1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
|
/** @file
PEI Dispatcher Dependency Evaluator
This routine evaluates a dependency expression (DEPENDENCY_EXPRESSION) to determine
if a driver can be scheduled for execution. The criteria for
schedulability is that the dependency expression is satisfied.
Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include "PeiMain.h"
#include "Dependency.h"
/**
This routine determines if a PPI has been installed.
The truth value of a GUID is determined by if the PPI has
been published and can be queried from the PPI database.
@param PeiServices An indirect pointer to the EFI_PEI_SERVICES table published by the PEI Foundation
@param Stack Reference to EVAL_STACK_ENTRY that contains PPI GUID to check
@retval TRUE if the PPI is already installed.
@retval FALSE if the PPI has yet to be installed.
**/
BOOLEAN
IsPpiInstalled (
IN EFI_PEI_SERVICES **PeiServices,
IN EVAL_STACK_ENTRY *Stack
)
{
VOID *PeiInstance;
EFI_STATUS Status;
EFI_GUID PpiGuid;
//
// If there is no GUID to evaluate, just return current result on stack.
//
if (Stack->Operator == NULL) {
return Stack->Result;
}
//
// Copy the Guid into a locale variable so that there are no
// possibilities of alignment faults for cross-compilation
// environments such as Intel?Itanium(TM).
//
CopyMem(&PpiGuid, Stack->Operator, sizeof(EFI_GUID));
//
// Check if the PPI is installed.
//
Status = PeiServicesLocatePpi(
&PpiGuid, // GUID
0, // INSTANCE
NULL, // EFI_PEI_PPI_DESCRIPTOR
&PeiInstance // PPI
);
if (EFI_ERROR(Status)) {
return FALSE;
}
return TRUE;
}
/**
This is the POSTFIX version of the dependency evaluator. When a
PUSH [PPI GUID] is encountered, a pointer to the GUID is stored on
the evaluation stack. When that entry is poped from the evaluation
stack, the PPI is checked if it is installed. This method allows
some time savings as not all PPIs must be checked for certain
operation types (AND, OR).
@param PeiServices An indirect pointer to the EFI_PEI_SERVICES table published by the PEI Foundation
@param DependencyExpression Pointer to a dependency expression. The Grammar adheres to
the BNF described above and is stored in postfix notation.
@retval TRUE if it is a well-formed Grammar
@retval FALSE if the dependency expression overflows the evaluation stack
if the dependency expression underflows the evaluation stack
if the dependency expression is not a well-formed Grammar.
**/
BOOLEAN
PeimDispatchReadiness (
IN EFI_PEI_SERVICES **PeiServices,
IN VOID *DependencyExpression
)
{
DEPENDENCY_EXPRESSION_OPERAND *Iterator;
EVAL_STACK_ENTRY *StackPtr;
EVAL_STACK_ENTRY EvalStack[MAX_GRAMMAR_SIZE];
Iterator = DependencyExpression;
StackPtr = &EvalStack[0];
while (TRUE) {
switch (*(Iterator++)) {
//
// For performance reason we put the frequently used items in front of
// the rarely used items
//
case (EFI_DEP_PUSH):
//
// Check to make sure the dependency grammar doesn't overflow the
// EvalStack on the push
//
if (StackPtr > &EvalStack[MAX_GRAMMAR_SIZE-1]) {
DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));
return FALSE;
}
//
// Push the pointer to the PUSH opcode operator (pointer to PPI GUID)
// We will evaluate if the PPI is insalled on the POP operation.
