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07f522d203
Applications need the ability to associate an address-range with some key and latter revert to its initial default key. Pkey-0 comes close to providing this function but falls short, because the current implementation disallows applications to explicitly associate pkey-0 to the address range. Lets make pkey-0 less special and treat it almost like any other key. Thus it can be explicitly associated with any address range, and can be freed. This gives the application more flexibility and power. The ability to free pkey-0 must be used responsibily, since pkey-0 is associated with almost all address-range by default. Even with this change pkey-0 continues to be slightly more special from the following point of view. (a) it is implicitly allocated. (b) it is the default key assigned to any address-range. (c) its permissions cannot be modified by userspace. NOTE: (c) is specific to powerpc only. pkey-0 is associated by default with all pages including kernel pages, and pkeys are also active in kernel mode. If any permission is denied on pkey-0, the kernel running in the context of the application will be unable to operate. Tested on powerpc. Signed-off-by: Ram Pai <linuxram@us.ibm.com> [mpe: Drop #define PKEY_0 0 in favour of plain old 0] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| 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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.