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, 72 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/cpu.c b/arch/arm/mach-imx/cpu.c
new file mode 100644
index 000000000..65c7224f5
--- /dev/null
+++ b/arch/arm/mach-imx/cpu.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include "hardware.h"
+#include "common.h"
+
+unsigned int __mxc_cpu_type;
+static unsigned int imx_soc_revision;
+
+void mxc_set_cpu_type(unsigned int type)
+{
+	__mxc_cpu_type = type;
+}
+
+void imx_set_soc_revision(unsigned int rev)
+{
+	imx_soc_revision = rev;
+}
+
+unsigned int imx_get_soc_revision(void)
+{
+	return imx_soc_revision;
+}
+
+void imx_print_silicon_rev(const char *cpu, int srev)
+{
+	if (srev == IMX_CHIP_REVISION_UNKNOWN)
+		pr_info("CPU identified as %s, unknown revision\n", cpu);
+	else
+		pr_info("CPU identified as %s, silicon rev %d.%d\n",
+				cpu, (srev >> 4) & 0xf, srev & 0xf);
+}
+
+void __init imx_set_aips(void __iomem *base)
+{
+	unsigned int reg;
+/*
+ * Set all MPROTx to be non-bufferable, trusted for R/W,
+ * not forced to user-mode.
+ */
+	imx_writel(0x77777777, base + 0x0);
+	imx_writel(0x77777777, base + 0x4);
+
+/*
+ * Set all OPACRx to be non-bufferable, to not require
+ * supervisor privilege level for access, allow for
+ * write access and untrusted master access.
+ */
+	imx_writel(0x0, base + 0x40);
+	imx_writel(0x0, base + 0x44);
+	imx_writel(0x0, base + 0x48);
+	imx_writel(0x0, base + 0x4C);
+	reg = imx_readl(base + 0x50) & 0x00FFFFFF;
+	imx_writel(reg, base + 0x50);
+}
+
+void __init imx_aips_allow_unprivileged_access(
+		const char *compat)
+{
+	void __iomem *aips_base_addr;
+	struct device_node *np;
+
+	for_each_compatible_node(np, NULL, compat) {
+		aips_base_addr = of_iomap(np, 0);
+		WARN_ON(!aips_base_addr);
+		imx_set_aips(aips_base_addr);
+	}
+}