1 /** @file
2 Ia32 arch functions to access IDT vector.
3
4 Copyright (c) 2013, Intel Corporation. All rights reserved.<BR>
5 This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php.
9
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13 **/
14
15 #include <PeCoffExtraActionLib.h>
16
17 /**
18 Read IDT entry to check if IDT entries are setup by Debug Agent.
19
20 @param[in] IdtDescriptor Pointer to IDT Descriptor.
21 @param[in] InterruptType Interrupt type.
22
23 @retval TRUE IDT entries were setup by Debug Agent.
24 @retval FALSE IDT entries were not setuo by Debug Agent.
25
26 **/
27 BOOLEAN
CheckDebugAgentHandler(IN IA32_DESCRIPTOR * IdtDescriptor,IN UINTN InterruptType)28 CheckDebugAgentHandler (
29 IN IA32_DESCRIPTOR *IdtDescriptor,
30 IN UINTN InterruptType
31 )
32 {
33 IA32_IDT_GATE_DESCRIPTOR *IdtEntry;
34 UINTN InterruptHandler;
35
36 IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
37 if (IdtEntry == NULL) {
38 return FALSE;
39 }
40
41 InterruptHandler = IdtEntry[InterruptType].Bits.OffsetLow +
42 (IdtEntry[InterruptType].Bits.OffsetHigh << 16);
43 if (InterruptHandler >= sizeof (UINT32) && *(UINT32 *)(InterruptHandler - sizeof (UINT32)) == AGENT_HANDLER_SIGNATURE) {
44 return TRUE;
45 } else {
46 return FALSE;
47 }
48 }
49
50 /**
51 Save IDT entry for INT1 and update it.
52
53 @param[in] IdtDescriptor Pointer to IDT Descriptor.
54 @param[out] SavedIdtEntry Original IDT entry returned.
55
56 **/
57 VOID
SaveAndUpdateIdtEntry1(IN IA32_DESCRIPTOR * IdtDescriptor,OUT IA32_IDT_GATE_DESCRIPTOR * SavedIdtEntry)58 SaveAndUpdateIdtEntry1 (
59 IN IA32_DESCRIPTOR *IdtDescriptor,
60 OUT IA32_IDT_GATE_DESCRIPTOR *SavedIdtEntry
61 )
62 {
63 IA32_IDT_GATE_DESCRIPTOR *IdtEntry;
64 UINT16 CodeSegment;
65 UINTN InterruptHandler;
66
67 IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
68 CopyMem (SavedIdtEntry, &IdtEntry[1], sizeof (IA32_IDT_GATE_DESCRIPTOR));
69
70 //
71 // Use current CS as the segment selector of interrupt gate in IDT
72 //
73 CodeSegment = AsmReadCs ();
74
75 InterruptHandler = (UINTN) &AsmInterruptHandle;
76 IdtEntry[1].Bits.OffsetLow = (UINT16)(UINTN)InterruptHandler;
77 IdtEntry[1].Bits.OffsetHigh = (UINT16)((UINTN)InterruptHandler >> 16);
78 IdtEntry[1].Bits.Selector = CodeSegment;
79 IdtEntry[1].Bits.GateType = IA32_IDT_GATE_TYPE_INTERRUPT_32;
80 }
81
82 /**
83 Restore IDT entry for INT1.
84
85 @param[in] IdtDescriptor Pointer to IDT Descriptor.
86 @param[in] RestoredIdtEntry IDT entry to be restored.
87
88 **/
89 VOID
RestoreIdtEntry1(IN IA32_DESCRIPTOR * IdtDescriptor,IN IA32_IDT_GATE_DESCRIPTOR * RestoredIdtEntry)90 RestoreIdtEntry1 (
91 IN IA32_DESCRIPTOR *IdtDescriptor,
92 IN IA32_IDT_GATE_DESCRIPTOR *RestoredIdtEntry
93 )
94 {
95 IA32_IDT_GATE_DESCRIPTOR *IdtEntry;
96
97 IdtEntry = (IA32_IDT_GATE_DESCRIPTOR *) IdtDescriptor->Base;
98 CopyMem (&IdtEntry[1], RestoredIdtEntry, sizeof (IA32_IDT_GATE_DESCRIPTOR));
99 }
100