//
StackPtr->Operator = (VOID *) Iterator;
Iterator = Iterator + sizeof (EFI_GUID);
DEBUG ((DEBUG_DISPATCH, " PUSH GUID(%g) = %a\n", StackPtr->Operator, IsPpiInstalled (PeiServices, StackPtr) ? "TRUE" : "FALSE"));
StackPtr++;
break;
case (EFI_DEP_AND):
case (EFI_DEP_OR):
if (*(Iterator - 1) == EFI_DEP_AND) {
DEBUG ((DEBUG_DISPATCH, " AND\n"));
} else {
DEBUG ((DEBUG_DISPATCH, " OR\n"));
}
//
// Check to make sure the dependency grammar doesn't underflow the
// EvalStack on the two POPs for the AND operation. Don't need to
// check for the overflow on PUSHing the result since we already
// did two POPs.
//
if (StackPtr < &EvalStack[2]) {
DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));
return FALSE;
}
//
// Evaluate the first POPed operator only. If the operand is
// EFI_DEP_AND and the POPed operator evaluates to FALSE, or the
// operand is EFI_DEP_OR and the POPed operator evaluates to TRUE,
// we don't need to check the second operator, and the result will be
// evaluation of the POPed operator. Otherwise, don't POP the second
// operator since it will now evaluate to the final result on the
// next operand that causes a POP.
//
StackPtr--;
//
// Iterator has increased by 1 after we retrieve the operand, so here we
// should get the value pointed by (Iterator - 1), in order to obtain the
// same operand.
//
if (*(Iterator - 1) == EFI_DEP_AND) {
if (!(IsPpiInstalled (PeiServices, StackPtr))) {
(StackPtr-1)->Result = FALSE;
(StackPtr-1)->Operator = NULL;
}
} else {
if (IsPpiInstalled (PeiServices, StackPtr)) {
(StackPtr-1)->Result = TRUE;
(StackPtr-1)->Operator = NULL;
}
}
break;
case (EFI_DEP_END):
DEBUG ((DEBUG_DISPATCH, " END\n"));
StackPtr--;
//
// Check to make sure EvalStack is balanced. If not, then there is
// an error in the dependency grammar, so return EFI_INVALID_PARAMETER.
//
if (StackPtr != &EvalStack[0]) {
DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));
return FALSE;
}
DEBUG ((DEBUG_DISPATCH, " RESULT = %a\n", IsPpiInstalled (PeiServices, StackPtr) ? "TRUE" : "FALSE"));
return IsPpiInstalled (PeiServices, StackPtr);
case (EFI_DEP_NOT):
DEBUG ((DEBUG_DISPATCH, " NOT\n"));
//
// Check to make sure the dependency grammar doesn't underflow the
// EvalStack on the POP for the NOT operation. Don't need to
// check for the overflow on PUSHing the result since we already
// did a POP.
//
if (StackPtr < &EvalStack[1]) {
DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));
return FALSE;
}
(StackPtr-1)->Result = (BOOLEAN) !IsPpiInstalled (PeiServices, (StackPtr-1));
(StackPtr-1)->Operator = NULL;
break;
case (EFI_DEP_TRUE):
case (EFI_DEP_FALSE):
if (*(Iterator - 1) == EFI_DEP_TRUE) {
DEBUG ((DEBUG_DISPATCH, " TRUE\n"));
} else {
DEBUG ((DEBUG_DISPATCH, " FALSE\n"));
}
//
// Check to make sure the dependency grammar doesn't overflow the
// EvalStack on the push
//
if (StackPtr > &EvalStack[MAX_GRAMMAR_SIZE-1]) {
DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Underflow Error)\n"));
return FALSE;
}
//
// Iterator has increased by 1 after we retrieve the operand, so here we
// should get the value pointed by (Iterator - 1), in order to obtain the
// same operand.
//
if (*(Iterator - 1) == EFI_DEP_TRUE) {
StackPtr->Result = TRUE;
} else {
StackPtr->Result = FALSE;
}
StackPtr->Operator = NULL;
StackPtr++;
break;
default:
DEBUG ((DEBUG_DISPATCH, " RESULT = FALSE (Invalid opcode)\n"));
//
// The grammar should never arrive here
//
return FALSE;
}
}
}
|