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, 112 insertions, 0 deletions

diff --git a/drivers/video/fbdev/sm712.h b/drivers/video/fbdev/sm712.h
new file mode 100644
index 000000000..83fe25fc6
--- /dev/null
+++ b/drivers/video/fbdev/sm712.h
@@ -0,0 +1,112 @@
+/*
+ * Silicon Motion SM712 frame buffer device
+ *
+ * Copyright (C) 2006 Silicon Motion Technology Corp.
+ * Authors:	Ge Wang, gewang@siliconmotion.com
+ *		Boyod boyod.yang@siliconmotion.com.cn
+ *
+ * Copyright (C) 2009 Lemote, Inc.
+ * Author: Wu Zhangjin, wuzhangjin@gmail.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.
+ */
+
+#define FB_ACCEL_SMI_LYNX 88
+
+#define SCREEN_X_RES          1024
+#define SCREEN_Y_RES_PC       768
+#define SCREEN_Y_RES_NETBOOK  600
+#define SCREEN_BPP            16
+
+#define dac_reg	(0x3c8)
+#define dac_val	(0x3c9)
+
+extern void __iomem *smtc_regbaseaddress;
+#define smtc_mmiowb(dat, reg)	writeb(dat, smtc_regbaseaddress + reg)
+
+#define smtc_mmiorb(reg)	readb(smtc_regbaseaddress + reg)
+
+#define SIZE_SR00_SR04      (0x04 - 0x00 + 1)
+#define SIZE_SR10_SR24      (0x24 - 0x10 + 1)
+#define SIZE_SR30_SR75      (0x75 - 0x30 + 1)
+#define SIZE_SR80_SR93      (0x93 - 0x80 + 1)
+#define SIZE_SRA0_SRAF      (0xAF - 0xA0 + 1)
+#define SIZE_GR00_GR08      (0x08 - 0x00 + 1)
+#define SIZE_AR00_AR14      (0x14 - 0x00 + 1)
+#define SIZE_CR00_CR18      (0x18 - 0x00 + 1)
+#define SIZE_CR30_CR4D      (0x4D - 0x30 + 1)
+#define SIZE_CR90_CRA7      (0xA7 - 0x90 + 1)
+
+static inline void smtc_crtcw(int reg, int val)
+{
+	smtc_mmiowb(reg, 0x3d4);
+	smtc_mmiowb(val, 0x3d5);
+}
+
+static inline void smtc_grphw(int reg, int val)
+{
+	smtc_mmiowb(reg, 0x3ce);
+	smtc_mmiowb(val, 0x3cf);
+}
+
+static inline void smtc_attrw(int reg, int val)
+{
+	smtc_mmiorb(0x3da);
+	smtc_mmiowb(reg, 0x3c0);
+	smtc_mmiorb(0x3c1);
+	smtc_mmiowb(val, 0x3c0);
+}
+
+static inline void smtc_seqw(int reg, int val)
+{
+	smtc_mmiowb(reg, 0x3c4);
+	smtc_mmiowb(val, 0x3c5);
+}
+
+static inline unsigned int smtc_seqr(int reg)
+{
+	smtc_mmiowb(reg, 0x3c4);
+	return smtc_mmiorb(0x3c5);
+}
+
+/* The next structure holds all information relevant for a specific video mode.
+ */
+
+struct modeinit {
+	int mmsizex;
+	int mmsizey;
+	int bpp;
+	int hz;
+	unsigned char init_misc;
+	unsigned char init_sr00_sr04[SIZE_SR00_SR04];
+	unsigned char init_sr10_sr24[SIZE_SR10_SR24];
+	unsigned char init_sr30_sr75[SIZE_SR30_SR75];
+	unsigned char init_sr80_sr93[SIZE_SR80_SR93];
+	unsigned char init_sra0_sraf[SIZE_SRA0_SRAF];
+	unsigned char init_gr00_gr08[SIZE_GR00_GR08];
+	unsigned char init_ar00_ar14[SIZE_AR00_AR14];
+	unsigned char init_cr00_cr18[SIZE_CR00_CR18];
+	unsigned char init_cr30_cr4d[SIZE_CR30_CR4D];
+	unsigned char init_cr90_cra7[SIZE_CR90_CRA7];
+};
+
+#ifdef __BIG_ENDIAN
+#define pal_rgb(r, g, b, val)	(((r & 0xf800) >> 8) | \
+				((g & 0xe000) >> 13) | \
+				((g & 0x1c00) << 3) | \
+				((b & 0xf800) >> 3))
+#define big_addr		0x800000
+#define mmio_addr		0x00800000
+#define seqw17()		smtc_seqw(0x17, 0x30)
+#define big_pixel_depth(p, d)	{if (p == 24) {p = 32; d = 32; } }
+#define big_swap(p)		(((p & 0xff00ff00) >> 8) | ((p & 0x00ff00ff) << 8))
+#else
+#define pal_rgb(r, g, b, val)	val
+#define big_addr		0
+#define mmio_addr		0x00c00000
+#define seqw17()		do { } while (0)
+#define big_pixel_depth(p, d)	do { } while (0)
+#define big_swap(p)		p
+#endif