Since it's likely to be useful for performance work with SVE let's have a
pidbench that gives us some numbers for consideration. In order to ensure
that we test exactly the scenario we want this is written in assembly - if
system libraries use SVE this would stop us exercising the case where the
process has never used SVE.
We exercise three cases:
- Never having used SVE.
- Having used SVE once.
- Using SVE after each syscall.
by spinning running getpid() for a fixed number of iterations with the
time measured using CNTVCT_EL0 reported on the console. This is obviously
a totally unrealistic benchmark which will show the extremes of any
performance variation but equally given the potential gotchas with use of
FP instructions by system libraries it's good to have some concrete code
shared to make it easier to compare notes on results.
Testing over multiple SVE vector lengths will need to be done with vlset
currently, the test could be extended to iterate over all of them if
desired.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211202165107.1075259-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
SME introduces a new mode called streaming mode in which the SVE registers
have a different vector length. Since the ptrace interface for this is
based on the existing SVE interface prepare for supporting this by moving
the regset specific configuration into struct and passing that around,
allowing these tests to be reused for streaming mode. As we will also have
to verify the interoperation of the SVE and streaming SVE regsets don't
just iterate over an array.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211210184133.320748-5-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
ARRAY_SIZE is defined in several selftests. Remove definitions from
individual test files and include header file for the define instead.
ARRAY_SIZE define is added in a separate patch to prepare for this
change.
Remove ARRAY_SIZE from vec-syscfg.c and pickup the one defined in
kselftest.h.
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
The various floating point test programs written in assembly have a bunch
of helper functions and macros which are cut'n'pasted between them. Factor
them out into a separate source file which is linked into all of them.
We don't include memcmp() since it isn't as generic as it should be and
directly branches to report an error in the programs.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211019181851.3341232-1-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
As part of the enumeration interface for setting vector lengths it is valid
to set vector lengths not supported in the system, these will be rounded to
a supported vector length and returned from the prctl(). Add a test which
exercises this for every valid vector length and makes sure that the return
value is as expected and that this is reflected in the actual system state.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Link: https://lore.kernel.org/r/20210929151925.9601-5-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
We had some test code for verifying that we can write the current VL via
the prctl() interface but the condition for the test was inverted which
wasn't noticed as it was never actually hooked up to the array of tests
we execute. Fix this.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210929151925.9601-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Currently the selftest for the SVE register set is not quite as thorough
as is desirable - it only validates that the value of a single Z register
is not modified by a partial write to a lower numbered Z register after
having previously been set through the FPSIMD regset.
Make this more thorough:
- Test the ability to set vector lengths and enumerate those supported in
the system.
- Validate data in all Z and P registers, plus FPSR and FPCR.
- Test reads via the FPSIMD regset after set via the SVE regset.
There's still some oversights, the main one being that due to the need to
generate a pattern in FFR and the fact that this rewrite is primarily
motivated by SME's streaming SVE which doesn't have FFR we don't currently
test FFR. Update the TODO to reflect those that occurred to me (and fix an
adjacent typo in there).
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-8-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
When verifying setting a Z register via ptrace we check each byte by hand,
iterating over the buffer using a pointer called p and treating each
register value written as a test. This creates output referring to "p[X]"
which is confusing since SVE also has predicate registers Pn. Tweak the
output to avoid confusion here.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-6-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
For some reason the SVE ptrace test code starts off by setting values in
some of the SVE vector registers in the parent process which it then never
interacts with when verifying the ptrace interfaces. This is not especially
relevant to what's being tested and somewhat confusing when reading the
code so let's remove it.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210913125505.52619-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
We provide interfaces for configuring the SVE vector length seen by
processes using prctl and also via /proc for configuring the default
values. Provide tests that exercise all these interfaces and verify that
they take effect as expected, though at present no test fully enumerates
all the possible vector lengths.
A subset of this is already tested via sve-probe-vls but the /proc
interfaces are not currently covered at all.
In preparation for the forthcoming support for SME, the Scalable Matrix
Extension, which has separately but similarly configured vector lengths
which we expect to offer similar userspace interfaces for, all the actual
files and prctls used are parameterised and we don't validate that the
architectural minimum vector length is the minimum we see.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20210803140450.46624-4-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
SVE provides an instruction RDVL which reports the currently configured
vector length. In order to validate that our vector length configuration
interfaces are working correctly without having to build the C code for
our test programs with SVE enabled provide a trivial assembly library
with a C callable function that executes RDVL. Since these interfaces
also control behaviour on exec*() provide a trivial wrapper program which
reports the currently configured vector length on stdout, tests can use
this to verify that behaviour on exec*() is as expected.
In preparation for providing similar helper functionality for SME, the
Scalable Matrix Extension, which allows separately configured vector
lengths to be read back both the assembler function and wrapper binary
have SVE included in their name.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20210803140450.46624-2-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The "First Fault Register" (FFR) is an SVE register that mimics a
predicate register, but clears bits when a load or store fails to handle
an element of a vector. The supposed usage scenario is to initialise
this register (using SETFFR), then *read* it later on to learn about
elements that failed to load or store. Explicit writes to this register
using the WRFFR instruction are only supposed to *restore* values
previously read from the register (for context-switching only).
As the manual describes, this register holds only certain values, it:
"... contains a monotonic predicate value, in which starting from bit 0
there are zero or more 1 bits, followed only by 0 bits in any remaining
bit positions."
Any other value is UNPREDICTABLE and is not supposed to be "restored"
into the register.
The SVE test currently tries to write a signature pattern into the
register, which is *not* a canonical FFR value. Apparently the existing
setups treat UNPREDICTABLE as "read-as-written", but a new
implementation actually only stores canonical values. As a consequence,
the sve-test fails immediately when comparing the FFR value:
-----------
# ./sve-test
Vector length: 128 bits
PID: 207
Mismatch: PID=207, iteration=0, reg=48
Expected [cf00]
Got [0f00]
Aborted
-----------
Fix this by only populating the FFR with proper canonical values.
Effectively the requirement described above limits us to 17 unique
values over 16 bits worth of FFR, so we condense our signature down to 4
bits (2 bits from the PID, 2 bits from the generation) and generate the
canonical pattern from it. Any bits describing elements above the
minimum 128 bit are set to 0.
This aligns the FFR usage to the architecture and fixes the test on
microarchitectures implementing FFR in a more restricted way.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviwed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210319120128.29452-1-andre.przywara@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Add programs sve-test and fpsimd-test which spin reading and writing to
the SVE and FPSIMD registers, verifying the operations they perform. The
intended use is to leave them running to stress the context switch code's
handling of these registers which isn't compatible with what kselftest
does so they're not integrated into the framework but there's no other
obvious testsuite where they fit so let's store them here.
These tests were written by Dave Martin and lightly adapted by me.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Add a test case that does some basic verification of the SVE ptrace
interface, forking off a child with known values in the registers and
then using ptrace to inspect and manipulate the SVE registers of the
child, including in FPSIMD mode to account for sharing between the SVE
and FPSIMD registers.
This program was written by Dave Martin and modified for kselftest by
me.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200819114837.51466-3-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
