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, 514 insertions, 0 deletions

diff --git a/drivers/video/fbdev/hitfb.c b/drivers/video/fbdev/hitfb.c
new file mode 100644
index 000000000..97db325df
--- /dev/null
+++ b/drivers/video/fbdev/hitfb.c
@@ -0,0 +1,514 @@
+/*
+ * linux/drivers/video/hitfb.c -- Hitachi LCD frame buffer device
+ *
+ * (C) 1999 Mihai Spatar
+ * (C) 2000 YAEGASHI Takeshi
+ * (C) 2003, 2004 Paul Mundt
+ * (C) 2003, 2004, 2006 Andriy Skulysh
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License. See the file COPYING in the main directory of this archive for
+ *  more details.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/fb.h>
+
+#include <asm/machvec.h>
+#include <linux/uaccess.h>
+#include <asm/io.h>
+#include <asm/hd64461.h>
+#include <cpu/dac.h>
+
+#define	WIDTH 640
+
+static struct fb_var_screeninfo hitfb_var = {
+	.activate	= FB_ACTIVATE_NOW,
+	.height		= -1,
+	.width		= -1,
+	.vmode		= FB_VMODE_NONINTERLACED,
+};
+
+static struct fb_fix_screeninfo hitfb_fix = {
+	.id		= "Hitachi HD64461",
+	.type		= FB_TYPE_PACKED_PIXELS,
+	.accel		= FB_ACCEL_NONE,
+};
+
+static volatile void __iomem *hitfb_offset_to_addr(unsigned int offset)
+{
+	return (__force volatile void __iomem *)(uintptr_t)offset;
+}
+
+static u16 hitfb_readw(unsigned int offset)
+{
+	return fb_readw(hitfb_offset_to_addr(offset));
+}
+
+static void hitfb_writew(u16 value, unsigned int offset)
+{
+	fb_writew(value, hitfb_offset_to_addr(offset));
+}
+
+static inline void hitfb_accel_wait(void)
+{
+	while (hitfb_readw(HD64461_GRCFGR) & HD64461_GRCFGR_ACCSTATUS)
+		;
+}
+
+static inline void hitfb_accel_start(int truecolor)
+{
+	if (truecolor) {
+		hitfb_writew(6, HD64461_GRCFGR);
+	} else {
+		hitfb_writew(7, HD64461_GRCFGR);
+	}
+}
+
+static inline void hitfb_accel_set_dest(int truecolor, u16 dx, u16 dy,
+					u16 width, u16 height)
+{
+	u32 saddr = WIDTH * dy + dx;
+	if (truecolor)
+		saddr <<= 1;
+
+	hitfb_writew(width-1, HD64461_BBTDWR);
+	hitfb_writew(height-1, HD64461_BBTDHR);
+
+	hitfb_writew(saddr & 0xffff, HD64461_BBTDSARL);
+	hitfb_writew(saddr >> 16, HD64461_BBTDSARH);
+
+}
+
+static inline void hitfb_accel_bitblt(int truecolor, u16 sx, u16 sy, u16 dx,
+				      u16 dy, u16 width, u16 height, u16 rop,
+				      u32 mask_addr)
+{
+	u32 saddr, daddr;
+	u32 maddr = 0;
+
+	height--;
+	width--;
+	hitfb_writew(rop, HD64461_BBTROPR);
+	if ((sy < dy) || ((sy == dy) && (sx <= dx))) {
+		saddr = WIDTH * (sy + height) + sx + width;
+		daddr = WIDTH * (dy + height) + dx + width;
+		if (mask_addr) {
+			if (truecolor)
+				maddr = ((width >> 3) + 1) * (height + 1) - 1;
+			else
+				maddr =
+				    (((width >> 4) + 1) * (height + 1) - 1) * 2;
+
+			hitfb_writew((1 << 5) | 1, HD64461_BBTMDR);
+		} else
+			hitfb_writew(1, HD64461_BBTMDR);
+	} else {
+		saddr = WIDTH * sy + sx;
+		daddr = WIDTH * dy + dx;
+		if (mask_addr) {
+			hitfb_writew((1 << 5), HD64461_BBTMDR);
+		} else {
+			hitfb_writew(0, HD64461_BBTMDR);
+		}
+	}
+	if (truecolor) {
+		saddr <<= 1;
+		daddr <<= 1;
+	}
+	hitfb_writew(width, HD64461_BBTDWR);
