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, 114 insertions, 0 deletions

diff --git a/arch/m68k/coldfire/m5272.c b/arch/m68k/coldfire/m5272.c
new file mode 100644
index 000000000..bf38cf1a7
--- /dev/null
+++ b/arch/m68k/coldfire/m5272.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/***************************************************************************/
+
+/*
+ *	m5272.c  -- platform support for ColdFire 5272 based boards
+ *
+ *	Copyright (C) 1999-2002, Greg Ungerer (gerg@snapgear.com)
+ *	Copyright (C) 2001-2002, SnapGear Inc. (www.snapgear.com)
+ */
+
+/***************************************************************************/
+
+#include <linux/clkdev.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/phy.h>
+#include <asm/machdep.h>
+#include <asm/coldfire.h>
+#include <asm/mcfsim.h>
+#include <asm/mcfuart.h>
+#include <asm/mcfclk.h>
+
+/***************************************************************************/
+
+/*
+ *	Some platforms need software versions of the GPIO data registers.
+ */
+unsigned short ppdata;
+unsigned char ledbank = 0xff;
+
+/***************************************************************************/
+
+DEFINE_CLK(pll, "pll.0", MCF_CLK);
+DEFINE_CLK(sys, "sys.0", MCF_BUSCLK);
+
+static struct clk_lookup m5272_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("mcftmr.2", NULL, &clk_sys),
+	CLKDEV_INIT("mcftmr.3", NULL, &clk_sys),
+	CLKDEV_INIT("mcfuart.0", NULL, &clk_sys),
+	CLKDEV_INIT("mcfuart.1", NULL, &clk_sys),
+	CLKDEV_INIT("mcfqspi.0", NULL, &clk_sys),
+	CLKDEV_INIT("fec.0", NULL, &clk_sys),
+};
+
+/***************************************************************************/
+
+static void __init m5272_uarts_init(void)
+{
+	u32 v;
+
+	/* Enable the output lines for the serial ports */
+	v = mcf_read32(MCFSIM_PBCNT);
+	v = (v & ~0x000000ff) | 0x00000055;
+	mcf_write32(v, MCFSIM_PBCNT);
+
+	v = mcf_read32(MCFSIM_PDCNT);
+	v = (v & ~0x000003fc) | 0x000002a8;
+	mcf_write32(v, MCFSIM_PDCNT);
+}
+
+/***************************************************************************/
+
+static void m5272_cpu_reset(void)
+{
+	local_irq_disable();
+	/* Set watchdog to reset, and enabled */
+	mcf_write16(0, MCFSIM_WIRR);
+	mcf_write16(1, MCFSIM_WRRR);
+	mcf_write16(0, MCFSIM_WCR);
+	for (;;)
+		/* wait for watchdog to timeout */;
+}
+
+/***************************************************************************/
+
+void __init config_BSP(char *commandp, int size)
+{
+#if defined (CONFIG_MOD5272)
+	/* Set base of device vectors to be 64 */
+	mcf_write8(0x40, MCFSIM_PIVR);
+#endif
+
+#if defined(CONFIG_NETtel) || defined(CONFIG_SCALES)
+	/* Copy command line from FLASH to local buffer... */
+	memcpy(commandp, (char *) 0xf0004000, size);
+	commandp[size-1] = 0;
+#elif defined(CONFIG_CANCam)
+	/* Copy command line from FLASH to local buffer... */
+	memcpy(commandp, (char *) 0xf0010000, size);
+	commandp[size-1] = 0;
+#endif
+
+	mach_reset = m5272_cpu_reset;
+	mach_sched_init = hw_timer_init;
+}
+
+/***************************************************************************/
+
+static int __init init_BSP(void)
+{
+	m5272_uarts_init();
+	clkdev_add_table(m5272_clk_lookup, ARRAY_SIZE(m5272_clk_lookup));
+	return 0;
+}
+
+arch_initcall(init_BSP);
+
+/***************************************************************************/