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, 416 insertions, 0 deletions

diff --git a/drivers/video/fbdev/macmodes.c b/drivers/video/fbdev/macmodes.c
new file mode 100644
index 000000000..b16a9d9be
--- /dev/null
+++ b/drivers/video/fbdev/macmodes.c
@@ -0,0 +1,416 @@
+/*
+ *  linux/drivers/video/macmodes.c -- Standard MacOS video modes
+ *
+ *	Copyright (C) 1998 Geert Uytterhoeven
+ *
+ *      2000 - Removal of OpenFirmware dependencies by:
+ *      - Ani Joshi
+ *      - Brad Douglas <brad@neruo.com>
+ *
+ *	2001 - Documented with DocBook
+ *	- Brad Douglas <brad@neruo.com>
+ *
+ *  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/errno.h>
+#include <linux/export.h>
+#include <linux/fb.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+#include "macmodes.h"
+
+    /*
+     *  MacOS video mode definitions
+     *
+     *  Order IS important! If you change these, don't forget to update
+     *  mac_modes[] below!
+     */
+
+#define DEFAULT_MODEDB_INDEX	0
+
+static const struct fb_videomode mac_modedb[] = {
+    {
+	/* 512x384, 60Hz, Non-Interlaced (15.67 MHz dot clock) */
+	"mac2", 60, 512, 384, 63828, 80, 16, 19, 1, 32, 3,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 640x480, 60 Hz, Non-Interlaced (25.175 MHz dotclock) */
+	"mac5", 60, 640, 480, 39722, 32, 32, 33, 10, 96, 2,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 640x480, 67Hz, Non-Interlaced (30.0 MHz dotclock) */
+	"mac6", 67, 640, 480, 33334, 80, 80, 39, 3, 64, 3,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 640x870, 75Hz (portrait), Non-Interlaced (57.28 MHz dot clock) */
+	"mac7", 75, 640, 870, 17457, 80, 32, 42, 3, 80, 3,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 800x600, 56 Hz, Non-Interlaced (36.00 MHz dotclock) */
+	"mac9", 56, 800, 600, 27778, 112, 40, 22, 1, 72, 2,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 800x600, 60 Hz, Non-Interlaced (40.00 MHz dotclock) */
+	"mac10", 60, 800, 600, 25000, 72, 56, 23, 1, 128, 4,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 800x600, 72 Hz, Non-Interlaced (50.00 MHz dotclock) */
+	"mac11", 72, 800, 600, 20000, 48, 72, 23, 37, 120, 6,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 800x600, 75 Hz, Non-Interlaced (49.50 MHz dotclock) */
+	"mac12", 75, 800, 600, 20203, 144, 32, 21, 1, 80, 3,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 832x624, 75Hz, Non-Interlaced (57.6 MHz dotclock) */
+	"mac13", 75, 832, 624, 17362, 208, 48, 39, 1, 64, 3,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1024x768, 60 Hz, Non-Interlaced (65.00 MHz dotclock) */
+	"mac14", 60, 1024, 768, 15385, 144, 40, 29, 3, 136, 6,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1024x768, 72 Hz, Non-Interlaced (75.00 MHz dotclock) */
+	"mac15", 72, 1024, 768, 13334, 128, 40, 29, 3, 136, 6,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1024x768, 75 Hz, Non-Interlaced (78.75 MHz dotclock) */
+	"mac16", 75, 1024, 768, 12699, 176, 16, 28, 1, 96, 3,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1024x768, 75 Hz, Non-Interlaced (78.75 MHz dotclock) */
+	"mac17", 75, 1024, 768, 12699, 160, 32, 28, 1, 96, 3,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1152x870, 75 Hz, Non-Interlaced (100.0 MHz dotclock) */
