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, 50 insertions, 0 deletions

diff --git a/arch/mips/econet/Kconfig b/arch/mips/econet/Kconfig
new file mode 100644
index 000000000..b37b9d25d
--- /dev/null
+++ b/arch/mips/econet/Kconfig
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0
+if ECONET
+
+choice
+	prompt "EcoNet SoC selection"
+	default SOC_ECONET_EN751221
+	help
+	  Select EcoNet MIPS SoC type. Individual SoCs within a family are
+	  very similar, so is it enough to select the right family, and
+	  then customize to the specific SoC using the device tree only.
+
+	config SOC_ECONET_EN751221
+		bool "EN751221 family"
+		select COMMON_CLK
+		select ECONET_EN751221_INTC
+		select HAVE_PCI
+		select IRQ_MIPS_CPU
+		select PCI_DRIVERS_GENERIC
+		select SMP
+		select SMP_UP
+		select SYS_SUPPORTS_SMP
+		help
+		  The EN751221 family includes EN7512, RN7513, EN7521, EN7526.
+		  They are based on single core MIPS 34Kc processors. To boot
+		  this kernel, you will need a device tree such as
+		  MIPS_RAW_APPENDED_DTB=y, and a root filesystem.
+endchoice
+
+choice
+	prompt "Devicetree selection"
+	default DTB_ECONET_NONE
+	help
+	  Select the devicetree.
+
+	config DTB_ECONET_NONE
+		bool "None"
+
+	config DTB_ECONET_SMARTFIBER_XP8421_B
+		bool "EN751221 SmartFiber XP8421-B"
+		depends on SOC_ECONET_EN751221
+		select BUILTIN_DTB
+		help
+		  The SmartFiber XP8421-B is a device based on the EN751221 SoC.
+		  It has 512MB of memory and 256MB of NAND flash. This kernel
+		  needs only an appended initramfs to boot. It can be loaded
+		  through XMODEM and booted from memory in the bootloader, or
+		  it can be packed in tclinux.trx format and written to flash.
+endchoice
+
+endif