+	hitfb_writew(height, HD64461_BBTDHR);
+	hitfb_writew(saddr & 0xffff, HD64461_BBTSSARL);
+	hitfb_writew(saddr >> 16, HD64461_BBTSSARH);
+	hitfb_writew(daddr & 0xffff, HD64461_BBTDSARL);
+	hitfb_writew(daddr >> 16, HD64461_BBTDSARH);
+	if (mask_addr) {
+		maddr += mask_addr;
+		hitfb_writew(maddr & 0xffff, HD64461_BBTMARL);
+		hitfb_writew(maddr >> 16, HD64461_BBTMARH);
+	}
+	hitfb_accel_start(truecolor);
+}
+
+static void hitfb_fillrect(struct fb_info *p, const struct fb_fillrect *rect)
+{
+	if (rect->rop != ROP_COPY)
+		cfb_fillrect(p, rect);
+	else {
+		hitfb_accel_wait();
+		hitfb_writew(0x00f0, HD64461_BBTROPR);
+		hitfb_writew(16, HD64461_BBTMDR);
+
+		if (p->var.bits_per_pixel == 16) {
+			hitfb_writew(((u32 *) (p->pseudo_palette))[rect->color],
+				  HD64461_GRSCR);
+			hitfb_accel_set_dest(1, rect->dx, rect->dy, rect->width,
+					     rect->height);
+			hitfb_accel_start(1);
+		} else {
+			hitfb_writew(rect->color, HD64461_GRSCR);
+			hitfb_accel_set_dest(0, rect->dx, rect->dy, rect->width,
+					     rect->height);
+			hitfb_accel_start(0);
+		}
+	}
+}
+
+static void hitfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
+{
+	hitfb_accel_wait();
+	hitfb_accel_bitblt(p->var.bits_per_pixel == 16, area->sx, area->sy,
+			   area->dx, area->dy, area->width, area->height,
+			   0x00cc, 0);
+}
+
+static int hitfb_pan_display(struct fb_var_screeninfo *var,
+			     struct fb_info *info)
+{
+	int xoffset = var->xoffset;
+	int yoffset = var->yoffset;
+
+	if (xoffset != 0)
+		return -EINVAL;
+
+	hitfb_writew((yoffset*info->fix.line_length)>>10, HD64461_LCDCBAR);
+
+	return 0;
+}
+
+static int hitfb_blank(int blank_mode, struct fb_info *info)
+{
+	unsigned short v;
+
+	if (blank_mode) {
+		v = hitfb_readw(HD64461_LDR1);
+		v &= ~HD64461_LDR1_DON;
+		hitfb_writew(v, HD64461_LDR1);
+
+		v = hitfb_readw(HD64461_LCDCCR);
+		v |= HD64461_LCDCCR_MOFF;
+		hitfb_writew(v, HD64461_LCDCCR);
+
+		v = hitfb_readw(HD64461_STBCR);
+		v |= HD64461_STBCR_SLCDST;
+		hitfb_writew(v, HD64461_STBCR);
+	} else {
+		v = hitfb_readw(HD64461_STBCR);
+		v &= ~HD64461_STBCR_SLCDST;
+		hitfb_writew(v, HD64461_STBCR);
+
+		v = hitfb_readw(HD64461_LCDCCR);
+		v &= ~(HD64461_LCDCCR_MOFF | HD64461_LCDCCR_STREQ);
+		hitfb_writew(v, HD64461_LCDCCR);
+
+		do {
+		    v = hitfb_readw(HD64461_LCDCCR);
+		} while(v&HD64461_LCDCCR_STBACK);
+
+		v = hitfb_readw(HD64461_LDR1);
+		v |= HD64461_LDR1_DON;
+		hitfb_writew(v, HD64461_LDR1);
+	}
+	return 0;
+}
+
+static int hitfb_setcolreg(unsigned regno, unsigned red, unsigned green,
+			   unsigned blue, unsigned transp, struct fb_info *info)
+{
+	if (regno >= 256)
+		return 1;
+
+	switch (info->var.bits_per_pixel) {
+	case 8:
+		hitfb_writew(regno << 8, HD64461_CPTWAR);
+		hitfb_writew(red >> 10, HD64461_CPTWDR);
+		hitfb_writew(green >> 10, HD64461_CPTWDR);
+		hitfb_writew(blue >> 10, HD64461_CPTWDR);
+		break;
+	case 16:
+		if (regno >= 16)
+			return 1;
+		((u32 *) (info->pseudo_palette))[regno] =
+		    ((red & 0xf800)) |
+		    ((green & 0xfc00) >> 5) | ((blue & 0xf800) >> 11);
+		break;
+	}
