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docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
================
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
ARM64 ELF hwcaps
================
This document describes the usage and semantics of the arm64 ELF hwcaps.
1. Introduction
---------------
Some hardware or software features are only available on some CPU
implementations, and/or with certain kernel configurations, but have no
architected discovery mechanism available to userspace code at EL0. The
kernel exposes the presence of these features to userspace through a set
of flags called hwcaps, exposed in the auxilliary vector.
arm64: HWCAP: add support for AT_HWCAP2 As we will exhaust the first 32 bits of AT_HWCAP let's start exposing AT_HWCAP2 to userspace to give us up to 64 caps. Whilst it's possible to use the remaining 32 bits of AT_HWCAP, we prefer to expand into AT_HWCAP2 in order to provide a consistent view to userspace between ILP32 and LP64. However internal to the kernel we prefer to continue to use the full space of elf_hwcap. To reduce complexity and allow for future expansion, we now represent hwcaps in the kernel as ordinals and use a KERNEL_HWCAP_ prefix. This allows us to support automatic feature based module loading for all our hwcaps. We introduce cpu_set_feature to set hwcaps which complements the existing cpu_have_feature helper. These helpers allow us to clean up existing direct uses of elf_hwcap and reduce any future effort required to move beyond 64 caps. For convenience we also introduce cpu_{have,set}_named_feature which makes use of the cpu_feature macro to allow providing a hwcap name without a {KERNEL_}HWCAP_ prefix. Signed-off-by: Andrew Murray <andrew.murray@arm.com> [will: use const_ilog2() and tweak documentation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-09 09:52:40 +00:00
Userspace software can test for features by acquiring the AT_HWCAP or
AT_HWCAP2 entry of the auxiliary vector, and testing whether the relevant
docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
flags are set, e.g.::
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
bool floating_point_is_present(void)
{
unsigned long hwcaps = getauxval(AT_HWCAP);
if (hwcaps & HWCAP_FP)
return true;
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
return false;
}
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
Where software relies on a feature described by a hwcap, it should check
the relevant hwcap flag to verify that the feature is present before
attempting to make use of the feature.
Features cannot be probed reliably through other means. When a feature
is not available, attempting to use it may result in unpredictable
behaviour, and is not guaranteed to result in any reliable indication
that the feature is unavailable, such as a SIGILL.
2. Interpretation of hwcaps
---------------------------
The majority of hwcaps are intended to indicate the presence of features
which are described by architected ID registers inaccessible to
userspace code at EL0. These hwcaps are defined in terms of ID register
fields, and should be interpreted with reference to the definition of
these fields in the ARM Architecture Reference Manual (ARM ARM).
docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
Such hwcaps are described below in the form::
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
Functionality implied by idreg.field == val.
Such hwcaps indicate the availability of functionality that the ARM ARM
defines as being present when idreg.field has value val, but do not
indicate that idreg.field is precisely equal to val, nor do they
indicate the absence of functionality implied by other values of
idreg.field.
Other hwcaps may indicate the presence of features which cannot be
described by ID registers alone. These may be described without
reference to ID registers, and may refer to other documentation.
3. The hwcaps exposed in AT_HWCAP
---------------------------------
HWCAP_FP
Functionality implied by ID_AA64PFR0_EL1.FP == 0b0000.
HWCAP_ASIMD
Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0000.
HWCAP_EVTSTRM
The generic timer is configured to generate events at a frequency of
approximately 100KHz.
HWCAP_AES
arm64: docs: Fix typos in ELF hwcaps Fix some typos in our hwcap documentation, where we refer to the wrong ID register for some of the capabilities. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com> [will: fix amusing binary constants] Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-10-01 14:24:47 +00:00
Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0001.
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
HWCAP_PMULL
arm64: docs: Fix typos in ELF hwcaps Fix some typos in our hwcap documentation, where we refer to the wrong ID register for some of the capabilities. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com> [will: fix amusing binary constants] Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-10-01 14:24:47 +00:00
Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0010.
