diff options
27 files changed, 593 insertions, 173 deletions
diff --git a/Documentation/driver-api/firmware/built-in-fw.rst b/Documentation/driver-api/firmware/built-in-fw.rst
new file mode 100644
index 000000000000..7300e66857f8
--- /dev/null
+++ b/Documentation/driver-api/firmware/built-in-fw.rst
@@ -0,0 +1,38 @@
+Built-in firmware
+Firmware can be built-in to the kernel, this means building the firmware
+into vmlinux directly, to enable avoiding having to look for firmware from
+the filesystem. Instead, firmware can be looked for inside the kernel
+directly. You can enable built-in firmware using the kernel configuration
+This should not be confused with CONFIG_FIRMWARE_IN_KERNEL, this is for drivers
+which enables firmware to be built as part of the kernel build process. This
+option, CONFIG_FIRMWARE_IN_KERNEL, will build all firmware for all drivers
+enabled which ship its firmware inside the Linux kernel source tree.
+There are a few reasons why you might want to consider building your firmware
+into the kernel with CONFIG_EXTRA_FIRMWARE though:
+* Speed
+* Firmware is needed for accessing the boot device, and the user doesn't
+ want to stuff the firmware into the boot initramfs.
+Even if you have these needs there are a few reasons why you may not be
+able to make use of built-in firmware:
+* Legalese - firmware is non-GPL compatible
+* Some firmware may be optional
+* Firmware upgrades are possible, therefore a new firmware would implicate
+ a complete kernel rebuild.
+* Some firmware files may be really large in size. The remote-proc subsystem
+ is an example subsystem which deals with these sorts of firmware
+* The firmware may need to be scraped out from some device specific location
+ dynamically, an example is calibration data for for some WiFi chipsets. This
+ calibration data can be unique per sold device.
diff --git a/Documentation/driver-api/firmware/core.rst b/Documentation/driver-api/firmware/core.rst
new file mode 100644
index 000000000000..1d1688cbc078
--- /dev/null
+++ b/Documentation/driver-api/firmware/core.rst
@@ -0,0 +1,16 @@
+Firmware API core features
+The firmware API has a rich set of core features available. This section
+documents these features.
+.. toctree::
+ fw_search_path
+ built-in-fw
+ firmware_cache
+ direct-fs-lookup
+ fallback-mechanisms
+ lookup-order
diff --git a/Documentation/driver-api/firmware/direct-fs-lookup.rst b/Documentation/driver-api/firmware/direct-fs-lookup.rst
new file mode 100644
index 000000000000..82b4d585a213
--- /dev/null
+++ b/Documentation/driver-api/firmware/direct-fs-lookup.rst
@@ -0,0 +1,30 @@
+Direct filesystem lookup
+Direct filesystem lookup is the most common form of firmware lookup performed
+by the kernel. The kernel looks for the firmware directly on the root
+filesystem in the paths documented in the section 'Firmware search paths'.
+The filesystem lookup is implemented in fw_get_filesystem_firmware(), it
+uses common core kernel file loader facility kernel_read_file_from_path().
+The max path allowed is PATH_MAX -- currently this is 4096 characters.
+It is recommended you keep /lib/firmware paths on your root filesystem,
+avoid having a separate partition for them in order to avoid possible
+races with lookups and avoid uses of the custom fallback mechanisms
+documented below.
+Firmware and initramfs
+Drivers which are built-in to the kernel should have the firmware integrated
+also as part of the initramfs used to boot the kernel given that otherwise
+a race is possible with loading the driver and the real rootfs not yet being
+available. Stuffing the firmware into initramfs resolves this race issue,
+however note that using initrd does not suffice to address the same race.
+There are circumstances that justify not wanting to include firmware into
+initramfs, such as dealing with large firmware firmware files for the
+remote-proc subsystem. For such cases using a userspace fallback mechanism
+is currently the only viable solution as only userspace can know for sure
+when the real rootfs is ready and mounted.
diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst
new file mode 100644
index 000000000000..d19354794e67
--- /dev/null
+++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst
@@ -0,0 +1,195 @@
+Fallback mechanisms
+A fallback mechanism is supported to allow to overcome failures to do a direct
+filesystem lookup on the root filesystem or when the firmware simply cannot be
+installed for practical reasons on the root filesystem. The kernel
+configuration options related to supporting the firmware fallback mechanism are:
+ * CONFIG_FW_LOADER_USER_HELPER: enables building the firmware fallback
+ mechanism. Most distributions enable this option today. If enabled but
+ CONFIG_FW_LOADER_USER_HELPER_FALLBACK is disabled, only the custom fallback
+ mechanism is available and for the request_firmware_nowait() call.
+ * CONFIG_FW_LOADER_USER_HELPER_FALLBACK: force enables each request to
+ enable the kobject uevent fallback mechanism on all firmware API calls
+ except request_firmware_direct(). Most distributions disable this option
+ today. The call request_firmware_nowait() allows for one alternative
+ fallback mechanism: if this kconfig option is enabled and your second
+ argument to request_firmware_nowait(), uevent, is set to false you are
+ informing the kernel that you have a custom fallback mechanism and it will
+ manually load the firmware. Read below for more details.
+Note that this means when having this configuration:
+the kobject uevent fallback mechanism will never take effect even
+for request_firmware_nowait() when uevent is set to true.
