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, 70 insertions, 0 deletions

diff --git a/arch/m68k/sun3/intersil.c b/arch/m68k/sun3/intersil.c
new file mode 100644
index 000000000..29674cfa9
--- /dev/null
+++ b/arch/m68k/sun3/intersil.c
@@ -0,0 +1,70 @@
+/*
+ * arch/m68k/sun3/intersil.c
+ *
+ * basic routines for accessing the intersil clock within the sun3 machines
+ *
+ * started 11/12/1999 Sam Creasey
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/rtc.h>
+
+#include <asm/errno.h>
+#include <asm/intersil.h>
+#include <asm/machdep.h>
+
+#include "sun3.h"
+
+/* bits to set for start/run of the intersil */
+#define STOP_VAL (INTERSIL_STOP | INTERSIL_INT_ENABLE | INTERSIL_24H_MODE)
+#define START_VAL (INTERSIL_RUN | INTERSIL_INT_ENABLE | INTERSIL_24H_MODE)
+
+/* get/set hwclock */
+
+int sun3_hwclk(int set, struct rtc_time *t)
+{
+	volatile struct intersil_dt *todintersil;
+	unsigned long flags;
+
+        todintersil = (struct intersil_dt *) &intersil_clock->counter;
+
+	local_irq_save(flags);
+
+	intersil_clock->cmd_reg = STOP_VAL;
+
+	/* set or read the clock */
+	if(set) {
+		todintersil->csec = 0;
+		todintersil->hour = t->tm_hour;
+		todintersil->minute = t->tm_min;
+		todintersil->second = t->tm_sec;
+		todintersil->month = t->tm_mon + 1;
+		todintersil->day = t->tm_mday;
+		todintersil->year = (t->tm_year - 68) % 100;
+		todintersil->weekday = t->tm_wday;
+	} else {
+		/* read clock */
+		t->tm_sec = todintersil->csec;
+		t->tm_hour = todintersil->hour;
+		t->tm_min = todintersil->minute;
+		t->tm_sec = todintersil->second;
+		t->tm_mon = todintersil->month - 1;
+		t->tm_mday = todintersil->day;
+		t->tm_year = todintersil->year + 68;
+		t->tm_wday = todintersil->weekday;
+		if (t->tm_year < 70)
+			t->tm_year += 100;
+	}
+
+	intersil_clock->cmd_reg = START_VAL;
+
+	local_irq_restore(flags);
+
+	return 0;
+
+}
+