2 SMM Driver Dispatcher Dependency Evaluator
4 This routine evaluates a dependency expression (DEPENDENCY_EXPRESSION) to determine
5 if a driver can be scheduled for execution. The criteria for
6 schedulability is that the dependency expression is satisfied.
8 Copyright (c) 2009 - 2010, Intel Corporation. All rights reserved.<BR>
9 This program and the accompanying materials are licensed and made available
10 under the terms and conditions of the BSD License which accompanies this
11 distribution. The full text of the license may be found at
12 http://opensource.org/licenses/bsd-license.php
14 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
15 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
19 #include "PiSmmCore.h"
22 /// EFI_DEP_REPLACE_TRUE - Used to dynamically patch the dependecy expression
23 /// to save time. A EFI_DEP_PUSH is evauated one an
24 /// replaced with EFI_DEP_REPLACE_TRUE. If PI spec's Vol 2
25 /// Driver Execution Environment Core Interface use 0xff
26 /// as new DEPEX opcode. EFI_DEP_REPLACE_TRUE should be
27 /// defined to a new value that is not conflicting with PI spec.
29 #define EFI_DEP_REPLACE_TRUE 0xff
32 /// Define the initial size of the dependency expression evaluation stack
34 #define DEPEX_STACK_SIZE_INCREMENT 0x1000
37 // Global stack used to evaluate dependency expressions
39 BOOLEAN
*mDepexEvaluationStack
= NULL
;
40 BOOLEAN
*mDepexEvaluationStackEnd
= NULL
;
41 BOOLEAN
*mDepexEvaluationStackPointer
= NULL
;
44 Grow size of the Depex stack
46 @retval EFI_SUCCESS Stack successfully growed.
47 @retval EFI_OUT_OF_RESOURCES There is not enough system memory to grow the stack.
58 Size
= DEPEX_STACK_SIZE_INCREMENT
;
59 if (mDepexEvaluationStack
!= NULL
) {
60 Size
= Size
+ (mDepexEvaluationStackEnd
- mDepexEvaluationStack
);
63 NewStack
= AllocatePool (Size
* sizeof (BOOLEAN
));
64 if (NewStack
== NULL
) {
65 return EFI_OUT_OF_RESOURCES
;
68 if (mDepexEvaluationStack
!= NULL
) {
70 // Copy to Old Stack to the New Stack
74 mDepexEvaluationStack
,
75 (mDepexEvaluationStackEnd
- mDepexEvaluationStack
) * sizeof (BOOLEAN
)
81 FreePool (mDepexEvaluationStack
);
85 // Make the Stack pointer point to the old data in the new stack
87 mDepexEvaluationStackPointer
= NewStack
+ (mDepexEvaluationStackPointer
- mDepexEvaluationStack
);
88 mDepexEvaluationStack
= NewStack
;
89 mDepexEvaluationStackEnd
= NewStack
+ Size
;
95 Push an element onto the Boolean Stack.
97 @param Value BOOLEAN to push.
99 @retval EFI_SUCCESS The value was pushed onto the stack.
100 @retval EFI_OUT_OF_RESOURCES There is not enough system memory to grow the stack.
111 // Check for a stack overflow condition
113 if (mDepexEvaluationStackPointer
== mDepexEvaluationStackEnd
) {
117 Status
= GrowDepexStack ();
118 if (EFI_ERROR (Status
)) {
124 // Push the item onto the stack
126 *mDepexEvaluationStackPointer
= Value
;
127 mDepexEvaluationStackPointer
++;
133 Pop an element from the Boolean stack.
135 @param Value BOOLEAN to pop.
137 @retval EFI_SUCCESS The value was popped onto the stack.
138 @retval EFI_ACCESS_DENIED The pop operation underflowed the stack.
147 // Check for a stack underflow condition
149 if (mDepexEvaluationStackPointer
== mDepexEvaluationStack
) {
150 return EFI_ACCESS_DENIED
;
154 // Pop the item off the stack
156 mDepexEvaluationStackPointer
--;
157 *Value
= *mDepexEvaluationStackPointer
;
162 This is the POSTFIX version of the dependency evaluator. This code does
163 not need to handle Before or After, as it is not valid to call this
164 routine in this case. The SOR is just ignored and is a nop in the grammer.
165 POSTFIX means all the math is done on top of the stack.
167 @param DriverEntry DriverEntry element to update.
169 @retval TRUE If driver is ready to run.
170 @retval FALSE If driver is not ready to run or some fatal error
176 IN EFI_SMM_DRIVER_ENTRY
*DriverEntry
186 DEBUG ((DEBUG_DISPATCH
, "Evaluate SMM DEPEX for FFS(%g)\n", &DriverEntry
->FileName
));
191 if (DriverEntry
->After
|| DriverEntry
->Before
) {
193 // If Before or After Depex skip as SmmInsertOnScheduledQueueWhileProcessingBeforeAndAfter ()
199 if (DriverEntry
->Depex
== NULL
) {
201 // A NULL Depex means that the SMM driver is not built correctly.
202 // All SMM drivers must have a valid depex expressiion.
