selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 74 insertions, 0 deletions

diff --git a/include/video/broadsheetfb.h b/include/video/broadsheetfb.h
new file mode 100644
index 000000000..548d28f4e
--- /dev/null
+++ b/include/video/broadsheetfb.h
@@ -0,0 +1,74 @@
+/*
+ * broadsheetfb.h - definitions for the broadsheet framebuffer driver
+ *
+ * Copyright (C) 2008 by Jaya Kumar
+ *
+ * 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.
+ *
+ */
+
+#ifndef _LINUX_BROADSHEETFB_H_
+#define _LINUX_BROADSHEETFB_H_
+
+/* Broadsheet command defines */
+#define BS_CMD_INIT_SYS_RUN	0x06
+#define BS_CMD_INIT_DSPE_CFG	0x09
+#define BS_CMD_INIT_DSPE_TMG	0x0A
+#define BS_CMD_INIT_ROTMODE	0x0B
+#define BS_CMD_RD_REG		0x10
+#define BS_CMD_WR_REG		0x11
+#define BS_CMD_LD_IMG		0x20
+#define BS_CMD_LD_IMG_AREA	0x22
+#define BS_CMD_LD_IMG_END	0x23
+#define BS_CMD_WAIT_DSPE_TRG	0x28
+#define BS_CMD_WAIT_DSPE_FREND	0x29
+#define BS_CMD_RD_WFM_INFO	0x30
+#define BS_CMD_UPD_INIT		0x32
+#define BS_CMD_UPD_FULL		0x33
+#define BS_CMD_UPD_GDRV_CLR	0x37
+
+/* Broadsheet register interface defines */
+#define BS_REG_REV		0x00
+#define BS_REG_PRC		0x02
+
+/* Broadsheet pin interface specific defines */
+#define BS_CS	0x01
+#define BS_DC 	0x02
+#define BS_WR 	0x03
+
+/* Broadsheet IO interface specific defines */
+#define BS_MMIO_CMD	0x01
+#define BS_MMIO_DATA	0x02
+
+/* struct used by broadsheet. board specific stuff comes from *board */
+struct broadsheetfb_par {
+	struct fb_info *info;
+	struct broadsheet_board *board;
+	void (*write_reg)(struct broadsheetfb_par *, u16 reg, u16 val);
+	u16 (*read_reg)(struct broadsheetfb_par *, u16 reg);
+	wait_queue_head_t waitq;
+	int panel_index;
+	struct mutex io_lock;
+};
+
+/* board specific routines */
+struct broadsheet_board {
+	struct module *owner;
+	int (*init)(struct broadsheetfb_par *);
+	int (*wait_for_rdy)(struct broadsheetfb_par *);
+	void (*cleanup)(struct broadsheetfb_par *);
+	int (*get_panel_type)(void);
+	int (*setup_irq)(struct fb_info *);
+
+	/* Functions for boards that use GPIO */
+	void (*set_ctl)(struct broadsheetfb_par *, unsigned char, u8);
+	void (*set_hdb)(struct broadsheetfb_par *, u16);
+	u16 (*get_hdb)(struct broadsheetfb_par *);
+
+	/* Functions for boards that have specialized MMIO */
+	void (*mmio_write)(struct broadsheetfb_par *, int type, u16);
+	u16 (*mmio_read)(struct broadsheetfb_par *);
+};
+#endif