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UEFI开发SlimBootloader调用FSP

jiangwei0512 人气:0

综述

FSP的全称是Firmware Support Package。FSP有以下的特性:

FSP中包含若干个部分,如下图所示:

按作用来分它包含三个大的组件,分别是:

FSP-T:它主要用来初始化CACHE以及其它早期需要的初始化,对应提供给外部的接口是TempRamInit()

FSP-M:它主要用来初始化内存以及其它需要的初始化,对应提供给外部的接口是FspMemoryInit()TempRamExit(),前者用于内存初始化,后者用于处理FSP-T中使用的CACHE内容;

FPS-S:它主要是CPU和芯片组的初始化,对应提供给外部的接口是FspSiliconInit()NotifyPhase(),其中后者又会在不同的阶段调用,包括PCIE扫描之后,ReadyToBoot时和EndOfBootServices的时候;

按功能来区分,每个组件都包含头部、配置和API三个部分。头部是固定的,配置用于一些可控的定制化,API就是功能代码。Bootloader要操作FSP,就需要完成文件配置,接口调用等。

BootLoader调用FSP的整个流程如下图所示:

Bootloader中需要有相应的代码做上述的操作,以Slim Bootloader为例,有一个IntelFsp2Pkg用来处理FSP相关的内容。不过需要注意,这里的IntelFsp2Pkg并不提供FSP源代码的,只是提供了EDK与FSP之间的中间层,真正的用来初始化Intel组件的FSP的代码并没有开源,所以这里也拿不到,不过可以拿到用于QEMU的FSP源代码,后续使用的就是这个。

编译

代码主要是https://gitee.com/jiangwei0512/edk2-beni中的QemuFspPkg,它是用在QEMU上的FSP,它有源码可以下载,而其它Intel的FSP基本是不开源的,没有办法下载到,所以这里只能用QEMU的FSP作为示例。

QEMU对应的FSP通过BuildFsp.py进行编译得到,该脚本执行三个步骤:

PostBuild

Prebuild的流程如下:

1.构建FspHeader.inf实际上就是创建FSP Header的头部,它是固定的格式,位于QemuFspPkg\FspHeader\FspHeader.aslc,内容如下:

TABLES mTable =
{
  {
    FSP_INFO_HEADER_SIGNATURE,                    // UINT32  Signature  (FSPH)
    sizeof(FSP_INFO_HEADER),                      // UINT32  HeaderLength;
    {0x00, 0x00},                                 // UINT8   Reserved1[2];
    FixedPcdGet8(PcdFspHeaderSpecVersion),        // UINT8   SpecVersion;
    FixedPcdGet8(PcdFspHeaderRevision),           // UINT8   HeaderRevision;
    FixedPcdGet32(PcdFspImageRevision),           // UINT32  ImageRevision;
    UINT64_TO_BYTE_ARRAY(
    FixedPcdGet64(PcdFspImageIdString)),          // CHAR8   ImageId[8];
    0x12345678,                                   // UINT32  ImageSize;
    0x12345678,                                   // UINT32  ImageBase;
    FixedPcdGet16(PcdFspImageAttributes),         // UINT16  ImageAttribute;
    FixedPcdGet16(PcdFspComponentAttributes),     // UINT16  ComponentAttribute; Bits[15:12] - 0001b: FSP-T, 0010b: FSP-M, 0011b: FSP-S
    0x12345678,                                   // UINT32  CfgRegionOffset;
    0x12345678,                                   // UINT32  CfgRegionSize;
    0x00000000,                                   // UINT32  Reserved2;
    0x00000000,                                   // UINT32  TempRamInitEntry;
    0x00000000,                                   // UINT32  Reserved3;
    0x00000000,                                   // UINT32  NotifyPhaseEntry;
    0x00000000,                                   // UINT32  FspMemoryInitEntry;
    0x00000000,                                   // UINT32  TempRamExitEntry;
    0x00000000,                                   // UINT32  FspSiliconInitEntry;
  },
  {
    FSP_INFO_EXTENDED_HEADER_SIGNATURE,           // UINT32  Signature  (FSPE)
    sizeof(FSP_INFO_EXTENDED_HEADER),             // UINT32  Length;
    FSPE_HEADER_REVISION_1,                       // UINT8   Revision;
    0x00,                                         // UINT8   Reserved;
    {FSP_PRODUCER_ID},                            // CHAR8   FspProducerId[6];
    0x00000001,                                   // UINT32  FspProducerRevision;
    0x00000000,                                   // UINT32  FspProducerDataSize;
  },
  {
    FSP_FSPP_SIGNATURE,                           // UINT32  Signature  (FSPP)
    sizeof(FSP_PATCH_TABLE),                      // UINT16  Length;
    FSPP_HEADER_REVISION_1,                       // UINT8   Revision;
    0x00,                                         // UINT8   Reserved;
    1                                             // UINT32  PatchEntryNum;
  },
    0xFFFFFFFC                                    // UINT32  Patch FVBASE at end of FV
};

