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RISC-V: Re-enable counter access from userspace

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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: e999143459 ("RISC-V: Add perf platform driver based on SBI PMU extension")
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220928131807.30386-1-palmer@rivosinc.com
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Palmer Dabbelt 2022-09-28 06:18:07 -07:00
parent a8616d2dc1
commit 5a5294fbe0
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GPG Key ID: 2E1319F35FBB1889
1 changed files with 5 additions and 2 deletions
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7
drivers/perf/riscv_pmu_sbi.c
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@ -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);