It is a rarely exercised case, so we want to have a test to ensure it
works as required.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Although we expect some small discrepancies for very large counts, we
seem to be able to count up to 64 billion instructions without too much
skew, so do so.
Also switch to using decimals for the instruction counts. This just
makes it easier to visually compare the expected vs actual values, as
well as the raw result from instructions.
Before:
instructions: result 68719476753 running/enabled 13101961654
cycles: result 38077343785 running/enabled 13101725752
Looped for 68719476736 instructions, overhead 17
Expected 68719476753
Actual 68719476753
Delta 0, 0.000000%
success: count_instructions
After:
instructions: result 64000000016 running/enabled 12197599964
cycles: result 35412471674 running/enabled 12197534110
Looped for 64000000000 instructions, overhead 16
Expected 64000000016
Actual 64000000016
Delta 0, 0.000000%
success: count_instructions
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Have a task eat some cpu while we are counting instructions to create
some scheduler pressure. The idea being to try and unearth any bugs we
have in counting that only appear when context switching is happening.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
There is at least one bug in core_busy_loop(), we use r0, but it's
not in the clobber list. We were getting away with this it seems but
that was luck.
It's also fishy to be touching the stack, even if we do it below the
stack pointer. It seems we get away with it, but looking at the
generated code that may just be luck.
So move it into assembler, do all the stack handling by hand. We create
a stack frame to save the non-volatiles in, so we can muck around with
them.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
start and end should be unsigned long.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Currently we ignore errors from our sub Makefiles. We inherited that
from the top-level selftests Makefile which aims to build and run as
many tests as possible and damn the torpedoes.
For the powerpc tests we'd instead like any errors to fail the build, so
we can automatically catch build failures.
We can achieve the best of both worlds by using -k, which tells make to
keep building when it hits an error, but still reports the error.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This gives us standardised success/failure output and also handles
killing the test if it runs forever (2 minutes).
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
The Power8 Performance Monitor Unit (PMU) has a new feature called Event
Based Branches (EBB). This commit adds tests of the kernel API for using
EBBs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Allows us to kill the test and any children it has spawned.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Correct the DSCR SPR becoming temporarily corrupted if a task is
context switched during a transaction.
The problem occurs while suspending the task and is caused by saving
the DSCR to thread.dscr after it has already been set to the CPU's
default value:
__switch_to() calls __switch_to_tm()
which calls tm_reclaim_task()
which calls tm_reclaim_thread()
which calls tm_reclaim()
where the DSCR is set to the CPU's default
__switch_to() calls _switch()
where thread.dscr is set to the DSCR
When the task is resumed, it's transaction will be doomed (as usual)
and the DSCR SPR will be corrupted, although the checkpointed value
will be correct. Therefore the DSCR will be immediately corrected by
the transaction aborting, unless it has been suspended. In that case
the incorrect value can be seen by the task until it resumes the
transaction.
The fix is to treat the DSCR similarly to the TAR and save it early
in __switch_to().
A program exposing the problem is added to the kernel self tests as:
tools/testing/selftests/powerpc/tm/tm-resched-dscr.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
CC: <stable@vger.kernel.org> [v3.10+]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Turn Anton's memcpy / copy_tofrom_user test into something that can
live in tools/testing/selftests.
It requires one turd in arch/powerpc/lib/memcpy_64.S, but it's pretty
harmless IMHO.
We are sailing very close to the wind with the feature macros. We define
them to nothing, which currently means we get a few extra nops and
include the unaligned calls.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit adds a test of instruction counting using the PMU on powerpc.
Although the bulk of the code is architecture agnostic, the code needs to
run a precisely sized loop which is implemented in assembler.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit adds support code used by upcoming powerpc tests.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit adds a powerpc subdirectory to tools/testing/selftests,
for tests that are powerpc specific.
On other architectures nothing is built. The makefile supports cross
compilation if the user sets ARCH and CROSS_COMPILE.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
