shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-05 10:31:46 +09:00
Code Issues Packages Projects Releases Wiki Activity

arm64: perf: correct PMUVer probing

Browse Source 
[ Upstream commit 0331365edb ]

The ID_AA64DFR0_EL1.PMUVer field doesn't follow the usual ID registers
scheme. While value 0xf indicates a non-architected PMU is implemented,
values 0x1 to 0xe indicate an increasingly featureful architected PMU,
as if the field were unsigned.

For more details, see ARM DDI 0487C.a, D10.1.4, "Alternative ID scheme
used for the Performance Monitors Extension version".

Currently, we treat the field as signed, and erroneously bail out for
values 0x8 to 0xe. Let's correct that.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mark Rutland
2018-02-14 17:21:57 +00:00
committed by Greg Kroah-Hartman
parent 33b3f7b5af
commit c5c0632b9c
1 changed files with 2 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm64/kernel/perf_event.c
View File

@@ -914,9 +914,9 @@ static void __armv8pmu_probe_pmu(void *info)
int pmuver;
dfr0 = read_sysreg(id_aa64dfr0_el1);
pmuver = cpuid_feature_extract_signed_field(dfr0,
pmuver = cpuid_feature_extract_unsigned_field(dfr0,
ID_AA64DFR0_PMUVER_SHIFT);
if (pmuver < 1)
if (pmuver == 0xf || pmuver == 0)
return;
probe->present = true;