From 5a5294fbe0200d1327f0e089135dad77b45aa2ee Mon Sep 17 00:00:00 2001 From: Palmer Dabbelt Date: Wed, 28 Sep 2022 06:18:07 -0700 Subject: [PATCH] RISC-V: Re-enable counter access from userspace These counters were part of the ISA when we froze the uABI, removing them breaks userspace. Link: https://lore.kernel.org/all/YxEhC%2FmDW1lFt36J@aurel32.net/ Fixes: e9991434596f ("RISC-V: Add perf platform driver based on SBI PMU extension") Tested-by: Conor Dooley Reviewed-by: Conor Dooley Link: https://lore.kernel.org/r/20220928131807.30386-1-palmer@rivosinc.com Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt --- drivers/perf/riscv_pmu_sbi.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c index 15e5a47be7d5..3852c18362f5 100644 --- a/drivers/perf/riscv_pmu_sbi.c +++ b/drivers/perf/riscv_pmu_sbi.c @@ -652,8 +652,11 @@ static int pmu_sbi_starting_cpu(unsigned int cpu, struct hlist_node *node) struct riscv_pmu *pmu = hlist_entry_safe(node, struct riscv_pmu, node); struct cpu_hw_events *cpu_hw_evt = this_cpu_ptr(pmu->hw_events); - /* Enable the access for TIME csr only from the user mode now */ - csr_write(CSR_SCOUNTEREN, 0x2); + /* + * Enable the access for CYCLE, TIME, and INSTRET CSRs from userspace, + * as is necessary to maintain uABI compatibility. + */ + csr_write(CSR_SCOUNTEREN, 0x7); /* Stop all the counters so that they can be enabled from perf */ pmu_sbi_stop_all(pmu); -- 2.39.5