info);
+	return 0;
+}
+
+/**
+ *      tcx_setcolreg - Optional function. Sets a color register.
+ *      @regno: boolean, 0 copy local, 1 get_user() function
+ *      @red: frame buffer colormap structure
+ *      @green: The green value which can be up to 16 bits wide
+ *      @blue:  The blue value which can be up to 16 bits wide.
+ *      @transp: If supported the alpha value which can be up to 16 bits wide.
+ *      @info: frame buffer info structure
+ */
+static int tcx_setcolreg(unsigned regno,
+			 unsigned red, unsigned green, unsigned blue,
+			 unsigned transp, struct fb_info *info)
+{
+	struct tcx_par *par = (struct tcx_par *) info->par;
+	struct bt_regs __iomem *bt = par->bt;
+	unsigned long flags;
+
+	if (regno >= 256)
+		return 1;
+
+	red >>= 8;
+	green >>= 8;
+	blue >>= 8;
+
+	spin_lock_irqsave(&par->lock, flags);
+
+	sbus_writel(regno << 24, &bt->addr);
+	sbus_writel(red << 24, &bt->color_map);
+	sbus_writel(green << 24, &bt->color_map);
+	sbus_writel(blue << 24, &bt->color_map);
+
+	spin_unlock_irqrestore(&par->lock, flags);
+
+	return 0;
+}
+
+/**
+ *      tcx_blank - Optional function.  Blanks the display.
+ *      @blank: the blank mode we want.
+ *      @info: frame buffer structure that represents a single frame buffer
+ */
+static int
+tcx_blank(int blank, struct fb_info *info)
+{
+	struct tcx_par *par = (struct tcx_par *) info->par;
+	struct tcx_thc __iomem *thc = par->thc;
+	unsigned long flags;
+	u32 val;
+
+	spin_lock_irqsave(&par->lock, flags);
+
+	val = sbus_readl(&thc->thc_misc);
+
+	switch (blank) {
+	case FB_BLANK_UNBLANK: /* Unblanking */
+		val &= ~(TCX_THC_MISC_VSYNC_DIS |
+			 TCX_THC_MISC_HSYNC_DIS);
+		val |= TCX_THC_MISC_VIDEO;
+		par->flags &= ~TCX_FLAG_BLANKED;
+		break;
+
+	case FB_BLANK_NORMAL: /* Normal blanking */
+		val &= ~TCX_THC_MISC_VIDEO;
+		par->flags |= TCX_FLAG_BLANKED;
+		break;
+
+	case FB_BLANK_VSYNC_SUSPEND: /* VESA blank (vsync off) */
+		val |= TCX_THC_MISC_VSYNC_DIS;
+		break;
+	case FB_BLANK_HSYNC_SUSPEND: /* VESA blank (hsync off) */
+		val |= TCX_THC_MISC_HSYNC_DIS;
+		break;
+
+	case FB_BLANK_POWERDOWN: /* Poweroff */
+		break;
+	}
+
+	sbus_writel(val, &thc->thc_misc);
+
+	spin_unlock_irqrestore(&par->lock, flags);
+
+	return 0;
+}
+
+static const struct sbus_mmap_map __tcx_mmap_map[TCX_MMAP_ENTRIES] = {
+	{
+		.voff	= TCX_RAM8BIT,
+		.size	= SBUS_MMAP_FBSIZE(1)
+	},
+	{
+		.voff	= TCX_RAM24BIT,
+		.size	= SBUS_MMAP_FBSIZE(4)
+	},
+	{
+		.voff	= TCX_UNK3,
+		.size	= SBUS_MMAP_FBSIZE(8)
+	},
+	{
+		.voff	= TCX_UNK4,
+		.size	= SBUS_MMAP_FBSIZE(8)
+	},
+	{
+		.voff	= TCX_CONTROLPLANE,
+		.size	= SBUS_MMAP_FBSIZE(4)
+	},
+	{
+		.voff	= TCX_UNK6,
+		.size	= SBUS_MMAP_FBSIZE(8)
+	},
+	{
+		.voff	= TCX_UNK7,
+		.size	= SBUS_MMAP_FBSIZE(8)
+	},
+	{
+		.voff	= TCX_TEC,
+		.size	= PAGE_SIZE
+	},
+	{
+		.voff	= TCX_BTREGS,
+		.size	= PAGE_SIZE
+	},
+	{
+		.voff	= TCX_THC,
+		.size	= PAGE_SIZE
+	},
+	{
+		.voff	= TCX_DHC,
+		.size	= PAGE_SIZE
