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, 144 insertions, 0 deletions

diff --git a/arch/mips/bcm63xx/dev-pcmcia.c b/arch/mips/bcm63xx/dev-pcmcia.c
new file mode 100644
index 000000000..9496cd236
--- /dev/null
+++ b/arch/mips/bcm63xx/dev-pcmcia.c
@@ -0,0 +1,144 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2008 Maxime Bizon <mbizon@freebox.fr>
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <asm/bootinfo.h>
+#include <linux/platform_device.h>
+#include <bcm63xx_cs.h>
+#include <bcm63xx_cpu.h>
+#include <bcm63xx_dev_pcmcia.h>
+#include <bcm63xx_io.h>
+#include <bcm63xx_regs.h>
+
+static struct resource pcmcia_resources[] = {
+	/* pcmcia registers */
+	{
+		/* start & end filled at runtime */
+		.flags		= IORESOURCE_MEM,
+	},
+
+	/* pcmcia memory zone resources */
+	{
+		.start		= BCM_PCMCIA_COMMON_BASE_PA,
+		.end		= BCM_PCMCIA_COMMON_END_PA,
+		.flags		= IORESOURCE_MEM,
+	},
+	{
+		.start		= BCM_PCMCIA_ATTR_BASE_PA,
+		.end		= BCM_PCMCIA_ATTR_END_PA,
+		.flags		= IORESOURCE_MEM,
+	},
+	{
+		.start		= BCM_PCMCIA_IO_BASE_PA,
+		.end		= BCM_PCMCIA_IO_END_PA,
+		.flags		= IORESOURCE_MEM,
+	},
+
+	/* PCMCIA irq */
+	{
+		/* start filled at runtime */
+		.flags		= IORESOURCE_IRQ,
+	},
+
+	/* declare PCMCIA IO resource also */
+	{
+		.start		= BCM_PCMCIA_IO_BASE_PA,
+		.end		= BCM_PCMCIA_IO_END_PA,
+		.flags		= IORESOURCE_IO,
+	},
+};
+
+static struct bcm63xx_pcmcia_platform_data pd;
+
+static struct platform_device bcm63xx_pcmcia_device = {
+	.name		= "bcm63xx_pcmcia",
+	.id		= 0,
+	.num_resources	= ARRAY_SIZE(pcmcia_resources),
+	.resource	= pcmcia_resources,
+	.dev		= {
+		.platform_data = &pd,
+	},
+};
+
+static int __init config_pcmcia_cs(unsigned int cs,
+				   u32 base, unsigned int size)
+{
+	int ret;
+
+	ret = bcm63xx_set_cs_status(cs, 0);
+	if (!ret)
+		ret = bcm63xx_set_cs_base(cs, base, size);
+	if (!ret)
+		ret = bcm63xx_set_cs_status(cs, 1);
+	return ret;
+}
+
+static const struct {
+	unsigned int	cs;
+	unsigned int	base;
+	unsigned int	size;
+} pcmcia_cs[3] __initconst = {
+	{
+		.cs	= MPI_CS_PCMCIA_COMMON,
+		.base	= BCM_PCMCIA_COMMON_BASE_PA,
+		.size	= BCM_PCMCIA_COMMON_SIZE
+	},
+	{
+		.cs	= MPI_CS_PCMCIA_ATTR,
+		.base	= BCM_PCMCIA_ATTR_BASE_PA,
+		.size	= BCM_PCMCIA_ATTR_SIZE
+	},
+	{
+		.cs	= MPI_CS_PCMCIA_IO,
+		.base	= BCM_PCMCIA_IO_BASE_PA,
+		.size	= BCM_PCMCIA_IO_SIZE
+	},
+};
+
+int __init bcm63xx_pcmcia_register(void)
+{
+	int ret, i;
+
+	if (!BCMCPU_IS_6348() && !BCMCPU_IS_6358())
+		return 0;
+
+	/* use correct pcmcia ready gpio depending on processor */
+	switch (bcm63xx_get_cpu_id()) {
+	case BCM6348_CPU_ID:
+		pd.ready_gpio = 22;
+		break;
+
+	case BCM6358_CPU_ID:
+		pd.ready_gpio = 18;
+		break;
+
+	default:
+		return -ENODEV;
+	}
+
+	pcmcia_resources[0].start = bcm63xx_regset_address(RSET_PCMCIA);
+	pcmcia_resources[0].end = pcmcia_resources[0].start +
+		RSET_PCMCIA_SIZE - 1;
+	pcmcia_resources[4].start = bcm63xx_get_irq_number(IRQ_PCMCIA);
+
+	/* configure pcmcia chip selects */
+	for (i = 0; i < 3; i++) {
+		ret = config_pcmcia_cs(pcmcia_cs[i].cs,
+				       pcmcia_cs[i].base,
+				       pcmcia_cs[i].size);
+		if (ret)
+			goto out_err;
+	}
+
+	return platform_device_register(&bcm63xx_pcmcia_device);
+
+out_err:
+	pr_err("unable to set pcmcia chip select\n");
+	return ret;
+}