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, 76 insertions, 0 deletions

diff --git a/arch/m68k/sun3x/config.c b/arch/m68k/sun3x/config.c
new file mode 100644
index 000000000..798ea72a0
--- /dev/null
+++ b/arch/m68k/sun3x/config.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Setup kernel for a Sun3x machine
+ *
+ * (C) 1999 Thomas Bogendoerfer (tsbogend@alpha.franken.de)
+ *
+ * based on code from Oliver Jowett <oliver@jowett.manawatu.gen.nz>
+ */
+
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/seq_file.h>
+#include <linux/console.h>
+#include <linux/init.h>
+
+#include <asm/machdep.h>
+#include <asm/irq.h>
+#include <asm/sun3xprom.h>
+#include <asm/sun3ints.h>
+#include <asm/setup.h>
+#include <asm/oplib.h>
+#include <asm/config.h>
+
+#include "time.h"
+#include "../sun3/sun3.h"
+
+volatile char *clock_va;
+
+void sun3_leds(unsigned char byte)
+{
+
+}
+
+static void sun3x_get_hardware_list(struct seq_file *m)
+{
+	seq_printf(m, "PROM Revision:\t%s\n", romvec->pv_monid);
+}
+
+/*
+ *  Setup the sun3x configuration info
+ */
+void __init config_sun3x(void)
+{
+
+	sun3x_prom_init();
+
+	mach_sched_init      = sun3x_sched_init;
+	mach_init_IRQ        = sun3_init_IRQ;
+
+	mach_reset           = sun3x_reboot;
+
+	mach_hwclk           = sun3x_hwclk;
+	mach_get_model       = sun3_get_model;
+	mach_get_hardware_list = sun3x_get_hardware_list;
+
+	sun3_intreg = (unsigned char *)SUN3X_INTREG;
+
+	/* only the serial console is known to work anyway... */
+#if 0
+	switch (*(unsigned char *)SUN3X_EEPROM_CONS) {
+	case 0x10:
+		serial_console = 1;
+		conswitchp = NULL;
+		break;
+	case 0x11:
+		serial_console = 2;
+		conswitchp = NULL;
+		break;
+	default:
+		serial_console = 0;
+		break;
+	}
+#endif
+
+}
+