+Justifying the firmware fallback mechanism
+Direct filesystem lookups may fail for a variety of reasons. Known reasons for
+this are worth itemizing and documenting as it justifies the need for the
+fallback mechanism:
+* Race against access with the root filesystem upon bootup.
+* Races upon resume from suspend. This is resolved by the firmware cache, but
+ the firmware cache is only supported if you use uevents, and its not
+ supported for request_firmware_into_buf().
+* Firmware is not accessible through typical means:
+ * It cannot be installed into the root filesystem
+ * The firmware provides very unique device specific data tailored for
+ the unit gathered with local information. An example is calibration
+ data for WiFi chipsets for mobile devices. This calibration data is
+ not common to all units, but tailored per unit. Such information may
+ be installed on a separate flash partition other than where the root
+ filesystem is provided.
+Types of fallback mechanisms
+There are really two fallback mechanisms available using one shared sysfs
+interface as a loading facility:
+* Kobject uevent fallback mechanism
+* Custom fallback mechanism
+First lets document the shared sysfs loading facility.
+Firmware sysfs loading facility
+In order to help device drivers upload firmware using a fallback mechanism
+the firmware infrastructure creates a sysfs interface to enable userspace
+to load and indicate when firmware is ready. The sysfs directory is created
+via fw_create_instance(). This call creates a new struct device named after
+the firmware requested, and establishes it in the device hierarchy by
+associating the device used to make the request as the device's parent.
+The sysfs directory's file attributes are defined and controlled through
+the new device's class (firmare_class) and group (fw_dev_attr_groups).
+This is actually where the original firmware_class.c file name comes from,
+as originally the only firmware loading mechanism available was the
+mechanism we now use as a fallback mechanism.
+To load firmware using the sysfs interface we expose a loading indicator,
+and a file upload firmware into:
+ * /sys/$DEVPATH/loading
+ * /sys/$DEVPATH/data
+To upload firmware you will echo 1 onto the loading file to indicate
+you are loading firmware. You then cat the firmware into the data file,
+and you notify the kernel the firmware is ready by echo'ing 0 onto
+the loading file.
+The firmware device used to help load firmware using sysfs is only created if
+direct firmware loading fails and if the fallback mechanism is enabled for your
+firmware request, this is set up with fw_load_from_user_helper(). It is
+important to re-iterate that no device is created if a direct filesystem lookup
+ echo 1 > /sys/$DEVPATH/loading
+Will clean any previous partial load at once and make the firmware API
+return an error. When loading firmware the firmware_class grows a buffer
+for the firmware in PAGE_SIZE increments to hold the image as it comes in.
+firmware_data_read() and firmware_loading_show() are just provided for the
+test_firmware driver for testing, they are not called in normal use or
+expected to be used regularly by userspace.
+Firmware kobject uevent fallback mechanism
+Since a device is created for the sysfs interface to help load firmware as a
+fallback mechanism userspace can be informed of the addition of the device by
+relying on kobject uevents. The addition of the device into the device
+hierarchy means the fallback mechanism for firmware loading has been initiated.
+For details of implementation refer to _request_firmware_load(), in particular
+on the use of dev_set_uevent_suppress() and kobject_uevent().
+The kernel's kobject uevent mechanism is implemented in lib/kobject_uevent.c,
+it issues uevents to userspace. As a supplement to kobject uevents Linux
+distributions could also enable CONFIG_UEVENT_HELPER_PATH, which makes use of
+core kernel's usermode helper (UMH) functionality to call out to a userspace
+helper for kobject uevents. In practice though no standard distribution has
+enabled this binary would be called each time kobject_uevent_env() gets called
+in the kernel for each kobject uevent triggered.
+Different implementations have been supported in userspace to take advantage of
+this fallback mechanism. When firmware loading was only possible using the
+sysfs mechanism the userspace component "hotplug" provided the functionality of
+monitoring for kobject events. Historically this was superseded be systemd's
+udev, however firmware loading support was removed from udev as of systemd
+commit be2ea723b1d0 ("udev: remove userspace firmware loading support")
+as of v217 on August, 2014. This means most Linux distributions today are
+not using or taking advantage of the firmware fallback mechanism provided
+by kobject uevents. This is specially exacerbated due to the fact that most
+distributions today disable CONFIG_FW_LOADER_USER_HELPER_FALLBACK.
+Refer to do_firmware_uevent() for details of the kobject event variables
+setup. Variables passwdd with a kobject add event:
+* FIRMWARE=firmware name
+* TIMEOUT=timeout value
+* ASYNC=whether or not the API request was asynchronous
+By default DEVPATH is set by the internal kernel kobject infrastructure.
+Below is an example simple kobject uevent script::
+ # Both $DEVPATH and $FIRMWARE are already provided in the environment.
+ MY_FW_DIR=/lib/firmware/
+ echo 1 > /sys/$DEVPATH/loading
+ cat $MY_FW_DIR/$FIRMWARE > /sys/$DEVPATH/data
+ echo 0 > /sys/$DEVPATH/loading
+Firmware custom fallback mechanism
+Users of the request_firmware_nowait() call have yet another option available
+at their disposal: rely on the sysfs fallback mechanism but request that no
+kobject uevents be issued to userspace. The original logic behind this
+was that utilities other than udev might be required to lookup firmware
+in non-traditional paths -- paths outside of the listing documented in the
+section 'Direct filesystem lookup'. This option is not available to any of
+the other API calls as uevents are always forced for them.
