lwn.git/Documentation/arm64/cpu-feature-registers.rst, branch docs-mw

docs: arm64: Move arm64 documentation under Documentation/arch/

2023-06-21T14:51:51+00:00

Architecture-specific documentation is being moved into Documentation/arch/ as a way of cleaning up the top-level documentation directory and making the docs hierarchy more closely match the source hierarchy. Move Documentation/arm64 into arch/ (along with the Chinese equvalent translations) and fix up documentation references. Cc: Will Deacon Cc: Alex Shi Cc: Hu Haowen Cc: Paolo Bonzini Acked-by: Catalin Marinas Reviewed-by: Yantengsi Signed-off-by: Jonathan Corbet

arm64: cpufeature: Fix the visibility of compat hwcaps

2022-11-03T18:04:56+00:00

Commit 237405ebef58 ("arm64: cpufeature: Force HWCAP to be based on the sysreg visible to user-space") forced the hwcaps to use sanitised user-space view of the id registers. However, the ID register structures used to select few compat cpufeatures (vfp, crc32, ...) are masked and hence such hwcaps do not appear in /proc/cpuinfo anymore for PER_LINUX32 personality. Add the ID register structures explicitly and set the relevant entry as visible. As these ID registers are now of type visible so make them available in 64-bit userspace by making necessary changes in register emulation logic and documentation. While at it, update the comment for structure ftr_generic_32bits[] which lists the ID register that use it. Fixes: 237405ebef58 ("arm64: cpufeature: Force HWCAP to be based on the sysreg visible to user-space") Cc: Suzuki K Poulose Reviewed-by: James Morse Signed-off-by: Amit Daniel Kachhap Link: https://lore.kernel.org/r/20221103082232.19189-1-amit.kachhap@arm.com Signed-off-by: Catalin Marinas

arm64: Add HWCAP advertising FEAT_WFXT

2022-04-20T12:24:44+00:00

In order to allow userspace to enjoy WFET, add a new HWCAP that advertises it when available. Signed-off-by: Marc Zyngier Acked-by: Catalin Marinas Link: https://lore.kernel.org/r/20220419182755.601427-9-maz@kernel.org

arm64: cpufeature: add HWCAP for FEAT_RPRES

2021-12-13T18:53:00+00:00

Add a new HWCAP to detect the Increased precision of Reciprocal Estimate and Reciprocal Square Root Estimate feature (FEAT_RPRES), introduced in Armv8.7. Also expose this to userspace in the ID_AA64ISAR2_EL1 feature register. Signed-off-by: Joey Gouly Cc: Will Deacon Cc: Jonathan Corbet Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20211210165432.8106-4-joey.gouly@arm.com Signed-off-by: Catalin Marinas

arm64: cpufeature: add HWCAP for FEAT_AFP

2021-12-13T18:52:59+00:00

Add a new HWCAP to detect the Alternate Floating-point Behaviour feature (FEAT_AFP), introduced in Armv8.7. Also expose this to userspace in the ID_AA64MMFR1_EL1 feature register. Signed-off-by: Joey Gouly Cc: Will Deacon Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20211210165432.8106-2-joey.gouly@arm.com Signed-off-by: Catalin Marinas

arm64: Add HWCAP for self-synchronising virtual counter

2021-10-19T09:56:20+00:00

Since userspace can make use of the CNTVSS_EL0 instruction, expose it via a HWCAP. Suggested-by: Will Deacon Acked-by: Will Deacon Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20211017124225.3018098-18-maz@kernel.org Signed-off-by: Will Deacon

arm64: mte: Add Memory Tagging Extension documentation

2020-09-04T11:46:07+00:00

Memory Tagging Extension (part of the ARMv8.5 Extensions) provides a mechanism to detect the sources of memory related errors which may be vulnerable to exploitation, including bounds violations, use-after-free, use-after-return, use-out-of-scope and use before initialization errors. Add Memory Tagging Extension documentation for the arm64 linux kernel support. Signed-off-by: Vincenzo Frascino Co-developed-by: Catalin Marinas Signed-off-by: Catalin Marinas Acked-by: Szabolcs Nagy Cc: Will Deacon

arm64: Documentation: Fix broken table in generated HTML

2020-07-08T21:20:41+00:00

cpu-feature-registers.rst is missing a new line before a couple of tables listing the visible fields, causing broken tables in the HTML documentation generated by "make htmldocs". Fix this by adding the missing new line. Reported-by: Peter Maydell Signed-off-by: Suzuki K Poulose Cc: Mark Rutland Cc: Will Deacon Cc: Catalin Marinas Link: https://lore.kernel.org/r/20200707143152.154541-1-suzuki.poulose@arm.com Signed-off-by: Will Deacon

arm64: Basic Branch Target Identification support

2020-03-16T17:19:48+00:00

This patch adds the bare minimum required to expose the ARMv8.5 Branch Target Identification feature to userspace. By itself, this does _not_ automatically enable BTI for any initial executable pages mapped by execve(). This will come later, but for now it should be possible to enable BTI manually on those pages by using mprotect() from within the target process. Other arches already using the generic mman.h are already using 0x10 for arch-specific prot flags, so we use that for PROT_BTI here. For consistency, signal handler entry points in BTI guarded pages are required to be annotated as such, just like any other function. This blocks a relatively minor attack vector, but comforming userspace will have the annotations anyway, so we may as well enforce them. Signed-off-by: Mark Brown Signed-off-by: Dave Martin Reviewed-by: Catalin Marinas Signed-off-by: Catalin Marinas

Merge branch 'for-next/rng' into for-next/core

2020-01-22T11:38:53+00:00

* for-next/rng: (2 commits) arm64: Use v8.5-RNG entropy for KASLR seed ...