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
HWCAP_SHA1
Functionality implied by ID_AA64ISAR0_EL1.SHA1 == 0b0001.
HWCAP_SHA2
Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0001.
HWCAP_CRC32
Functionality implied by ID_AA64ISAR0_EL1.CRC32 == 0b0001.
HWCAP_ATOMICS
Functionality implied by ID_AA64ISAR0_EL1.Atomic == 0b0010.
HWCAP_FPHP
Functionality implied by ID_AA64PFR0_EL1.FP == 0b0001.
HWCAP_ASIMDHP
Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0001.
HWCAP_CPUID
EL0 access to certain ID registers is available, to the extent
docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
described by Documentation/arm64/cpu-feature-registers.rst.
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
These ID registers may imply the availability of features.
HWCAP_ASIMDRDM
Functionality implied by ID_AA64ISAR0_EL1.RDM == 0b0001.
HWCAP_JSCVT
Functionality implied by ID_AA64ISAR1_EL1.JSCVT == 0b0001.
HWCAP_FCMA
Functionality implied by ID_AA64ISAR1_EL1.FCMA == 0b0001.
HWCAP_LRCPC
Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0001.
HWCAP_DCPOP
Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0001.
arm64: Expose DC CVADP to userspace ARMv8.5 builds upon the ARMv8.2 DC CVAP instruction by introducing a DC CVADP instruction which cleans the data cache to the point of deep persistence. Let's expose this support via the arm64 ELF hwcaps. Signed-off-by: Andrew Murray <andrew.murray@arm.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-09 09:52:43 +00:00
HWCAP2_DCPODP
Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0010.
arm64: docs: describe ELF hwcaps We don't document our ELF hwcaps, leaving developers to interpret them according to hearsay, guesswork, or (in exceptional cases) inspection of the current kernel code. This is less than optimal, and it would be far better if we had some definitive description of each of the ELF hwcaps that developers could refer to. This patch adds a document describing the (native) arm64 ELF hwcaps. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> [ Updated new hwcap entries in the document ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-11 13:01:03 +00:00
HWCAP_SHA3
Functionality implied by ID_AA64ISAR0_EL1.SHA3 == 0b0001.
HWCAP_SM3
Functionality implied by ID_AA64ISAR0_EL1.SM3 == 0b0001.
HWCAP_SM4
Functionality implied by ID_AA64ISAR0_EL1.SM4 == 0b0001.
HWCAP_ASIMDDP
Functionality implied by ID_AA64ISAR0_EL1.DP == 0b0001.
HWCAP_SHA512
arm64: docs: Fix typos in ELF hwcaps Fix some typos in our hwcap documentation, where we refer to the wrong ID register for some of the capabilities. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com> [will: fix amusing binary constants] Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-10-01 14:24:47 +00:00
Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0010.
arm64/sve: Detect SVE and activate runtime support This patch enables detection of hardware SVE support via the cpufeatures framework, and reports its presence to the kernel and userspace via the new ARM64_SVE cpucap and HWCAP_SVE hwcap respectively. Userspace can also detect SVE using ID_AA64PFR0_EL1, using the cpufeatures MRS emulation. When running on hardware that supports SVE, this enables runtime kernel support for SVE, and allows user tasks to execute SVE instructions and make of the of the SVE-specific user/kernel interface extensions implemented by this series. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-31 15:51:19 +00:00
HWCAP_SVE
Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001.
arm64: v8.4: Support for new floating point multiplication instructions ARM v8.4 extensions add new neon instructions for performing a multiplication of each FP16 element of one vector with the corresponding FP16 element of a second vector, and to add or subtract this without an intermediate rounding to the corresponding FP32 element in a third vector. This patch detects this feature and let the userspace know about it via a HWCAP bit and MRS emulation. Cc: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2017-12-13 10:13:56 +00:00
arm64: Expose SVE2 features for userspace This patch provides support for reporting the presence of SVE2 and its optional features to userspace. This will also enable visibility of SVE2 for guests, when KVM support for SVE-enabled guests is available. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-18 17:41:38 +00:00
HWCAP2_SVE2
Functionality implied by ID_AA64ZFR0_EL1.SVEVer == 0b0001.
