[PATCH] MdeModulePkg/PerformanceLib: add lock protection

[Heyi Guo <heyi.guo@linaro.org>]

DXE performance gauge record access functions might be reentered since
we are supporting something like USB hot-plug, which is a timer event
where gBS->ConnectController might be called and then PERF will be
called in CoreConnectSingleController.

When StartGaugeEx is being reentered, not only the gauge record might
be overwritten, more serious situation will be caused if gauge data
buffer reallocation procedure is interrupted, between line 180 and 187
in DxeCorePerformanceLib.c specifically. There, mMaxGaugeRecords will
be doubled twice (denoted as 4X), but mGaugeData only points to a
buffer of size 2X, which will probably cause the following 2X memory
to be overflowed when gauge records are increased.

So we add EFI lock with with TPL_NOTIFY in
StartGaugeEx/EndGaugeEx/GetGaugeEx to avoid memory overflow and gauge
data corruption.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Heyi Guo <heyi.guo@linaro.org>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
---
 .../DxeCorePerformanceLib/DxeCorePerformanceLib.c  | 67 +++++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Library/DxeCorePerformanceLib/DxeCorePerformanceLib.c b/MdeModulePkg/Library/DxeCorePerformanceLib/DxeCorePerformanceLib.c
index 51f488a..7c0e207 100644
--- a/MdeModulePkg/Library/DxeCorePerformanceLib/DxeCorePerformanceLib.c
+++ b/MdeModulePkg/Library/DxeCorePerformanceLib/DxeCorePerformanceLib.c
@@ -63,6 +63,11 @@ PERFORMANCE_EX_PROTOCOL mPerformanceExInterface = {
 
 PERFORMANCE_PROPERTY  mPerformanceProperty;
 
+//
+//  Gauge record lock to avoid data corruption or even memory overflow
+//
+STATIC EFI_LOCK mPerfRecordLock = EFI_INITIALIZE_LOCK_VARIABLE (TPL_NOTIFY);
+
 /**
   Searches in the gauge array with keyword Handle, Token, Module and Identifier.
 
@@ -162,6 +167,12 @@ StartGaugeEx (
   UINTN                     OldGaugeDataSize;
   GAUGE_DATA_HEADER         *OldGaugeData;
   UINT32                    Index;
+  EFI_STATUS                Status;
+
+  Status = EfiAcquireLockOrFail (&mPerfRecordLock);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
   Index = mGaugeData->NumberOfEntries;
   if (Index >= mMaxGaugeRecords) {
@@ -175,6 +186,7 @@ StartGaugeEx (
 
     NewGaugeData = AllocateZeroPool (GaugeDataSize);
     if (NewGaugeData == NULL) {
+      EfiReleaseLock (&mPerfRecordLock);
       return EFI_OUT_OF_RESOURCES;
     }
 
@@ -209,6 +221,8 @@ StartGaugeEx (
 
   mGaugeData->NumberOfEntries++;
 
+  EfiReleaseLock (&mPerfRecordLock);
+
   return EFI_SUCCESS;
 }
 
@@ -250,6 +264,12 @@ EndGaugeEx (
 {
   GAUGE_DATA_ENTRY_EX *GaugeEntryExArray;
   UINT32              Index;
+  EFI_STATUS          Status;
+
+  Status = EfiAcquireLockOrFail (&mPerfRecordLock);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
 
   if (TimeStamp == 0) {
     TimeStamp = GetPerformanceCounter ();
@@ -257,11 +277,13 @@ EndGaugeEx (
 
   Index = InternalSearchForGaugeEntry (Handle, Token, Module, Identifier);
   if (Index >= mGaugeData->NumberOfEntries) {
+    EfiReleaseLock (&mPerfRecordLock);
     return EFI_NOT_FOUND;
   }
   GaugeEntryExArray = (GAUGE_DATA_ENTRY_EX *) (mGaugeData + 1);
   GaugeEntryExArray[Index].EndTimeStamp = TimeStamp;
 
+  EfiReleaseLock (&mPerfRecordLock);
   return EFI_SUCCESS;
 }
 
@@ -274,6 +296,8 @@ EndGaugeEx (
   If it stands for a valid entry, then EFI_SUCCESS is returned and
   GaugeDataEntryEx stores the pointer to that entry.
 
+  This internal function is added to avoid releasing lock before each return statement.
+
   @param  LogEntryKey             The key for the previous performance measurement log entry.
                                   If 0, then the first performance measurement log entry is retrieved.
   @param  GaugeDataEntryEx        The indirect pointer to the extended gauge data entry specified by LogEntryKey
@@ -287,7 +311,7 @@ EndGaugeEx (
 **/
 EFI_STATUS
 EFIAPI
-GetGaugeEx (
+InternalGetGaugeEx (
   IN  UINTN                 LogEntryKey,
   OUT GAUGE_DATA_ENTRY_EX   **GaugeDataEntryEx
   )
@@ -314,6 +338,47 @@ GetGaugeEx (
 }
 
 /**
+  Retrieves a previously logged performance measurement.
+  It can also retrieve the log created by StartGauge and EndGauge of PERFORMANCE_PROTOCOL,
+  and then assign the Identifier with 0.
+
+  Retrieves the performance log entry from the performance log specified by LogEntryKey.
+  If it stands for a valid entry, then EFI_SUCCESS is returned and
+  GaugeDataEntryEx stores the pointer to that entry.
+
+  @param  LogEntryKey             The key for the previous performance measurement log entry.
+                                  If 0, then the first performance measurement log entry is retrieved.
+  @param  GaugeDataEntryEx        The indirect pointer to the extended gauge data entry specified by LogEntryKey
+                                  if the retrieval is successful.
+
+  @retval EFI_SUCCESS             The GuageDataEntryEx is successfully found based on LogEntryKey.
+  @retval EFI_NOT_FOUND           The LogEntryKey is the last entry (equals to the total entry number).
+  @retval EFI_INVALIDE_PARAMETER  The LogEntryKey is not a valid entry (greater than the total entry number).
+  @retval EFI_INVALIDE_PARAMETER  GaugeDataEntryEx is NULL.
+
+**/
+EFI_STATUS
+EFIAPI
+GetGaugeEx (
+  IN  UINTN                 LogEntryKey,
+  OUT GAUGE_DATA_ENTRY_EX   **GaugeDataEntryEx
+  )
+{
+  EFI_STATUS                Status;
+
+  Status = EfiAcquireLockOrFail (&mPerfRecordLock);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  Status = InternalGetGaugeEx (LogEntryKey, GaugeDataEntryEx);
+
+  EfiReleaseLock (&mPerfRecordLock);
+
+  return Status;
+}
+
+/**
   Adds a record at the end of the performance measurement log
   that records the start time of a performance measurement.
 
-- 
2.7.4