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, 48 insertions, 0 deletions

diff --git a/arch/arm/mach-omap1/serial.h b/arch/arm/mach-omap1/serial.h
new file mode 100644
index 000000000..4700e384c
--- /dev/null
+++ b/arch/arm/mach-omap1/serial.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2009 Texas Instruments
+ * Added OMAP4 support- Santosh Shilimkar <santosh.shilimkar@ti.com>
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __ASM_ARCH_SERIAL_H
+#define __ASM_ARCH_SERIAL_H
+
+#include <linux/init.h>
+
+/*
+ * Memory entry used for the DEBUG_LL UART configuration, relative to
+ * start of RAM. See also uncompress.h and debug-macro.S.
+ *
+ * Note that using a memory location for storing the UART configuration
+ * has at least two limitations:
+ *
+ * 1. Kernel uncompress code cannot overlap OMAP_UART_INFO as the
+ *    uncompress code could then partially overwrite itself
+ * 2. We assume printascii is called at least once before paging_init,
+ *    and addruart has a chance to read OMAP_UART_INFO
+ */
+#define OMAP_UART_INFO_OFS	0x3ffc
+
+#define OMAP_PORT_SHIFT		2
+#define OMAP7XX_PORT_SHIFT	0
+
+#define OMAP1510_BASE_BAUD	(12000000/16)
+#define OMAP16XX_BASE_BAUD	(48000000/16)
+
+/*
+ * DEBUG_LL port encoding stored into the UART1 scratchpad register by
+ * decomp_setup in uncompress.h
+ */
+#define OMAP1UART1		11
+#define OMAP1UART2		12
+#define OMAP1UART3		13
+
+#ifndef __ASSEMBLER__
+extern void omap_serial_init(void);
+#endif
+
+#endif