+	},
+	{
+		.voff	= TCX_ALT,
+		.size	= PAGE_SIZE
+	},
+	{
+		.voff	= TCX_UNK2,
+		.size	= 0x20000
+	},
+	{ .size = 0 }
+};
+
+static int tcx_sbusfb_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	struct tcx_par *par = (struct tcx_par *)info->par;
+
+	return sbusfb_mmap_helper(par->mmap_map,
+				  info->fix.smem_start, info->fix.smem_len,
+				  par->which_io, vma);
+}
+
+static int tcx_sbusfb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
+{
+	struct tcx_par *par = (struct tcx_par *) info->par;
+
+	return sbusfb_ioctl_helper(cmd, arg, info,
+				   FBTYPE_TCXCOLOR,
+				   (par->lowdepth ? 8 : 24),
+				   info->fix.smem_len);
+}
+
+/*
+ *  Initialisation
+ */
+
+static void
+tcx_init_fix(struct fb_info *info, int linebytes)
+{
+	struct tcx_par *par = (struct tcx_par *)info->par;
+	const char *tcx_name;
+
+	if (par->lowdepth)
+		tcx_name = "TCX8";
+	else
+		tcx_name = "TCX24";
+
+	strscpy(info->fix.id, tcx_name, sizeof(info->fix.id));
+
+	info->fix.type = FB_TYPE_PACKED_PIXELS;
+	info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
+
+	info->fix.line_length = linebytes;
+
+	info->fix.accel = FB_ACCEL_SUN_TCX;
+}
+
+static void tcx_unmap_regs(struct platform_device *op, struct fb_info *info,
+			   struct tcx_par *par)
+{
+	if (par->tec)
+		of_iounmap(&op->resource[7],
+			   par->tec, sizeof(struct tcx_tec));
+	if (par->thc)
+		of_iounmap(&op->resource[9],
+			   par->thc, sizeof(struct tcx_thc));
+	if (par->bt)
+		of_iounmap(&op->resource[8],
+			   par->bt, sizeof(struct bt_regs));
+	if (par->cplane)
+		of_iounmap(&op->resource[4],
+			   par->cplane, info->fix.smem_len * sizeof(u32));
+	if (info->screen_base)
+		of_iounmap(&op->resource[0],
+			   info->screen_base, info->fix.smem_len);
+}
+
+static int tcx_probe(struct platform_device *op)
+{
+	struct device_node *dp = op->dev.of_node;
+	struct fb_info *info;
+	struct tcx_par *par;
+	int linebytes, i, err;
+
+	info = framebuffer_alloc(sizeof(struct tcx_par), &op->dev);
+
+	err = -ENOMEM;
+	if (!info)
+		goto out_err;
+	par = info->par;
+
+	spin_lock_init(&par->lock);
+
+	par->lowdepth = of_property_read_bool(dp, "tcx-8-bit");
+
+	sbusfb_fill_var(&info->var, dp, 8);
+	info->var.red.length = 8;
+	info->var.green.length = 8;
+	info->var.blue.length = 8;
+
+	linebytes = of_getintprop_default(dp, "linebytes",
+					  info->var.xres);
+	info->fix.smem_len = PAGE_ALIGN(linebytes * info->var.yres);
+
+	par->tec = of_ioremap(&op->resource[7], 0,
+				  sizeof(struct tcx_tec), "tcx tec");
+	par->thc = of_ioremap(&op->resource[9], 0,
+				  sizeof(struct tcx_thc), "tcx thc");
+	par->bt = of_ioremap(&op->resource[8], 0,
+				 sizeof(struct bt_regs), "tcx dac");
+	info->screen_base = of_ioremap(&op->resource[0], 0,
+					   info->fix.smem_len, "tcx ram");
+	if (!par->tec || !par->thc ||
+	    !par->bt || !info->screen_base)
+		goto out_unmap_regs;
+
+	memcpy(&par->mmap_map, &__tcx_mmap_map, sizeof(par->mmap_map));