+	"mac18", 75, 1152, 870, 10000, 128, 48, 39, 3, 128, 3,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1280x960, 75 Hz, Non-Interlaced (126.00 MHz dotclock) */
+	"mac19", 75, 1280, 960, 7937, 224, 32, 36, 1, 144, 3,
+	0, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1280x1024, 75 Hz, Non-Interlaced (135.00 MHz dotclock) */
+	"mac20", 75, 1280, 1024, 7408, 232, 64, 38, 1, 112, 3,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1152x768, 60 Hz, Titanium PowerBook */
+	"mac21", 60, 1152, 768, 15386, 158, 26, 29, 3, 136, 6,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }, {
+	/* 1600x1024, 60 Hz, Non-Interlaced (112.27 MHz dotclock) */
+	"mac22", 60, 1600, 1024, 8908, 88, 104, 1, 10, 16, 1,
+	FB_SYNC_HOR_HIGH_ACT|FB_SYNC_VERT_HIGH_ACT, FB_VMODE_NONINTERLACED
+    }
+
+#if 0
+    /* Anyone who has timings for these? */
+    {
+	/* VMODE_512_384_60I: 512x384, 60Hz, Interlaced (NTSC) */
+	"mac1", 60, 512, 384, pixclock, left, right, upper, lower, hslen, vslen,
+	sync, FB_VMODE_INTERLACED
+    }, {
+	/* VMODE_640_480_50I: 640x480, 50Hz, Interlaced (PAL) */
+	"mac3", 50, 640, 480, pixclock, left, right, upper, lower, hslen, vslen,
+	sync, FB_VMODE_INTERLACED
+    }, {
+	/* VMODE_640_480_60I: 640x480, 60Hz, Interlaced (NTSC) */
+	"mac4", 60, 640, 480, pixclock, left, right, upper, lower, hslen, vslen,
+	sync, FB_VMODE_INTERLACED
+    }, {
+	/* VMODE_768_576_50I: 768x576, 50Hz (PAL full frame), Interlaced */
+	"mac8", 50, 768, 576, pixclock, left, right, upper, lower, hslen, vslen,
+	sync, FB_VMODE_INTERLACED
+    },
+#endif
+};
+
+
+    /*
+     *  Mapping between MacOS video mode numbers and video mode definitions
+     *
+     *  These MUST be ordered in
+     *    - increasing resolution
+     *    - decreasing pixel clock period
+     */
+
+static const struct mode_map {
+    int vmode;
+    const struct fb_videomode *mode;
+} mac_modes[] = {
+    /* 512x384 */
+    { VMODE_512_384_60, &mac_modedb[0] },
+    /* 640x480 */
+    { VMODE_640_480_60, &mac_modedb[1] },
+    { VMODE_640_480_67, &mac_modedb[2] },
+    /* 640x870 */
+    { VMODE_640_870_75P, &mac_modedb[3] },
+    /* 800x600 */
+    { VMODE_800_600_56, &mac_modedb[4] },
+    { VMODE_800_600_60, &mac_modedb[5] },
+    { VMODE_800_600_75, &mac_modedb[7] },
+    { VMODE_800_600_72, &mac_modedb[6] },
+    /* 832x624 */
+    { VMODE_832_624_75, &mac_modedb[8] },
+    /* 1024x768 */
+    { VMODE_1024_768_60, &mac_modedb[9] },
+    { VMODE_1024_768_70, &mac_modedb[10] },
+    { VMODE_1024_768_75V, &mac_modedb[11] },
+    { VMODE_1024_768_75, &mac_modedb[12] },
+    /* 1152x768 */
+    { VMODE_1152_768_60, &mac_modedb[16] },
+    /* 1152x870 */
+    { VMODE_1152_870_75, &mac_modedb[13] },
+    /* 1280x960 */
+    { VMODE_1280_960_75, &mac_modedb[14] },
+    /* 1280x1024 */
+    { VMODE_1280_1024_75, &mac_modedb[15] },
+    /* 1600x1024 */
+    { VMODE_1600_1024_60, &mac_modedb[17] },
+    { -1, NULL }
+};
+
+
+    /*
+     *  Mapping between monitor sense values and MacOS video mode numbers
+     */
+
+static const struct monitor_map {
+    int sense;
+    int vmode;
+} mac_monitors[] = {
+    { 0x000, VMODE_1280_1024_75 },	/* 21" RGB */
+    { 0x114, VMODE_640_870_75P },	/* Portrait Monochrome */
+    { 0x221, VMODE_512_384_60 },	/* 12" RGB*/