+Since uevents are only meaningful if the fallback mechanism is enabled
+in your kernel it would seem odd to enable uevents with kernels that do not
+have the fallback mechanism enabled in their kernels. Unfortunately we also
+rely on the uevent flag which can be disabled by request_firmware_nowait() to
+also setup the firmware cache for firmware requests. As documented above,
+the firmware cache is only set up if uevent is enabled for an API call.
+Although this can disable the firmware cache for request_firmware_nowait()
+calls, users of this API should not use it for the purposes of disabling
+the cache as that was not the original purpose of the flag. Not setting
+the uevent flag means you want to opt-in for the firmware fallback mechanism
+but you want to suppress kobject uevents, as you have a custom solution which
+will monitor for your device addition into the device hierarchy somehow and
+load firmware for you through a custom path.
+Firmware fallback timeout
+The firmware fallback mechanism has a timeout. If firmware is not loaded
+onto the sysfs interface by the timeout value an error is sent to the
+driver. By default the timeout is set to 60 seconds if uevents are
+desirable, otherwise MAX_JIFFY_OFFSET is used (max timeout possible).
+The logic behind using MAX_JIFFY_OFFSET for non-uevents is that a custom
+solution will have as much time as it needs to load firmware.
+You can customize the firmware timeout by echo'ing your desired timeout into
+the following file:
+* /sys/class/firmware/timeout
+If you echo 0 into it means MAX_JIFFY_OFFSET will be used. The data type
+for the timeout is an int.
diff --git a/Documentation/driver-api/firmware/firmware_cache.rst b/Documentation/driver-api/firmware/firmware_cache.rst
new file mode 100644
index 000000000000..2210e5bfb332
--- /dev/null
+++ b/Documentation/driver-api/firmware/firmware_cache.rst
@@ -0,0 +1,51 @@
+Firmware cache
+When Linux resumes from suspend some device drivers require firmware lookups to
+re-initialize devices. During resume there may be a period of time during which
+firmware lookups are not possible, during this short period of time firmware
+requests will fail. Time is of essence though, and delaying drivers to wait for
+the root filesystem for firmware delays user experience with device
+functionality. In order to support these requirements the firmware
+infrastructure implements a firmware cache for device drivers for most API
+calls, automatically behind the scenes.
+The firmware cache makes using certain firmware API calls safe during a device
+driver's suspend and resume callback. Users of these API calls needn't cache
+the firmware by themselves for dealing with firmware loss during system resume.
+The firmware cache works by requesting for firmware prior to suspend and
+caching it in memory. Upon resume device drivers using the firmware API will
+have access to the firmware immediately, without having to wait for the root
+filesystem to mount or dealing with possible race issues with lookups as the
+root filesystem mounts.
+Some implementation details about the firmware cache setup:
+* The firmware cache is setup by adding a devres entry for each device that
+ uses all synchronous call except :c:func:`request_firmware_into_buf`.
+* If an asynchronous call is used the firmware cache is only set up for a
+ device if if the second argument (uevent) to request_firmware_nowait() is
+ true. When uevent is true it requests that a kobject uevent be sent to
+ userspace for the firmware request. For details refer to the Fackback
+ mechanism documented below.
+* If the firmware cache is determined to be needed as per the above two
+ criteria the firmware cache is setup by adding a devres entry for the
+ device making the firmware request.
+* The firmware devres entry is maintained throughout the lifetime of the
+ device. This means that even if you release_firmware() the firmware cache
+ will still be used on resume from suspend.
+* The timeout for the fallback mechanism is temporarily reduced to 10 seconds
+ as the firmware cache is set up during suspend, the timeout is set back to
+ the old value you had configured after the cache is set up.
+* Upon suspend any pending non-uevent firmware requests are killed to avoid
+ stalling the kernel, this is done with kill_requests_without_uevent(). Kernel
+ calls requiring the non-uevent therefore need to implement their own firmware
+ cache mechanism but must not use the firmware API on suspend.
diff --git a/Documentation/driver-api/firmware/fw_search_path.rst b/Documentation/driver-api/firmware/fw_search_path.rst
new file mode 100644
index 000000000000..a360f1009fa3
--- /dev/null
+++ b/Documentation/driver-api/firmware/fw_search_path.rst
@@ -0,0 +1,26 @@
+Firmware search paths
+The following search paths are used to look for firmware on your
+root filesystem.
+* fw_path_para - module parameter - default is empty so this is ignored
+* /lib/firmware/updates/UTS_RELEASE/
+* /lib/firmware/updates/
+* /lib/firmware/UTS_RELEASE/
+* /lib/firmware/
+The module parameter ''path'' can be passed to the firmware_class module
+to activate the first optional custom fw_path_para. The custom path can
+only be up to 256 characters long. The kernel parameter passed would be:
+* 'firmware_class.path=$CUSTOMIZED_PATH'
+There is an alternative to customize the path at run time after bootup, you
+can use the file:
+* /sys/module/firmware_class/parameters/path
+You would echo into it your custom path and firmware requested will be
+searched for there first.
