[PATCH] perf test record user-regs: Fix mask for vg register

[PATCH] perf test record user-regs: Fix mask for vg register

[vmolnaro]

From: Veronika Molnarova <vmolnaro@redhat.com>

The 'vg' register for arm64 shows up in --user_regs as available when
masking the variable AT_HWCAP with 1 << 22 returns '1' as done in
perf_regs.c. However, in subtests for support of SVE, the check for
the 'vg' register is done by masking the variable AT_HWCAP with the value
0x200000 which is equals to 1 << 21 instead of 1 << 22. This results in
inconsistencies on certain systems where the test expects that the 'vg'
register is not operational when it is, and vice-versa.

During the testing on a machine that the test expected not to have the
'vg' register available, the perf record with option --user-regs showed
records for the 'vg' register together with all of the others, which
means that the mask for the subtest of perf_event_attr is off by one.
Change the value of the mask from 0x200000 to 0x400000 to correct it.

Signed-off-by: Veronika Molnarova <vmolnaro@redhat.com>
---
 tools/perf/tests/attr/test-record-user-regs-no-sve-aarch64 | 2 +-
 tools/perf/tests/attr/test-record-user-regs-sve-aarch64    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/attr/test-record-user-regs-no-sve-aarch64 b/tools/perf/tests/attr/test-record-user-regs-no-sve-aarch64
index fbb065842880..bed765450ca9 100644
--- a/tools/perf/tests/attr/test-record-user-regs-no-sve-aarch64
+++ b/tools/perf/tests/attr/test-record-user-regs-no-sve-aarch64
@@ -6,4 +6,4 @@ args    = --no-bpf-event --user-regs=vg kill >/dev/null 2>&1
 ret     = 129
 test_ret = true
 arch    = aarch64
-auxv    = auxv["AT_HWCAP"] & 0x200000 == 0
+auxv    = auxv["AT_HWCAP"] & 0x400000 == 0
diff --git a/tools/perf/tests/attr/test-record-user-regs-sve-aarch64 b/tools/perf/tests/attr/test-record-user-regs-sve-aarch64
index c598c803221d..a65113cd7311 100644
--- a/tools/perf/tests/attr/test-record-user-regs-sve-aarch64
+++ b/tools/perf/tests/attr/test-record-user-regs-sve-aarch64
@@ -6,7 +6,7 @@ args    = --no-bpf-event --user-regs=vg kill >/dev/null 2>&1
 ret     = 1
 test_ret = true
 arch    = aarch64
-auxv    = auxv["AT_HWCAP"] & 0x200000 == 0x200000
+auxv    = auxv["AT_HWCAP"] & 0x400000 == 0x400000
 kernel_since = 6.1
 
 [event:base-record]
-- 
2.41.0

Re: [PATCH] perf test record user-regs: Fix mask for vg register

[Leo Yan]

On Fri, Dec 01, 2023 at 08:46:17PM +0100, vmolnaro@redhat.com wrote:
> From: Veronika Molnarova <vmolnaro@redhat.com>
> 
> The 'vg' register for arm64 shows up in --user_regs as available when
> masking the variable AT_HWCAP with 1 << 22 returns '1' as done in
> perf_regs.c. However, in subtests for support of SVE, the check for
> the 'vg' register is done by masking the variable AT_HWCAP with the value
> 0x200000 which is equals to 1 << 21 instead of 1 << 22. This results in
> inconsistencies on certain systems where the test expects that the 'vg'
> register is not operational when it is, and vice-versa.
> 
> During the testing on a machine that the test expected not to have the
> 'vg' register available, the perf record with option --user-regs showed
> records for the 'vg' register together with all of the others, which
> means that the mask for the subtest of perf_event_attr is off by one.
> Change the value of the mask from 0x200000 to 0x400000 to correct it.
> 
> Signed-off-by: Veronika Molnarova <vmolnaro@redhat.com>

LGTM, except I think it's good to add fix tag:

  Fixes: 9440ebdc333d ("perf test arm64: Add attr tests for new VG register")

With above fix tag:

Reviewed-by: Leo Yan <leo.yan@linaro.org>

Re: [PATCH] perf test record user-regs: Fix mask for vg register

[Arnaldo Carvalho de Melo]

Em Sun, Dec 03, 2023 at 02:13:53PM +0800, Leo Yan escreveu:
> On Fri, Dec 01, 2023 at 08:46:17PM +0100, vmolnaro@redhat.com wrote:
> > From: Veronika Molnarova <vmolnaro@redhat.com>
> > 
> > The 'vg' register for arm64 shows up in --user_regs as available when
> > masking the variable AT_HWCAP with 1 << 22 returns '1' as done in
> > perf_regs.c. However, in subtests for support of SVE, the check for
> > the 'vg' register is done by masking the variable AT_HWCAP with the value
> > 0x200000 which is equals to 1 << 21 instead of 1 << 22. This results in
> > inconsistencies on certain systems where the test expects that the 'vg'
> > register is not operational when it is, and vice-versa.
> > 
> > During the testing on a machine that the test expected not to have the
> > 'vg' register available, the perf record with option --user-regs showed
> > records for the 'vg' register together with all of the others, which
> > means that the mask for the subtest of perf_event_attr is off by one.
> > Change the value of the mask from 0x200000 to 0x400000 to correct it.
> > 
> > Signed-off-by: Veronika Molnarova <vmolnaro@redhat.com>
> 
> LGTM, except I think it's good to add fix tag:
> 
>   Fixes: 9440ebdc333d ("perf test arm64: Add attr tests for new VG register")
> 
> With above fix tag:
> 
> Reviewed-by: Leo Yan <leo.yan@linaro.org>

b4 even collected the fixes, that I checked and is in tree, etc.

Thanks, applied.

- Arnaldo