[PATCH] lib: sbi_pmu: Add FW counter index validation when reading high bits on RV64

[James Raphael Tiovalen]

Currently, when we attempt to read the upper 32 bits of a firmware
counter on RV64 or higher, we just set `sbiret.value` to 0 without
validating the counter index. The SBI specification requires us to set
`sbiret.error` to `SBI_ERR_INVALID_PARAM` if the counter index points to
a hardware counter or an invalid counter. Add a validation check to
ensure compliance with the specification on RV64 or higher.

Fixes: 51951d9e9af8 ("lib: sbi_pmu: Implement sbi_pmu_counter_fw_read_hi")
Signed-off-by: James Raphael Tiovalen <jamestiotio at gmail.com>
---
 include/sbi/sbi_pmu.h   | 2 ++
 lib/sbi/sbi_ecall_pmu.c | 1 +
 lib/sbi/sbi_pmu.c       | 8 ++++++++
 3 files changed, 11 insertions(+)

diff --git a/include/sbi/sbi_pmu.h b/include/sbi/sbi_pmu.h
index c0e25f5a..51d4a345 100644
--- a/include/sbi/sbi_pmu.h
+++ b/include/sbi/sbi_pmu.h
@@ -138,6 +138,8 @@ int sbi_pmu_add_raw_event_counter_map(uint64_t select, uint64_t select_mask, u32
 
 int sbi_pmu_ctr_fw_read(uint32_t cidx, uint64_t *cval);
 
+int sbi_pmu_is_fw_ctr_idx(uint32_t cidx);
+
 int sbi_pmu_ctr_stop(unsigned long cidx_base, unsigned long cidx_mask,
 		     unsigned long flag);
 
diff --git a/lib/sbi/sbi_ecall_pmu.c b/lib/sbi/sbi_ecall_pmu.c
index 868e8665..0765d959 100644
--- a/lib/sbi/sbi_ecall_pmu.c
+++ b/lib/sbi/sbi_ecall_pmu.c
@@ -58,6 +58,7 @@ static int sbi_ecall_pmu_handler(unsigned long extid, unsigned long funcid,
 		ret = sbi_pmu_ctr_fw_read(regs->a0, &temp);
 		out->value = temp >> 32;
 #else
+		ret = sbi_pmu_is_fw_ctr_idx(regs->a0);
 		out->value = 0;
 #endif
 		break;
diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
index e084005d..d7ebe4e2 100644
--- a/lib/sbi/sbi_pmu.c
+++ b/lib/sbi/sbi_pmu.c
@@ -227,6 +227,14 @@ static bool pmu_ctr_idx_validate(unsigned long cbase, unsigned long cmask)
 	return cmask && cbase + sbi_fls(cmask) < total_ctrs;
 }
 
+int sbi_pmu_is_fw_ctr_idx(uint32_t cidx)
+{
+	if (cidx < num_hw_ctrs || cidx >= total_ctrs)
+		return SBI_EINVAL;
+
+	return 0;
+}
+
 int sbi_pmu_ctr_fw_read(uint32_t cidx, uint64_t *cval)
 {
 	int event_idx_type;
-- 
2.43.0