diff --git a/Documentation/driver-api/firmware/index.rst b/Documentation/driver-api/firmware/index.rst
new file mode 100644
index 000000000000..1abe01793031
--- /dev/null
+++ b/Documentation/driver-api/firmware/index.rst
@@ -0,0 +1,16 @@
+Linux Firmware API
+.. toctree::
+ introduction
+ core
+ request_firmware
+.. only:: subproject and html
+ Indices
+ =======
+ * :ref:`genindex`
diff --git a/Documentation/driver-api/firmware/introduction.rst b/Documentation/driver-api/firmware/introduction.rst
new file mode 100644
index 000000000000..211cb44eb972
--- /dev/null
+++ b/Documentation/driver-api/firmware/introduction.rst
@@ -0,0 +1,27 @@
+The firmware API enables kernel code to request files required
+for functionality from userspace, the uses vary:
+* Microcode for CPU errata
+* Device driver firmware, required to be loaded onto device
+ microcontrollers
+* Device driver information data (calibration data, EEPROM overrides),
+ some of which can be completely optional.
+Types of firmware requests
+There are two types of calls:
+* Synchronous
+* Asynchronous
+Which one you use vary depending on your requirements, the rule of thumb
+however is you should strive to use the asynchronous APIs unless you also
+are already using asynchronous initialization mechanisms which will not
+stall or delay boot. Even if loading firmware does not take a lot of time
+processing firmware might, and this can still delay boot or initialization,
+as such mechanisms such as asynchronous probe can help supplement drivers.
diff --git a/Documentation/driver-api/firmware/lookup-order.rst b/Documentation/driver-api/firmware/lookup-order.rst
new file mode 100644
index 000000000000..88c81739683c
--- /dev/null
+++ b/Documentation/driver-api/firmware/lookup-order.rst
@@ -0,0 +1,18 @@
+Firmware lookup order
+Different functionality is available to enable firmware to be found.
+Below is chronological order of how firmware will be looked for once
+a driver issues a firmware API call.
+* The ''Built-in firmware'' is checked first, if the firmware is present we
+ return it immediately
+* The ''Firmware cache'' is looked at next. If the firmware is found we
+ return it immediately
+* The ''Direct filesystem lookup'' is performed next, if found we
+ return it immediately
+* If no firmware has been found and the fallback mechanism was enabled
+ the sysfs interface is created. After this either a kobject uevent
+ is issued or the custom firmware loading is relied upon for firmware
+ loading up to the timeout value.
diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst
new file mode 100644
index 000000000000..cc0aea880824
--- /dev/null
+++ b/Documentation/driver-api/firmware/request_firmware.rst
@@ -0,0 +1,56 @@
+request_firmware API
+You would typically load firmware and then load it into your device somehow.
+The typical firmware work flow is reflected below::
+ if(request_firmware(&fw_entry, $FIRMWARE, device) == 0)
+ copy_fw_to_device(fw_entry->data, fw_entry->size);
+ release_firmware(fw_entry);
+Synchronous firmware requests
+Synchronous firmware requests will wait until the firmware is found or until
+an error is returned.
+.. kernel-doc:: drivers/base/firmware_class.c
+ :functions: request_firmware
+.. kernel-doc:: drivers/base/firmware_class.c
+ :functions: request_firmware_direct
+.. kernel-doc:: drivers/base/firmware_class.c
+ :functions: request_firmware_into_buf
+Asynchronous firmware requests
+Asynchronous firmware requests allow driver code to not have to wait
+until the firmware or an error is returned. Function callbacks are
+provided so that when the firmware or an error is found the driver is
+informed through the callback. request_firmware_nowait() cannot be called
+in atomic contexts.
+.. kernel-doc:: drivers/base/firmware_class.c
+ :functions: request_firmware_nowait
+request firmware API expected driver use
+Once an API call returns you process the firmware and then release the
+firmware. For example if you used request_firmware() and it returns,
+the driver has the firmware image accessible in fw_entry->{data,size}.
+If something went wrong request_firmware() returns non-zero and fw_entry
+is set to NULL. Once your driver is done with processing the firmware it
+can call call release_firmware(fw_entry) to release the firmware image
+and any related resource.
diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst
index c5a1cd0a4ae7..dbd34c9c1d93 100644
--- a/Documentation/driver-api/index.rst
+++ b/Documentation/driver-api/index.rst
@@ -31,6 +31,7 @@ available subsections can be seen below.
+ firmware/index
.. only:: subproject and html
diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README
deleted file mode 100644
index cafdca8b3b15..000000000000
--- a/Documentation/firmware_class/README
+++ /dev/null
@@ -1,128 +0,0 @@
- request_firmware() hotplug interface:
- ------------------------------------
- Copyright (C) 2003 Manuel Estrada Sainz
- Why:
- ---
- Today, the most extended way to use firmware in the Linux kernel is linking
- it statically in a header file. Which has political and technical issues:
- 1) Some firmware is not legal to redistribute.
- 2) The firmware occupies memory permanently, even though it often is just
- used once.
- 3) Some people, like the Debian crowd, don't consider some firmware free
- enough and remove entire drivers (e.g.: keyspan).