HWCAP2_SVEAES
Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0001.
HWCAP2_SVEPMULL
Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0010.
HWCAP2_SVEBITPERM
Functionality implied by ID_AA64ZFR0_EL1.BitPerm == 0b0001.
HWCAP2_SVESHA3
Functionality implied by ID_AA64ZFR0_EL1.SHA3 == 0b0001.
HWCAP2_SVESM4
Functionality implied by ID_AA64ZFR0_EL1.SM4 == 0b0001.
arm64: v8.4: Support for new floating point multiplication instructions ARM v8.4 extensions add new neon instructions for performing a multiplication of each FP16 element of one vector with the corresponding FP16 element of a second vector, and to add or subtract this without an intermediate rounding to the corresponding FP32 element in a third vector. This patch detects this feature and let the userspace know about it via a HWCAP bit and MRS emulation. Cc: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2017-12-13 10:13:56 +00:00
HWCAP_ASIMDFHM
Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0001.
arm64: Expose Arm v8.4 features Expose the new features introduced by Arm v8.4 extensions to Arm v8-A profile. These include : 1) Data indpendent timing of instructions. (DIT, exposed as HWCAP_DIT) 2) Unaligned atomic instructions and Single-copy atomicity of loads and stores. (AT, expose as HWCAP_USCAT) 3) LDAPR and STLR instructions with immediate offsets (extension to LRCPC, exposed as HWCAP_ILRCPC) 4) Flag manipulation instructions (TS, exposed as HWCAP_FLAGM). Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-03-12 10:04:14 +00:00
HWCAP_DIT
Functionality implied by ID_AA64PFR0_EL1.DIT == 0b0001.
HWCAP_USCAT
Functionality implied by ID_AA64MMFR2_EL1.AT == 0b0001.
HWCAP_ILRCPC
arm64: docs: Fix typos in ELF hwcaps Fix some typos in our hwcap documentation, where we refer to the wrong ID register for some of the capabilities. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com> [will: fix amusing binary constants] Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-10-01 14:24:47 +00:00
Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0010.
arm64: Expose Arm v8.4 features Expose the new features introduced by Arm v8.4 extensions to Arm v8-A profile. These include : 1) Data indpendent timing of instructions. (DIT, exposed as HWCAP_DIT) 2) Unaligned atomic instructions and Single-copy atomicity of loads and stores. (AT, expose as HWCAP_USCAT) 3) LDAPR and STLR instructions with immediate offsets (extension to LRCPC, exposed as HWCAP_ILRCPC) 4) Flag manipulation instructions (TS, exposed as HWCAP_FLAGM). Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-03-12 10:04:14 +00:00
HWCAP_FLAGM
Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0001.
arm64: docs: Document SSBS HWCAP We advertise the MRS/MSR instructions for toggling SSBS at EL0 using an HWCAP, so document it along with the others. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-10-01 14:24:48 +00:00
arm64: Expose ARMv8.5 CondM capability to userspace ARMv8.5 adds new instructions XAFLAG and AXFLAG to translate the representation of the results of floating point comparisons between the native ARM format and an alternative format used by some software. Add a hwcap allowing userspace to determine if they are present, since we referred to earlier CondM extensions as FLAGM call these extensions FLAGM2. Signed-off-by: Mark Brown <broonie@kernel.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2019-06-18 18:10:54 +00:00
HWCAP2_FLAGM2
Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0010.
arm64: docs: Document SSBS HWCAP We advertise the MRS/MSR instructions for toggling SSBS at EL0 using an HWCAP, so document it along with the others. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-10-01 14:24:48 +00:00
HWCAP_SSBS
Functionality implied by ID_AA64PFR1_EL1.SSBS == 0b0010.
