diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/arm64/cpu-feature-registers.rst | 17 | ||||
| -rw-r--r-- | Documentation/arm64/elf_hwcaps.rst | 8 | ||||
| -rw-r--r-- | Documentation/arm64/pointer-authentication.rst | 9 | ||||
| -rw-r--r-- | Documentation/arm64/sve.rst | 2 | ||||
| -rw-r--r-- | Documentation/arm64/tagged-address-abi.rst | 2 | ||||
| -rw-r--r-- | Documentation/memory-barriers.txt | 8 |
6 files changed, 39 insertions, 7 deletions
diff --git a/Documentation/arm64/cpu-feature-registers.rst b/Documentation/arm64/cpu-feature-registers.rst index 9f9b8fd06089..749ae970c319 100644 --- a/Documentation/arm64/cpu-feature-registers.rst +++ b/Documentation/arm64/cpu-feature-registers.rst @@ -275,6 +275,23 @@ infrastructure: | SVEVer | [3-0] | y | +------------------------------+---------+---------+ + 8) ID_AA64MMFR1_EL1 - Memory model feature register 1 + + +------------------------------+---------+---------+ + | Name | bits | visible | + +------------------------------+---------+---------+ + | AFP | [47-44] | y | + +------------------------------+---------+---------+ + + 9) ID_AA64ISAR2_EL1 - Instruction set attribute register 2 + + +------------------------------+---------+---------+ + | Name | bits | visible | + +------------------------------+---------+---------+ + | RPRES | [7-4] | y | + +------------------------------+---------+---------+ + + Appendix I: Example ------------------- diff --git a/Documentation/arm64/elf_hwcaps.rst b/Documentation/arm64/elf_hwcaps.rst index af106af8e1c0..b72ff17d600a 100644 --- a/Documentation/arm64/elf_hwcaps.rst +++ b/Documentation/arm64/elf_hwcaps.rst @@ -251,6 +251,14 @@ HWCAP2_ECV Functionality implied by ID_AA64MMFR0_EL1.ECV == 0b0001. +HWCAP2_AFP + + Functionality implied by ID_AA64MFR1_EL1.AFP == 0b0001. + +HWCAP2_RPRES + + Functionality implied by ID_AA64ISAR2_EL1.RPRES == 0b0001. + 4. Unused AT_HWCAP bits ----------------------- diff --git a/Documentation/arm64/pointer-authentication.rst b/Documentation/arm64/pointer-authentication.rst index f127666ea3a8..e5dad2e40aa8 100644 --- a/Documentation/arm64/pointer-authentication.rst +++ b/Documentation/arm64/pointer-authentication.rst @@ -53,11 +53,10 @@ The number of bits that the PAC occupies in a pointer is 55 minus the virtual address size configured by the kernel. For example, with a virtual address size of 48, the PAC is 7 bits wide. -Recent versions of GCC can compile code with APIAKey-based return -address protection when passed the -msign-return-address option. This -uses instructions in the HINT space (unless -march=armv8.3-a or higher -is also passed), and such code can run on systems without the pointer -authentication extension. +When ARM64_PTR_AUTH_KERNEL is selected, the kernel will be compiled +with HINT space pointer authentication instructions protecting +function returns. Kernels built with this option will work on hardware +with or without pointer authentication support. In addition to exec(), keys can also be reinitialized to random values using the PR_PAC_RESET_KEYS prctl. A bitmask of PR_PAC_APIAKEY, diff --git a/Documentation/arm64/sve.rst b/Documentation/arm64/sve.rst index 03137154299e..9d9a4de5bc34 100644 --- a/Documentation/arm64/sve.rst +++ b/Documentation/arm64/sve.rst @@ -255,7 +255,7 @@ prctl(PR_SVE_GET_VL) vector length change (which would only normally be the case between a fork() or vfork() and the corresponding execve() in typical use). - To extract the vector length from the result, and it with + To extract the vector length from the result, bitwise and it with PR_SVE_VL_LEN_MASK. Return value: a nonnegative value on success, or a negative value on error: diff --git a/Documentation/arm64/tagged-address-abi.rst b/Documentation/arm64/tagged-address-abi.rst index 0c9120ec58ae..540a1d4fc6c9 100644 --- a/Documentation/arm64/tagged-address-abi.rst +++ b/Documentation/arm64/tagged-address-abi.rst @@ -49,7 +49,7 @@ how the user addresses are used by the kernel: - ``brk()``, ``mmap()`` and the ``new_address`` argument to ``mremap()`` as these have the potential to alias with existing - user addresses. + user addresses. NOTE: This behaviour changed in v5.6 and so some earlier kernels may incorrectly accept valid tagged pointers for the ``brk()``, diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index 7367ada13208..b12df9137e1c 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1950,6 +1950,14 @@ There are some more advanced barrier functions: For load from persistent memory, existing read memory barriers are sufficient to ensure read ordering. + (*) io_stop_wc(); + + For memory accesses with write-combining attributes (e.g. those returned + by ioremap_wc(), the CPU may wait for prior accesses to be merged with + subsequent ones. io_stop_wc() can be used to prevent the merging of + write-combining memory accesses before this macro with those after it when + such wait has performance implications. + =============================== IMPLICIT KERNEL MEMORY BARRIERS =============================== |