- High level behavior (mixed):
- ============================
- 1), kernel(driver):
- - calls request_firmware(&fw_entry, $FIRMWARE, device)
- - kernel searches the firmware image with name $FIRMWARE directly
- in the below search path of root filesystem:
- User customized search path by module parameter 'path'[1]
- "/lib/firmware/updates/" UTS_RELEASE,
- "/lib/firmware/updates",
- "/lib/firmware/" UTS_RELEASE,
- "/lib/firmware"
- - If found, goto 7), else goto 2)
- [1], the 'path' is a string parameter which length should be less
- than 256, user should pass 'firmware_class.path=$CUSTOMIZED_PATH'
- if firmware_class is built in kernel(the general situation)
- 2), userspace:
- - /sys/class/firmware/xxx/{loading,data} appear.
- - hotplug gets called with a firmware identifier in $FIRMWARE
- and the usual hotplug environment.
- - hotplug: echo 1 > /sys/class/firmware/xxx/loading
- 3), kernel: Discard any previous partial load.
- 4), userspace:
- - hotplug: cat appropriate_firmware_image > \
- /sys/class/firmware/xxx/data
- 5), kernel: grows a buffer in PAGE_SIZE increments to hold the image as it
- comes in.
- 6), userspace:
- - hotplug: echo 0 > /sys/class/firmware/xxx/loading
- 7), kernel: request_firmware() returns and the driver has the firmware
- image in fw_entry->{data,size}. If something went wrong
- request_firmware() returns non-zero and fw_entry is set to
- 8), kernel(driver): Driver code calls release_firmware(fw_entry) releasing
- the firmware image and any related resource.
- High level behavior (driver code):
- ==================================
- if(request_firmware(&fw_entry, $FIRMWARE, device) == 0)
- copy_fw_to_device(fw_entry->data, fw_entry->size);
- release_firmware(fw_entry);
- Sample/simple hotplug script:
- ============================
- # Both $DEVPATH and $FIRMWARE are already provided in the environment.
- HOTPLUG_FW_DIR=/usr/lib/hotplug/firmware/
- echo 1 > /sys/$DEVPATH/loading
- echo 0 > /sys/$DEVPATH/loading
- Random notes:
- ============
- - "echo -1 > /sys/class/firmware/xxx/loading" will cancel the load at
- once and make request_firmware() return with error.
- - firmware_data_read() and firmware_loading_show() are just provided
- for testing and completeness, they are not called in normal use.
- - There is also /sys/class/firmware/timeout which holds a timeout in
- seconds for the whole load operation.
- - request_firmware_nowait() is also provided for convenience in
- user contexts to request firmware asynchronously, but can't be called
- in atomic contexts.
- about in-kernel persistence:
- ---------------------------
- Under some circumstances, as explained below, it would be interesting to keep
- firmware images in non-swappable kernel memory or even in the kernel image
- (probably within initramfs).
- Note that this functionality has not been implemented.
- - Why OPTIONAL in-kernel persistence may be a good idea sometimes:
- - If the device that needs the firmware is needed to access the
- filesystem. When upon some error the device has to be reset and the
- firmware reloaded, it won't be possible to get it from userspace.
- e.g.:
- - A diskless client with a network card that needs firmware.
- - The filesystem is stored in a disk behind an scsi device
- that needs firmware.
- - Replacing buggy DSDT/SSDT ACPI tables on boot.
- Note: this would require the persistent objects to be included
- within the kernel image, probably within initramfs.
- And the same device can be needed to access the filesystem or not depending
- on the setup, so I think that the choice on what firmware to make
- persistent should be left to userspace.
- about firmware cache:
- --------------------
- After firmware cache mechanism is introduced during system sleep,
- request_firmware can be called safely inside device's suspend and
- resume callback, and callers needn't cache the firmware by
- themselves any more for dealing with firmware loss during system
- resume.
diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 647e4761dbf3..c2456839214a 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -406,7 +406,7 @@ int platform_device_add(struct platform_device *pdev)
if (p && insert_resource(p, r)) {
- dev_err(&pdev->dev, "failed to claim resource %d\n", i);
+ dev_err(&pdev->dev, "failed to claim resource %d: %pR\n", i, r);
ret = -EBUSY;
goto failed;
diff --git a/drivers/macintosh/windfarm_core.c b/drivers/macintosh/windfarm_core.c
index 465d770ab0bb..5e013d781a74 100644
--- a/drivers/macintosh/windfarm_core.c
+++ b/drivers/macintosh/windfarm_core.c
@@ -74,8 +74,8 @@ static inline void wf_notify(int event, void *param)
static int wf_critical_overtemp(void)
- static char * critical_overtemp_path = "/sbin/critical_overtemp";
- char *argv[] = { critical_overtemp_path, NULL };
+ static char const critical_overtemp_path[] = "/sbin/critical_overtemp";
+ char *argv[] = { (char *)critical_overtemp_path, NULL };
static char *envp[] = { "HOME=/",
diff --git a/drivers/net/hamradio/baycom_epp.c b/drivers/net/hamradio/baycom_epp.c
index 7d054697b199..594fa1407e29 100644
--- a/drivers/net/hamradio/baycom_epp.c
+++ b/drivers/net/hamradio/baycom_epp.c
@@ -299,7 +299,7 @@ static inline void baycom_int_freq(struct baycom_state *bc)
* eppconfig_path should be setable via /proc/sys.