arm64: docs: document pointer authentication Now that we've added code to support pointer authentication, add some documentation so that people can figure out if/how to use it. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Reviewed-by: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Andrew Jones <drjones@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:31 +00:00
HWCAP_PACA
Functionality implied by ID_AA64ISAR1_EL1.APA == 0b0001 or
ID_AA64ISAR1_EL1.API == 0b0001, as described by
docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
Documentation/arm64/pointer-authentication.rst.
arm64: docs: document pointer authentication Now that we've added code to support pointer authentication, add some documentation so that people can figure out if/how to use it. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Reviewed-by: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Andrew Jones <drjones@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:31 +00:00
HWCAP_PACG
Functionality implied by ID_AA64ISAR1_EL1.GPA == 0b0001 or
ID_AA64ISAR1_EL1.GPI == 0b0001, as described by
docs: arm64: convert docs to ReST and rename to .rst The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-12 17:52:38 +00:00
Documentation/arm64/pointer-authentication.rst.
arm64: HWCAP: add support for AT_HWCAP2 As we will exhaust the first 32 bits of AT_HWCAP let's start exposing AT_HWCAP2 to userspace to give us up to 64 caps. Whilst it's possible to use the remaining 32 bits of AT_HWCAP, we prefer to expand into AT_HWCAP2 in order to provide a consistent view to userspace between ILP32 and LP64. However internal to the kernel we prefer to continue to use the full space of elf_hwcap. To reduce complexity and allow for future expansion, we now represent hwcaps in the kernel as ordinals and use a KERNEL_HWCAP_ prefix. This allows us to support automatic feature based module loading for all our hwcaps. We introduce cpu_set_feature to set hwcaps which complements the existing cpu_have_feature helper. These helpers allow us to clean up existing direct uses of elf_hwcap and reduce any future effort required to move beyond 64 caps. For convenience we also introduce cpu_{have,set}_named_feature which makes use of the cpu_feature macro to allow providing a hwcap name without a {KERNEL_}HWCAP_ prefix. Signed-off-by: Andrew Murray <andrew.murray@arm.com> [will: use const_ilog2() and tweak documentation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-09 09:52:40 +00:00
arm64: Expose FRINT capabilities to userspace ARMv8.5 introduces the FRINT series of instructions for rounding floating point numbers to integers. Provide a capability to userspace in order to allow applications to determine if the system supports these instructions. Signed-off-by: Mark Brown <broonie@kernel.org> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2019-06-18 18:10:55 +00:00
HWCAP2_FRINT
Functionality implied by ID_AA64ISAR1_EL1.FRINTTS == 0b0001.
arm64: HWCAP: add support for AT_HWCAP2 As we will exhaust the first 32 bits of AT_HWCAP let's start exposing AT_HWCAP2 to userspace to give us up to 64 caps. Whilst it's possible to use the remaining 32 bits of AT_HWCAP, we prefer to expand into AT_HWCAP2 in order to provide a consistent view to userspace between ILP32 and LP64. However internal to the kernel we prefer to continue to use the full space of elf_hwcap. To reduce complexity and allow for future expansion, we now represent hwcaps in the kernel as ordinals and use a KERNEL_HWCAP_ prefix. This allows us to support automatic feature based module loading for all our hwcaps. We introduce cpu_set_feature to set hwcaps which complements the existing cpu_have_feature helper. These helpers allow us to clean up existing direct uses of elf_hwcap and reduce any future effort required to move beyond 64 caps. For convenience we also introduce cpu_{have,set}_named_feature which makes use of the cpu_feature macro to allow providing a hwcap name without a {KERNEL_}HWCAP_ prefix. Signed-off-by: Andrew Murray <andrew.murray@arm.com> [will: use const_ilog2() and tweak documentation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-09 09:52:40 +00:00
4. Unused AT_HWCAP bits
-----------------------
For interoperation with userspace, the kernel guarantees that bits 62
and 63 of AT_HWCAP will always be returned as 0.
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