204 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Depex is empty)\n"));
210 // Clean out memory leaks in Depex Boolean stack. Leaks are only caused by
211 // incorrectly formed DEPEX expressions
213 mDepexEvaluationStackPointer
= mDepexEvaluationStack
;
216 Iterator
= DriverEntry
->Depex
;
220 // Check to see if we are attempting to fetch dependency expression instructions
221 // past the end of the dependency expression.
223 if (((UINTN
)Iterator
- (UINTN
)DriverEntry
->Depex
) >= DriverEntry
->DepexSize
) {
224 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Attempt to fetch past end of depex)\n"));
229 // Look at the opcode of the dependency expression instruction.
235 // For a well-formed Dependency Expression, the code should never get here.
236 // The BEFORE and AFTER are processed prior to this routine's invocation.
237 // If the code flow arrives at this point, there was a BEFORE or AFTER
238 // that were not the first opcodes.
240 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected BEFORE or AFTER opcode)\n"));
244 // These opcodes can only appear once as the first opcode. If it is found
245 // at any other location, then the dependency expression evaluates to FALSE
247 if (Iterator
!= DriverEntry
->Depex
) {
248 DEBUG ((DEBUG_DISPATCH
, " SOR\n"));
249 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected SOR opcode)\n"));
252 DEBUG ((DEBUG_DISPATCH
, " SOR = Requested\n"));
254 // Otherwise, it is the first opcode and should be treated as a NOP.
260 // Push operator is followed by a GUID. Test to see if the GUID protocol
261 // is installed and push the boolean result on the stack.
263 CopyMem (&DriverGuid
, Iterator
+ 1, sizeof (EFI_GUID
));
265 Status
= SmmLocateProtocol (&DriverGuid
, NULL
, &Interface
);
266 if (EFI_ERROR (Status
)) {
268 // For SMM Driver, it may depend on uefi protocols
270 Status
= gBS
->LocateProtocol (&DriverGuid
, NULL
, &Interface
);
273 if (EFI_ERROR (Status
)) {
274 DEBUG ((DEBUG_DISPATCH
, " PUSH GUID(%g) = FALSE\n", &DriverGuid
));
275 Status
= PushBool (FALSE
);
277 DEBUG ((DEBUG_DISPATCH
, " PUSH GUID(%g) = TRUE\n", &DriverGuid
));
278 *Iterator
= EFI_DEP_REPLACE_TRUE
;
279 Status
= PushBool (TRUE
);
281 if (EFI_ERROR (Status
)) {
282 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
286 Iterator
+= sizeof (EFI_GUID
);
290 DEBUG ((DEBUG_DISPATCH
, " AND\n"));
291 Status
= PopBool (&Operator
);
292 if (EFI_ERROR (Status
)) {
293 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
297 Status
= PopBool (&Operator2
);
298 if (EFI_ERROR (Status
)) {
299 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
303 Status
= PushBool ((BOOLEAN
)(Operator
&& Operator2
));
304 if (EFI_ERROR (Status
)) {
305 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
311 DEBUG ((DEBUG_DISPATCH
, " OR\n"));
312 Status
= PopBool (&Operator
);
313 if (EFI_ERROR (Status
)) {
314 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
318 Status
= PopBool (&Operator2
);
319 if (EFI_ERROR (Status
)) {
320 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
324 Status
= PushBool ((BOOLEAN
)(Operator
|| Operator2
));
325 if (EFI_ERROR (Status
)) {
326 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
332 DEBUG ((DEBUG_DISPATCH
, " NOT\n"));
333 Status
= PopBool (&Operator
);
334 if (EFI_ERROR (Status
)) {
335 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
339 Status
= PushBool ((BOOLEAN
)(!Operator
));
340 if (EFI_ERROR (Status
)) {
341 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
347 DEBUG ((DEBUG_DISPATCH
, " TRUE\n"));
348 Status
= PushBool (TRUE
);
349 if (EFI_ERROR (Status
)) {
350 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
356 DEBUG ((DEBUG_DISPATCH
, " FALSE\n"));
357 Status
= PushBool (FALSE
);
358 if (EFI_ERROR (Status
)) {
359 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
365 DEBUG ((DEBUG_DISPATCH
, " END\n"));
366 Status
= PopBool (&Operator
);
367 if (EFI_ERROR (Status
)) {
368 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
371 DEBUG ((DEBUG_DISPATCH
, " RESULT = %a\n", Operator
? "TRUE" : "FALSE"));
374 case EFI_DEP_REPLACE_TRUE
:
375 CopyMem (&DriverGuid
, Iterator
+ 1, sizeof (EFI_GUID
));
376 DEBUG ((DEBUG_DISPATCH
, " PUSH GUID(%g) = TRUE\n", &DriverGuid
));
377 Status
= PushBool (TRUE
);
378 if (EFI_ERROR (Status
)) {
379 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unexpected error)\n"));
383 Iterator
+= sizeof (EFI_GUID
);
387 DEBUG ((DEBUG_DISPATCH
, " RESULT = FALSE (Unknown opcode)\n"));
392 // Skip over the Dependency Op Code we just processed in the switch.
393 // The math is done out of order, but it should not matter. That is
394 // we may add in the sizeof (EFI_GUID) before we account for the OP Code.
395 // This is not an issue, since we just need the correct end result. You
396 // need to be careful using Iterator in the loop as it's intermediate value