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, 109 insertions, 0 deletions

diff --git a/arch/arm/mach-omap1/io.c b/arch/arm/mach-omap1/io.c
new file mode 100644
index 000000000..1f20fe99b
--- /dev/null
+++ b/arch/arm/mach-omap1/io.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/arch/arm/mach-omap1/io.c
+ *
+ * OMAP1 I/O mapping code
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/omap-dma.h>
+
+#include <asm/tlb.h>
+#include <asm/mach/map.h>
+
+#include "tc.h"
+#include "iomap.h"
+#include "common.h"
+
+/*
+ * The machine specific code may provide the extra mapping besides the
+ * default mapping provided here.
+ */
+static struct map_desc omap1_io_desc[] __initdata = {
+	{
+		.virtual	= OMAP1_IO_VIRT,
+		.pfn		= __phys_to_pfn(OMAP1_IO_PHYS),
+		.length		= OMAP1_IO_SIZE,
+		.type		= MT_DEVICE
+	}, {
+		.virtual	= OMAP1_DSP_BASE,
+		.pfn		= __phys_to_pfn(OMAP1_DSP_START),
+		.length		= OMAP1_DSP_SIZE,
+		.type		= MT_DEVICE
+	}, {
+		.virtual	= OMAP1_DSPREG_BASE,
+		.pfn		= __phys_to_pfn(OMAP1_DSPREG_START),
+		.length		= OMAP1_DSPREG_SIZE,
+		.type		= MT_DEVICE
+	}
+};
+
+/*
+ * Maps common IO regions for omap1
+ */
+void __init omap1_map_io(void)
+{
+	iotable_init(omap1_io_desc, ARRAY_SIZE(omap1_io_desc));
+}
+
+/*
+ * Common low-level hardware init for omap1.
+ */
+void __init omap1_init_early(void)
+{
+	omap_check_revision();
+
+	/* REVISIT: Refer to OMAP5910 Errata, Advisory SYS_1: "Timeout Abort
+	 * on a Posted Write in the TIPB Bridge".
+	 */
+	omap_writew(0x0, MPU_PUBLIC_TIPB_CNTL);
+	omap_writew(0x0, MPU_PRIVATE_TIPB_CNTL);
+}
+
+void __init omap1_init_late(void)
+{
+	omap_serial_wakeup_init();
+}
+
+/*
+ * NOTE: Please use ioremap + __raw_read/write where possible instead of these
+ */
+
+u8 omap_readb(u32 pa)
+{
+	return __raw_readb(OMAP1_IO_ADDRESS(pa));
+}
+EXPORT_SYMBOL(omap_readb);
+
+u16 omap_readw(u32 pa)
+{
+	return __raw_readw(OMAP1_IO_ADDRESS(pa));
+}
+EXPORT_SYMBOL(omap_readw);
+
+u32 omap_readl(u32 pa)
+{
+	return __raw_readl(OMAP1_IO_ADDRESS(pa));
+}
+EXPORT_SYMBOL(omap_readl);
+
+void omap_writeb(u8 v, u32 pa)
+{
+	__raw_writeb(v, OMAP1_IO_ADDRESS(pa));
+}
+EXPORT_SYMBOL(omap_writeb);
+
+void omap_writew(u16 v, u32 pa)
+{
+	__raw_writew(v, OMAP1_IO_ADDRESS(pa));
+}
+EXPORT_SYMBOL(omap_writew);
+
+void omap_writel(u32 v, u32 pa)
+{
+	__raw_writel(v, OMAP1_IO_ADDRESS(pa));
+}
+EXPORT_SYMBOL(omap_writel);