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diff --git a/Lesson_07/README.md b/Lesson_07/README.md deleted file mode 100644 index 66e8689..0000000 --- a/Lesson_07/README.md +++ /dev/null @@ -1,229 +0,0 @@ -Let's print GUID for all the protocols that are exist in our `IMAGE_HANDLE`. - -First understand what `EFI_GUID` internally means in the edk2 codebase: - -https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Uefi/UefiBaseType.h -``` -/// -/// 128-bit buffer containing a unique identifier value. -/// -typedef GUID EFI_GUID; -``` -`GUID` structure is defined in https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Base.h : -``` -/// -/// 128 bit buffer containing a unique identifier value. -/// Unless otherwise specified, aligned on a 64 bit boundary. -/// -typedef struct { - UINT32 Data1; - UINT16 Data2; - UINT16 Data3; - UINT8 Data4[8]; -} GUID; -``` -Fortunately we don't have to manually print all these fields by hand. `Print` function has a format option `%g` to print GUIDs, so we could simply print GUIDs with a code like this: -``` -Print("GUID=%g\n", myGUID); -``` -More information about `Print` formating options can be found at https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Library/PrintLib.h - - -We want to print `EFI_GUID` field from the `PROTOCOL_ENTRY` structure which are referred from the `PROTOCOL_INTERFACE` structures. So we need to define both of these structures in our file for the same reason we've defined `IHANDLE` earlier. - -``` -typedef struct { - UINTN Signature; - /// Link Entry inserted to mProtocolDatabase - LIST_ENTRY AllEntries; - /// ID of the protocol - EFI_GUID ProtocolID; - /// All protocol interfaces - LIST_ENTRY Protocols; - /// Registerd notification handlers - LIST_ENTRY Notify; -} PROTOCOL_ENTRY; - -typedef struct { - UINTN Signature; - /// Link on IHANDLE.Protocols - LIST_ENTRY Link; - /// Back pointer - IHANDLE *Handle; - /// Link on PROTOCOL_ENTRY.Protocols - LIST_ENTRY ByProtocol; - /// The protocol ID - PROTOCOL_ENTRY *Protocol; - /// The interface value - VOID *Interface; - /// OPEN_PROTOCOL_DATA list - LIST_ENTRY OpenList; - UINTN OpenListCount; - -} PROTOCOL_INTERFACE; -``` - -`PROTOCOL_INTERFACE` structures that are connected to any HANDLE are interlinked with each other with a help of a `LIST_ENTRY Link` field that connects them to a double linked list. - -As you may remember `LIST_ENTRY` is defined like this: -``` -/// -/// LIST_ENTRY structure definition. -/// -typedef struct _LIST_ENTRY LIST_ENTRY; - -/// -/// _LIST_ENTRY structure definition. -/// -struct _LIST_ENTRY { - LIST_ENTRY *ForwardLink; - LIST_ENTRY *BackLink; -}; -``` -Each of these fields inside these structure points to another `LIST_ENTRY` structure that is placed in another `PROTOCOL_INTERFACE`. - -So this connection looks like this: - -``` -typedef struct { typedef struct { - UINTN Signature; UINTN Signature; - struct LIST_ENTRY { |---------> struct LIST_ENTRY { - LIST_ENTRY *ForwardLink; -----------------| LIST_ENTRY *ForwardLink; - LIST_ENTRY *BackLink; LIST_ENTRY *BackLink; - } Link; } Link; - IHANDLE *Handle; IHANDLE *Handle; - LIST_ENTRY ByProtocol; LIST_ENTRY ByProtocol; - PROTOCOL_ENTRY *Protocol; PROTOCOL_ENTRY *Protocol; - VOID *Interface; VOID *Interface; - LIST_ENTRY OpenList; LIST_ENTRY OpenList; - UINTN OpenListCount; UINTN OpenListCount; -} PROTOCOL_INTERFACE; } PROTOCOL_INTERFACE; -``` - -But in reality we want a pointer not to `Link` field of another `PROTOCOL_INTERFACE` structure, we want a pointer to another `PROTCOL_INTERFACE` structure inself. - -Therefore one more thing that we would need is a couple of macros: -``` -#define offsetof(a,b) ((INTN)(&(((a*)(0))->b))) - -#define container_of(ptr, type, member) ({ \ - const typeof( ((type *)0)->member ) *__mptr = (ptr); \ - (type *)( (char *)__mptr - offsetof(type,member) );}) -``` -These macros can be familiar to you if you've investigated linux kernel programming. This is where I got them from anyway. - -`contianer_of` macro helps to get a pointer to a structure if you have a pointer