user/sven/linux.git/include/linux/sysfs.h, branch v6.9.11

sysfs: Introduce DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE()

2024-02-23T06:34:26Z

One of the first users of DEFINE_SYSFS_GROUP_VISIBLE() did this: static umode_t dp0_attr_visible(struct kobject *kobj, struct attribute *attr, int n) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return attr->mode; return 0; } static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SYSFS_GROUP_VISIBLE(dp0); ...i.e. the _group_visible() helper is identical to the _attr_visible() helper. Use the "simple" helper to reduce that to: static bool dp0_group_visible(struct kobject *kobj) { struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj)); if (slave->prop.dp0_prop) return true; return false; } DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(dp0); Remove the need to specify per attribute visibility if the goal is to hide the entire group. Signed-off-by: Dan Williams Link: https://lore.kernel.org/r/170863446625.1479840.10593839479268727913.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman

sysfs: Document new "group visible" helpers

2024-02-23T06:34:26Z

Add documentation and examples for how to use DEFINE_SYSFS_GROUP_VISIBLE() and SYSFS_GROUP_VISIBLE(). Recall that the motivation for this work is that it is easier to reason about the lifetime of statically defined sysfs attributes that become visible at device_add() time rather than dynamically adding them later. DEFINE_SYSFS_GROUP_VISIBLE() tackles one of the reasons to opt for dynamically created attributes which did not have a facility for hiding empty directories. Signed-off-by: Dan Williams Link: https://lore.kernel.org/r/170863446065.1479840.10697164014098377292.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Greg Kroah-Hartman

sysfs: Introduce a mechanism to hide static attribute_groups

2024-02-19T08:04:56Z

Add a mechanism for named attribute_groups to hide their directory at sysfs_update_group() time, or otherwise skip emitting the group directory when the group is first registered. It piggybacks on is_visible() in a similar manner as SYSFS_PREALLOC, i.e. special flags in the upper bits of the returned mode. To use it, specify a symbol prefix to DEFINE_SYSFS_GROUP_VISIBLE(), and then pass that same prefix to SYSFS_GROUP_VISIBLE() when assigning the @is_visible() callback: DEFINE_SYSFS_GROUP_VISIBLE($prefix) struct attribute_group $prefix_group = { .name = $name, .is_visible = SYSFS_GROUP_VISIBLE($prefix), }; SYSFS_GROUP_VISIBLE() expects a definition of $prefix_group_visible() and $prefix_attr_visible(), where $prefix_group_visible() just returns true / false and $prefix_attr_visible() behaves as normal. The motivation for this capability is to centralize PCI device authentication in the PCI core with a named sysfs group while keeping that group hidden for devices and platforms that do not meet the requirements. In a PCI topology, most devices will not support authentication, a small subset will support just PCI CMA (Component Measurement and Authentication), a smaller subset will support PCI CMA + PCIe IDE (Link Integrity and Encryption), and only next generation server hosts will start to include a platform TSM (TEE Security Manager). Without this capability the alternatives are: * Check if all attributes are invisible and if so, hide the directory. Beyond trouble getting this to work [1], this is an ABI change for scenarios if userspace happens to depend on group visibility absent any attributes. I.e. this new capability avoids regression since it does not retroactively apply to existing cases. * Publish an empty /sys/bus/pci/devices/$pdev/tsm/ directory for all PCI devices (i.e. for the case when TSM platform support is present, but device support is absent). Unfortunate that this will be a vestigial empty directory in the vast majority of cases. * Reintroduce usage of runtime calls to sysfs_{create,remove}_group() in the PCI core. Bjorn has already indicated that he does not want to see any growth of pci_sysfs_init() [2]. * Drop the named group and simulate a directory by prefixing all TSM-related attributes with "tsm_". Unfortunate to not use the naming capability of a sysfs group as intended. In comparison, there is a small potential for regression if for some reason an @is_visible() callback had dependencies on how many times it was called. Additionally, it is no longer an error to update a group that does not have its directory already present, and it is no longer a WARN() to remove a group that was never visible. Link: https://lore.kernel.org/all/2024012321-envious-procedure-4a58@gregkh/ [1] Link: https://lore.kernel.org/linux-pci/20231019200110.GA1410324@bhelgaas/ [2] Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman Link: https://lore.kernel.org/r/2024013028-deflator-flaring-ec62@gregkh Signed-off-by: Greg Kroah-Hartman

kernfs: sysfs: support custom llseek method for sysfs entries

2023-10-05T11:42:11Z

As of now, seeking in sysfs files is handled by generic_file_llseek(). There are situations where one may want to customize seeking logic: - Many sysfs entries are fixed files while generic_file_llseek() accepts past-the-end positions. Not only being useless by itself, this also means a bug in userspace code will trigger not at lseek(), but at some later point making debugging harder. - generic_file_llseek() relies on f_mapping->host to get the file size which might not be correct for all sysfs entries. See commit 636b21b50152 ("PCI: Revoke mappings like devmem") as an example. Implement llseek method to override this behavior at sysfs attribute level. The method is optional, and if it is absent, generic_file_llseek() is called to preserve backwards compatibility. Signed-off-by: Valentine Sinitsyn Link: https://lore.kernel.org/r/20230925084013.309399-1-valesini@yandex-team.ru Signed-off-by: Greg Kroah-Hartman

