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| author | Athira Rajeev <atrajeev@linux.vnet.ibm.com> | 2020-07-17 17:38:23 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-07-22 14:56:42 +0300 |
| commit | 1cade527f6e9bec6a6412d0641643c359ada8096 (patch) | |
| tree | 9d5f4e5e45d68ac56c36fa8872e895e595db7c62 /arch/powerpc/perf/isa207-common.c | |
| parent | 80350a4bac992e3404067d31ff901ae9ff76aaa8 (diff) | |
| download | linux-1cade527f6e9bec6a6412d0641643c359ada8096.tar.xz | |
powerpc/perf: BHRB control to disable BHRB logic when not used
PowerISA v3.1 has few updates for the Branch History Rolling
Buffer(BHRB).
BHRB disable is controlled via Monitor Mode Control Register A (MMCRA)
bit, namely "BHRB Recording Disable (BHRBRD)". This field controls
whether BHRB entries are written when BHRB recording is enabled by
other bits. This patch implements support for this BHRB disable bit.
By setting 0b1 to this bit will disable the BHRB and by setting 0b0 to
this bit will have BHRB enabled. This addresses backward
compatibility (for older OS), since this bit will be cleared and
hardware will be writing to BHRB by default.
This patch addresses changes to set MMCRA (BHRBRD) at boot for
power10 (there by the core will run faster) and enable this feature
only on runtime ie, on explicit need from user. Also save/restore
MMCRA in the restore path of state-loss idle state to make sure we
keep BHRB disabled if it was not enabled on request at runtime.
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1594996707-3727-12-git-send-email-atrajeev@linux.vnet.ibm.com
Diffstat (limited to 'arch/powerpc/perf/isa207-common.c')
| -rw-r--r-- | arch/powerpc/perf/isa207-common.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/powerpc/perf/isa207-common.c b/arch/powerpc/perf/isa207-common.c index 77643f3ae464..964437adec18 100644 --- a/arch/powerpc/perf/isa207-common.c +++ b/arch/powerpc/perf/isa207-common.c @@ -404,6 +404,13 @@ int isa207_compute_mmcr(u64 event[], int n_ev, mmcra = mmcr1 = mmcr2 = mmcr3 = 0; + /* + * Disable bhrb unless explicitly requested + * by setting MMCRA (BHRBRD) bit. + */ + if (cpu_has_feature(CPU_FTR_ARCH_31)) + mmcra |= MMCRA_BHRB_DISABLE; + /* Second pass: assign PMCs, set all MMCR1 fields */ for (i = 0; i < n_ev; ++i) { pmc = (event[i] >> EVENT_PMC_SHIFT) & EVENT_PMC_MASK; @@ -479,6 +486,11 @@ int isa207_compute_mmcr(u64 event[], int n_ev, mmcra |= val << MMCRA_IFM_SHIFT; } + /* set MMCRA (BHRBRD) to 0 if there is user request for BHRB */ + if (cpu_has_feature(CPU_FTR_ARCH_31) && + (has_branch_stack(pevents[i]) || (event[i] & EVENT_WANTS_BHRB))) + mmcra &= ~MMCRA_BHRB_DISABLE; + if (pevents[i]->attr.exclude_user) mmcr2 |= MMCR2_FCP(pmc); |