Linux
Character Drivers and Misc
fd44b777bcd241eaaa427d28e9d01278

1. Low-Level Requirements

 MID: fd44b777bcd241eaaa427d28e9d01278
897e208488da42eb84e299dade7f6495

1.1. devmem

 MID: 897e208488da42eb84e299dade7f6495
61217c39f904471bb9580b9cbbea16b8

1.1.1. Requirements

 MID: 61217c39f904471bb9580b9cbbea16b8
a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75
Function expectation 3 has no related test.
Function expectation 3.1 has no related test.
1.1.1.1. read_mem SPDX-Req-ID: a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75 SPDX-Req-HKey: e06c773fa9ac085073414a8acdbd3a2fdaea3a90af0a6873462876c1c55ce682 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
read_mem - read from physical memory (/dev/mem).
@file: struct file associated with /dev/mem.
@buf: user-space buffer to copy data to.
@count: number of bytes to read.
@ppos: pointer to the current file position, representing the physical
address to read from.

This function checks if the requested physical memory range is valid
and accessible by the user, then it copies data to the input
user-space buffer up to the requested number of bytes.

Function's expectations:

1. This function shall check if the value pointed by ppos exceeds the
maximum addressable physical address;

2. This function shall check if the physical address range to be read
is valid (i.e. it falls within a memory block and if it can be mapped
to the kernel address space);

3. For each memory page falling in the requested physical range
[ppos, ppos + count - 1]:
3.1. this function shall check if user space access is allowed (if
config STRICT_DEVMEM is not set, access is always granted);

3.2. if access is allowed, the memory content from the page range falling
within the requested physical range shall be copied to the user space
buffer;

3.3. zeros shall be copied to the user space buffer (for the page range
falling within the requested physical range):
3.3.1. if access to the memory page is restricted or,
3.2.2. if the current page is page 0 on HW architectures where page 0 is
not mapped.

4. The file position '*ppos' shall be advanced by the number of bytes
successfully copied to user space (including zeros).

Context: process context.

Return:
* the number of bytes copied to user on success
* %-EFAULT - the requested address range is not valid or a fault happened
when copying to user-space (i.e. copy_from_kernel_nofault() failed)
* %-EPERM - access to any of the required physical pages is not allowed
* %-ENOMEM - out of memory error for auxiliary kernel buffers supporting
the operation of copying content from the physical pages
6e16917c09ee583de5dc9e8a24a406e75bb229554699a501cfa8efdb308862d7
Function expectation 1 has no related test.
Function expectation 3 has no related test.
Function expectation 3.1 has no related test.
Function expectation 3.2 has no related test.
Function expectation 3.3 has no related test.
Function expectation 3.3.1 has no related test.
Function expectation 3.3.2 has no related test.
Function expectation 4 has no related test.
1.1.1.2. write_mem SPDX-Req-ID: 6e16917c09ee583de5dc9e8a24a406e75bb229554699a501cfa8efdb308862d7 SPDX-Req-HKey: 83f393fd3b6191e7ad88da40799254f4227893e7212c59e9a41ff429b1eba555 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
write_mem - write to physical memory (/dev/mem).
@file: struct file associated with /dev/mem.
@buf: user-space buffer containing the data to write.
@count: number of bytes to write.
@ppos: pointer to the current file position, representing the physical
address to write to.

This function checks if the target physical memory range is valid
and accessible by the user, then it writes data from the input
user-space buffer up to the requested number of bytes.

Function's expectations:
1. This function shall check if the value pointed by ppos exceeds the
maximum addressable physical address;

2. This function shall check if the physical address range to be written
is valid (i.e. it falls within a memory block and if it can be mapped
to the kernel address space);

3. For each memory page falling in the physical range to be written
[ppos, ppos + count - 1]:
3.1. this function shall check if user space access is allowed (if
config STRICT_DEVMEM is not set, access is always granted);

3.2. the content from the user space buffer shall be copied to the page
range falling within the physical range to be written if access is
allowed;

3.3. the data to be copied from the user space buffer (for the page range
falling within the range to be written) shall be skipped:
3.3.1. if access to the memory page is restricted or,
3.3.2. if the current page is page 0 on HW architectures where page 0
is not mapped.

4. The file position '*ppos' shall be advanced by the number of bytes
successfully copied from user space (including skipped bytes).

Context: process context.

