[PATCH] lib: sbi_pmu: Before using we should ensure PMU init done

[yang.zhang]

From: "yang.zhang" <yang.zhang at hexintek.com>

If trap earlier before sbi_pmu_init done, some path would call
sbi_pmu_ctr_incr_fw, then it would go wrong:
1. if phs_ptr_offset is zero, then it get a wrong pmu state ptr
2. if phs_ptr_offset is ok, but we didn't call pmu_set_hart_state_ptr
it would be NULL POINT

Of course, the above situation will not occur at present, but i think
it's reasonable that we should check it before we use it.

Test:
1. I test it on our platform, for now we only support LR/SC not AMO.
So when call spin_lock, would trap for amo instruction then emulate
it with LR/SC, then it goes wrong.Of course, this case is special only
for us, but other trap earlier cases maybe also encounter this situation.
2.I aslo test on qemu thead-c906, but need do some changes for simulating
this scenario.
  2.1 revert f067bb84cf2dd6493ff3fa49294d3ec80481ad75, the commit causes
  we can't emulate some instructions from M mode, i think the requirement
  may be not reasonable.
  2.2 Then, insert a 'rdtime' instruction before pmu_get_hart_state_ptr in
  sbi_pmu_init, then something goes wrong.

Signed-off-by: yang.zhang <yang.zhang at hexintek.com>
---
 lib/sbi/sbi_pmu.c | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
index 6209ccc..4eccb82 100644
--- a/lib/sbi/sbi_pmu.c
+++ b/lib/sbi/sbi_pmu.c
@@ -74,7 +74,7 @@ struct sbi_pmu_hart_state {
 static unsigned long phs_ptr_offset;
 
 #define pmu_get_hart_state_ptr(__scratch)				\
-	sbi_scratch_read_type((__scratch), void *, phs_ptr_offset)
+	phs_ptr_offset ? sbi_scratch_read_type((__scratch), void *, phs_ptr_offset) : NULL
 
 #define pmu_thishart_state_ptr()					\
 	pmu_get_hart_state_ptr(sbi_scratch_thishart_ptr())
@@ -207,6 +207,9 @@ int sbi_pmu_ctr_fw_read(uint32_t cidx, uint64_t *cval)
 	uint32_t event_code;
 	struct sbi_pmu_hart_state *phs = pmu_thishart_state_ptr();
 
+	if (unlikely(!phs))
+		return SBI_EINVAL;
+
 	event_idx_type = pmu_ctr_validate(phs, cidx, &event_code);
 	if (event_idx_type != SBI_PMU_EVENT_TYPE_FW)
 		return SBI_EINVAL;
@@ -432,6 +435,10 @@ int sbi_pmu_ctr_start(unsigned long cbase, unsigned long cmask,
 		      unsigned long flags, uint64_t ival)
 {
 	struct sbi_pmu_hart_state *phs = pmu_thishart_state_ptr();
+
+	if (unlikely(!phs))
+		return SBI_EINVAL;
+
 	int event_idx_type;
 	uint32_t event_code;
 	int ret = SBI_EINVAL;
@@ -535,6 +542,10 @@ int sbi_pmu_ctr_stop(unsigned long cbase, unsigned long cmask,
 		     unsigned long flag)
 {
 	struct sbi_pmu_hart_state *phs = pmu_thishart_state_ptr();
+
+	if (unlikely(!phs))
+		return SBI_EINVAL;
+
 	int ret = SBI_EINVAL;
 	int event_idx_type;
 	uint32_t event_code;
@@ -794,6 +805,10 @@ int sbi_pmu_ctr_cfg_match(unsigned long cidx_base, unsigned long cidx_mask,
 			  uint64_t event_data)
 {
 	struct sbi_pmu_hart_state *phs = pmu_thishart_state_ptr();
+
+	if (unlikely(!phs))
+		return SBI_EINVAL;
+
 	int ret, event_type, ctr_idx = SBI_ENOTSUPP;
 	u32 event_code;
 
@@ -869,6 +884,9 @@ int sbi_pmu_ctr_incr_fw(enum sbi_pmu_fw_event_code_id fw_id)
 	uint64_t *fcounter = NULL;
 	struct sbi_pmu_hart_state *phs = pmu_thishart_state_ptr();
 
+	if (unlikely(!phs))
+		return 0;
+
 	if (likely(!phs->fw_counters_started))
 		return 0;
 
@@ -967,7 +985,12 @@ void sbi_pmu_exit(struct sbi_scratch *scratch)
 	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_10)
 		csr_write(CSR_MCOUNTEREN, -1);
 
-	pmu_reset_event_map(pmu_get_hart_state_ptr(scratch));
+	struct sbi_pmu_hart_state *phs = pmu_get_hart_state_ptr(scratch);
+
+	if (unlikely(!phs))
+		return;
+
+	pmu_reset_event_map(phs);
 }
 
 int sbi_pmu_init(struct sbi_scratch *scratch, bool cold_boot)
-- 
2.25.1