里面的某些数据在之后还会被修改,通过这个头部就可以找到对应API的位置,从而进行调用。

2.UPD txt文件是Build\QemuFspPkg\DEBUG_VS2019\FV(根据编译工具的不同,对应的目录可能存在差异)下的如下内容:

txt文件名对应的是三个FSP组件的GUID(位于BuildFsp.py):

    FspGuid = {
        'FspTUpdGuid'       : '34686CA3-34F9-4901-B82A-BA630F0714C6',
        'FspMUpdGuid'       : '39A250DB-E465-4DD1-A2AC-E2BD3C0E2385',
        'FspSUpdGuid'       : 'CAE3605B-5B34-4C85-B3D7-27D54273C40F'
    }

里面的内容主要是一些PCD,以39A250DB-E465-4DD1-A2AC-E2BD3C0E2385.txt为例:

## @file
#
#  THIS IS AUTO-GENERATED FILE BY BUILD TOOLS AND PLEASE DO NOT MAKE MODIFICATION.
#
#  This file lists all VPD informations for a platform collected by build.exe.
#
# Copyright (c) 2022, 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.
#
gQemuFspPkgTokenSpaceGuid.Signature|DEFAULT|0x0000|8|0x4D5F4450554D4551
gQemuFspPkgTokenSpaceGuid.Revision|DEFAULT|0x0008|1|0x01
gQemuFspPkgTokenSpaceGuid.Reserved|DEFAULT|0x0009|23|{0x00}
gQemuFspPkgTokenSpaceGuid.Revision|DEFAULT|0x0020|1|0x01
gQemuFspPkgTokenSpaceGuid.Reserved|DEFAULT|0x0021|3|{0x00}
gQemuFspPkgTokenSpaceGuid.NvsBufferPtr|DEFAULT|0x0024|4|0x00000000
gQemuFspPkgTokenSpaceGuid.StackBase|DEFAULT|0x0028|4|0x00070000
gQemuFspPkgTokenSpaceGuid.StackSize|DEFAULT|0x002C|4|0x00010000
gQemuFspPkgTokenSpaceGuid.BootLoaderTolumSize|DEFAULT|0x0030|4|0x00000000
gPlatformFspPkgTokenSpaceGuid.Bootmode|DEFAULT|0x0034|4|0x00000000
gQemuFspPkgTokenSpaceGuid.Reserved1|DEFAULT|0x0038|8|{0x00}
gQemuFspPkgTokenSpaceGuid.SerialDebugPortAddress|DEFAULT|0x0040|4|0x00000000
gQemuFspPkgTokenSpaceGuid.SerialDebugPortType|DEFAULT|0x0044|1|0x02
gQemuFspPkgTokenSpaceGuid.SerialDebugPortDevice|DEFAULT|0x0045|1|0x02
gQemuFspPkgTokenSpaceGuid.SerialDebugPortStrideSize|DEFAULT|0x0046|1|0x02
gQemuFspPkgTokenSpaceGuid.UnusedUpdSpace0|DEFAULT|0x0047|0x0031|{0}
gQemuFspPkgTokenSpaceGuid.ReservedFspmUpd|DEFAULT|0x0078|4|{0x00}
gQemuFspPkgTokenSpaceGuid.UnusedUpdSpace1|DEFAULT|0x007C|0x0002|{0}
gQemuFspPkgTokenSpaceGuid.UpdTerminator|DEFAULT|0x007E|2|0x55AA

txt文件的来源是QemuFspPkg\QemuFspPkg.dsc,里面有这些PCD的初始化值,位于[PcdsDynamicVpd.Upd]这个Section,其中的UnusedUpdSpaceX也是在dsc文件中通过PCD指定的偏移来确定的。

