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, 138 insertions, 0 deletions

diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
new file mode 100644
index 000000000..6d2f66810
--- /dev/null
+++ b/drivers/i2c/muxes/Kconfig
@@ -0,0 +1,138 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Multiplexer I2C chip drivers configuration
+#
+
+menu "Multiplexer I2C Chip support"
+	depends on I2C_MUX
+
+config I2C_ARB_GPIO_CHALLENGE
+	tristate "GPIO-based I2C arbitration"
+	depends on GPIOLIB || COMPILE_TEST
+	depends on OF
+	help
+	  If you say yes to this option, support will be included for an
+	  I2C multimaster arbitration scheme using GPIOs and a challenge &
+	  response mechanism where masters have to claim the bus by asserting
+	  a GPIO.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-arb-gpio-challenge.
+
+config I2C_MUX_GPIO
+	tristate "GPIO-based I2C multiplexer"
+	depends on GPIOLIB
+	help
+	  If you say yes to this option, support will be included for a
+	  GPIO based I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which is controlled
+	  through GPIO pins.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-gpio.
+
+config I2C_MUX_GPMUX
+	tristate "General Purpose I2C multiplexer"
+	select MULTIPLEXER
+	depends on OF
+	help
+	  If you say yes to this option, support will be included for a
+	  general purpose I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which in turn is controlled
+	  by a MUX-controller from the MUX subsystem.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-gpmux.
+
+config I2C_MUX_LTC4306
+	tristate "LTC LTC4306/5 I2C multiplexer"
+	select GPIOLIB
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the Analog Devices
+	  LTC4306 or LTC4305 I2C mux/switch devices.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-ltc4306.
+
+config I2C_MUX_PCA9541
+	tristate "NXP PCA9541 I2C Master Selector"
+	help
+	  If you say yes here you get support for the NXP PCA9541
+	  I2C Master Selector.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-pca9541.
+
+config I2C_MUX_PCA954x
+	tristate "NXP PCA954x/PCA984x and Maxim MAX735x/MAX736x I2C Mux/switches"
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  If you say yes here you get support for NXP PCA954x/PCA984x
+	  and Maxim MAX735x/MAX736x I2C mux/switch devices.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-pca954x.
+
+config I2C_MUX_PINCTRL
+	tristate "pinctrl-based I2C multiplexer"
+	depends on PINCTRL
+	depends on OF
+	help
+	  If you say yes to this option, support will be included for an I2C
+	  multiplexer that uses the pinctrl subsystem, i.e. pin multiplexing.
+	  This is useful for SoCs whose I2C module's signals can be routed to
+	  different sets of pins at run-time.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called i2c-mux-pinctrl.
+
+config I2C_MUX_REG
+	tristate "Register-based I2C multiplexer"
+	depends on HAS_IOMEM
+	help
+	  If you say yes to this option, support will be included for a
+	  register based I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which is controlled
+	  by a single register.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-reg.
+
+config I2C_DEMUX_PINCTRL
+	tristate "pinctrl-based I2C demultiplexer"
+	depends on PINCTRL && OF
+	select OF_DYNAMIC
+	help
+	  If you say yes to this option, support will be included for an I2C
+	  demultiplexer that uses the pinctrl subsystem. This is useful if you
+	  want to change the I2C master at run-time depending on features.
+
+config I2C_MUX_MLXCPLD
+	tristate "Mellanox CPLD based I2C multiplexer"
+	help
+	  If you say yes to this option, support will be included for a
+	  CPLD based I2C multiplexer. This driver provides access to
+	  I2C busses connected through a MUX, which is controlled
+	  by a CPLD register.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-mlxcpld.
+
+config I2C_MUX_MULE
+	tristate "Theobroma Systems Mule I2C device multiplexer"
+	depends on OF && SENSORS_AMC6821
+	help
+	  Mule is an MCU that emulates a set of I2C devices, among which
+	  devices that are reachable through an I2C-mux. The devices on the mux
+	  can be selected by writing the appropriate device number to an I2C
+	  configuration register.
+
+	  If you say yes to this option, support will be included for a
+	  Theobroma Systems Mule I2C multiplexer. This driver provides access to
+	  I2C devices connected on this mux.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-mule.
+
+endmenu