Return:
* the number of bytes copied from user-space on success
* %-EFBIG - the value pointed by ppos exceeds the maximum addressable
physical address
* %-EFAULT - the physical address range is not valid or no bytes could
be copied from user-space
* %-EPERM - access to any of the required pages is not allowed
032b3f1c9e61452bf826328d95fae043c4ea4b966ad6583a0377554d3c4f2d76
Requirement has no related tests.
Function expectation 1 has no related test.
Function expectation 2 has no related test.
Function expectation 3 has no related test.
Function expectation 4 has no related test.
Function expectation 5 has no related test.
1.1.1.3. mmap_mem SPDX-Req-ID: 032b3f1c9e61452bf826328d95fae043c4ea4b966ad6583a0377554d3c4f2d76 SPDX-Req-HKey: 12f2a3571b30462c24cd92d073513eba9e91a052a45057073b1c17de2584546f SPDX-Req-Sys: Character Drivers and Misc RELATIONS (File): SPDX-Req-Text:
mmap_mem - map physical memory into user space (/dev/mem).
@file: file structure for the device.
@vma: virtual memory area structure describing the user mapping.

This function checks if the requested physical memory range is valid
and accessible by the user, then it maps the physical memory range to
user-mode address space.

Function's expectations:
1. This function shall check if the requested physical address range to be
mapped fits within the maximum addressable physical range;

2. This function shall check if the requested physical range corresponds to
a valid physical range and if access is allowed on it (if config STRICT_DEVMEM
is not set, access is always allowed);

3. This function shall check if the input virtual memory area can be used for
a private mapping (always OK if there is an MMU);

4. This function shall set the virtual memory area operations to
&mmap_mem_ops;

5. This function shall establish a mapping between the user-space
virtual memory area described by vma and the physical memory
range specified by vma->vm_pgoff and size;

Context: process context.

Return:
* 0 on success
* %-EAGAIN - invalid or unsupported mapping requested (remap_pfn_range()
fails)
* %-EINVAL - requested physical range to be mapped is not valid
* %-EPERM - no permission to access the requested physical range
feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14
Function expectation 1 has no related test.
Function expectation 2.3 has no related test.
Function expectation 3 has no related test.
1.1.1.4. memory_lseek SPDX-Req-ID: feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14 SPDX-Req-HKey: 17745d554ee1aca155176037541afce34a4c901070a0bdc84d114e8a147a8052 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
memory_lseek - change the file position.
@file: file structure for the device.
@offset: file offset to seek to.
@orig: where to start seeking from (see whence in the llseek manpage).

This function changes the file position according to the input offset
and orig parameters.

Function's expectations:
1. This function shall lock the semaphore of the inode corresponding to the
input file before any operation and unlock it before returning.

2. This function shall check the orig value and accordingly:
2.1. if it is equal to SEEK_CUR, the current file position shall be
incremented by the input offset;
2.2. if it is equal to SEEK_SET, the current file position shall be
set to the input offset value;
2.3. any other value shall result in an error condition.

3. Before writing the current file position, the new position value
shall be checked to not overlap with Linux ERRNO values.

Assumptions of Use:
1. the input file pointer is expected to be valid.

Notes:
The memory devices use the full 32/64 bits of the offset, and so we cannot
check against negative addresses: they are ok. The return value is weird,
though, in that case (0).

Also note that seeking relative to the "end of file" isn't supported:
it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.

Context: process context, locks/unlocks inode->i_rwsem

Return:
* the new file position on success
* %-EOVERFLOW - the new position value equals or exceeds
(unsigned long long) -MAX_ERRNO
* %-EINVAL - the orig parameter is invalid
 SPDX-Req-Note: The memory devices use the full 32/64 bits of the offset, and so we cannot
check against negative addresses: they are ok. The return value is weird,
though, in that case (0).
 SPDX-Req-Note: Also note that seeking relative to the "end of file" isn't supported:
it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.
6638528f181fca48b6554dc9dc34a070ce1860a9fd0e2f5857f17f0de915f5d9
Requirement has no related tests.
Function expectation 1 has no related test.
Function expectation 2 has no related test.
Function expectation 3 has no related test.
1.1.1.5. open_port SPDX-Req-ID: 6638528f181fca48b6554dc9dc34a070ce1860a9fd0e2f5857f17f0de915f5d9 SPDX-Req-HKey: d236556a51f674d4e8b40b7e942b552e2944f21edee75826b3f17b5d4486413f SPDX-Req-Sys: Character Drivers and Misc RELATIONS (File): SPDX-Req-Text:
open_port - open the I/O port device (/dev/port).
@inode: inode of the device file.
@filp: file structure for the device.

