drivers/perf: riscv: Return error for default case

[ Upstream commit 2c206cdede567f53035c622e846678a996f39d69 ]

If the upper two bits has an invalid valid (0x1), the event mapping
is not reliable as it returns an uninitialized variable.

Return appropriate value for the default case.

Fixes: f0c9363db2 ("perf/riscv-sbi: Add platform specific firmware event handling")

Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20241212-pmu_event_fixes_v2-v2-2-813e8a4f5962@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/perf/riscv_pmu_sbi.c

@@ -507,7 +507,7 @@ static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
 {
 	u32 type = event->attr.type;
 	u64 config = event->attr.config;
-	int ret;
+	int ret = -ENOENT;
 
 	/*
 	 * Ensure we are finished checking standard hardware events for
@@ -551,10 +551,11 @@ static int pmu_sbi_event_map(struct perf_event *event, u64 *econfig)
 			ret = SBI_PMU_EVENT_TYPE_FW << 16 | RISCV_PLAT_FW_EVENT;
 			*econfig = config & RISCV_PMU_PLAT_FW_EVENT_MASK;
 			break;
+		default:
+			break;
 		}
 		break;
 	default:
-		ret = -ENOENT;
 		break;
 	}