-static char eppconfig_path[256] = "/usr/sbin/eppfpga";
+static char const eppconfig_path[] = "/usr/sbin/eppfpga";
static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/usr/bin:/bin", NULL };
@@ -308,8 +308,12 @@ static int eppconfig(struct baycom_state *bc)
char modearg[256];
char portarg[16];
- char *argv[] = { eppconfig_path, "-s", "-p", portarg, "-m", modearg,
- NULL };
+ char *argv[] = {
+ (char *)eppconfig_path,
+ "-s",
+ "-p", portarg,
+ "-m", modearg,
+ NULL };
/* set up arguments */
sprintf(modearg, "%sclk,%smodem,fclk=%d,bps=%d,divider=%d%s,extstat",
diff --git a/drivers/pnp/pnpbios/core.c b/drivers/pnp/pnpbios/core.c
index c38a5b9733c8..0ced908e7aa8 100644
--- a/drivers/pnp/pnpbios/core.c
+++ b/drivers/pnp/pnpbios/core.c
@@ -98,6 +98,7 @@ static struct completion unload_sem;
static int pnp_dock_event(int dock, struct pnp_docking_station_info *info)
+ static char const sbin_pnpbios[] = "/sbin/pnpbios";
char *argv[3], **envp, *buf, *scratch;
int i = 0, value;
@@ -112,7 +113,7 @@ static int pnp_dock_event(int dock, struct pnp_docking_station_info *info)
* integrated into the driver core and use the usual infrastructure
* like sysfs and uevents
- argv[0] = "/sbin/pnpbios";
+ argv[0] = (char *)sbin_pnpbios;
argv[1] = "dock";
argv[2] = NULL;
@@ -139,7 +140,7 @@ static int pnp_dock_event(int dock, struct pnp_docking_station_info *info)
info->location_id, info->serial, info->capabilities);
envp[i] = NULL;
- value = call_usermodehelper(argv [0], argv, envp, UMH_WAIT_EXEC);
+ value = call_usermodehelper(sbin_pnpbios, argv, envp, UMH_WAIT_EXEC);
return 0;
diff --git a/drivers/staging/greybus/svc_watchdog.c b/drivers/staging/greybus/svc_watchdog.c
index 3729460fb954..12cef5c06e27 100644
--- a/drivers/staging/greybus/svc_watchdog.c
+++ b/drivers/staging/greybus/svc_watchdog.c
@@ -44,14 +44,14 @@ static int svc_watchdog_pm_notifier(struct notifier_block *notifier,
static void greybus_reset(struct work_struct *work)
- static char start_path[256] = "/system/bin/start";
+ static char const start_path[] = "/system/bin/start";
static char *envp[] = {
static char *argv[] = {
- start_path,
+ (char *)start_path,
diff --git a/drivers/staging/rtl8192e/rtl8192e/rtl_dm.c b/drivers/staging/rtl8192e/rtl8192e/rtl_dm.c
index 9bc284812c30..dbb58fb16482 100644
--- a/drivers/staging/rtl8192e/rtl8192e/rtl_dm.c
+++ b/drivers/staging/rtl8192e/rtl8192e/rtl_dm.c
@@ -268,8 +268,8 @@ void rtl92e_dm_watchdog(struct net_device *dev)
static void _rtl92e_dm_check_ac_dc_power(struct net_device *dev)
struct r8192_priv *priv = rtllib_priv(dev);
- static char *ac_dc_script = "/etc/acpi/wireless-rtl-ac-dc-power.sh";
- char *argv[] = {ac_dc_script, DRV_NAME, NULL};
+ static char const ac_dc_script[] = "/etc/acpi/wireless-rtl-ac-dc-power.sh";
+ char *argv[] = {(char *)ac_dc_script, DRV_NAME, NULL};
static char *envp[] = {"HOME=/",
@@ -1823,7 +1823,7 @@ static void _rtl92e_dm_check_rf_ctrl_gpio(void *data)
enum rt_rf_power_state eRfPowerStateToSet;
bool bActuallySet = false;
char *argv[3];
- static char *RadioPowerPath = "/etc/acpi/events/RadioPower.sh";
+ static char const RadioPowerPath[] = "/etc/acpi/events/RadioPower.sh";
static char *envp[] = {"HOME=/", "TERM=linux", "PATH=/usr/bin:/bin",
@@ -1862,7 +1862,7 @@ static void _rtl92e_dm_check_rf_ctrl_gpio(void *data)
argv[1] = "RFON";
- argv[0] = RadioPowerPath;
+ argv[0] = (char *)RadioPowerPath;
argv[2] = NULL;
call_usermodehelper(RadioPowerPath, argv, envp, UMH_WAIT_PROC);
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index cf4c636ff4da..439b946c4808 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -41,6 +41,9 @@ static bool kernfs_lockdep(struct kernfs_node *kn)
static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen)
+ if (!kn)
+ return strlcpy(buf, "(null)", buflen);
return strlcpy(buf, kn->parent ? kn->name : "/", buflen);
@@ -110,6 +113,8 @@ static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a,
* kn_to: /n1/n2/n3 [depth=3]
* result: /../..
+ * [3] when @kn_to is NULL result will be "(null)"
+ *
* Returns the length of the full path. If the full length is equal to or
* greater than @buflen, @buf contains the truncated path with the trailing
* '\0'. On error, -errno is returned.
@@ -123,6 +128,9 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
size_t depth_from, depth_to, len = 0;
int i, j;
+ if (!kn_to)
+ return strlcpy(buf, "(null)", buflen);
if (!kn_from)
kn_from = kernfs_root(kn_to)->kn;
@@ -166,6 +174,8 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
* similar to strlcpy(). It returns the length of @kn's name and if @buf
* isn't long enough, it's filled upto @buflen-1 and nul terminated.