3.UPD bin文件名也对应到前面提到的GUID,以39A250DB-E465-4DD1-A2AC-E2BD3C0E2385.bin为例:

bin文件跟txt文件中的PCD值是一一对应的。

4.UPD头文件和bsf文件比较直观,不做详细说明,它们也是通过QemuFspPkg\QemuFspPkg.dsc创建的。UPD头文件中还包含一个通用的头部结构体:

#pragma pack(1)
///
/// FSP_UPD_HEADER Configuration.
///
typedef struct {
  ///
  /// UPD Region Signature. This signature will be
  /// "XXXXXX_T" for FSP-T
  /// "XXXXXX_M" for FSP-M
  /// "XXXXXX_S" for FSP-S
  /// Where XXXXXX is an unique signature
  ///
  UINT64                      Signature;
  ///
  /// Revision of the Data structure.
  ///   For FSP spec 2.0/2.1 value is 1.
  ///   For FSP spec 2.2 value is 2.
  ///
  UINT8                       Revision;
  UINT8                       Reserved[23];
} FSP_UPD_HEADER;
#pragma pack()

每个平台的UPD和bsf内容都是不同的,甚至同一个平台的不同版本也可能存在差异,不同的FSP-X对应不同的UPD,分别是FSPT_UPDFSPM_UPDFSPS_UPD,它们分别存放在FsptUpd.h、FspmUpd.h和FspsUpd.h中。以FSPM_UPD结构体为例:

/** Fsp M UPD Configuration **/
typedef struct {
/** Offset 0x0000 **/
  FSP_UPD_HEADER              FspUpdHeader;
/** Offset 0x0020 **/
  FSPM_ARCH_UPD               FspmArchUpd;
/** Offset 0x0040 **/
  FSP_M_CONFIG                FspmConfig;
/** Offset 0x007C **/
  UINT8                       UnusedUpdSpace1[2];
/** Offset 0x007E **/
  UINT16                      UpdTerminator;
} FSPM_UPD;

其中的内容跟前面的UPD txt中的PCD一一对应。

上述的文件都在Build\QemuFspPkg\DEBUG_VS2019\FV(根据编译工具的不同,对应的目录可能存在差异)创建,总的来说就是为了创建FSP的UPD配置文件和对应用在代码中的头文件,头文件会被拷贝到其它位置也是为了代码能够调用到。而UPD配置文件会通过二进制的方式包含到QemuFspPkg\QemuFspPkg.fdf,下面是一个示例:

#
# Project specific configuration data files
#
!ifndef $(CFG_PREBUILD)
FILE RAW = $(FSP_M_UPD_FFS_GUID) {
    SECTION RAW = $(OUTPUT_DIRECTORY)/$(TARGET)_$(TOOL_CHAIN_TAG)/FV/$(FSP_M_UPD_TOOL_GUID).bin
}
!endif

Build

该过程仅仅是执行build操作而已,对应的代码:

def Build (target, toolchain):
    cmd = '%s -p QemuFspPkg/QemuFspPkg.dsc -a IA32 -b %s -t %s -y Report%s.log' % (
        'build' if os.name == 'posix' else 'build.bat', target, toolchain, target)
    ret = subprocess.call(cmd.split(' '))
    if ret:
        Fatal('Failed to do Build QEMU FSP!')
    print('End of Build...')

