c790c3d2b0
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
83 lines
1.0 KiB
ArmAsm
83 lines
1.0 KiB
ArmAsm
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright 2019, Michael Ellerman, IBM Corp.
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*/
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#include <ppc-asm.h>
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.data
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jump_table:
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.long 0x0
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.long (.Lstate_1 - .Lstate_0)
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.long (.Lstate_2 - .Lstate_0)
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.long (.Lstate_3 - .Lstate_0)
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.long (.Lstate_4 - .Lstate_0)
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.long (.Lstate_5 - .Lstate_0)
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.long (.Lstate_6 - .Lstate_0)
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.long (.Lstate_7 - .Lstate_0)
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.text
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#define ITER_SHIFT 31
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.macro state number
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.balign 32
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.Lstate_\number:
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.if \number==7
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li r3, 0
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.else
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li r3, \number+1
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.endif
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b .Lloop
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.endm
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FUNC_START(pattern_cache_loop)
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li r3, 0
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li r4, 1
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sldi r4, r4, ITER_SHIFT
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.Lloop: cmpdi r4, 0
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beqlr
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addi r4, r4, -1
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ld r6, jump_table@got(%r2)
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sldi r5, r3, 2
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lwax r6, r5, r6
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ld r7, .Lstate_0@got(%r2)
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add r6, r6, r7
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mtctr r6
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bctr
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state 0
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state 1
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state 2
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state 3
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state 4
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state 5
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state 6
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state 7
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FUNC_END(pattern_cache_loop)
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FUNC_START(indirect_branch_loop)
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li r3, 1
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sldi r3, r3, ITER_SHIFT
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1: cmpdi r3, 0
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beqlr
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addi r3, r3, -1
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ld r4, 2f@got(%r2)
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mtctr r4
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bctr
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.balign 32
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2: b 1b
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FUNC_END(indirect_branch_loop)
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