The ARM erratum 832075 applies to certain revisions of Cortex-A57,
one of the workarounds is to change device loads into using
load-aquire semantics.
This is achieved using the alternatives framework.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

The ARM errata 819472, 826319, 827319 and 824069 define the same
workaround for these hardware issues in certain Cortex-A53 parts.
Use the new alternatives framework and the CPU MIDR detection to
patch "cache clean" into "cache clean and invalidate" instructions if
an affected CPU is detected at runtime.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
[will: add __maybe_unused to squash gcc warning]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

After each CPU has been started, we iterate through a list of
CPU features or bugs to detect CPUs which need (or could benefit
from) kernel code patches.
For each feature/bug there is a function which checks if that
particular CPU is affected. We will later provide some more generic
functions for common things like testing for certain MIDR ranges.
We do this for every CPU to cover big.LITTLE systems properly as
well.
If a certain feature/bug has been detected, the capability bit will
be set, so that later the call to apply_alternatives() will trigger
the actual code patching.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

For taking note if at least one CPU in the system needs a bug
workaround or would benefit from a code optimization, we create a new
bitmap to hold (artificial) feature bits.
Since elf_hwcap is part of the userland ABI, we keep it alone and
introduce a new data structure for that (along with some accessors).
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

This enables support for the generic CPU feature modalias implementation that
wires up optional CPU features to udev based module autoprobing.

A file <asm/cpufeature.h> is provided that maps CPU feature numbers to
elf_hwcap bits, which is the standard way on arm64 to advertise optional CPU
features both internally and to user space.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
[catalin.marinas@arm.com: removed unnecessary "!!"]
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>