check_cpu_capabilities runs through a given list of caps and
checks if the system has the cap, updates the system capability
bitmap and also runs any enable() methods associated with them.
All of this is not quite obvious from the name 'check'. This
patch splits the check_cpu_capabilities into two parts :

1) update_cpu_capabilities
 => Runs through the given list and updates the system
    wide capability map.
2) enable_cpu_capabilities
 => Runs through the given list and invokes enable() (if any)
    for the caps enabled on the system.

Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Suggested-by: NCatalin Marinas <catalin.marinsa@arm.com>
Signed-off-by: NSuzuki K. Poulose <suzuki.poulose@arm.com>
Tested-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

This patch implements Cavium ThunderX erratum 23154.

The gicv3 of ThunderX requires a modified version for reading the IAR
status to ensure data synchronization. Since this is in the fast-path
and called with each interrupt, runtime patching is used using jump
label patching for smallest overhead (no-op). This is the same
technique as used for tracepoints.
Signed-off-by: NRobert Richter <rrichter@cavium.com>
Reviewed-by: NMarc Zygnier <marc.zyngier@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Cc: Tirumalesh Chalamarla <tchalamarla@cavium.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/1442869119-1814-3-git-send-email-rric@kernel.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Register MIDR_EL1 is masked to get variant and revision fields, then
compared against midr_range_min and midr_range_max when checking
whether CPU is affected by any particular erratum. However, variant
and revision fields in MIDR_EL1 are separated by 16 bits, so the min
and max of midr range should be constructed accordingly, otherwise
the patch will not be applied when variant field is non-0.

Cc: stable@vger.kernel.org # 3.19+
Acked-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NPaul Walmsley <paul@pwsan.com>
Signed-off-by: NBo Yan <byan@nvidia.com>
[will: use MIDR_VARIANT_SHIFT to construct upper bound]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When running a compat (AArch32) userspace on Cortex-A53, a load at EL0
from a virtual address that matches the bottom 32 bits of the virtual
address used by a recent load at (AArch64) EL1 might return incorrect
data.

This patch works around the issue by writing to the contextidr_el1
register on the exception return path when returning to a 32-bit task.
This workaround is patched in at runtime based on the MIDR value of the
processor.
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Tested-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

As we detect more architectural features at runtime, it makes
sense to reuse the existing framework whilst avoiding to call
a feature an erratum...

This patch extract the core capability parsing, moves it into
a new file (cpufeature.c), and let the CPU errata detection code
use it.
Reviewed-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Consistently use the plural form for alternatives pr_fmt strings.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Not all of the errata we have workarounds for apply necessarily to all
SoCs, so people compiling a kernel for one very specific SoC may not
need to patch the kernel.
Introduce a new submenu in the "Platform selection" menu to allow
people to turn off certain bugs if they are not affected. By default
all of them are enabled.
Normal users or distribution kernels shouldn't bother to deselect any
bugs here, since the alternatives framework will take care of
patching them in only if needed.
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
[will: moved kconfig menu under `Kernel Features']
Signed-off-by: NWill Deacon <will.deacon@arm.com>

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>