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, 86 insertions, 0 deletions

diff --git a/drivers/pmdomain/renesas/r8a7795-sysc.c b/drivers/pmdomain/renesas/r8a7795-sysc.c
new file mode 100644
index 000000000..cbe1ff0fc
--- /dev/null
+++ b/drivers/pmdomain/renesas/r8a7795-sysc.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas R-Car H3 System Controller
+ *
+ * Copyright (C) 2016-2017 Glider bvba
+ */
+
+#include <linux/bits.h>
+#include <linux/kernel.h>
+#include <linux/sys_soc.h>
+
+#include <dt-bindings/power/r8a7795-sysc.h>
+
+#include "rcar-sysc.h"
+
+static struct rcar_sysc_area r8a7795_areas[] __initdata = {
+	{ "always-on",	    0, 0, R8A7795_PD_ALWAYS_ON,	-1, PD_ALWAYS_ON },
+	{ "ca57-scu",	0x1c0, 0, R8A7795_PD_CA57_SCU,	R8A7795_PD_ALWAYS_ON,
+	  PD_SCU },
+	{ "ca57-cpu0",	 0x80, 0, R8A7795_PD_CA57_CPU0,	R8A7795_PD_CA57_SCU,
+	  PD_CPU_NOCR },
+	{ "ca57-cpu1",	 0x80, 1, R8A7795_PD_CA57_CPU1,	R8A7795_PD_CA57_SCU,
+	  PD_CPU_NOCR },
+	{ "ca57-cpu2",	 0x80, 2, R8A7795_PD_CA57_CPU2,	R8A7795_PD_CA57_SCU,
+	  PD_CPU_NOCR },
+	{ "ca57-cpu3",	 0x80, 3, R8A7795_PD_CA57_CPU3,	R8A7795_PD_CA57_SCU,
+	  PD_CPU_NOCR },
+	{ "ca53-scu",	0x140, 0, R8A7795_PD_CA53_SCU,	R8A7795_PD_ALWAYS_ON,
+	  PD_SCU },
+	{ "ca53-cpu0",	0x200, 0, R8A7795_PD_CA53_CPU0,	R8A7795_PD_CA53_SCU,
+	  PD_CPU_NOCR },
+	{ "ca53-cpu1",	0x200, 1, R8A7795_PD_CA53_CPU1,	R8A7795_PD_CA53_SCU,
+	  PD_CPU_NOCR },
+	{ "ca53-cpu2",	0x200, 2, R8A7795_PD_CA53_CPU2,	R8A7795_PD_CA53_SCU,
+	  PD_CPU_NOCR },
+	{ "ca53-cpu3",	0x200, 3, R8A7795_PD_CA53_CPU3,	R8A7795_PD_CA53_SCU,
+	  PD_CPU_NOCR },
+	{ "a3vp",	0x340, 0, R8A7795_PD_A3VP,	R8A7795_PD_ALWAYS_ON },
+	{ "cr7",	0x240, 0, R8A7795_PD_CR7,	R8A7795_PD_ALWAYS_ON },
+	{ "a3vc",	0x380, 0, R8A7795_PD_A3VC,	R8A7795_PD_ALWAYS_ON },
+	{ "a2vc1",	0x3c0, 1, R8A7795_PD_A2VC1,	R8A7795_PD_A3VC },
+	{ "3dg-a",	0x100, 0, R8A7795_PD_3DG_A,	R8A7795_PD_ALWAYS_ON },
+	{ "3dg-b",	0x100, 1, R8A7795_PD_3DG_B,	R8A7795_PD_3DG_A },
+	{ "3dg-c",	0x100, 2, R8A7795_PD_3DG_C,	R8A7795_PD_3DG_B },
+	{ "3dg-d",	0x100, 3, R8A7795_PD_3DG_D,	R8A7795_PD_3DG_C },
+	{ "3dg-e",	0x100, 4, R8A7795_PD_3DG_E,	R8A7795_PD_3DG_D },
+	{ "a3ir",	0x180, 0, R8A7795_PD_A3IR,	R8A7795_PD_ALWAYS_ON },
+};
+
+
+	/*
+	 * Fixups for R-Car H3 revisions
+	 */
+
+#define NO_EXTMASK	BIT(1)		/* Missing SYSCEXTMASK register */
+
+static const struct soc_device_attribute r8a7795_quirks_match[] __initconst = {
+	{
+		.soc_id = "r8a7795", .revision = "ES2.*",
+		.data = (void *)(NO_EXTMASK),
+	},
+	{ /* sentinel */ }
+};
+
+static int __init r8a7795_sysc_init(void)
+{
+	const struct soc_device_attribute *attr;
+	u32 quirks = 0;
+
+	attr = soc_device_match(r8a7795_quirks_match);
+	if (attr)
+		quirks = (uintptr_t)attr->data;
+
+	if (quirks & NO_EXTMASK)
+		r8a7795_sysc_info.extmask_val = 0;
+
+	return 0;
+}
+
+struct rcar_sysc_info r8a7795_sysc_info __initdata = {
+	.init = r8a7795_sysc_init,
+	.areas = r8a7795_areas,
+	.num_areas = ARRAY_SIZE(r8a7795_areas),
+	.extmask_offs = 0x2f8,
+	.extmask_val = BIT(0),
+};