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>

4 files changed, 135 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
diff --git a/arch/mips/econet/Makefile b/arch/mips/econet/Makefile
new file mode 100644
index 000000000..7e4529e7d
--- /dev/null
+++ b/arch/mips/econet/Makefile
@@ -0,0 +1,2 @@
+
+obj-y := init.o
diff --git a/arch/mips/econet/Platform b/arch/mips/econet/Platform
new file mode 100644
index 000000000..ea5616447
--- /dev/null
+++ b/arch/mips/econet/Platform
@@ -0,0 +1,5 @@
+# To address a 7.2MB kernel size limit in the EcoNet SDK bootloader,
+# we put the load address well above where the bootloader loads and then use
+# zboot. So please set CONFIG_ZBOOT_LOAD_ADDRESS to the address where your
+# bootloader actually places the kernel.
+load-$(CONFIG_ECONET)	+= 0xffffffff81000000
diff --git a/arch/mips/econet/init.c b/arch/mips/econet/init.c
new file mode 100644
index 000000000..6f43ffb20
--- /dev/null
+++ b/arch/mips/econet/init.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * EcoNet setup code
+ *
+ * Copyright (C) 2025 Caleb James DeLisle <cjd@cjdns.fr>
+ */
+
+#include <linux/init.h>
+#include <linux/of_clk.h>
+#include <linux/irqchip.h>
+
+#include <asm/addrspace.h>
+#include <asm/io.h>
+#include <asm/bootinfo.h>
+#include <asm/time.h>
+#include <asm/prom.h>
+#include <asm/smp-ops.h>
+#include <asm/reboot.h>
+
+#define CR_AHB_RSTCR		((void __iomem *)CKSEG1ADDR(0x1fb00040))
+#define RESET			BIT(31)
+
+#define UART_BASE		CKSEG1ADDR(0x1fbf0003)
+#define UART_REG_SHIFT		2
+
+static void hw_reset(char *command)
+{
+	iowrite32(RESET, CR_AHB_RSTCR);
+}
+
+/* 1. Bring up early printk. */
+void __init prom_init(void)
+{
+	setup_8250_early_printk_port(UART_BASE, UART_REG_SHIFT, 0);
+	_machine_restart = hw_reset;
+}
+
+/* 2. Parse the DT and find memory */
+void __init plat_mem_setup(void)
+{
+	void *dtb;
+
+	set_io_port_base(KSEG1);
+
+	dtb = get_fdt();
+	if (!dtb)
+		panic("no dtb found");
+
+	__dt_setup_arch(dtb);
+
+	early_init_dt_scan_memory();
+}
+
+/* 3. Overload __weak device_tree_init(), add SMP_UP ops */
+void __init device_tree_init(void)
+{
+	unflatten_and_copy_device_tree();
+
+	register_up_smp_ops();
+}
+
+const char *get_system_type(void)
+{
+	return "EcoNet-EN75xx";
+}
+
+/* 4. Initialize the IRQ subsystem */
+void __init arch_init_irq(void)
+{
+	irqchip_init();
+}
+
+/* 5. Timers */
+void __init plat_time_init(void)
+{
+	of_clk_init(NULL);
+	timer_probe();
+}