+    { 0x331, VMODE_1280_1024_75 },	/* 21" RGB (Radius) */
+    { 0x334, VMODE_1280_1024_75 },	/* 21" mono (Radius) */
+    { 0x335, VMODE_1280_1024_75 },	/* 21" mono */
+    { 0x40A, VMODE_640_480_60I },	/* NTSC */
+    { 0x51E, VMODE_640_870_75P },	/* Portrait RGB */
+    { 0x603, VMODE_832_624_75 },	/* 12"-16" multiscan */
+    { 0x60b, VMODE_1024_768_70 },	/* 13"-19" multiscan */
+    { 0x623, VMODE_1152_870_75 },	/* 13"-21" multiscan */
+    { 0x62b, VMODE_640_480_67 },	/* 13"/14" RGB */
+    { 0x700, VMODE_640_480_50I },	/* PAL */
+    { 0x714, VMODE_640_480_60I },	/* NTSC */
+    { 0x717, VMODE_800_600_75 },	/* VGA */
+    { 0x72d, VMODE_832_624_75 },	/* 16" RGB (Goldfish) */
+    { 0x730, VMODE_768_576_50I },	/* PAL (Alternate) */
+    { 0x73a, VMODE_1152_870_75 },	/* 3rd party 19" */
+    { 0x73f, VMODE_640_480_67 },	/* no sense lines connected at all */
+    { 0xBEEF, VMODE_1600_1024_60 },	/* 22" Apple Cinema Display */
+    { -1,    VMODE_640_480_60 },	/* catch-all, must be last */
+};
+
+/**
+ *	mac_vmode_to_var - converts vmode/cmode pair to var structure
+ *	@vmode: MacOS video mode
+ *	@cmode: MacOS color mode
+ *	@var: frame buffer video mode structure
+ *
+ *	Converts a MacOS vmode/cmode pair to a frame buffer video
+ *	mode structure.
+ *
+ *	Returns negative errno on error, or zero for success.
+ *
+ */
+
+int mac_vmode_to_var(int vmode, int cmode, struct fb_var_screeninfo *var)
+{
+    const struct fb_videomode *mode = NULL;
+    const struct mode_map *map;
+
+    for (map = mac_modes; map->vmode != -1; map++)
+	if (map->vmode == vmode) {
+	    mode = map->mode;
+	    break;
+	}
+    if (!mode)
+	return -EINVAL;
+
+    memset(var, 0, sizeof(struct fb_var_screeninfo));
+    switch (cmode) {
+	case CMODE_8:
+	    var->bits_per_pixel = 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;
+	    break;
+
+	case CMODE_16:
+	    var->bits_per_pixel = 16;
+	    var->red.offset = 10;
+	    var->red.length = 5;
+	    var->green.offset = 5;
+	    var->green.length = 5;
+	    var->blue.offset = 0;
+	    var->blue.length = 5;
+	    break;
+
+	case CMODE_32:
+	    var->bits_per_pixel = 32;
+	    var->red.offset = 16;
+	    var->red.length = 8;
+	    var->green.offset = 8;
+	    var->green.length = 8;
+	    var->blue.offset = 0;
+	    var->blue.length = 8;
+	    var->transp.offset = 24;
+	    var->transp.length = 8;
+	    break;
+
+	default:
+	    return -EINVAL;
+    }
+    var->xres = mode->xres;
+    var->yres = mode->yres;
+    var->xres_virtual = mode->xres;
+    var->yres_virtual = mode->yres;
+    var->height = -1;
+    var->width = -1;
+    var->pixclock = mode->pixclock;
+    var->left_margin = mode->left_margin;
+    var->right_margin = mode->right_margin;
+    var->upper_margin = mode->upper_margin;
+    var->lower_margin = mode->lower_margin;
+    var->hsync_len = mode->hsync_len;
+    var->vsync_len = mode->vsync_len;
+    var->sync = mode->sync;
+    var->vmode = mode->vmode;
+    return 0;
+}
+EXPORT_SYMBOL(mac_vmode_to_var);
+
+/**
+ *	mac_var_to_vmode - convert var structure to MacOS vmode/cmode pair
+ *	@var: frame buffer video mode structure
+ *	@vmode: MacOS video mode
+ *	@cmode: MacOS color mode
+ *
+ *	Converts a frame buffer video mode structure to a MacOS
+ *	vmode/cmode pair.
