arm64/perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF

ID_AA64DFR0_PMUVER_IMP_DEF, indicating an "implementation defined" PMU,
never actually gets used although there are '0xf' instances scattered
all around. Use the symbolic name instead of the raw hex constant.

Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Anshuman Khandual <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: Anshuman Khandual

arch/arm64/include/asm/cpufeature.h

@@ -552,7 +552,7 @@ cpuid_feature_cap_perfmon_field(u64 features, int field, u64 cap)
 	u64 mask = GENMASK_ULL(field + 3, field);
 
 	/* Treat IMPLEMENTATION DEFINED functionality as unimplemented */
-	if (val == 0xf)
+	if (val == ID_AA64DFR0_PMUVER_IMP_DEF)
 		val = 0;
 
 	if (val > cap) {

arch/arm64/kernel/perf_event.c

@@ -1055,7 +1055,7 @@ static void __armv8pmu_probe_pmu(void *info)
 	dfr0 = read_sysreg(id_aa64dfr0_el1);
 	pmuver = cpuid_feature_extract_unsigned_field(dfr0,
 			ID_AA64DFR0_PMUVER_SHIFT);
-	if (pmuver == 0xf || pmuver == 0)
+	if (pmuver == ID_AA64DFR0_PMUVER_IMP_DEF || pmuver == 0)
 		return;
 
 	cpu_pmu->pmuver = pmuver;