+ * Fills buffer with "(null)" if @kn is NULL.
+ *
* This function can be called from any context.
int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index 1fc07a9c70e9..e122da696f1b 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -614,6 +614,7 @@ nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
struct nfs4_client *clp = ls->ls_stid.sc_client;
char addr_str[INET6_ADDRSTRLEN];
+ static char const nfsd_recall_failed[] = "/sbin/nfsd-recall-failed";
static char *envp[] = {
@@ -629,12 +630,13 @@ nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
"nfsd: client %s failed to respond to layout recall. "
" Fencing..\n", addr_str);
- argv[0] = "/sbin/nfsd-recall-failed";
+ argv[0] = (char *)nfsd_recall_failed;
argv[1] = addr_str;
argv[2] = ls->ls_file->f_path.mnt->mnt_sb->s_id;
argv[3] = NULL;
- error = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
+ error = call_usermodehelper(nfsd_recall_failed, argv, envp,
if (error) {
printk(KERN_ERR "nfsd: fence failed for client %s: %d!\n",
addr_str, error);
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index c0befcf41b58..9d571acd3a48 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -52,8 +52,7 @@ extern struct srcu_struct debugfs_srcu;
* Must only be called under the protection established by
* debugfs_use_file_start().
-static inline const struct file_operations *
-debugfs_real_fops(const struct file *filp)
+static inline const struct file_operations *debugfs_real_fops(const struct file *filp)
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index fcfd2bf14d3f..c4e441e00db5 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -56,7 +56,7 @@ struct file;
struct subprocess_info {
struct work_struct work;
struct completion *complete;
- char *path;
+ const char *path;
char **argv;
char **envp;
int wait;
@@ -67,10 +67,11 @@ struct subprocess_info {
extern int
-call_usermodehelper(char *path, char **argv, char **envp, int wait);
+call_usermodehelper(const char *path, char **argv, char **envp, int wait);
extern struct subprocess_info *
-call_usermodehelper_setup(char *path, char **argv, char **envp, gfp_t gfp_mask,
+call_usermodehelper_setup(const char *path, char **argv, char **envp,
+ gfp_t gfp_mask,
int (*init)(struct subprocess_info *info, struct cred *new),
void (*cleanup)(struct subprocess_info *), void *data);
diff --git a/include/trace/events/cgroup.h b/include/trace/events/cgroup.h
index ab68640a18d0..c226f50e88fa 100644
--- a/include/trace/events/cgroup.h
+++ b/include/trace/events/cgroup.h
@@ -61,19 +61,15 @@ DECLARE_EVENT_CLASS(cgroup,
__field( int, id )
__field( int, level )
__dynamic_array(char, path,
- cgrp->kn ? cgroup_path(cgrp, NULL, 0) + 1
- : strlen("(null)"))
+ cgroup_path(cgrp, NULL, 0) + 1)
__entry->root = cgrp->root->hierarchy_id;
__entry->id = cgrp->id;
__entry->level = cgrp->level;
- if (cgrp->kn)
- cgroup_path(cgrp, __get_dynamic_array(path),
- __get_dynamic_array_len(path));
- else
- __assign_str(path, "(null)");
+ cgroup_path(cgrp, __get_dynamic_array(path),
+ __get_dynamic_array_len(path));
TP_printk("root=%d id=%d level=%d path=%s",
@@ -119,8 +115,7 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
__field( int, dst_id )
__field( int, dst_level )
__dynamic_array(char, dst_path,
- dst_cgrp->kn ? cgroup_path(dst_cgrp, NULL, 0) + 1
- : strlen("(null)"))
+ cgroup_path(dst_cgrp, NULL, 0) + 1)
__field( int, pid )
__string( comm, task->comm )
@@ -129,11 +124,8 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
__entry->dst_root = dst_cgrp->root->hierarchy_id;
__entry->dst_id = dst_cgrp->id;
__entry->dst_level = dst_cgrp->level;
- if (dst_cgrp->kn)
- cgroup_path(dst_cgrp, __get_dynamic_array(dst_path),
- __get_dynamic_array_len(dst_path));
- else
- __assign_str(dst_path, "(null)");
+ cgroup_path(dst_cgrp, __get_dynamic_array(dst_path),
+ __get_dynamic_array_len(dst_path));
__entry->pid = task->pid;
__assign_str(comm, task->comm);
diff --git a/kernel/kmod.c b/kernel/kmod.c
index d45c96073afb..0c407f905ca4 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -516,7 +516,7 @@ static void helper_unlock(void)
* Function must be runnable in either a process context or the
* context in which call_usermodehelper_exec is called.
-struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
+struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
char **envp, gfp_t gfp_mask,
int (*init)(struct subprocess_info *info, struct cred *new),
void (*cleanup)(struct subprocess_info *info),
@@ -528,7 +528,12 @@ struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
goto out;
INIT_WORK(&sub_info->work, call_usermodehelper_exec_work);
sub_info->path = path;
sub_info->argv = argv;
sub_info->envp = envp;
@@ -566,6 +571,15 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
retval = -EBUSY;
goto out;
+ /*
+ * If there is no binary for us to call, then just return and get out of
+ * here. This allows us to set STATIC_USERMODEHELPER_PATH to "" and
+ * disable all call_usermodehelper() calls.
