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, 68 insertions, 0 deletions

diff --git a/arch/m68k/coldfire/m5206.c b/arch/m68k/coldfire/m5206.c
new file mode 100644
index 000000000..eff7d56bb
--- /dev/null
+++ b/arch/m68k/coldfire/m5206.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/***************************************************************************/
+
+/*
+ *	m5206.c  -- platform support for ColdFire 5206 based boards
+ *
+ *	Copyright (C) 1999-2002, Greg Ungerer (gerg@snapgear.com)
+ * 	Copyright (C) 2000-2001, Lineo Inc. (www.lineo.com) 
+ */
+
+/***************************************************************************/
+
+#include <linux/clkdev.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <asm/machdep.h>
+#include <asm/coldfire.h>
+#include <asm/mcfsim.h>
+#include <asm/mcfclk.h>
+
+/***************************************************************************/
+
+DEFINE_CLK(pll, "pll.0", MCF_CLK);
+DEFINE_CLK(sys, "sys.0", MCF_BUSCLK);
+
+static struct clk_lookup m5206_clk_lookup[] = {
+	CLKDEV_INIT(NULL, "pll.0", &clk_pll),
+	CLKDEV_INIT(NULL, "sys.0", &clk_sys),
+	CLKDEV_INIT("mcftmr.0", NULL, &clk_sys),
+	CLKDEV_INIT("mcftmr.1", NULL, &clk_sys),
+	CLKDEV_INIT("mcfuart.0", NULL, &clk_sys),
+	CLKDEV_INIT("mcfuart.1", NULL, &clk_sys),
+	CLKDEV_INIT("imx1-i2c.0", NULL, &clk_sys),
+};
+
+/***************************************************************************/
+
+static void __init m5206_i2c_init(void)
+{
+#if IS_ENABLED(CONFIG_I2C_IMX)
+	mcf_write8(MCFSIM_ICR_AUTOVEC | MCFSIM_ICR_LEVEL5 | MCFSIM_ICR_PRI0,
+	       MCFSIM_I2CICR);
+	mcf_mapirq2imr(MCF_IRQ_I2C0, MCFINTC_I2C);
+#endif /* IS_ENABLED(CONFIG_I2C_IMX) */
+}
+
+void __init config_BSP(char *commandp, int size)
+{
+#if defined(CONFIG_NETtel)
+	/* Copy command line from FLASH to local buffer... */
+	memcpy(commandp, (char *) 0xf0004000, size);
+	commandp[size-1] = 0;
+#endif /* CONFIG_NETtel */
+
+	mach_sched_init = hw_timer_init;
+
+	/* Only support the external interrupts on their primary level */
+	mcf_mapirq2imr(25, MCFINTC_EINT1);
+	mcf_mapirq2imr(28, MCFINTC_EINT4);
+	mcf_mapirq2imr(31, MCFINTC_EINT7);
+	m5206_i2c_init();
+
+	clkdev_add_table(m5206_clk_lookup, ARRAY_SIZE(m5206_clk_lookup));
+}
+
+/***************************************************************************/