This function checks if the caller can access the port device and sets
the f_mapping pointer of filp to the i_mapping pointer of inode.

Function's expectations:
1. This function shall check if the caller has sufficient capabilities to
perform raw I/O access;

2. This function shall check if the kernel is locked down with the
&LOCKDOWN_DEV_MEM restriction;

3. If the input inode corresponds to /dev/mem, the f_mapping pointer
of the input file structure shall be set to the i_mapping pointer
of the input inode;

Assumptions of Use:
1. The input inode and filp are expected to be valid.

Context: process context.

Return:
* 0 on success
* %-EPERM - caller lacks the required capability (CAP_SYS_RAWIO)
* any error returned by securty_locked_down()
46dc914c8b39c0763e1d407cf985e16e68b5c153cdbdae6e03173972db455da0
1.1.1.6. memory_open SPDX-Req-ID: 46dc914c8b39c0763e1d407cf985e16e68b5c153cdbdae6e03173972db455da0 SPDX-Req-HKey: 7e47f36178f4b7e69ecb2d9f1f08c1d126afac6d1bedf260a8021a318f59fc5b SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
memory_open - set the filp f_op to the memory device fops and invoke open().
@inode: inode of the device file.
@filp: file structure for the device.

Function's expectations:
1. This function shall retrieve the minor number associated with the input
inode and the memory device corresponding to such minor number;

2. The file operations pointer shall be set to the memory device file operations;

3. The file mode member of the input filp shall be OR'd with the device mode;

4. The memory device open() file operation shall be invoked.

Assumptions of Use:
1. The input inode and filp are expected to be non-NULL.

Context: process context.

Return:
* 0 on success
* %-ENXIO - the minor number corresponding to the input inode cannot be
associated with any device or the corresponding device has a NULL fops
pointer
* any error returned by the device specific open function pointer
d22df905261145ffaccd62838bcffe1e

1.1.2. Tests

 MID: d22df905261145ffaccd62838bcffe1e
  • 46dc914c8b39c0763e1d407cf985e16e68b5c153cdbdae6e03173972db455da0
    1.1.1.6. memory_open SPDX-Req-ID: 46dc914c8b39c0763e1d407cf985e16e68b5c153cdbdae6e03173972db455da0 SPDX-Req-HKey: 7e47f36178f4b7e69ecb2d9f1f08c1d126afac6d1bedf260a8021a318f59fc5b SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    memory_open - set the filp f_op to the memory device fops and invoke open().
    @inode: inode of the device file.
    @filp: file structure for the device.

    Function's expectations:
    1. This function shall retrieve the minor number associated with the input
    inode and the memory device corresponding to such minor number;

    2. The file operations pointer shall be set to the memory device file operations;

    3. The file mode member of the input filp shall be OR'd with the device mode;

    4. The memory device open() file operation shall be invoked.

    Assumptions of Use:
    1. The input inode and filp are expected to be non-NULL.

    Context: process context.

    Return:
    * 0 on success
    * %-ENXIO - the minor number corresponding to the input inode cannot be
    associated with any device or the corresponding device has a NULL fops
    pointer
    * any error returned by the device specific open function pointer
selftests-devmem-access
1.1.2.1. memory_open FE_1, FE_2, FE_4 MID: selftests/devmem:access RELATIONS (Parent): RELATIONS (File): DESCRIPTION: Test whether /dev/mem is accessible
  • 46dc914c8b39c0763e1d407cf985e16e68b5c153cdbdae6e03173972db455da0
    1.1.1.6. memory_open SPDX-Req-ID: 46dc914c8b39c0763e1d407cf985e16e68b5c153cdbdae6e03173972db455da0 SPDX-Req-HKey: 7e47f36178f4b7e69ecb2d9f1f08c1d126afac6d1bedf260a8021a318f59fc5b SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    memory_open - set the filp f_op to the memory device fops and invoke open().
    @inode: inode of the device file.
    @filp: file structure for the device.

    Function's expectations:
    1. This function shall retrieve the minor number associated with the input
    inode and the memory device corresponding to such minor number;

    2. The file operations pointer shall be set to the memory device file operations;

    3. The file mode member of the input filp shall be OR'd with the device mode;

    4. The memory device open() file operation shall be invoked.

    Assumptions of Use:
    1. The input inode and filp are expected to be non-NULL.

    Context: process context.