+ */
+ if (strlen(sub_info->path) == 0)
+ goto out;
* Set the completion pointer only if there is a waiter.
* This makes it possible to use umh_complete to free
@@ -613,7 +627,7 @@ EXPORT_SYMBOL(call_usermodehelper_exec);
* This function is the equivalent to use call_usermodehelper_setup() and
* call_usermodehelper_exec().
-int call_usermodehelper(char *path, char **argv, char **envp, int wait)
+int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
struct subprocess_info *info;
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
diff --git a/security/Kconfig b/security/Kconfig
index 118f4549404e..d900f47eaa68 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -158,6 +158,41 @@ config HARDENED_USERCOPY_PAGESPAN
been removed. This config is intended to be used only while
trying to find such users.
+ bool "Force all usermode helper calls through a single binary"
+ help
+ By default, the kernel can call many different userspace
+ binary programs through the "usermode helper" kernel
+ interface. Some of these binaries are statically defined
+ either in the kernel code itself, or as a kernel configuration
+ option. However, some of these are dynamically created at
+ runtime, or can be modified after the kernel has started up.
+ To provide an additional layer of security, route all of these
+ calls through a single executable that can not have its name
+ changed.
+ Note, it is up to this single binary to then call the relevant
+ "real" usermode helper binary, based on the first argument
+ passed to it. If desired, this program can filter and pick
+ and choose what real programs are called.
+ If you wish for all usermode helper programs are to be
+ disabled, choose this option and then set
+ STATIC_USERMODEHELPER_PATH to an empty string.
+ string "Path to the static usermode helper binary"
+ default "/sbin/usermode-helper"
+ help
+ The binary called by the kernel when any usermode helper
+ program is wish to be run. The "real" application's name will
+ be in the first argument passed to this program on the command
+ line.
+ If you wish for all usermode helper programs to be disabled,
+ specify an empty string here (i.e. "").
source security/selinux/Kconfig
source security/smack/Kconfig
source security/tomoyo/Kconfig
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 43affcf10b22..9822e500d50d 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -72,7 +72,7 @@ static void umh_keys_cleanup(struct subprocess_info *info)
* Call a usermode helper with a specific session keyring.
-static int call_usermodehelper_keys(char *path, char **argv, char **envp,
+static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
struct key *session_keyring, int wait)
struct subprocess_info *info;
@@ -95,6 +95,7 @@ static int call_sbin_request_key(struct key_construction *cons,
const char *op,
void *aux)
+ static char const request_key[] = "/sbin/request-key";
const struct cred *cred = current_cred();
key_serial_t prkey, sskey;
struct key *key = cons->key, *authkey = cons->authkey, *keyring,
@@ -161,7 +162,7 @@ static int call_sbin_request_key(struct key_construction *cons,
/* set up the argument list */
i = 0;
- argv[i++] = "/sbin/request-key";
+ argv[i++] = (char *)request_key;
argv[i++] = (char *) op;
argv[i++] = key_str;
argv[i++] = uid_str;
@@ -172,7 +173,7 @@ static int call_sbin_request_key(struct key_construction *cons,
argv[i] = NULL;
/* do it */
- ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
+ ret = call_usermodehelper_keys(request_key, argv, envp, keyring,
kdebug("usermode -> 0x%x", ret);
if (ret >= 0) {
diff --git a/tools/testing/selftests/firmware/fw_filesystem.sh b/tools/testing/selftests/firmware/fw_filesystem.sh
index 5c495ad7958a..e35691239350 100755
--- a/tools/testing/selftests/firmware/fw_filesystem.sh
+++ b/tools/testing/selftests/firmware/fw_filesystem.sh
@@ -5,9 +5,24 @@
# know so we can be sure we're not accidentally testing the user helper.
set -e
-modprobe test_firmware
+TEST_DIR=$(dirname $0)
+ if [ ! -d $DIR ]; then
+ echo "$0: $DIR not present"
+ echo "You must have the following enabled in your kernel:"
+ cat $TEST_DIR/config
+ exit 1
+ fi
+trap "test_modprobe" EXIT
+if [ ! -d $DIR ]; then
+ modprobe test_firmware
# CONFIG_FW_LOADER_USER_HELPER has a sysfs class under /sys/class/firmware/
# These days no one enables CONFIG_FW_LOADER_USER_HELPER so check for that
@@ -48,18 +63,18 @@ echo "ABCD0123" >"$FW"
NAME=$(basename "$FW")
-if printf '\000' >"$DIR"/trigger_request; then
+if printf '\000' >"$DIR"/trigger_request 2> /dev/null; then
echo "$0: empty filename should not succeed" >&2
exit 1
-if printf '\000' >"$DIR"/trigger_async_request; then
+if printf '\000' >"$DIR"/trigger_async_request 2> /dev/null; then
echo "$0: empty filename should not succeed (async)" >&2
exit 1
# Request a firmware that doesn't exist, it should fail.
-if echo -n "nope-$NAME" >"$DIR"/trigger_request; then
+if echo -n "nope-$NAME" >"$DIR"/trigger_request 2> /dev/null; then
echo "$0: firmware shouldn't have loaded" >&2
exit 1

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