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, 61 insertions, 0 deletions

diff --git a/arch/mips/generic/irq.c b/arch/mips/generic/irq.c
new file mode 100644
index 000000000..933119262
--- /dev/null
+++ b/arch/mips/generic/irq.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2016 Imagination Technologies
+ * Author: Paul Burton <paul.burton@mips.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clocksource.h>
+#include <linux/init.h>
+#include <linux/types.h>
+
+#include <asm/irq.h>
+#include <asm/mips-cps.h>
+#include <asm/time.h>
+
+int get_c0_fdc_int(void)
+{
+	int mips_cpu_fdc_irq;
+
+	if (mips_gic_present())
+		mips_cpu_fdc_irq = gic_get_c0_fdc_int();
+	else if (cpu_has_veic)
+		panic("Unimplemented!");
+	else if (cp0_fdc_irq >= 0)
+		mips_cpu_fdc_irq = MIPS_CPU_IRQ_BASE + cp0_fdc_irq;
+	else
+		mips_cpu_fdc_irq = -1;
+
+	return mips_cpu_fdc_irq;
+}
+
+int get_c0_perfcount_int(void)
+{
+	int mips_cpu_perf_irq;
+
+	if (mips_gic_present())
+		mips_cpu_perf_irq = gic_get_c0_perfcount_int();
+	else if (cpu_has_veic)
+		panic("Unimplemented!");
+	else if (cp0_perfcount_irq >= 0)
+		mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
+	else
+		mips_cpu_perf_irq = -1;
+
+	return mips_cpu_perf_irq;
+}
+
+unsigned int get_c0_compare_int(void)
+{
+	int mips_cpu_timer_irq;
+
+	if (mips_gic_present())
+		mips_cpu_timer_irq = gic_get_c0_compare_int();
+	else if (cpu_has_veic)
+		panic("Unimplemented!");
+	else
+		mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
+
+	return mips_cpu_timer_irq;
+}