1 /** @file
2 UEFI Dxe DebugLib constructor that prevent some debug service after ExitBootServices event,
3 because some pointer is nulled at that phase.
4
5 Copyright (c) 2018, Microsoft Corporation
6 Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.<BR>
7
8 SPDX-License-Identifier: BSD-2-Clause-Patent
9 **/
10
11 #include <Uefi.h>
12 #include <Library/BaseLib.h>
13 #include <Library/BaseMemoryLib.h>
14
15 //
16 // BOOLEAN value to indicate if it is at the post ExitBootServices pahse
17 //
18 BOOLEAN mPostEBS = FALSE;
19
20 static EFI_EVENT mExitBootServicesEvent;
21
22 //
23 // Pointer to SystemTable
24 // This library instance may have a cycle consume with UefiBootServicesTableLib
25 // because of the constructors.
26 //
27 EFI_BOOT_SERVICES *mDebugBS;
28
29 /**
30 This routine sets the mPostEBS for exit boot servies true
31 to prevent DebugPort protocol dereferences when the pointer is nulled.
32
33 @param Event Event whose notification function is being invoked.
34 @param Context Pointer to the notification function's context.
35
36 **/
37 VOID
38 EFIAPI
ExitBootServicesCallback(EFI_EVENT Event,VOID * Context)39 ExitBootServicesCallback (
40 EFI_EVENT Event,
41 VOID* Context
42 )
43 {
44 mPostEBS = TRUE;
45 return;
46 }
47
48 /**
49 The constructor gets the pointers to boot services table.
50 And create a event to indicate it is after ExitBootServices.
51
52 @param ImageHandle The firmware allocated handle for the EFI image.
53 @param SystemTable A pointer to the EFI System Table.
54
55 @retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.
56
57 **/
58 EFI_STATUS
59 EFIAPI
DxeDebugLibConstructor(IN EFI_HANDLE ImageHandle,IN EFI_SYSTEM_TABLE * SystemTable)60 DxeDebugLibConstructor(
61 IN EFI_HANDLE ImageHandle,
62 IN EFI_SYSTEM_TABLE *SystemTable
63 )
64 {
65 mDebugBS = SystemTable->BootServices;
66
67 mDebugBS->CreateEvent (
68 EVT_SIGNAL_EXIT_BOOT_SERVICES,
69 TPL_NOTIFY,
70 ExitBootServicesCallback,
71 NULL,
72 &mExitBootServicesEvent
73 );
74
75 return EFI_SUCCESS;
76 }
77
78 /**
79 The destructor closes Exit Boot Services Event.
80
81 @param ImageHandle The firmware allocated handle for the EFI image.
82 @param SystemTable A pointer to the EFI System Table.
83
84 @retval EFI_SUCCESS The destructor always returns EFI_SUCCESS.
85
86 **/
87 EFI_STATUS
88 EFIAPI
DxeDebugLibDestructor(IN EFI_HANDLE ImageHandle,IN EFI_SYSTEM_TABLE * SystemTable)89 DxeDebugLibDestructor(
90 IN EFI_HANDLE ImageHandle,
91 IN EFI_SYSTEM_TABLE *SystemTable
92 )
93 {
94 if (mExitBootServicesEvent != NULL) {
95 SystemTable->BootServices->CloseEvent (mExitBootServicesEvent);
96 }
97
98 return EFI_SUCCESS;
99 }
100