driver-core: Introduce BIN_ATTR_ADMIN_{RO,RW}

2022-07-19T22:38:04Z

Many binary attributes need to limit access to CAP_SYS_ADMIN only; ie many binary attributes specify is_visible with 0400 or 0600. Make setting the permissions of such attributes more explicit by defining BIN_ATTR_ADMIN_{RO,RW}. Cc: Bjorn Helgaas Suggested-by: Dan Williams Suggested-by: Krzysztof Wilczyński Reviewed-by: Jonathan Cameron Reviewed-by: Greg Kroah-Hartman Signed-off-by: Ira Weiny Link: https://lore.kernel.org/r/20220719205249.566684-6-ira.weiny@intel.com Signed-off-by: Dan Williams

sysfs: Rename struct bin_attribute member to f_mapping

2021-08-05T12:47:31Z

There are two users of iomem_get_mapping(), the struct file and struct bin_attribute. The former has a member called "f_mapping" and the latter has a member called "mapping", and both are poniters to struct address_space. Rename struct bin_attribute member to "f_mapping" to keep both meaning and the usage consistent with other users of iomem_get_mapping(). Acked-by: Bjorn Helgaas Signed-off-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20210729233235.1508920-3-kw@linux.com Signed-off-by: Greg Kroah-Hartman

sysfs: Invoke iomem_get_mapping() from the sysfs open callback

2021-08-05T12:47:31Z

Defer invocation of the iomem_get_mapping() to the sysfs open callback so that it can be executed as needed when the binary sysfs object has been accessed. To do that, convert the "mapping" member of the struct bin_attribute from a pointer to the struct address_space into a function pointer with a signature that requires the same return type, and then updates the sysfs_kf_bin_open() to invoke provided function should the function pointer be valid. Also, convert every invocation of iomem_get_mapping() into a function pointer assignment, therefore allowing for the iomem_get_mapping() invocation to be deferred to when the sysfs open callback runs. Thus, this change removes the need for the fs_initcalls to complete before any other sub-system that uses the iomem_get_mapping() would be able to invoke it safely without leading to a failure and an Oops related to an invalid iomem_get_mapping() access. Suggested-by: Dan Williams Reviewed-by: Dan Williams Acked-by: Bjorn Helgaas Signed-off-by: Dan Williams Signed-off-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20210729233235.1508920-2-kw@linux.com Signed-off-by: Greg Kroah-Hartman

sysfs: Add helper BIN_ATTRIBUTE_GROUPS

2021-05-21T20:13:13Z

New helper BIN_ATTRIBUTE_GROUPS() does the same as ATTRIBUTE_GROUPS(), just for binary attributes. Signed-off-by: Heiner Kallweit Link: https://lore.kernel.org/r/e20db248-ed30-cf5d-a37c-b538dceaa5b2@gmail.com Signed-off-by: Greg Kroah-Hartman

sysfs: Support zapping of binary attr mmaps

2021-01-12T13:26:31Z

We want to be able to revoke pci mmaps so that the same access rules applies as for /dev/kmem. Revoke support for devmem was added in 3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims the region"). The simplest way to achieve this is by having the same filp->f_mapping for all mappings, so that unmap_mapping_range can find them all, no matter through which file they've been created. Since this must be set at open time we need sysfs support for this. Add an optional mapping parameter bin_attr, which is only consulted when there's also an mmap callback, since without mmap support allowing to adjust the ->f_mapping makes no sense. Reviewed-by: Greg Kroah-Hartman Signed-off-by: Daniel Vetter Cc: Jason Gunthorpe Cc: Kees Cook Cc: Dan Williams Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: Bjorn Helgaas Cc: linux-pci@vger.kernel.org Cc: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" Cc: Christian Brauner Cc: "David S. Miller" Cc: Michael Ellerman Cc: Sourabh Jain Cc: Daniel Vetter Cc: Mauro Carvalho Chehab Cc: Nayna Jain Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-12-daniel.vetter@ffwll.ch

sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output

2020-10-02T10:02:30Z

Output defects can exist in sysfs content using sprintf and snprintf. sprintf does not know the PAGE_SIZE maximum of the temporary buffer used for outputting sysfs content and it's possible to overrun the PAGE_SIZE buffer length. Add a generic sysfs_emit function that knows that the size of the temporary buffer and ensures that no overrun is done. Add a generic sysfs_emit_at function that can be used in multiple call situations that also ensures that no overrun is done. Validate the output buffer argument to be page aligned. Validate the offset len argument to be within the PAGE_SIZE buf. Signed-off-by: Joe Perches Link: https://lore.kernel.org/r/884235202216d464d61ee975f7465332c86f76b2.1600285923.git.joe@perches.com Signed-off-by: Greg Kroah-Hartman