    Return:
    * 0 on success
    * %-ENXIO - the minor number corresponding to the input inode cannot be
    associated with any device or the corresponding device has a NULL fops
    pointer
    * any error returned by the device specific open function pointer
selftests-devmem-open_devnum
1.1.2.2. memory_open FE_3 MID: selftests/devmem:open_devnum RELATIONS (Parent): RELATIONS (File): DESCRIPTION: Test open /dev/mem provides the correct min, maj
selftests-devmem-strict_devmem
1.1.2.3. test_strict_devmem MID: selftests/devmem:strict_devmem RELATIONS (File): DESCRIPTION: Test Strict Devmem enabled - Dependency
  • a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75
    1.1.1.1. read_mem SPDX-Req-ID: a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75 SPDX-Req-HKey: e06c773fa9ac085073414a8acdbd3a2fdaea3a90af0a6873462876c1c55ce682 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    read_mem - read from physical memory (/dev/mem).
    @file: struct file associated with /dev/mem.
    @buf: user-space buffer to copy data to.
    @count: number of bytes to read.
    @ppos: pointer to the current file position, representing the physical
    address to read from.

    This function checks if the requested physical memory range is valid
    and accessible by the user, then it copies data to the input
    user-space buffer up to the requested number of bytes.

    Function's expectations:

    1. This function shall check if the value pointed by ppos exceeds the
    maximum addressable physical address;

    2. This function shall check if the physical address range to be read
    is valid (i.e. it falls within a memory block and if it can be mapped
    to the kernel address space);

    3. For each memory page falling in the requested physical range
    [ppos, ppos + count - 1]:
    3.1. this function shall check if user space access is allowed (if
    config STRICT_DEVMEM is not set, access is always granted);

    3.2. if access is allowed, the memory content from the page range falling
    within the requested physical range shall be copied to the user space
    buffer;

    3.3. zeros shall be copied to the user space buffer (for the page range
    falling within the requested physical range):
    3.3.1. if access to the memory page is restricted or,
    3.2.2. if the current page is page 0 on HW architectures where page 0 is
    not mapped.

    4. The file position '*ppos' shall be advanced by the number of bytes
    successfully copied to user space (including zeros).

    Context: process context.

    Return:
    * the number of bytes copied to user on success
    * %-EFAULT - the requested address range is not valid or a fault happened
    when copying to user-space (i.e. copy_from_kernel_nofault() failed)
    * %-EPERM - access to any of the required physical pages is not allowed
    * %-ENOMEM - out of memory error for auxiliary kernel buffers supporting
    the operation of copying content from the physical pages
selftests-devmem-read_at_addr_32bit_ge
1.1.2.4. read_mem FE_1 MID: selftests/devmem:read_at_addr_32bit_ge RELATIONS (Parent): RELATIONS (File): DESCRIPTION: Test read 64bit ppos vs 32 bit addr
  • a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75
    1.1.1.1. read_mem SPDX-Req-ID: a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75 SPDX-Req-HKey: e06c773fa9ac085073414a8acdbd3a2fdaea3a90af0a6873462876c1c55ce682 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    read_mem - read from physical memory (/dev/mem).
    @file: struct file associated with /dev/mem.
    @buf: user-space buffer to copy data to.
    @count: number of bytes to read.
    @ppos: pointer to the current file position, representing the physical
    address to read from.

    This function checks if the requested physical memory range is valid
    and accessible by the user, then it copies data to the input
    user-space buffer up to the requested number of bytes.

    Function's expectations:

    1. This function shall check if the value pointed by ppos exceeds the
    maximum addressable physical address;

    2. This function shall check if the physical address range to be read
    is valid (i.e. it falls within a memory block and if it can be mapped
    to the kernel address space);

    3. For each memory page falling in the requested physical range
    [ppos, ppos + count - 1]:
    3.1. this function shall check if user space access is allowed (if
    config STRICT_DEVMEM is not set, access is always granted);

    3.2. if access is allowed, the memory content from the page range falling
    within the requested physical range shall be copied to the user space
    buffer;

    3.3. zeros shall be copied to the user space buffer (for the page range
    falling within the requested physical range):
    3.3.1. if access to the memory page is restricted or,
    3.2.2. if the current page is page 0 on HW architectures where page 0 is
    not mapped.

    4. The file position '*ppos' shall be advanced by the number of bytes
    successfully copied to user space (including zeros).

    Context: process context.

