commit 44b3834b2e upstream.
Cortex-A57 and Cortex-A72 have an erratum where an interrupt that
occurs between a pair of AES instructions in aarch32 mode may corrupt
the ELR. The task will subsequently produce the wrong AES result.
The AES instructions are part of the cryptographic extensions, which are
optional. User-space software will detect the support for these
instructions from the hwcaps. If the platform doesn't support these
instructions a software implementation should be used.
Remove the hwcap bits on affected parts to indicate user-space should
not use the AES instructions.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/r/20220714161523.279570-3-james.morse@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
[florian: resolved conflicts in arch/arm64/tools/cpucaps and cpu_errata.c]
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e89d120c4b upstream.
The AMU counter AMEVCNTR01 (constant counter) should increment at the same
rate as the system counter. On affected Cortex-A510 cores, AMEVCNTR01
increments incorrectly giving a significantly higher output value. This
results in inaccurate task scheduler utilization tracking and incorrect
feedback on CPU frequency.
Work around this problem by returning 0 when reading the affected counter
in key locations that results in disabling all users of this counter from
using it either for frequency invariance or as FFH reference counter. This
effect is the same to firmware disabling affected counters.
Details on how the two features are affected by this erratum:
- AMU counters will not be used for frequency invariance for affected
CPUs and CPUs in the same cpufreq policy. AMUs can still be used for
frequency invariance for unaffected CPUs in the system. Although
unlikely, if no alternative method can be found to support frequency
invariance for affected CPUs (cpufreq based or solution based on
platform counters) frequency invariance will be disabled. Please check
the chapter on frequency invariance at
Documentation/scheduler/sched-capacity.rst for details of its effect.
- Given that FFH can be used to fetch either the core or constant counter
values, restrictions are lifted regarding any of these counters
returning a valid (!0) value. Therefore FFH is considered supported
if there is a least one CPU that support AMUs, independent of any
counters being disabled or affected by this erratum. Clarifying
comments are now added to the cpc_ffh_supported(), cpu_read_constcnt()
and cpu_read_corecnt() functions.
The above is achieved through adding a new erratum: ARM64_ERRATUM_2457168.
Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/r/20220819103050.24211-1-ionela.voinescu@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 558c303c97 upstream.
Speculation attacks against some high-performance processors can
make use of branch history to influence future speculation.
When taking an exception from user-space, a sequence of branches
or a firmware call overwrites or invalidates the branch history.
The sequence of branches is added to the vectors, and should appear
before the first indirect branch. For systems using KPTI the sequence
is added to the kpti trampoline where it has a free register as the exit
from the trampoline is via a 'ret'. For systems not using KPTI, the same
register tricks are used to free up a register in the vectors.
For the firmware call, arch-workaround-3 clobbers 4 registers, so
there is no choice but to save them to the EL1 stack. This only happens
for entry from EL0, so if we take an exception due to the stack access,
it will not become re-entrant.
For KVM, the existing branch-predictor-hardening vectors are used.
When a spectre version of these vectors is in use, the firmware call
is sufficient to mitigate against Spectre-BHB. For the non-spectre
versions, the sequence of branches is added to the indirect vector.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When confronted with a mixture of CPUs, some of which support 32-bit
applications and others which don't, we quite sensibly treat the system
as 64-bit only for userspace and prevent execve() of 32-bit binaries.
Unfortunately, some crazy folks have decided to build systems like this
with the intention of running 32-bit applications, so relax our
sanitisation logic to continue to advertise 32-bit support to userspace
on these systems and track the real 32-bit capable cores in a cpumask
instead. For now, the default behaviour remains but will be tied to
a command-line option in a later patch.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210608180313.11502-3-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
The arm64 code allocates an internal constant to every CPU feature it can
detect, distinct from the public hwcap numbers we use to expose some
features to userspace. Currently this is maintained manually which is an
irritating source of conflicts when working on new features, to avoid this
replace the header with a simple text file listing the names we've assigned
and sort it to minimise conflicts.
As part of doing this we also do the Kbuild hookup required to hook up
an arch tools directory and to generate header files in there.
This will result in a renumbering and reordering of the existing constants,
since they are all internal only the values should not be important. The
reordering will impact the order in which some steps in enumeration handle
features but the algorithm is not intended to depend on this and I haven't
seen any issues when testing. Due to the UAO cpucap having been removed in
the past we end up with ARM64_NCAPS being 1 smaller than it was before.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210428121231.11219-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
