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, 55 insertions, 0 deletions

diff --git a/arch/arm/mach-mediatek/mediatek.c b/arch/arm/mach-mediatek/mediatek.c
new file mode 100644
index 000000000..fd3a8834f
--- /dev/null
+++ b/arch/arm/mach-mediatek/mediatek.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Device Tree support for Mediatek SoCs
+ *
+ * Copyright (c) 2014 MundoReader S.L.
+ * Author: Matthias Brugger <matthias.bgg@gmail.com>
+ */
+#include <linux/init.h>
+#include <linux/io.h>
+#include <asm/mach/arch.h>
+#include <linux/of.h>
+#include <linux/of_clk.h>
+#include <linux/clocksource.h>
+
+
+#define GPT6_CON_MT65xx 0x10008060
+#define GPT_ENABLE      0x31
+
+static void __init mediatek_timer_init(void)
+{
+	void __iomem *gpt_base;
+
+	if (of_machine_is_compatible("mediatek,mt6589") ||
+	    of_machine_is_compatible("mediatek,mt7623") ||
+	    of_machine_is_compatible("mediatek,mt8135") ||
+	    of_machine_is_compatible("mediatek,mt8127")) {
+		/* turn on GPT6 which ungates arch timer clocks */
+		gpt_base = ioremap(GPT6_CON_MT65xx, 0x04);
+
+		/* enable clock and set to free-run */
+		writel(GPT_ENABLE, gpt_base);
+		iounmap(gpt_base);
+	}
+
+	of_clk_init(NULL);
+	timer_probe();
+};
+
+static const char * const mediatek_board_dt_compat[] = {
+	"mediatek,mt2701",
+	"mediatek,mt6572",
+	"mediatek,mt6582",
+	"mediatek,mt6589",
+	"mediatek,mt6592",
+	"mediatek,mt7623",
+	"mediatek,mt7629",
+	"mediatek,mt8127",
+	"mediatek,mt8135",
+	NULL,
+};
+
+DT_MACHINE_START(MEDIATEK_DT, "Mediatek Cortex-A7 (Device Tree)")
+	.dt_compat	= mediatek_board_dt_compat,
+	.init_time	= mediatek_timer_init,
+MACHINE_END