+	return 0;
+}
+
+static int hitfb_sync(struct fb_info *info)
+{
+	hitfb_accel_wait();
+
+	return 0;
+}
+
+static int hitfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
+{
+	int maxy;
+
+	var->xres = info->var.xres;
+	var->xres_virtual = info->var.xres;
+	var->yres = info->var.yres;
+
+	if ((var->bits_per_pixel != 8) && (var->bits_per_pixel != 16))
+		var->bits_per_pixel = info->var.bits_per_pixel;
+
+	if (var->yres_virtual < var->yres)
+		var->yres_virtual = var->yres;
+
+	maxy = info->fix.smem_len / var->xres;
+
+	if (var->bits_per_pixel == 16)
+		maxy /= 2;
+
+	if (var->yres_virtual > maxy)
+		var->yres_virtual = maxy;
+
+	var->xoffset = 0;
+	var->yoffset = 0;
+
+	switch (var->bits_per_pixel) {
+	case 8:
+		var->red.offset = 0;
+		var->red.length = 8;
+		var->green.offset = 0;
+		var->green.length = 8;
+		var->blue.offset = 0;
+		var->blue.length = 8;
+		var->transp.offset = 0;
+		var->transp.length = 0;
+		break;
+	case 16:		/* RGB 565 */
+		var->red.offset = 11;
+		var->red.length = 5;
+		var->green.offset = 5;
+		var->green.length = 6;
+		var->blue.offset = 0;
+		var->blue.length = 5;
+		var->transp.offset = 0;
+		var->transp.length = 0;
+		break;
+	}
+
+	return 0;
+}
+
+static int hitfb_set_par(struct fb_info *info)
+{
+	unsigned short ldr3;
+
+	switch (info->var.bits_per_pixel) {
+	case 8:
+		info->fix.line_length = info->var.xres;
+		info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
+		info->fix.ypanstep = 16;
+		break;
+	case 16:
+		info->fix.line_length = info->var.xres*2;
+		info->fix.visual = FB_VISUAL_TRUECOLOR;
+		info->fix.ypanstep = 8;
+		break;
+	}
+
+	hitfb_writew(info->fix.line_length, HD64461_LCDCLOR);
+	ldr3 = hitfb_readw(HD64461_LDR3);
+	ldr3 &= ~15;
+	ldr3 |= (info->var.bits_per_pixel == 8) ? 4 : 8;
+	hitfb_writew(ldr3, HD64461_LDR3);
+	return 0;
+}
+
+static const struct fb_ops hitfb_ops = {
+	.owner		= THIS_MODULE,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
+	.fb_check_var	= hitfb_check_var,
+	.fb_set_par	= hitfb_set_par,
+	.fb_setcolreg	= hitfb_setcolreg,
+	.fb_blank	= hitfb_blank,
+	.fb_sync	= hitfb_sync,
+	.fb_pan_display = hitfb_pan_display,
+	.fb_fillrect	= hitfb_fillrect,
+	.fb_copyarea	= hitfb_copyarea,
+	.fb_imageblit	= cfb_imageblit,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
+};
+
+static int hitfb_probe(struct platform_device *dev)
+{
+	unsigned short lcdclor, ldr3, ldvndr;
+	struct fb_info *info;
+	int ret;
+
+	if (fb_get_options("hitfb", NULL))
+		return -ENODEV;
+
+	hitfb_fix.mmio_start = HD64461_IO_OFFSET(0x1000);
+	hitfb_fix.mmio_len = 0x1000;
+	hitfb_fix.smem_start = HD64461_IO_OFFSET(0x02000000);
+	hitfb_fix.smem_len = 512 * 1024;
+
+	lcdclor = hitfb_readw(HD64461_LCDCLOR);
+	ldvndr = hitfb_readw(HD64461_LDVNDR);
+	ldr3 = hitfb_readw(HD64461_LDR3);
+
+	switch (ldr3 & 15) {
+	default:
+	case 4:
+		hitfb_var.bits_per_pixel = 8;
+		hitfb_var.xres = lcdclor;
+		break;
+	case 8:
+		hitfb_var.bits_per_pixel = 16;
+		hitfb_var.xres = lcdclor / 2;
+		break;
+	}
+	hitfb_fix.line_length = lcdclor;
+	hitfb_fix.visual = (hitfb_var.bits_per_pixel == 8) ?
