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, 99 insertions, 0 deletions

diff --git a/arch/powerpc/boot/pq2.c b/arch/powerpc/boot/pq2.c
new file mode 100644
index 000000000..de27f1c07
--- /dev/null
+++ b/arch/powerpc/boot/pq2.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PowerQUICC II support functions
+ *
+ * Author: Scott Wood <scottwood@freescale.com>
+ *
+ * Copyright (c) 2007 Freescale Semiconductor, Inc.
+ */
+
+#include "ops.h"
+#include "types.h"
+#include "fsl-soc.h"
+#include "pq2.h"
+#include "stdio.h"
+#include "io.h"
+
+#define PQ2_SCCR (0x10c80/4) /* System Clock Configuration Register */
+#define PQ2_SCMR (0x10c88/4) /* System Clock Mode Register */
+
+static int pq2_corecnf_map[] = {
+	3, 2, 2, 2, 4, 4, 5, 9, 6, 11, 8, 10, 3, 12, 7, -1,
+	6, 5, 13, 2, 14, 4, 15, 9, 0, 11, 8, 10, 16, 12, 7, -1
+};
+
+/* Get various clocks from crystal frequency.
+ * Returns zero on failure and non-zero on success.
+ */
+int pq2_get_clocks(u32 crystal, u32 *sysfreq, u32 *corefreq,
+                   u32 *timebase, u32 *brgfreq)
+{
+	u32 *immr;
+	u32 sccr, scmr, mainclk, busclk;
+	int corecnf, busdf, plldf, pllmf, dfbrg;
+
+	immr = fsl_get_immr();
+	if (!immr) {
+		printf("pq2_get_clocks: Couldn't get IMMR base.\r\n");
+		return 0;
+	}
+
+	sccr = in_be32(&immr[PQ2_SCCR]);
+	scmr = in_be32(&immr[PQ2_SCMR]);
+
+	dfbrg = sccr & 3;
+	corecnf = (scmr >> 24) & 0x1f;
+	busdf = (scmr >> 20) & 0xf;
+	plldf = (scmr >> 12) & 1;
+	pllmf = scmr & 0xfff;
+
+	mainclk = crystal * (pllmf + 1) / (plldf + 1);
+	busclk = mainclk / (busdf + 1);
+
+	if (sysfreq)
+		*sysfreq = mainclk / 2;
+	if (timebase)
+		*timebase = busclk / 4;
+	if (brgfreq)
+		*brgfreq = mainclk / (1 << ((dfbrg + 1) * 2));
+
+	if (corefreq) {
+		int coremult = pq2_corecnf_map[corecnf];
+
+		if (coremult < 0)
+			*corefreq = mainclk / 2;
+		else if (coremult == 0)
+			return 0;
+		else
+			*corefreq = busclk * coremult / 2;
+	}
+
+	return 1;
+}
+
+/* Set common device tree fields based on the given clock frequencies. */
+void pq2_set_clocks(u32 sysfreq, u32 corefreq, u32 timebase, u32 brgfreq)
+{
+	void *node;
+
+	dt_fixup_cpu_clocks(corefreq, timebase, sysfreq);
+
+	node = finddevice("/soc/cpm");
+	if (node)
+		setprop(node, "clock-frequency", &sysfreq, 4);
+
+	node = finddevice("/soc/cpm/brg");
+	if (node)
+		setprop(node, "clock-frequency", &brgfreq, 4);
+}
+
+int pq2_fixup_clocks(u32 crystal)
+{
+	u32 sysfreq, corefreq, timebase, brgfreq;
+
+	if (!pq2_get_clocks(crystal, &sysfreq, &corefreq, &timebase, &brgfreq))
+		return 0;
+
+	pq2_set_clocks(sysfreq, corefreq, timebase, brgfreq);
+	return 1;
+}