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, 136 insertions, 0 deletions

diff --git a/arch/mips/sibyte/Kconfig b/arch/mips/sibyte/Kconfig
new file mode 100644
index 000000000..5fb92fe84
--- /dev/null
+++ b/arch/mips/sibyte/Kconfig
@@ -0,0 +1,136 @@
+# SPDX-License-Identifier: GPL-2.0
+config SIBYTE_SB1250
+	bool
+	select CEVT_SB1250
+	select CSRC_SB1250
+	select HAVE_PCI
+	select IRQ_MIPS_CPU
+	select SIBYTE_ENABLE_LDT_IF_PCI
+	select SIBYTE_HAS_ZBUS_PROFILING
+	select SIBYTE_SB1xxx_SOC
+	select SYS_SUPPORTS_SMP
+
+config SIBYTE_BCM1125
+	bool
+	select CEVT_SB1250
+	select CSRC_SB1250
+	select HAVE_PCI
+	select IRQ_MIPS_CPU
+	select SIBYTE_BCM112X
+	select SIBYTE_HAS_ZBUS_PROFILING
+	select SIBYTE_SB1xxx_SOC
+
+config SIBYTE_BCM112X
+	bool
+	select CEVT_SB1250
+	select CSRC_SB1250
+	select IRQ_MIPS_CPU
+	select SIBYTE_SB1xxx_SOC
+	select SIBYTE_HAS_ZBUS_PROFILING
+
+config SIBYTE_BCM1x80
+	bool
+	select CEVT_BCM1480
+	select CSRC_BCM1480
+	select HAVE_PCI
+	select IRQ_MIPS_CPU
+	select SIBYTE_HAS_ZBUS_PROFILING
+	select SIBYTE_SB1xxx_SOC
+	select SYS_SUPPORTS_SMP
+
+config SIBYTE_SB1xxx_SOC
+	bool
+	select IRQ_MIPS_CPU
+	select SWAP_IO_SPACE
+	select SYS_SUPPORTS_32BIT_KERNEL
+	select SYS_SUPPORTS_64BIT_KERNEL
+	select FW_CFE
+	select SYS_HAS_EARLY_PRINTK
+
+choice
+	prompt "SiByte SOC Stepping"
+	depends on SIBYTE_SB1xxx_SOC
+
+config CPU_SB1_PASS_2_1250
+	bool "1250 An"
+	depends on SIBYTE_SB1250
+	select CPU_SB1_PASS_2
+	help
+	  Also called BCM1250 Pass 2
+
+config CPU_SB1_PASS_2_2
+	bool "1250 Bn"
+	depends on SIBYTE_SB1250
+	select CPU_HAS_PREFETCH
+	help
+	  Also called BCM1250 Pass 2.2
+
+config CPU_SB1_PASS_4
+	bool "1250 Cn"
+	depends on SIBYTE_SB1250
+	select CPU_HAS_PREFETCH
+	help
+	  Also called BCM1250 Pass 3
+
+config CPU_SB1_PASS_2_112x
+	bool "112x Hybrid"
+	depends on SIBYTE_BCM112X
+	select CPU_SB1_PASS_2
+
+config CPU_SB1_PASS_3
+	bool "112x An"
+	depends on SIBYTE_BCM112X
+	select CPU_HAS_PREFETCH
+
+endchoice
+
+config CPU_SB1_PASS_2
+	bool
+
+config SIBYTE_HAS_LDT
+	bool
+
+config SIBYTE_ENABLE_LDT_IF_PCI
+	bool
+	select SIBYTE_HAS_LDT if PCI
+
+config SB1_CEX_ALWAYS_FATAL
+	bool "All cache exceptions considered fatal (no recovery attempted)"
+	depends on SIBYTE_SB1xxx_SOC
+
+config SB1_CERR_STALL
+	bool "Stall (rather than panic) on fatal cache error"
+	depends on SIBYTE_SB1xxx_SOC
+
+config SIBYTE_CFE_CONSOLE
+	bool "Use firmware console"
+	depends on SIBYTE_SB1xxx_SOC
+	help
+	  Use the CFE API's console write routines during boot.  Other console
+	  options (VT console, sb1250 duart console, etc.) should not be
+	  configured.
+
+config SIBYTE_BUS_WATCHER
+	bool "Support for Bus Watcher statistics"
+	depends on SIBYTE_SB1xxx_SOC && \
+		(SIBYTE_BCM112X || SIBYTE_SB1250 || SIBYTE_BCM1x80)
+	help
+	  Handle and keep statistics on the bus error interrupts (COR_ECC,
+	  BAD_ECC, IO_BUS).
+
+config SIBYTE_BW_TRACE
+	bool "Capture bus trace before bus error"
+	depends on SIBYTE_BUS_WATCHER
+	help
+	  Run a continuous bus trace, dumping the raw data as soon as
+	  a ZBbus error is detected.  Cannot work if ZBbus profiling
+	  is turned on, and also will interfere with JTAG-based trace
+	  buffer activity.  Raw buffer data is dumped to console, and
+	  must be processed off-line.
+
+config SIBYTE_TBPROF
+	tristate "Support for ZBbus profiling"
+	depends on SIBYTE_HAS_ZBUS_PROFILING
+
+config SIBYTE_HAS_ZBUS_PROFILING
+	bool