+ *
+ *	Returns negative errno on error, or zero for success.
+ *
+ */
+
+int mac_var_to_vmode(const struct fb_var_screeninfo *var, int *vmode,
+		     int *cmode)
+{
+    const struct mode_map *map;
+
+    if (var->bits_per_pixel <= 8)
+	*cmode = CMODE_8;
+    else if (var->bits_per_pixel <= 16)
+	*cmode = CMODE_16;
+    else if (var->bits_per_pixel <= 32)
+	*cmode = CMODE_32;
+    else
+	return -EINVAL;
+
+    /*
+     * Find the mac_mode with a matching resolution or failing that, the
+     * closest larger resolution. Skip modes with a shorter pixel clock period.
+     */
+    for (map = mac_modes; map->vmode != -1; map++) {
+	const struct fb_videomode *mode = map->mode;
+
+	if (var->xres > mode->xres || var->yres > mode->yres)
+	    continue;
+	if (var->xres_virtual > mode->xres || var->yres_virtual > mode->yres)
+	    continue;
+	if (var->pixclock > mode->pixclock)
+	    continue;
+	if ((var->vmode & FB_VMODE_MASK) != mode->vmode)
+	    continue;
+	*vmode = map->vmode;
+
+	/*
+	 * Having found a good resolution, find the matching pixel clock
+	 * or failing that, the closest longer pixel clock period.
+	 */
+	map++;
+	while (map->vmode != -1) {
+	    const struct fb_videomode *clk_mode = map->mode;
+
+	    if (mode->xres != clk_mode->xres || mode->yres != clk_mode->yres)
+		break;
+	    if (var->pixclock > mode->pixclock)
+	        break;
+	    if (mode->vmode != clk_mode->vmode)
+		continue;
+	    *vmode = map->vmode;
+	    map++;
+	}
+	return 0;
+    }
+    return -EINVAL;
+}
+
+/**
+ *	mac_map_monitor_sense - Convert monitor sense to vmode
+ *	@sense: Macintosh monitor sense number
+ *
+ *	Converts a Macintosh monitor sense number to a MacOS
+ *	vmode number.
+ *
+ *	Returns MacOS vmode video mode number.
+ *
+ */
+
+int mac_map_monitor_sense(int sense)
+{
+    const struct monitor_map *map;
+
+    for (map = mac_monitors; map->sense != -1; map++)
+	if (map->sense == sense)
+	    break;
+    return map->vmode;
+}
+EXPORT_SYMBOL(mac_map_monitor_sense);
+
+/**
+ *	mac_find_mode - find a video mode
+ *	@var: frame buffer user defined part of display
+ *	@info: frame buffer info structure
+ *	@mode_option: video mode name (see mac_modedb[])
+ *	@default_bpp: default color depth in bits per pixel
+ *
+ *	Finds a suitable video mode.  Tries to set mode specified
+ *	by @mode_option.  If the name of the wanted mode begins with
+ *	'mac', the Mac video mode database will be used, otherwise it
+ *	will fall back to the standard video mode database.
+ *
+ *	Note: Function marked as __init and can only be used during
+ *	system boot.
+ *
+ *	Returns error code from fb_find_mode (see fb_find_mode
+ *	function).
+ *
+ */
+
+int mac_find_mode(struct fb_var_screeninfo *var, struct fb_info *info,
+		  const char *mode_option, unsigned int default_bpp)
+{
+    const struct fb_videomode *db = NULL;
+    unsigned int dbsize = 0;
+
+    if (mode_option && !strncmp(mode_option, "mac", 3)) {
+	mode_option += 3;
+	db = mac_modedb;
+	dbsize = ARRAY_SIZE(mac_modedb);
+    }
+    return fb_find_mode(var, info, mode_option, db, dbsize,
+			&mac_modedb[DEFAULT_MODEDB_INDEX], default_bpp);
+}
+EXPORT_SYMBOL(mac_find_mode);
+
+MODULE_DESCRIPTION("MacOS video mode library");
+MODULE_LICENSE("GPL");