8896dd968b
commit 2952db0fd51b0890f728df94ac563c21407f4f43 upstream. Many drivers have ioctl() handlers that are completely compatible between 32-bit and 64-bit architectures, except for the argument that is passed down from user space and may have to be passed through compat_ptr() in order to become a valid 64-bit pointer. Using ".compat_ptr = compat_ptr_ioctl" in file operations should let us simplify a lot of those drivers to avoid #ifdef checks, and convert additional drivers that don't have proper compat handling yet. On most architectures, the compat_ptr_ioctl() just passes all arguments to the corresponding ->ioctl handler. The exception is arch/s390, where compat_ptr() clears the top bit of a 32-bit pointer value, so user space pointers to the second 2GB alias the first 2GB, as is the case for native 32-bit s390 user space. The compat_ptr_ioctl() function must therefore be used only with ioctl functions that either ignore the argument or pass a pointer to a compatible data type. If any ioctl command handled by fops->unlocked_ioctl passes a plain integer instead of a pointer, or any of the passed data types is incompatible between 32-bit and 64-bit architectures, a proper handler is required instead of compat_ptr_ioctl. Signed-off-by: Arnd Bergmann <arnd@arndb.de> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.