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, 145 insertions, 0 deletions

diff --git a/arch/arm/mach-sa1100/clock.c b/arch/arm/mach-sa1100/clock.c
new file mode 100644
index 000000000..eafeb3850
--- /dev/null
+++ b/arch/arm/mach-sa1100/clock.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/arch/arm/mach-sa1100/clock.c
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+
+#include <mach/hardware.h>
+#include <mach/generic.h>
+
+static const char * const clk_tucr_parents[] = {
+	"clk32768", "clk3686400",
+};
+
+static DEFINE_SPINLOCK(tucr_lock);
+
+static int clk_gpio27_enable(struct clk_hw *hw)
+{
+	unsigned long flags;
+
+	/*
+	 * First, set up the 3.6864MHz clock on GPIO 27 for the SA-1111:
+	 * (SA-1110 Developer's Manual, section 9.1.2.1)
+	 */
+	local_irq_save(flags);
+	GAFR |= GPIO_32_768kHz;
+	GPDR |= GPIO_32_768kHz;
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static void clk_gpio27_disable(struct clk_hw *hw)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	GPDR &= ~GPIO_32_768kHz;
+	GAFR &= ~GPIO_32_768kHz;
+	local_irq_restore(flags);
+}
+
+static const struct clk_ops clk_gpio27_ops = {
+	.enable = clk_gpio27_enable,
+	.disable = clk_gpio27_disable,
+};
+
+static const char * const clk_gpio27_parents[] = {
+	"tucr-mux",
+};
+
+static const struct clk_init_data clk_gpio27_init_data __initconst = {
+	.name = "gpio27",
+	.ops = &clk_gpio27_ops,
+	.parent_names = clk_gpio27_parents,
+	.num_parents = ARRAY_SIZE(clk_gpio27_parents),
+};
+
+/*
+ * Derived from the table 8-1 in the SA1110 manual, the MPLL appears to
+ * multiply its input rate by 4 x (4 + PPCR).  This calculation gives
+ * the exact rate.  The figures given in the table are the rates rounded
+ * to 100kHz.  Stick with sa11x0_getspeed() for the time being.
+ */
+static unsigned long clk_mpll_recalc_rate(struct clk_hw *hw,
+	unsigned long prate)
+{
+	return sa11x0_getspeed(0) * 1000;
+}
+
+static const struct clk_ops clk_mpll_ops = {
+	.recalc_rate = clk_mpll_recalc_rate,
+};
+
+static const char * const clk_mpll_parents[] = {
+	"clk3686400",
+};
+
+static const struct clk_init_data clk_mpll_init_data __initconst = {
+	.name = "mpll",
+	.ops = &clk_mpll_ops,
+	.parent_names = clk_mpll_parents,
+	.num_parents = ARRAY_SIZE(clk_mpll_parents),
+	.flags = CLK_GET_RATE_NOCACHE | CLK_IS_CRITICAL,
+};
+
+int __init sa11xx_clk_init(void)
+{
+	struct clk_hw *hw;
+	int ret;
+
+	hw = clk_hw_register_fixed_rate(NULL, "clk32768", NULL, 0, 32768);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	clk_hw_register_clkdev(hw, NULL, "sa1100-rtc");
+
+	hw = clk_hw_register_fixed_rate(NULL, "clk3686400", NULL, 0, 3686400);
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+
+	clk_hw_register_clkdev(hw, "OSTIMER0", NULL);
+
+	hw = kzalloc_obj(*hw);
+	if (!hw)
+		return -ENOMEM;
+	hw->init = &clk_mpll_init_data;
+	ret = clk_hw_register(NULL, hw);
+	if (ret) {
+		kfree(hw);
+		return ret;
+	}
+
+	clk_hw_register_clkdev(hw, NULL, "sa11x0-fb");
+	clk_hw_register_clkdev(hw, NULL, "sa11x0-pcmcia");
+	clk_hw_register_clkdev(hw, NULL, "sa11x0-pcmcia.0");
+	clk_hw_register_clkdev(hw, NULL, "sa11x0-pcmcia.1");
+	clk_hw_register_clkdev(hw, NULL, "1800");
+
+	hw = clk_hw_register_mux(NULL, "tucr-mux", clk_tucr_parents,
+				 ARRAY_SIZE(clk_tucr_parents), 0,
+				 (void __iomem *)&TUCR, FShft(TUCR_TSEL),
+				 FAlnMsk(TUCR_TSEL), 0, &tucr_lock);
+	clk_set_rate(hw->clk, 3686400);
+
+	hw = kzalloc_obj(*hw);
+	if (!hw)
+		return -ENOMEM;
+	hw->init = &clk_gpio27_init_data;
+	ret = clk_hw_register(NULL, hw);
+	if (ret) {
+		kfree(hw);
+		return ret;
+	}
+
+	clk_hw_register_clkdev(hw, NULL, "sa1111.0");
+
+	return 0;
+}