]> git.ipfire.org Git - thirdparty/kernel/stable.git/commit
drivers/perf: hisi_pcie: Record hardware counts correctly
authorYicong Yang <yangyicong@hisilicon.com>
Thu, 29 Aug 2024 09:03:30 +0000 (17:03 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 4 Oct 2024 14:28:52 +0000 (16:28 +0200)
commit6206a0edb29bcb57f89255538c66f25b653230dc
tree2cd7545d2673e7628f868027192dc01a44f064f0
parent39dd1f1f48d39272260a88d7f927f0b435016e16
drivers/perf: hisi_pcie: Record hardware counts correctly

[ Upstream commit daecd3373a16a039ad241086e30a1ec46fc9d61f ]

Currently we set the period and record it as the initial value of the
counter without checking it's set to the hardware successfully or not.
However the counter maybe unwritable if the target event is unsupported
by the device. In such case we will pass user a wrong count:

[start counts when setting the period]
hwc->prev_count = 0x8000000000000000
device.counter_value = 0 // the counter is not set as the period
[when user reads the counter]
event->count = device.counter_value - hwc->prev_count
             = 0x8000000000000000 // wrong. should be 0.

Fix this by record the hardware counter counts correctly when setting
the period.

Fixes: 8404b0fbc7fb ("drivers/perf: hisi: Add driver for HiSilicon PCIe PMU")
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240829090332.28756-2-yangyicong@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/perf/hisilicon/hisi_pcie_pmu.c