可以看到执行对象是QemuFspPkg.dsc。完成这一步之后会生成FSP-M.Fv、FSP-S.Fv、FSP-T.Fv和QEMUFSP.fd。

到这里FSP二进制已经生成,就是QEMUFSP.fd,但是它不能直接使用,还需要后续操作。

PostBuild

这一步主要是通过PatchFv.py来修改前文生成的QEMUFSP.fd,Patch前后:

这里具体Patch了哪部分内容,需要先了解FSP二进制的组成部分,可以参考FSP二进制组成分析。这里Patch的大部分都是FSP Header中的内容,对应的默认初始化内容就是前面提到的QemuFspPkg\FspHeader\FspHeader.aslc,其结构体如下:

///
/// FSP Information Header as described in FSP v2.0 Spec section 5.1.1.
///
typedef struct {
  ///
  /// Byte 0x00: Signature ('FSPH') for the FSP Information Header.
  ///
  UINT32  Signature;
  ///
  /// Byte 0x04: Length of the FSP Information Header.
  ///
  UINT32  HeaderLength;
  ///
  /// Byte 0x08: Reserved.
  ///
  UINT8   Reserved1[2];
  ///
  /// Byte 0x0A: Indicates compliance with a revision of this specification in the BCD format.
  ///
  UINT8   SpecVersion;
  ///
  /// Byte 0x0B: Revision of the FSP Information Header.
  ///
  UINT8   HeaderRevision;
  ///
  /// Byte 0x0C: Revision of the FSP binary.
  ///
  UINT32  ImageRevision;
  ///
  /// Byte 0x10: Signature string that will help match the FSP Binary to a supported HW configuration.
  ///
  CHAR8   ImageId[8];
  ///
  /// Byte 0x18: Size of the entire FSP binary.
  ///
  UINT32  ImageSize;
  ///
  /// Byte 0x1C: FSP binary preferred base address.
  ///
  UINT32  ImageBase;
  ///
  /// Byte 0x20: Attribute for the FSP binary.
  ///
  UINT16  ImageAttribute;
  ///
  /// Byte 0x22: Attributes of the FSP Component.
  ///
  UINT16  ComponentAttribute;
  ///
  /// Byte 0x24: Offset of the FSP configuration region.
  ///
  UINT32  CfgRegionOffset;
  ///
  /// Byte 0x28: Size of the FSP configuration region.
  ///
  UINT32  CfgRegionSize;
  ///
  /// Byte 0x2C: Reserved2.
  ///
  UINT32  Reserved2;
  ///
  /// Byte 0x30: The offset for the API to setup a temporary stack till the memory is initialized.
  ///
  UINT32  TempRamInitEntryOffset;
  ///
  /// Byte 0x34: Reserved3.
  ///
  UINT32  Reserved3;
  ///
  /// Byte 0x38: The offset for the API to inform the FSP about the different stages in the boot process.
  ///
  UINT32  NotifyPhaseEntryOffset;
  ///
  /// Byte 0x3C: The offset for the API to initialize the memory.
  ///
  UINT32  FspMemoryInitEntryOffset;
  ///
  /// Byte 0x40: The offset for the API to tear down temporary RAM.
  ///
  UINT32  TempRamExitEntryOffset;
  ///
  /// Byte 0x44: The offset for the API to initialize the CPU and chipset.
  ///
  UINT32  FspSiliconInitEntryOffset;
  ///
  /// Byte 0x48: Offset for the API for the optional Multi-Phase processor and chipset initialization.
  ///            This value is only valid if FSP HeaderRevision is >= 5.
  ///            If the value is set to 0x00000000, then this API is not available in this component.
  ///
  UINT32  FspMultiPhaseSiInitEntryOffset;
} FSP_INFO_HEADER;

其中的ImageSizeImageBaseImageAttributeComponentAttributeCfgRegionOffsetCfgRegionSizeTempRamInitEntryOffsetFspMemoryInitEntryOffsetTempRamExitEntryOffsetFspSiliconInitEntryOffsetNotifyPhaseEntryOffset等都需要修改。

因为每个FSP-X都有一个FSP_INFO_HEADER结构体,所以前提提到的XXXOffset会针对不同的FSP-X组件做对应的修改,比如FSP-T只需要TempRamInitEntryOffset

除了FSP Header的Patch,这里还有一个点被Patch了:

它们对应的是模块的入口(IntelFsp2Pkg\FspSecCore\Ia32\FspHelper.nasm):

global ASM_PFX(FspInfoHeaderRelativeOff)
ASM_PFX(FspInfoHeaderRelativeOff):
   DD    0x12345678               ; This value must be patched by the build script

