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linux/tools/testing/selftests/powerpc/include
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Michael Ellerman c790c3d2b0 selftests/powerpc: Add a test of spectre_v2 mitigations 
This test uses the PMU to count branch prediction hits/misses for a
known loop, and compare the result to the reported spectre v2
mitigation.

This gives us a way of sanity checking that the reported mitigation is
actually in effect.

Sample output for some cases, eg:

  Power9:
    sysfs reports: 'Vulnerable'
     PM_BR_PRED_CCACHE: result        368 running/enabled 5792777124
    PM_BR_MPRED_CCACHE: result        319 running/enabled 5792775546
     PM_BR_PRED_PCACHE: result 2147483281 running/enabled 5792773128
    PM_BR_MPRED_PCACHE: result  213604201 running/enabled 5792771640
    Miss percent 9 %
    OK - Measured branch prediction rates match reported spectre v2 mitigation.

    sysfs reports: 'Mitigation: Indirect branch serialisation (kernel only)'
     PM_BR_PRED_CCACHE: result        895 running/enabled 5780320920
    PM_BR_MPRED_CCACHE: result        822 running/enabled 5780312414
     PM_BR_PRED_PCACHE: result 2147482754 running/enabled 5780308836
    PM_BR_MPRED_PCACHE: result  213639731 running/enabled 5780307912
    Miss percent 9 %
    OK - Measured branch prediction rates match reported spectre v2 mitigation.

    sysfs reports: 'Mitigation: Indirect branch cache disabled'
     PM_BR_PRED_CCACHE: result 2147483649 running/enabled 20540186160
    PM_BR_MPRED_CCACHE: result 2147483649 running/enabled 20540180056
     PM_BR_PRED_PCACHE: result          0 running/enabled 20540176090
    PM_BR_MPRED_PCACHE: result          0 running/enabled 20540174182
    Miss percent 100 %
    OK - Measured branch prediction rates match reported spectre v2 mitigation.

  Power8:
    sysfs reports: 'Vulnerable'
     PM_BR_PRED_CCACHE: result 2147483649 running/enabled 3505888142
    PM_BR_MPRED_CCACHE: result          9 running/enabled 3505882788
    Miss percent 0 %
    OK - Measured branch prediction rates match reported spectre v2 mitigation.

    sysfs reports: 'Mitigation: Indirect branch cache disabled'
     PM_BR_PRED_CCACHE: result 2147483649 running/enabled 16931421988
    PM_BR_MPRED_CCACHE: result 2147483649 running/enabled 16931416478
    Miss percent 100 %
    OK - Measured branch prediction rates match reported spectre v2 mitigation.
    success: spectre_v2

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190520105520.22274-1-mpe@ellerman.id.au
2019-10-30 15:43:57 +11:00
..
basic_asm.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fpu_asm.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
gpr_asm.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
instructions.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
reg.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 191 2019-05-30 11:29:21 -07:00
subunit.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 191 2019-05-30 11:29:21 -07:00
utils.h selftests/powerpc: Add a test of spectre_v2 mitigations 2019-10-30 15:43:57 +11:00
vmx_asm.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
vsx_asm.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00