+	    FB_VISUAL_PSEUDOCOLOR : FB_VISUAL_TRUECOLOR;
+	hitfb_var.yres = ldvndr + 1;
+	hitfb_var.xres_virtual = hitfb_var.xres;
+	hitfb_var.yres_virtual = hitfb_fix.smem_len / lcdclor;
+	switch (hitfb_var.bits_per_pixel) {
+	case 8:
+		hitfb_var.red.offset = 0;
+		hitfb_var.red.length = 8;
+		hitfb_var.green.offset = 0;
+		hitfb_var.green.length = 8;
+		hitfb_var.blue.offset = 0;
+		hitfb_var.blue.length = 8;
+		hitfb_var.transp.offset = 0;
+		hitfb_var.transp.length = 0;
+		break;
+	case 16:		/* RGB 565 */
+		hitfb_var.red.offset = 11;
+		hitfb_var.red.length = 5;
+		hitfb_var.green.offset = 5;
+		hitfb_var.green.length = 6;
+		hitfb_var.blue.offset = 0;
+		hitfb_var.blue.length = 5;
+		hitfb_var.transp.offset = 0;
+		hitfb_var.transp.length = 0;
+		break;
+	}
+
+	info = framebuffer_alloc(sizeof(u32) * 16, &dev->dev);
+	if (unlikely(!info))
+		return -ENOMEM;
+
+	info->fbops = &hitfb_ops;
+	info->var = hitfb_var;
+	info->fix = hitfb_fix;
+	info->pseudo_palette = info->par;
+	info->flags = FBINFO_HWACCEL_YPAN |
+		FBINFO_HWACCEL_FILLRECT | FBINFO_HWACCEL_COPYAREA;
+
+	info->screen_base = (char __iomem *)(uintptr_t)hitfb_fix.smem_start;
+
+	ret = fb_alloc_cmap(&info->cmap, 256, 0);
+	if (unlikely(ret < 0))
+		goto err_fb;
+
+	ret = register_framebuffer(info);
+	if (unlikely(ret < 0))
+		goto err;
+
+	platform_set_drvdata(dev, info);
+
+	fb_info(info, "%s frame buffer device\n", info->fix.id);
+
+	return 0;
+
+err:
+	fb_dealloc_cmap(&info->cmap);
+err_fb:
+	framebuffer_release(info);
+	return ret;
+}
+
+static void hitfb_remove(struct platform_device *dev)
+{
+	struct fb_info *info = platform_get_drvdata(dev);
+
+	unregister_framebuffer(info);
+	fb_dealloc_cmap(&info->cmap);
+	framebuffer_release(info);
+}
+
+static int hitfb_suspend(struct device *dev)
+{
+	u16 v;
+
+	hitfb_blank(1, NULL);
+	v = hitfb_readw(HD64461_STBCR);
+	v |= HD64461_STBCR_SLCKE_IST;
+	hitfb_writew(v, HD64461_STBCR);
+
+	return 0;
+}
+
+static int hitfb_resume(struct device *dev)
+{
+	u16 v;
+
+	v = hitfb_readw(HD64461_STBCR);
+	v &= ~HD64461_STBCR_SLCKE_OST;
+	msleep(100);
+	v = hitfb_readw(HD64461_STBCR);
+	v &= ~HD64461_STBCR_SLCKE_IST;
+	hitfb_writew(v, HD64461_STBCR);
+	hitfb_blank(0, NULL);
+
+	return 0;
+}
+
+static const struct dev_pm_ops hitfb_dev_pm_ops = {
+	.suspend	= hitfb_suspend,
+	.resume		= hitfb_resume,
+};
+
+static struct platform_driver hitfb_driver = {
+	.probe		= hitfb_probe,
+	.remove		= hitfb_remove,
+	.driver		= {
+		.name	= "hitfb",
+		.pm	= &hitfb_dev_pm_ops,
+	},
+};
+
+static struct platform_device hitfb_device = {
+	.name	= "hitfb",
+	.id	= -1,
+};
+
+static int __init hitfb_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&hitfb_driver);
+	if (!ret) {
+		ret = platform_device_register(&hitfb_device);
+		if (ret)
+			platform_driver_unregister(&hitfb_driver);
+	}
+	return ret;
+}
+
+
+static void __exit hitfb_exit(void)
+{
+	platform_device_unregister(&hitfb_device);
+	platform_driver_unregister(&hitfb_driver);
+}
+
+module_init(hitfb_init);
+module_exit(hitfb_exit);
+
+MODULE_LICENSE("GPL");