    Return:
    * the number of bytes copied to user on success
    * %-EFAULT - the requested address range is not valid or a fault happened
    when copying to user-space (i.e. copy_from_kernel_nofault() failed)
    * %-EPERM - access to any of the required physical pages is not allowed
    * %-ENOMEM - out of memory error for auxiliary kernel buffers supporting
    the operation of copying content from the physical pages
selftests-devmem-read_outside_linear_map
1.1.2.5. read_mem FE_2 MID: selftests/devmem:read_outside_linear_map RELATIONS (Parent): RELATIONS (File): DESCRIPTION: Test read outside linear map
  • a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75
    1.1.1.1. read_mem SPDX-Req-ID: a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75 SPDX-Req-HKey: e06c773fa9ac085073414a8acdbd3a2fdaea3a90af0a6873462876c1c55ce682 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    read_mem - read from physical memory (/dev/mem).
    @file: struct file associated with /dev/mem.
    @buf: user-space buffer to copy data to.
    @count: number of bytes to read.
    @ppos: pointer to the current file position, representing the physical
    address to read from.

    This function checks if the requested physical memory range is valid
    and accessible by the user, then it copies data to the input
    user-space buffer up to the requested number of bytes.

    Function's expectations:

    1. This function shall check if the value pointed by ppos exceeds the
    maximum addressable physical address;

    2. This function shall check if the physical address range to be read
    is valid (i.e. it falls within a memory block and if it can be mapped
    to the kernel address space);

    3. For each memory page falling in the requested physical range
    [ppos, ppos + count - 1]:
    3.1. this function shall check if user space access is allowed (if
    config STRICT_DEVMEM is not set, access is always granted);

    3.2. if access is allowed, the memory content from the page range falling
    within the requested physical range shall be copied to the user space
    buffer;

    3.3. zeros shall be copied to the user space buffer (for the page range
    falling within the requested physical range):
    3.3.1. if access to the memory page is restricted or,
    3.2.2. if the current page is page 0 on HW architectures where page 0 is
    not mapped.

    4. The file position '*ppos' shall be advanced by the number of bytes
    successfully copied to user space (including zeros).

    Context: process context.

    Return:
    * the number of bytes copied to user on success
    * %-EFAULT - the requested address range is not valid or a fault happened
    when copying to user-space (i.e. copy_from_kernel_nofault() failed)
    * %-EPERM - access to any of the required physical pages is not allowed
    * %-ENOMEM - out of memory error for auxiliary kernel buffers supporting
    the operation of copying content from the physical pages
selftests-devmem-read_secret_area
1.1.2.6. read_mem FE_??? MID: selftests/devmem:read_secret_area RELATIONS (Parent): RELATIONS (File): DESCRIPTION: Test read memfd_secret area can not being accessed
  • a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75
    1.1.1.1. read_mem SPDX-Req-ID: a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75 SPDX-Req-HKey: e06c773fa9ac085073414a8acdbd3a2fdaea3a90af0a6873462876c1c55ce682 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    read_mem - read from physical memory (/dev/mem).
    @file: struct file associated with /dev/mem.
    @buf: user-space buffer to copy data to.
    @count: number of bytes to read.
    @ppos: pointer to the current file position, representing the physical
    address to read from.

    This function checks if the requested physical memory range is valid
    and accessible by the user, then it copies data to the input
    user-space buffer up to the requested number of bytes.

    Function's expectations:

    1. This function shall check if the value pointed by ppos exceeds the
    maximum addressable physical address;

    2. This function shall check if the physical address range to be read
    is valid (i.e. it falls within a memory block and if it can be mapped
    to the kernel address space);

    3. For each memory page falling in the requested physical range
    [ppos, ppos + count - 1]:
    3.1. this function shall check if user space access is allowed (if
    config STRICT_DEVMEM is not set, access is always granted);

    3.2. if access is allowed, the memory content from the page range falling
    within the requested physical range shall be copied to the user space
    buffer;

    3.3. zeros shall be copied to the user space buffer (for the page range
    falling within the requested physical range):
    3.3.1. if access to the memory page is restricted or,
    3.2.2. if the current page is page 0 on HW architectures where page 0 is
    not mapped.

    4. The file position '*ppos' shall be advanced by the number of bytes
    successfully copied to user space (including zeros).

    Context: process context.

