Re: [PATCH v5 3/6] perf test: Add a test for the new Arm CPU ID comparison behavior

[John Garry]

On 16/08/2023 10:14, James Clark wrote:
> On 15/08/2023 10:47, John Garry wrote:
> > On 11/08/2023 15:39, James Clark wrote:
> > > Now that variant and revision fields are taken into account the behavior
> > > is slightly more complicated so add a test to ensure that this behaves
> > > as expected.
> > >
> > > Signed-off-by: James Clark <james.clark@xxxxxxx>
> > > ---
> > >    tools/perf/arch/arm64/include/arch-tests.h |  3 ++
> > >    tools/perf/arch/arm64/tests/Build          |  1 +
> > >    tools/perf/arch/arm64/tests/arch-tests.c   |  4 +++
> > >    tools/perf/arch/arm64/tests/cpuid-match.c  | 38 ++++++++++++++++++++++
> > >    4 files changed, 46 insertions(+)
> > >    create mode 100644 tools/perf/arch/arm64/tests/cpuid-match.c
> > >
> > > diff --git a/tools/perf/arch/arm64/include/arch-tests.h
> > > b/tools/perf/arch/arm64/include/arch-tests.h
> > > index 452b3d904521..474d7cf5afbd 100644
> > > --- a/tools/perf/arch/arm64/include/arch-tests.h
> > > +++ b/tools/perf/arch/arm64/include/arch-tests.h
> > > @@ -2,6 +2,9 @@
> > >    #ifndef ARCH_TESTS_H
> > >    #define ARCH_TESTS_H
> > >    +struct test_suite;
> > > +
> > > +int test__cpuid_match(struct test_suite *test, int subtest);
> > >    extern struct test_suite *arch_tests[];
> > >      #endif
> > > diff --git a/tools/perf/arch/arm64/tests/Build
> > > b/tools/perf/arch/arm64/tests/Build
> > > index a61c06bdb757..e337c09e7f56 100644
> > > --- a/tools/perf/arch/arm64/tests/Build
> > > +++ b/tools/perf/arch/arm64/tests/Build
> > > @@ -2,3 +2,4 @@ perf-y += regs_load.o
> > >    perf-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o
> > >      perf-y += arch-tests.o
> > > +perf-y += cpuid-match.o
> > > diff --git a/tools/perf/arch/arm64/tests/arch-tests.c
> > > b/tools/perf/arch/arm64/tests/arch-tests.c
> > > index ad16b4f8f63e..74932e72c727 100644
> > > --- a/tools/perf/arch/arm64/tests/arch-tests.c
> > > +++ b/tools/perf/arch/arm64/tests/arch-tests.c
> > > @@ -3,9 +3,13 @@
> > >    #include "tests/tests.h"
> > >    #include "arch-tests.h"
> > >    +
> > > +DEFINE_SUITE("arm64 CPUID matching", cpuid_match);
> > > +
> > >    struct test_suite *arch_tests[] = {
> > >    #ifdef HAVE_DWARF_UNWIND_SUPPORT
> > >        &suite__dwarf_unwind,
> > >    #endif
> > > +    &suite__cpuid_match,
> > >        NULL,
> > >    };
> > > diff --git a/tools/perf/arch/arm64/tests/cpuid-match.c
> > > b/tools/perf/arch/arm64/tests/cpuid-match.c
> > > new file mode 100644
> > > index 000000000000..af0871b54ae7
> > > --- /dev/null
> > > +++ b/tools/perf/arch/arm64/tests/cpuid-match.c
> > > @@ -0,0 +1,38 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +#include <linux/compiler.h>
> > > +
> > > +#include "arch-tests.h"
> > > +#include "tests/tests.h"
> > > +#include "util/header.h"
> > > +
> > > +int test__cpuid_match(struct test_suite *test __maybe_unused,
> > > +                 int subtest __maybe_unused)
> > > +{
> > > +    /* midr with no leading zeros matches */
> > > +    if (strcmp_cpuid_str("0x410fd0c0", "0x00000000410fd0c0"))
> > > +        return -1;
> > > +    /* Upper case matches */
> > > +    if (strcmp_cpuid_str("0x410fd0c0", "0x00000000410FD0C0"))
> > > +        return -1;
> > > +    /* r0p0 = r0p0 matches */
> > > +    if (strcmp_cpuid_str("0x00000000410fd480", "0x00000000410fd480"))
> > > +        return -1;
> > > +    /* r0p1 > r0p0 matches */
> > > +    if (strcmp_cpuid_str("0x00000000410fd480", "0x00000000410fd481"))
> > > +        return -1;
> > > +    /* r1p0 > r0p0 matches*/
> > > +    if (strcmp_cpuid_str("0x00000000410fd480", "0x00000000411fd480"))
> > > +        return -1;
> > > +    /* r0p0 < r0p1 doesn't match */
> > > +    if (!strcmp_cpuid_str("0x00000000410fd481", "0x00000000410fd480"))
> > > +        return -1;
> > > +    /* r0p0 < r1p0 doesn't match */
> > > +    if (!strcmp_cpuid_str("0x00000000411fd480", "0x00000000410fd480"))
> > > +        return -1;
> > > +    /* Different CPU doesn't match */
> > > +    if (!strcmp_cpuid_str("0x00000000410fd4c0", "0x00000000430f0af0"))
> > > +        return -1;
> > > +
> > > +    return 0;
> > > +}
> > > +
> >
> > Would it be possible to put this in core test code, since x86 also
> > supports strcmp_cpuid_str()?
>
> That's how I started, but Ian suggested to move it to an arch specific
> folder because that's what it was testing.

Yeah, I see that comment now.

> We could still add test__cpuid_match() in the x86 folder rather than
> adding it with #ifdefs

I was thinking to make cpuid_match_array[] exposed by the arch code and 
have a "weak", i.e. version for other archs.

, but I don't think it needs to be done here
> because I haven't touched the x86 code.

For the moment, I don't feel too strongly about this and it can be done 
as a follow-up

Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>

> > Maybe we would have an structure per arch of cpuids and expected
> > results, like
> >
> > struct cpuid_match {
> >      char *cpuid1;
> >      char *cpuid1;
> >      int expected_result;
> > };
> >
> >
> > #ifdef ARM64
> >   cpuid_match_array[] = {
> >      {"0x410fd0c0", "0x00000000410FD0C0", -1},
> >      {"0x00000000410fd480", "0x00000000410fd480", -1},
> >      ...
> >      {} /* sentinel */
> >
> > };
> > #else if defined(X86)
> >   cpuid_match_array[] = {
> >      {....}
> >      ...
> >      {} /* sentinel */
> >
> > };
> > #else
> > /* no support */
> > #endif
> >
> > Thanks,
> > John