diff options
Diffstat (limited to 'Documentation/core-api')
| -rw-r--r-- | Documentation/core-api/idr.rst | 3 | ||||
| -rw-r--r-- | Documentation/core-api/kernel-api.rst | 2 | ||||
| -rw-r--r-- | Documentation/core-api/protection-keys.rst | 44 | ||||
| -rw-r--r-- | Documentation/core-api/symbol-namespaces.rst | 4 |
4 files changed, 27 insertions, 26 deletions
diff --git a/Documentation/core-api/idr.rst b/Documentation/core-api/idr.rst index 2eb5afdb9931..18d724867064 100644 --- a/Documentation/core-api/idr.rst +++ b/Documentation/core-api/idr.rst @@ -17,6 +17,9 @@ solution to the problem to avoid everybody inventing their own. The IDR provides the ability to map an ID to a pointer, while the IDA provides only ID allocation, and as a result is much more memory-efficient. +The IDR interface is deprecated; please use the :doc:`XArray <xarray>` +instead. + IDR usage ========= diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst index d6b3f94b9f1f..0793c400d4b0 100644 --- a/Documentation/core-api/kernel-api.rst +++ b/Documentation/core-api/kernel-api.rst @@ -223,7 +223,7 @@ Module Loading Inter Module support -------------------- -Refer to the file kernel/module.c for more information. +Refer to the files in kernel/module/ for more information. Hardware Interfaces =================== diff --git a/Documentation/core-api/protection-keys.rst b/Documentation/core-api/protection-keys.rst index ec575e72d0b2..bf28ac0401f3 100644 --- a/Documentation/core-api/protection-keys.rst +++ b/Documentation/core-api/protection-keys.rst @@ -4,31 +4,29 @@ Memory Protection Keys ====================== -Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature -which is found on Intel's Skylake (and later) "Scalable Processor" -Server CPUs. It will be available in future non-server Intel parts -and future AMD processors. - -For anyone wishing to test or use this feature, it is available in -Amazon's EC2 C5 instances and is known to work there using an Ubuntu -17.04 image. - -Memory Protection Keys provides a mechanism for enforcing page-based -protections, but without requiring modification of the page tables -when an application changes protection domains. It works by -dedicating 4 previously ignored bits in each page table entry to a -"protection key", giving 16 possible keys. - -There is also a new user-accessible register (PKRU) with two separate -bits (Access Disable and Write Disable) for each key. Being a CPU -register, PKRU is inherently thread-local, potentially giving each +Memory Protection Keys provide a mechanism for enforcing page-based +protections, but without requiring modification of the page tables when an +application changes protection domains. + +Pkeys Userspace (PKU) is a feature which can be found on: + * Intel server CPUs, Skylake and later + * Intel client CPUs, Tiger Lake (11th Gen Core) and later + * Future AMD CPUs + +Pkeys work by dedicating 4 previously Reserved bits in each page table entry to +a "protection key", giving 16 possible keys. + +Protections for each key are defined with a per-CPU user-accessible register +(PKRU). Each of these is a 32-bit register storing two bits (Access Disable +and Write Disable) for each of 16 keys. + +Being a CPU register, PKRU is inherently thread-local, potentially giving each thread a different set of protections from every other thread. -There are two new instructions (RDPKRU/WRPKRU) for reading and writing -to the new register. The feature is only available in 64-bit mode, -even though there is theoretically space in the PAE PTEs. These -permissions are enforced on data access only and have no effect on -instruction fetches. +There are two instructions (RDPKRU/WRPKRU) for reading and writing to the +register. The feature is only available in 64-bit mode, even though there is +theoretically space in the PAE PTEs. These permissions are enforced on data +access only and have no effect on instruction fetches. Syscalls ======== diff --git a/Documentation/core-api/symbol-namespaces.rst b/Documentation/core-api/symbol-namespaces.rst index 5ad9e0abe42c..12e4aecdae94 100644 --- a/Documentation/core-api/symbol-namespaces.rst +++ b/Documentation/core-api/symbol-namespaces.rst @@ -51,8 +51,8 @@ namespace ``USB_STORAGE``, use:: The corresponding ksymtab entry struct ``kernel_symbol`` will have the member ``namespace`` set accordingly. A symbol that is exported without a namespace will refer to ``NULL``. There is no default namespace if none is defined. ``modpost`` -and kernel/module.c make use the namespace at build time or module load time, -respectively. +and kernel/module/main.c make use the namespace at build time or module load +time, respectively. 2.2 Using the DEFAULT_SYMBOL_NAMESPACE define ============================================= |