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, 84 insertions, 0 deletions

diff --git a/arch/arm/mach-omap1/fb.c b/arch/arm/mach-omap1/fb.c
new file mode 100644
index 000000000..b6e952b03
--- /dev/null
+++ b/arch/arm/mach-omap1/fb.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * File: arch/arm/plat-omap/fb.c
+ *
+ * Framebuffer device registration for TI OMAP platforms
+ *
+ * Copyright (C) 2006 Nokia Corporation
+ * Author: Imre Deak <imre.deak@nokia.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/memblock.h>
+#include <linux/io.h>
+#include <linux/omapfb.h>
+#include <linux/dma-mapping.h>
+#include <linux/irq.h>
+
+#include <asm/mach/map.h>
+
+#include "irqs.h"
+
+#if IS_ENABLED(CONFIG_FB_OMAP)
+
+static bool omapfb_lcd_configured;
+static struct omapfb_platform_data omapfb_config;
+
+static u64 omap_fb_dma_mask = ~(u32)0;
+
+static struct resource omap_fb_resources[] = {
+	{
+		.name  = "irq",
+		.start = INT_LCD_CTRL,
+		.flags = IORESOURCE_IRQ,
+	},
+	{
+		.name  = "irq",
+		.start = INT_SOSSI_MATCH,
+		.flags = IORESOURCE_IRQ,
+	},
+};
+
+static struct platform_device omap_fb_device = {
+	.name		= "omapfb",
+	.id		= -1,
+	.dev = {
+		.dma_mask		= &omap_fb_dma_mask,
+		.coherent_dma_mask	= DMA_BIT_MASK(32),
+		.platform_data		= &omapfb_config,
+	},
+	.num_resources = ARRAY_SIZE(omap_fb_resources),
+	.resource = omap_fb_resources,
+};
+
+void __init omapfb_set_lcd_config(const struct omap_lcd_config *config)
+{
+	omapfb_config.lcd = *config;
+	omapfb_lcd_configured = true;
+}
+
+static int __init omap_init_fb(void)
+{
+	/*
+	 * If the board file has not set the lcd config with
+	 * omapfb_set_lcd_config(), don't bother registering the omapfb device
+	 */
+	if (!omapfb_lcd_configured)
+		return 0;
+
+	return platform_device_register(&omap_fb_device);
+}
+
+arch_initcall(omap_init_fb);
+
+#else
+
+void __init omapfb_set_lcd_config(const struct omap_lcd_config *config)
+{
+}
+
+#endif