to one of its fields. - -If you want to understand how it works internally in C language I suggest you to look at the https://stackoverflow.com/questions/15832301/understanding-container-of-macro-in-the-linux-kernel - -With all of this information final code for our `UefiMain` function would look like this: -``` -EFI_STATUS -EFIAPI -UefiMain ( - IN EFI_HANDLE ImageHandle, - IN EFI_SYSTEM_TABLE *SystemTable - ) -{ - IHANDLE* MyHandle = ImageHandle; - Print(L"Signature: %c %c %c %c\n", (MyHandle->Signature >> 0) & 0xff, - (MyHandle->Signature >> 8) & 0xff, - (MyHandle->Signature >> 16) & 0xff, - (MyHandle->Signature >> 24) & 0xff); - - Print(L"Back Protocol Interface Link: %p\n", MyHandle->Protocols.BackLink); - Print(L"Forward Protocol Interface Link: %p\n", MyHandle->Protocols.ForwardLink); - - LIST_ENTRY *FirstLink = MyHandle->Protocols.ForwardLink; - LIST_ENTRY *CurrentLink = FirstLink; - do { - PROTOCOL_INTERFACE* MyProtocolInterface = container_of(CurrentLink, PROTOCOL_INTERFACE, Link); - - Print(L"\n"); - Print(L"Current Link: %p\n", CurrentLink); - Print(L"Signature: %c %c %c %c\n", (MyProtocolInterface->Signature >> 0) & 0xff, - (MyProtocolInterface->Signature >> 8) & 0xff, - (MyProtocolInterface->Signature >> 16) & 0xff, - (MyProtocolInterface->Signature >> 24) & 0xff); - - Print(L"Back Link: %p\n", MyProtocolInterface->Link.BackLink); - Print(L"Forward Link: %p\n", MyProtocolInterface->Link.ForwardLink); - Print(L"GUID=%g\n", MyProtocolInterface->Protocol->ProtocolID); - CurrentLink = MyProtocolInterface->Link.ForwardLink; - } while (CurrentLink != FirstLink); - - return EFI_SUCCESS; -} -``` - -If we compile and run our app in OVMF (I hope at this time I don't need to repeat how to do it): -``` -FS0:\> ImageHandle.efi -h n d l -Back Protocol Interface Link: 68D4320 -Forward Protocol Interface Link: 6891520 - -Current Link: 6891520 -p i f c -Back Link: 6891430 -Forward Link: 6891B20 -GUID=752F3136-4E16-4FDC-A22A-E5F46812F4CA - -Current Link: 6891B20 -p i f c -Back Link: 6891520 -Forward Link: 68D4320 -GUID=BC62157E-3E33-4FEC-9920-2D3B36D750DF - -Current Link: 68D4320 -p i f c -Back Link: 6891B20 -Forward Link: 6891430 -GUID=5B1B31A1-9562-11D2-8E3F-00A0C969723B - -Current Link: 6891430 - ? ? ? -Back Link: 68D4320 -Forward Link: 6891520 -GUID=00000000-0000-0000-0000-000000000000 -``` - -Let's find first GUID by executing grep on the edk2 source: -``` -$ grep -i 752F3136 -r ./ --exclude-dir=Build -./MdePkg/Include/Protocol/ShellParameters.h: 0x752f3136, 0x4e16, 0x4fdc, { 0xa2, 0x2a, 0xe5, 0xf4, 0x68, 0x12, 0xf4, 0xca } \ -./MdePkg/MdePkg.dec: gEfiShellParametersProtocolGuid = { 0x752f3136, 0x4e16, 0x4fdc, {0xa2, 0x2a, 0xe5, 0xf4, 0x68, 0x12, 0xf4, 0xca }} -``` - -https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Protocol/ShellParameters.h -``` -#define EFI_SHELL_PARAMETERS_PROTOCOL_GUID \ - { \ - 0x752f3136, 0x4e16, 0x4fdc, { 0xa2, 0x2a, 0xe5, 0xf4, 0x68, 0x12, 0xf4, 0xca } \ - } -``` -You can also see in in a https://github.com/tianocore/edk2/blob/master/MdePkg/MdePkg.dec file: -``` - ## Include/Protocol/ShellParameters.h - gEfiShellParametersProtocolGuid = { 0x752f3136, 0x4e16, 0x4fdc, {0xa2, 0x2a, 0xe5, 0xf4, 0x68, 0x12, 0xf4, 0xca }} -``` - -The next two GUIDs you can find in UEFI the specification. - -`EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL` - When installed, the Loaded Image Device Path Protocol specifies the device path that was used when a PE/COFF image was loaded through the EFI Boot Service LoadImage(). - -``` -#define EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL_GUID \ -{0xbc62157e,0x3e33,0x4fec,\ - {0x99,0x20,0x2d,0x3b,0x36,0xd7,0x50,0xdf}} -``` - -`EFI_LOADED_IMAGE_PROTOCOL` - Can be used on any image handle to obtain information about the loaded image. -``` -#define EFI_LOADED_IMAGE_PROTOCOL_GUID\ - {0x5B1B31A1,0x9562,0x11d2,\ - {0x8E,0x3F,0x00,0xA0,0xC9,0x69,0x72,0x3B}} -``` - -The last `PROTOCOL_INTERFACE` structure doesn't have a valid "p i f c" signature (in my case it is 0x20 0x0E 0xED 0x06), so we don't need to look at its GUID. - |