Previously, in sbi_pmu_ctr_cfg_match() function, ctr_idx was used immediately
after pmu_ctr_find_fw() or pmu_ctr_find_hw() calls. In first case, array index
was (ctr_idx - num_hw_ctrs), in second - ctr_idx. But pmu_ctr_find_fw() and
pmu_ctr_find_hw() functions can return negative value, in which case writing
in arrays with such indexes would corrupt sbi_pmu_hart_state structure.
To avoid this situation, direct ctr_idx value check added.
Signed-off-by: Alexander Chuprunov <alexander.chuprunov@syntacore.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250918090706.2217603-4-alexander.chuprunov@syntacore.com
Signed-off-by: Anup Patel <anup@brainfault.org>
Generally, hardware performance counters can only be started, stopped,
or configured from machine-mode using mcountinhibit and mhpmeventX CSRs.
Also, in opensbi only sbi_pmu_ctr_cfg_match() managed mhpmeventX. But
in generic Linux driver, when perf starts, Linux calls both
sbi_pmu_ctr_cfg_match() and sbi_pmu_ctr_start(), while after hart suspend
only sbi_pmu_ctr_start() command called through SBI interface. This doesn't
work properly in case when suspend state resets HPM registers. In order
to keep counter integrity, sbi_pmu_ctr_start() modified. First, we're saving
hw_counters_data, and after hart suspend this value is restored if
event is currently active.
Signed-off-by: Alexander Chuprunov <alexander.chuprunov@syntacore.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20250918090706.2217603-2-alexander.chuprunov@syntacore.com
Signed-off-by: Anup Patel <anup@brainfault.org>
