diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/core-api/protection-keys.rst | 38 | ||||
| -rw-r--r-- | Documentation/devicetree/bindings/net/brcm,unimac-mdio.yaml | 1 | ||||
| -rw-r--r-- | Documentation/process/maintainer-soc.rst | 42 |
3 files changed, 68 insertions, 13 deletions
diff --git a/Documentation/core-api/protection-keys.rst b/Documentation/core-api/protection-keys.rst index bf28ac0401f3..7eb7c6023e09 100644 --- a/Documentation/core-api/protection-keys.rst +++ b/Documentation/core-api/protection-keys.rst @@ -12,7 +12,10 @@ 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 + * arm64 CPUs implementing the Permission Overlay Extension (FEAT_S1POE) +x86_64 +====== Pkeys work by dedicating 4 previously Reserved bits in each page table entry to a "protection key", giving 16 possible keys. @@ -28,6 +31,22 @@ 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. +arm64 +===== + +Pkeys use 3 bits in each page table entry, to encode a "protection key index", +giving 8 possible keys. + +Protections for each key are defined with a per-CPU user-writable system +register (POR_EL0). This is a 64-bit register encoding read, write and execute +overlay permissions for each protection key index. + +Being a CPU register, POR_EL0 is inherently thread-local, potentially giving +each thread a different set of protections from every other thread. + +Unlike x86_64, the protection key permissions also apply to instruction +fetches. + Syscalls ======== @@ -38,11 +57,10 @@ There are 3 system calls which directly interact with pkeys:: int pkey_mprotect(unsigned long start, size_t len, unsigned long prot, int pkey); -Before a pkey can be used, it must first be allocated with -pkey_alloc(). An application calls the WRPKRU instruction -directly in order to change access permissions to memory covered -with a key. In this example WRPKRU is wrapped by a C function -called pkey_set(). +Before a pkey can be used, it must first be allocated with pkey_alloc(). An +application writes to the architecture specific CPU register directly in order +to change access permissions to memory covered with a key. In this example +this is wrapped by a C function called pkey_set(). :: int real_prot = PROT_READ|PROT_WRITE; @@ -64,9 +82,9 @@ is no longer in use:: munmap(ptr, PAGE_SIZE); pkey_free(pkey); -.. note:: pkey_set() is a wrapper for the RDPKRU and WRPKRU instructions. - An example implementation can be found in - tools/testing/selftests/x86/protection_keys.c. +.. note:: pkey_set() is a wrapper around writing to the CPU register. + Example implementations can be found in + tools/testing/selftests/mm/pkey-{arm64,powerpc,x86}.h Behavior ======== @@ -96,3 +114,7 @@ with a read():: The kernel will send a SIGSEGV in both cases, but si_code will be set to SEGV_PKERR when violating protection keys versus SEGV_ACCERR when the plain mprotect() permissions are violated. + +Note that kernel accesses from a kthread (such as io_uring) will use a default +value for the protection key register and so will not be consistent with +userspace's value of the register or mprotect(). diff --git a/Documentation/devicetree/bindings/net/brcm,unimac-mdio.yaml b/Documentation/devicetree/bindings/net/brcm,unimac-mdio.yaml index 23dfe0838dca..63bee5b542f5 100644 --- a/Documentation/devicetree/bindings/net/brcm,unimac-mdio.yaml +++ b/Documentation/devicetree/bindings/net/brcm,unimac-mdio.yaml @@ -26,6 +26,7 @@ properties: - brcm,asp-v2.1-mdio - brcm,asp-v2.2-mdio - brcm,unimac-mdio + - brcm,bcm6846-mdio reg: minItems: 1 diff --git a/Documentation/process/maintainer-soc.rst b/Documentation/process/maintainer-soc.rst index 12637530d68f..fe9d8bcfbd2b 100644 --- a/Documentation/process/maintainer-soc.rst +++ b/Documentation/process/maintainer-soc.rst @@ -30,10 +30,13 @@ tree as a dedicated branch covering multiple subsystems. The main SoC tree is housed on git.kernel.org: https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git/ +Maintainers +----------- + Clearly this is quite a wide range of topics, which no one person, or even small group of people are capable of maintaining. Instead, the SoC subsystem -is comprised of many submaintainers, each taking care of individual platforms -and driver subdirectories. +is comprised of many submaintainers (platform maintainers), each taking care of +individual platforms and driver subdirectories. In this regard, "platform" usually refers to a series of SoCs from a given vendor, for example, Nvidia's series of Tegra SoCs. Many submaintainers operate on a vendor level, responsible for multiple product lines. For several reasons, @@ -43,14 +46,43 @@ MAINTAINERS file. Most of these submaintainers have their own trees where they stage patches, sending pull requests to the main SoC tree. These trees are usually, but not -always, listed in MAINTAINERS. The main SoC maintainers can be reached via the -alias soc@kernel.org if there is no platform-specific maintainer, or if they -are unresponsive. +always, listed in MAINTAINERS. What the SoC tree is not, however, is a location for architecture-specific code changes. Each architecture has its own maintainers that are responsible for architectural details, CPU errata and the like. +Submitting Patches for Given SoC +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +All typical platform related patches should be sent via SoC submaintainers +(platform-specific maintainers). This includes also changes to per-platform or +shared defconfigs (scripts/get_maintainer.pl might not provide correct +addresses in such case). + +Submitting Patches to the Main SoC Maintainers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The main SoC maintainers can be reached via the alias soc@kernel.org only in +following cases: + +1. There are no platform-specific maintainers. + +2. Platform-specific maintainers are unresponsive. + +3. Introducing a completely new SoC platform. Such new SoC work should be sent + first to common mailing lists, pointed out by scripts/get_maintainer.pl, for + community review. After positive community review, work should be sent to + soc@kernel.org in one patchset containing new arch/foo/Kconfig entry, DTS + files, MAINTAINERS file entry and optionally initial drivers with their + Devicetree bindings. The MAINTAINERS file entry should list new + platform-specific maintainers, who are going to be responsible for handling + patches for the platform from now on. + +Note that the soc@kernel.org is usually not the place to discuss the patches, +thus work sent to this address should be already considered as acceptable by +the community. + Information for (new) Submaintainers ------------------------------------ |