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Add MonotonicCounter driver, which produces MonotonicCounter arch protocols
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e70d34ca 1/*++\r
2\r
3Copyright (c) 2006 - 2007, Intel Corporation\r
4All rights reserved. This program and the accompanying materials\r
5are licensed and made available under the terms and conditions of the BSD License\r
6which accompanies this distribution. The full text of the license may be found at\r
7http://opensource.org/licenses/bsd-license.php\r
8\r
9THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
10WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
11\r
12Module Name:\r
13\r
14 MonotonicCounter.c\r
15\r
16Abstract:\r
17\r
18 Produced the Monotonic Counter Services as defined in the DXE CIS\r
19\r
20Revision History:\r
21\r
22--*/\r
23\r
24#include "MonotonicCounter.h"\r
25\r
26//\r
27// The Monotonic Counter Handle\r
28//\r
29EFI_HANDLE mMonotonicCounterHandle = NULL;\r
30\r
31//\r
32// The current Monotonic count value\r
33//\r
34UINT64 mEfiMtc;\r
35\r
36//\r
37// Event to use to update the Mtc's high part when wrapping\r
38//\r
39EFI_EVENT mEfiMtcEvent;\r
40\r
41//\r
42// EfiMtcName - Variable name of the MTC value\r
43//\r
44CHAR16 *mEfiMtcName = (CHAR16 *) L"MTC";\r
45\r
46//\r
47// EfiMtcGuid - Guid of the MTC value\r
48//\r
49EFI_GUID mEfiMtcGuid = { 0xeb704011, 0x1402, 0x11d3, { 0x8e, 0x77, 0x0, 0xa0, 0xc9, 0x69, 0x72, 0x3b } };\r
50\r
51//\r
52// Worker functions\r
53//\r
54STATIC\r
55EFI_STATUS\r
56EFIAPI\r
57MonotonicCounterDriverGetNextMonotonicCount (\r
58 OUT UINT64 *Count\r
59 )\r
60/*++\r
61\r
62Routine Description:\r
63\r
64Arguments:\r
65\r
66Returns:\r
67\r
68--*/\r
69{\r
70 EFI_TPL OldTpl;\r
71\r
72 //\r
73 // Can not be called after ExitBootServices()\r
74 //\r
75 if (EfiAtRuntime ()) {\r
76 return EFI_UNSUPPORTED;\r
77 }\r
78 //\r
79 // Check input parameters\r
80 //\r
81 if (Count == NULL) {\r
82 return EFI_INVALID_PARAMETER;\r
83 }\r
84 //\r
85 // Update the monotonic counter with a lock\r
86 //\r
87 OldTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
88 *Count = mEfiMtc;\r
89 mEfiMtc++;\r
90 gBS->RestoreTPL (OldTpl);\r
91\r
92 //\r
93 // If the MSB bit of the low part toggled, then signal that the high\r
94 // part needs updated now\r
95 //\r
96 if ((((UINT32) mEfiMtc) ^ ((UINT32) *Count)) & 0x80000000) {\r
97 gBS->SignalEvent (mEfiMtcEvent);\r
98 }\r
99\r
100 return EFI_SUCCESS;\r
101}\r
102\r
103\r
104/**\r
105 Returns the next high 32 bits of the platform's monotonic counter.\r
106\r
107 The GetNextHighMonotonicCount() function returns the next high 32 bits\r
108 of the platform's monotonic counter. The platform's monotonic counter is\r
109 comprised of two 32 bit quantities: the high 32 bits and the low 32 bits.\r
110 During boot service time the low 32 bit value is volatile: it is reset to\r
111 zero on every system reset and is increased by 1 on every call to GetNextMonotonicCount().\r
112 The high 32 bit value is non-volatile and is increased by 1 whenever the system resets\r
113 or whenever the low 32 bit count [returned by GetNextMonoticCount()] overflows.\r
114 The GetNextMonotonicCount() function is only available at boot services time.\r
115 If the operating system wishes to extend the platform monotonic counter to runtime,\r
116 it may do so by utilizing GetNextHighMonotonicCount(). To do this, before calling\r
117 ExitBootServices() the operating system would call GetNextMonotonicCount() to obtain\r
118 the current platform monotonic count. The operating system would then provide an\r
119 interface that returns the next count by:\r
120 Adding 1 to the last count.\r
121 Before the lower 32 bits of the count overflows, call GetNextHighMonotonicCount().\r
122 This will increase the high 32 bits of the platform's non-volatile portion of the monotonic\r
123 count by 1.\r
124\r
125 This function may only be called at Runtime.\r
126\r
127 @param[out] HighCount Pointer to returned value.\r
128\r
129 @retval EFI_INVALID_PARAMETER If HighCount is NULL.\r