    Return:
    * the number of bytes copied to user on success
    * %-EFAULT - the requested address range is not valid or a fault happened
    when copying to user-space (i.e. copy_from_kernel_nofault() failed)
    * %-EPERM - access to any of the required physical pages is not allowed
    * %-ENOMEM - out of memory error for auxiliary kernel buffers supporting
    the operation of copying content from the physical pages
selftests-devmem-read_allowed_area
1.1.2.7. read_mem FE_3.2 MID: selftests/devmem:read_allowed_area RELATIONS (Parent): RELATIONS (File): DESCRIPTION: test read allowed area
  • a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75
    1.1.1.1. read_mem SPDX-Req-ID: a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75 SPDX-Req-HKey: e06c773fa9ac085073414a8acdbd3a2fdaea3a90af0a6873462876c1c55ce682 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    read_mem - read from physical memory (/dev/mem).
    @file: struct file associated with /dev/mem.
    @buf: user-space buffer to copy data to.
    @count: number of bytes to read.
    @ppos: pointer to the current file position, representing the physical
    address to read from.

    This function checks if the requested physical memory range is valid
    and accessible by the user, then it copies data to the input
    user-space buffer up to the requested number of bytes.

    Function's expectations:

    1. This function shall check if the value pointed by ppos exceeds the
    maximum addressable physical address;

    2. This function shall check if the physical address range to be read
    is valid (i.e. it falls within a memory block and if it can be mapped
    to the kernel address space);

    3. For each memory page falling in the requested physical range
    [ppos, ppos + count - 1]:
    3.1. this function shall check if user space access is allowed (if
    config STRICT_DEVMEM is not set, access is always granted);

    3.2. if access is allowed, the memory content from the page range falling
    within the requested physical range shall be copied to the user space
    buffer;

    3.3. zeros shall be copied to the user space buffer (for the page range
    falling within the requested physical range):
    3.3.1. if access to the memory page is restricted or,
    3.2.2. if the current page is page 0 on HW architectures where page 0 is
    not mapped.

    4. The file position '*ppos' shall be advanced by the number of bytes
    successfully copied to user space (including zeros).

    Context: process context.

    Return:
    * the number of bytes copied to user on success
    * %-EFAULT - the requested address range is not valid or a fault happened
    when copying to user-space (i.e. copy_from_kernel_nofault() failed)
    * %-EPERM - access to any of the required physical pages is not allowed
    * %-ENOMEM - out of memory error for auxiliary kernel buffers supporting
    the operation of copying content from the physical pages
selftests-devmem-read_allowed_area_ppos_advance
1.1.2.8. read_mem FE_4 MID: selftests/devmem:read_allowed_area_ppos_advance RELATIONS (Parent): RELATIONS (File): DESCRIPTION: test read allowed area increments ppos
  • a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75
    1.1.1.1. read_mem SPDX-Req-ID: a89784c55426aec4b8ba345f281a0ec478d43897a0a248618cb140c03c770c75 SPDX-Req-HKey: e06c773fa9ac085073414a8acdbd3a2fdaea3a90af0a6873462876c1c55ce682 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    read_mem - read from physical memory (/dev/mem).
    @file: struct file associated with /dev/mem.
    @buf: user-space buffer to copy data to.
    @count: number of bytes to read.
    @ppos: pointer to the current file position, representing the physical
    address to read from.

    This function checks if the requested physical memory range is valid
    and accessible by the user, then it copies data to the input
    user-space buffer up to the requested number of bytes.

    Function's expectations:

    1. This function shall check if the value pointed by ppos exceeds the
    maximum addressable physical address;

    2. This function shall check if the physical address range to be read
    is valid (i.e. it falls within a memory block and if it can be mapped
    to the kernel address space);

    3. For each memory page falling in the requested physical range
    [ppos, ppos + count - 1]:
    3.1. this function shall check if user space access is allowed (if
    config STRICT_DEVMEM is not set, access is always granted);

    3.2. if access is allowed, the memory content from the page range falling
    within the requested physical range shall be copied to the user space
    buffer;

    3.3. zeros shall be copied to the user space buffer (for the page range
    falling within the requested physical range):
    3.3.1. if access to the memory page is restricted or,
    3.2.2. if the current page is page 0 on HW architectures where page 0 is
    not mapped.

    4. The file position '*ppos' shall be advanced by the number of bytes
    successfully copied to user space (including zeros).

    Context: process context.