+	if (!par->lowdepth) {
+		par->cplane = of_ioremap(&op->resource[4], 0,
+					     info->fix.smem_len * sizeof(u32),
+					     "tcx cplane");
+		if (!par->cplane)
+			goto out_unmap_regs;
+	} else {
+		par->mmap_map[1].size = SBUS_MMAP_EMPTY;
+		par->mmap_map[4].size = SBUS_MMAP_EMPTY;
+		par->mmap_map[5].size = SBUS_MMAP_EMPTY;
+		par->mmap_map[6].size = SBUS_MMAP_EMPTY;
+	}
+
+	info->fix.smem_start = op->resource[0].start;
+	par->which_io = op->resource[0].flags & IORESOURCE_BITS;
+
+	for (i = 0; i < TCX_MMAP_ENTRIES; i++) {
+		int j;
+
+		switch (i) {
+		case 10:
+			j = 12;
+			break;
+
+		case 11: case 12:
+			j = i - 1;
+			break;
+
+		default:
+			j = i;
+			break;
+		}
+		par->mmap_map[i].poff = op->resource[j].start - info->fix.smem_start;
+	}
+
+	info->fbops = &tcx_ops;
+
+	/* Initialize brooktree DAC. */
+	sbus_writel(0x04 << 24, &par->bt->addr);         /* color planes */
+	sbus_writel(0xff << 24, &par->bt->control);
+	sbus_writel(0x05 << 24, &par->bt->addr);
+	sbus_writel(0x00 << 24, &par->bt->control);
+	sbus_writel(0x06 << 24, &par->bt->addr);         /* overlay plane */
+	sbus_writel(0x73 << 24, &par->bt->control);
+	sbus_writel(0x07 << 24, &par->bt->addr);
+	sbus_writel(0x00 << 24, &par->bt->control);
+
+	tcx_reset(info);
+
+	tcx_blank(FB_BLANK_UNBLANK, info);
+
+	if (fb_alloc_cmap(&info->cmap, 256, 0))
+		goto out_unmap_regs;
+
+	fb_set_cmap(&info->cmap, info);
+	tcx_init_fix(info, linebytes);
+
+	err = register_framebuffer(info);
+	if (err < 0)
+		goto out_dealloc_cmap;
+
+	dev_set_drvdata(&op->dev, info);
+
+	printk(KERN_INFO "%pOF: TCX at %lx:%lx, %s\n",
+	       dp,
+	       par->which_io,
+	       info->fix.smem_start,
+	       par->lowdepth ? "8-bit only" : "24-bit depth");
+
+	return 0;
+
+out_dealloc_cmap:
+	fb_dealloc_cmap(&info->cmap);
+
+out_unmap_regs:
+	tcx_unmap_regs(op, info, par);
+	framebuffer_release(info);
+
+out_err:
+	return err;
+}
+
+static void tcx_remove(struct platform_device *op)
+{
+	struct fb_info *info = dev_get_drvdata(&op->dev);
+	struct tcx_par *par = info->par;
+
+	unregister_framebuffer(info);
+	fb_dealloc_cmap(&info->cmap);
+
+	tcx_unmap_regs(op, info, par);
+
+	framebuffer_release(info);
+}
+
+static const struct of_device_id tcx_match[] = {
+	{
+		.name = "SUNW,tcx",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, tcx_match);
+
+static struct platform_driver tcx_driver = {
+	.driver = {
+		.name = "tcx",
+		.of_match_table = tcx_match,
+	},
+	.probe		= tcx_probe,
+	.remove		= tcx_remove,
+};
+
+static int __init tcx_init(void)
+{
+	if (fb_get_options("tcxfb", NULL))
+		return -ENODEV;
+
+	return platform_driver_register(&tcx_driver);
+}
+
+static void __exit tcx_exit(void)
+{
+	platform_driver_unregister(&tcx_driver);
+}
+
+module_init(tcx_init);
+module_exit(tcx_exit);
+
+MODULE_DESCRIPTION("framebuffer driver for TCX chipsets");
+MODULE_AUTHOR("David S. Miller <davem@davemloft.net>");
+MODULE_VERSION("2.0");
+MODULE_LICENSE("GPL");