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, 91 insertions, 0 deletions

diff --git a/arch/microblaze/configs/mmu_defconfig b/arch/microblaze/configs/mmu_defconfig
new file mode 100644
index 000000000..fbbdcb394
--- /dev/null
+++ b/arch/microblaze/configs/mmu_defconfig
@@ -0,0 +1,91 @@
+CONFIG_SYSVIPC=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_AUDIT=y
+CONFIG_IKCONFIG=y
+CONFIG_IKCONFIG_PROC=y
+CONFIG_EXPERT=y
+CONFIG_BASE_SMALL=y
+CONFIG_KALLSYMS_ALL=y
+CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR=1
+CONFIG_XILINX_MICROBLAZE0_USE_PCMP_INSTR=1
+CONFIG_XILINX_MICROBLAZE0_USE_BARREL=1
+CONFIG_XILINX_MICROBLAZE0_USE_DIV=1
+CONFIG_XILINX_MICROBLAZE0_USE_HW_MUL=2
+CONFIG_XILINX_MICROBLAZE0_USE_FPU=2
+CONFIG_HZ_100=y
+CONFIG_CMDLINE_BOOL=y
+CONFIG_CMDLINE_FORCE=y
+CONFIG_HIGHMEM=y
+CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
+CONFIG_PARTITION_ADVANCED=y
+# CONFIG_EFI_PARTITION is not set
+CONFIG_CMA=y
+CONFIG_NET=y
+CONFIG_PACKET=y
+CONFIG_UNIX=y
+CONFIG_INET=y
+CONFIG_IP_PNP=y
+CONFIG_IP_PNP_DHCP=y
+CONFIG_IP_PNP_BOOTP=y
+CONFIG_IP_PNP_RARP=y
+# CONFIG_IPV6 is not set
+CONFIG_BRIDGE=m
+CONFIG_PCI=y
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_MTD=y
+CONFIG_MTD_CFI=y
+CONFIG_MTD_CFI_INTELEXT=y
+CONFIG_MTD_CFI_AMDSTD=y
+CONFIG_BLK_DEV_RAM=y
+CONFIG_BLK_DEV_RAM_SIZE=8192
+CONFIG_NETDEVICES=y
+CONFIG_XILINX_EMACLITE=y
+CONFIG_XILINX_AXI_EMAC=y
+CONFIG_XILINX_LL_TEMAC=y
+CONFIG_MARVELL_PHY=y
+# CONFIG_INPUT is not set
+# CONFIG_SERIO is not set
+# CONFIG_VT is not set
+CONFIG_SERIAL_8250=y
+CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_OF_PLATFORM=y
+CONFIG_SERIAL_UARTLITE=y
+CONFIG_SERIAL_UARTLITE_CONSOLE=y
+# CONFIG_HW_RANDOM is not set
+CONFIG_XILINX_HWICAP=y
+CONFIG_I2C=y
+CONFIG_I2C_XILINX=y
+CONFIG_SPI=y
+CONFIG_SPI_XILINX=y
+CONFIG_GPIOLIB=y
+CONFIG_GPIO_SYSFS=y
+CONFIG_GPIO_XILINX=y
+CONFIG_POWER_RESET=y
+CONFIG_POWER_RESET_GPIO_RESTART=y
+# CONFIG_HWMON is not set
+CONFIG_WATCHDOG=y
+CONFIG_XILINX_WATCHDOG=y
+CONFIG_FB=y
+CONFIG_FB_XILINX=y
+# CONFIG_USB_SUPPORT is not set
+CONFIG_UIO=y
+CONFIG_UIO_PDRV_GENIRQ=y
+CONFIG_UIO_DMEM_GENIRQ=y
+CONFIG_EXT4_FS=y
+# CONFIG_DNOTIFY is not set
+CONFIG_TMPFS=y
+CONFIG_CRAMFS=y
+CONFIG_ROMFS_FS=y
+CONFIG_NFS_FS=y
+CONFIG_ROOT_NFS=y
+CONFIG_CIFS=y
+CONFIG_ENCRYPTED_KEYS=y
+CONFIG_DMA_CMA=y
+CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
+CONFIG_KGDB=y
+CONFIG_KGDB_TESTS=y
+CONFIG_KGDB_KDB=y
+CONFIG_DETECT_HUNG_TASK=y
+CONFIG_DEBUG_SPINLOCK=y