    Return:
    * the number of bytes copied to user on success
    * %-EFAULT - the requested address range is not valid or a fault happened
    when copying to user-space (i.e. copy_from_kernel_nofault() failed)
    * %-EPERM - access to any of the required physical pages is not allowed
    * %-ENOMEM - out of memory error for auxiliary kernel buffers supporting
    the operation of copying content from the physical pages
selftests-devmem-read_restricted_area
1.1.2.9. read_mem FE_3.3, FE_3.3.1, FE_3.2.2 MID: selftests/devmem:read_restricted_area RELATIONS (Parent): RELATIONS (File): DESCRIPTION: test read restricted returns zeros
  • 6e16917c09ee583de5dc9e8a24a406e75bb229554699a501cfa8efdb308862d7
    1.1.1.2. write_mem SPDX-Req-ID: 6e16917c09ee583de5dc9e8a24a406e75bb229554699a501cfa8efdb308862d7 SPDX-Req-HKey: 83f393fd3b6191e7ad88da40799254f4227893e7212c59e9a41ff429b1eba555 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    write_mem - write to physical memory (/dev/mem).
    @file: struct file associated with /dev/mem.
    @buf: user-space buffer containing the data to write.
    @count: number of bytes to write.
    @ppos: pointer to the current file position, representing the physical
    address to write to.

    This function checks if the target physical memory range is valid
    and accessible by the user, then it writes data from the input
    user-space buffer up to the requested number of bytes.

    Function's expectations:
    1. This function shall check if the value pointed by ppos exceeds the
    maximum addressable physical address;

    2. This function shall check if the physical address range to be written
    is valid (i.e. it falls within a memory block and if it can be mapped
    to the kernel address space);

    3. For each memory page falling in the physical range to be written
    [ppos, ppos + count - 1]:
    3.1. this function shall check if user space access is allowed (if
    config STRICT_DEVMEM is not set, access is always granted);

    3.2. the content from the user space buffer shall be copied to the page
    range falling within the physical range to be written if access is
    allowed;

    3.3. the data to be copied from the user space buffer (for the page range
    falling within the range to be written) shall be skipped:
    3.3.1. if access to the memory page is restricted or,
    3.3.2. if the current page is page 0 on HW architectures where page 0
    is not mapped.

    4. The file position '*ppos' shall be advanced by the number of bytes
    successfully copied from user space (including skipped bytes).

    Context: process context.

    Return:
    * the number of bytes copied from user-space on success
    * %-EFBIG - the value pointed by ppos exceeds the maximum addressable
    physical address
    * %-EFAULT - the physical address range is not valid or no bytes could
    be copied from user-space
    * %-EPERM - access to any of the required pages is not allowed
selftests-devmem-write_outside_area
1.1.2.10. write_mem - FE_2 MID: selftests/devmem:write_outside_area RELATIONS (Parent): RELATIONS (File): DESCRIPTION: test write outside
  • feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14
    1.1.1.4. memory_lseek SPDX-Req-ID: feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14 SPDX-Req-HKey: 17745d554ee1aca155176037541afce34a4c901070a0bdc84d114e8a147a8052 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    memory_lseek - change the file position.
    @file: file structure for the device.
    @offset: file offset to seek to.
    @orig: where to start seeking from (see whence in the llseek manpage).

    This function changes the file position according to the input offset
    and orig parameters.

    Function's expectations:
    1. This function shall lock the semaphore of the inode corresponding to the
    input file before any operation and unlock it before returning.

    2. This function shall check the orig value and accordingly:
    2.1. if it is equal to SEEK_CUR, the current file position shall be
    incremented by the input offset;
    2.2. if it is equal to SEEK_SET, the current file position shall be
    set to the input offset value;
    2.3. any other value shall result in an error condition.

    3. Before writing the current file position, the new position value
    shall be checked to not overlap with Linux ERRNO values.

    Assumptions of Use:
    1. the input file pointer is expected to be valid.

    Notes:
    The memory devices use the full 32/64 bits of the offset, and so we cannot
    check against negative addresses: they are ok. The return value is weird,
    though, in that case (0).

    Also note that seeking relative to the "end of file" isn't supported:
    it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.

    Context: process context, locks/unlocks inode->i_rwsem

    Return:
    * the new file position on success
    * %-EOVERFLOW - the new position value equals or exceeds
    (unsigned long long) -MAX_ERRNO
    * %-EINVAL - the orig parameter is invalid
     SPDX-Req-Note: The memory devices use the full 32/64 bits of the offset, and so we cannot
    check against negative addresses: they are ok. The return value is weird,
    though, in that case (0).
     SPDX-Req-Note: Also note that seeking relative to the "end of file" isn't supported:
    it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.
selftests-devmem-seek_seek_set
1.1.2.11. memory_lseek FE_2, FE_2.2 MID: selftests/devmem:seek_seek_set RELATIONS (Parent): RELATIONS (File): DESCRIPTION: test seek funcction SEEK_SET
  • feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14
    1.1.1.4. memory_lseek SPDX-Req-ID: feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14 SPDX-Req-HKey: 17745d554ee1aca155176037541afce34a4c901070a0bdc84d114e8a147a8052 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    memory_lseek - change the file position.
    @file: file structure for the device.
    @offset: file offset to seek to.
    @orig: where to start seeking from (see whence in the llseek manpage).