130 @retval EFI_SUCCESS Operation is successful.\r
131 @retval EFI_OUT_OF_RESOURCES If variable service reports that not enough storage\r
132 is available to hold the variable and its data.\r
133 @retval EFI_DEVICE_ERROR The variable could not be saved due to a hardware failure.\r
134\r
135**/\r
136STATIC\r
137EFI_STATUS\r
138EFIAPI\r
139MonotonicCounterDriverGetNextHighMonotonicCount (\r
140 OUT UINT32 *HighCount\r
141 )\r
142/*++\r
143\r
144Routine Description:\r
145\r
146Arguments:\r
147\r
148Returns:\r
149\r
150--*/\r
151{\r
152 EFI_TPL OldTpl;\r
153\r
154 //\r
155 // Check input parameters\r
156 //\r
157 if (HighCount == NULL) {\r
158 return EFI_INVALID_PARAMETER;\r
159 }\r
160\r
161 if (!EfiAtRuntime ()) {\r
162 //\r
163 // Use a lock if called before ExitBootServices()\r
164 //\r
165 OldTpl = gBS->RaiseTPL (TPL_HIGH_LEVEL);\r
166 *HighCount = (UINT32) RShiftU64 (mEfiMtc, 32) + 1;\r
167 mEfiMtc = LShiftU64 (*HighCount, 32);\r
168 gBS->RestoreTPL (OldTpl);\r
169 } else {\r
170 *HighCount = (UINT32) RShiftU64 (mEfiMtc, 32) + 1;\r
171 mEfiMtc = LShiftU64 (*HighCount, 32);\r
172 }\r
173 //\r
174 // Update the NvRam store to match the new high part\r
175 //\r
176 return EfiSetVariable (\r
177 mEfiMtcName,\r
178 &mEfiMtcGuid,\r
179 EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS,\r
180 sizeof (UINT32),\r
181 HighCount\r
182 );\r
183\r
184}\r
185\r
186STATIC\r
187VOID\r
188EFIAPI\r
189EfiMtcEventHandler (\r
190 IN EFI_EVENT Event,\r
191 IN VOID *Context\r
192 )\r
193/*++\r
194\r
195Routine Description:\r
196\r
197 Monotonic count event handler. This handler updates the high monotonic count.\r
198\r
199Arguments:\r
200\r
201 Event The event to handle\r
202 Context The event context\r
203\r
204Returns:\r
205\r
206 EFI_SUCCESS The event has been handled properly\r
207 EFI_NOT_FOUND An error occurred updating the variable.\r
208\r
209--*/\r
210{\r
211 UINT32 HighCount;\r
212\r
213 MonotonicCounterDriverGetNextHighMonotonicCount (&HighCount);\r
214}\r
215\r
216EFI_STATUS\r
217EFIAPI\r
218MonotonicCounterDriverInitialize (\r
219 IN EFI_HANDLE ImageHandle,\r
220 IN EFI_SYSTEM_TABLE *SystemTable\r
221 )\r
222/*++\r
223\r
224Routine Description:\r
225\r
226Arguments:\r
227 (Standard EFI Image entry - EFI_IMAGE_ENTRY_POINT)\r
228\r
229Returns:\r
230\r
231--*/\r
232{\r
233 EFI_STATUS Status;\r
234 UINT32 HighCount;\r
235 UINTN BufferSize;\r
236\r
237 //\r
238 // Make sure the Monotonic Counter Architectural Protocol is not already installed in the system\r
239 //\r
240 ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiMonotonicCounterArchProtocolGuid);\r
241\r
242 //\r
243 // Initialize event to handle overflows\r
244 //\r
245 Status = gBS->CreateEvent (\r
246 EVT_NOTIFY_SIGNAL,\r
247 TPL_CALLBACK,\r
248 EfiMtcEventHandler,\r
249 NULL,\r
250 &mEfiMtcEvent\r
251 );\r
252\r
253 ASSERT_EFI_ERROR (Status);\r
254\r
255 //\r
256 // Read the last high part\r
257 //\r
258 BufferSize = sizeof (UINT32);\r
259 Status = EfiGetVariable (\r
260 mEfiMtcName,\r
261 &mEfiMtcGuid,\r
262 NULL,\r
263 &BufferSize,\r
264 &HighCount\r
265 );\r
266 if (EFI_ERROR (Status)) {\r
267 HighCount = 0;\r
268 }\r
269 //\r
270 // Set the current value\r
271 //\r
272 mEfiMtc = LShiftU64 (HighCount, 32);\r
273\r
274 //\r
275 // Increment the upper 32 bits for this boot\r
276 // Continue even if it fails. It will only fail if the variable services are\r
277 // not functional.\r
278 //\r
279 Status = MonotonicCounterDriverGetNextHighMonotonicCount (&HighCount);\r
280\r
281 //\r
282 // Fill in the EFI Boot Services and EFI Runtime Services Monotonic Counter Fields\r
283 //\r
284 gBS->GetNextMonotonicCount = MonotonicCounterDriverGetNextMonotonicCount;\r
285 gRT->GetNextHighMonotonicCount = MonotonicCounterDriverGetNextHighMonotonicCount;\r
286\r
287 //\r
288 // Install the Monotonic Counter Architctural Protocol onto a new handle\r
289 //\r
290 Status = gBS->InstallMultipleProtocolInterfaces (\r
291 &mMonotonicCounterHandle,\r
292 &gEfiMonotonicCounterArchProtocolGuid,\r
293 NULL,\r
294 NULL\r
295 );\r
296 ASSERT_EFI_ERROR (Status);\r
297\r
298 return EFI_SUCCESS;\r
299}\r