    This function changes the file position according to the input offset
    and orig parameters.

    Function's expectations:
    1. This function shall lock the semaphore of the inode corresponding to the
    input file before any operation and unlock it before returning.

    2. This function shall check the orig value and accordingly:
    2.1. if it is equal to SEEK_CUR, the current file position shall be
    incremented by the input offset;
    2.2. if it is equal to SEEK_SET, the current file position shall be
    set to the input offset value;
    2.3. any other value shall result in an error condition.

    3. Before writing the current file position, the new position value
    shall be checked to not overlap with Linux ERRNO values.

    Assumptions of Use:
    1. the input file pointer is expected to be valid.

    Notes:
    The memory devices use the full 32/64 bits of the offset, and so we cannot
    check against negative addresses: they are ok. The return value is weird,
    though, in that case (0).

    Also note that seeking relative to the "end of file" isn't supported:
    it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.

    Context: process context, locks/unlocks inode->i_rwsem

    Return:
    * the new file position on success
    * %-EOVERFLOW - the new position value equals or exceeds
    (unsigned long long) -MAX_ERRNO
    * %-EINVAL - the orig parameter is invalid
     SPDX-Req-Note: The memory devices use the full 32/64 bits of the offset, and so we cannot
    check against negative addresses: they are ok. The return value is weird,
    though, in that case (0).
     SPDX-Req-Note: Also note that seeking relative to the "end of file" isn't supported:
    it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.
selftests-devmem-seek_seek_cur
1.1.2.12. memory_lseek FE_2, FE_2.1 MID: selftests/devmem:seek_seek_cur RELATIONS (Parent): RELATIONS (File): DESCRIPTION: test seek function SEEK_CUR
  • feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14
    1.1.1.4. memory_lseek SPDX-Req-ID: feb4cb915f91d319078204293f6cf99eb50e775a8f670e478e30e84bd6979a14 SPDX-Req-HKey: 17745d554ee1aca155176037541afce34a4c901070a0bdc84d114e8a147a8052 SPDX-Req-Sys: Character Drivers and Misc RELATIONS (Child): RELATIONS (File): SPDX-Req-Text:
    memory_lseek - change the file position.
    @file: file structure for the device.
    @offset: file offset to seek to.
    @orig: where to start seeking from (see whence in the llseek manpage).

    This function changes the file position according to the input offset
    and orig parameters.

    Function's expectations:
    1. This function shall lock the semaphore of the inode corresponding to the
    input file before any operation and unlock it before returning.

    2. This function shall check the orig value and accordingly:
    2.1. if it is equal to SEEK_CUR, the current file position shall be
    incremented by the input offset;
    2.2. if it is equal to SEEK_SET, the current file position shall be
    set to the input offset value;
    2.3. any other value shall result in an error condition.

    3. Before writing the current file position, the new position value
    shall be checked to not overlap with Linux ERRNO values.

    Assumptions of Use:
    1. the input file pointer is expected to be valid.

    Notes:
    The memory devices use the full 32/64 bits of the offset, and so we cannot
    check against negative addresses: they are ok. The return value is weird,
    though, in that case (0).

    Also note that seeking relative to the "end of file" isn't supported:
    it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.

    Context: process context, locks/unlocks inode->i_rwsem

    Return:
    * the new file position on success
    * %-EOVERFLOW - the new position value equals or exceeds
    (unsigned long long) -MAX_ERRNO
    * %-EINVAL - the orig parameter is invalid
     SPDX-Req-Note: The memory devices use the full 32/64 bits of the offset, and so we cannot
    check against negative addresses: they are ok. The return value is weird,
    though, in that case (0).
     SPDX-Req-Note: Also note that seeking relative to the "end of file" isn't supported:
    it has no meaning, so passing orig equal to SEEK_END returns -EINVAL.
selftests-devmem-seek_seek_other
1.1.2.13. memory_lseek FE_2, FE2.3 MID: selftests/devmem:seek_seek_other RELATIONS (Parent): RELATIONS (File): DESCRIPTION: test seek function SEEK_END other