从上面的代码也可以看到这部分是需要Patch的。

FSP二进制组成分析

二进制的组成如下:

FSP每个组件都是一个FV,所以都有一个FV Header(EFI_FIRMWARE_VOLUME_HEADER,位于MdePkg\Include\Pi\PiFirmwareVolume.h),大小是0x48个字节,之后是一个FV Extended Header(EFI_FIRMWARE_VOLUME_EXT_HEADER,位于MdePkg\Include\Pi\PiFirmwareVolume.h),之后才是FSP的内容,如下图所示:

FSP组件的第一个模块是FSP Header,对应二进制(Header的第一个成员是"FSPH",最后一个成员是0xFFFFFFFC)中:

这里可以看到里面有一些数据比较奇怪,都是0x12345678和0x00000000,这些都是占位符,并不是真正的有效数据,是通过FspHeader.aslc生成的,在后期这些数据会被Patch成有效的值。

FSP组件的第二个模块是UPD数据,它在Prebuild中生成,对应的数据(UPD数据的第一个成员是Signature(本例中是QEMUPD_T),最后一个成员是0x55AA):

再之后是通用的模块。以QEMU中的FSP对应的fdf文件为例:

#
# FSP header
#
INF  RuleOverride = FSPHEADER   $(FSP_PACKAGE)/FspHeader/FspHeader.inf
#
# Project specific configuration data files
#
!ifndef $(CFG_PREBUILD)
FILE RAW = $(FSP_T_UPD_FFS_GUID) {
    SECTION RAW = $(OUTPUT_DIRECTORY)/$(TARGET)_$(TOOL_CHAIN_TAG)/FV/$(FSP_T_UPD_TOOL_GUID).bin
}
!endif
INF RuleOverride = RELOC   IntelFsp2Pkg/FspSecCore/FspSecCoreT.inf

使用

用于Slim Bootloader的FSP需要放到前者指定的目录,对于QEMU来说对应的是Silicon\QemuSocPkg\FspBin,同时FSP对应的UPD头文件也需要放到指定目录。之后执行Slim Bootloader的各个阶段都会调用FSP的API接口,这里一一说明。

Stage1A

Stage1A阶段会执行FSP中的FspTempRamInit()接口,由于是执行阶段的早期,这里只有汇编部分的代码,具体的位置在BootloaderCorePkg\Stage1A\Ia32\SecEntry.nasm,对应代码:

global  ASM_PFX(_ModuleEntryPoint)
ASM_PFX(_ModuleEntryPoint):
        movd    mm0, eax
        ;
        ; Read time stamp
        ;
        rdtsc
        mov     esi, eax
        mov     edi, edx
        ;
        ; Early board hooks
        ;
        mov     esp, EarlyBoardInitRet
        jmp     ASM_PFX(EarlyBoardInit)
EarlyBoardInitRet:
        mov     esp, FspTempRamInitRet
        jmp     ASM_PFX(FspTempRamInit)

这里jmp到BootloaderCorePkg\Library\FspApiLib\Ia32\FspTempRamInit.nasm:

global  ASM_PFX(FspTempRamInit)
ASM_PFX(FspTempRamInit):
        ;
        ; This hook is called to initialize temporay RAM
        ; ESI, EDI need to be preserved
        ; ESP contains return address
        ; ECX, EDX return the temprary RAM start and end
        ;
        ;
        ; Get FSP-T base in EAX
        ;
        mov     ebp, esp
        mov     eax, dword [ASM_PFX(PcdGet32(PcdFSPTBase))]
        ;
        ; Find the fsp info header
        ; Jump to TempRamInit API
        ;
        add     eax, dword [eax + 094h + FSP_HEADER_TEMPRAMINIT_OFFSET]
        mov     esp, TempRamInitStack
        jmp     eax
TempRamInitDone:
        mov     esp, ebp
        jmp     esp

FSP中的FspTempRamInit()真正的入口是PcdGet32(PcdFSPTBase)+ 094h + FSP_HEADER_TEMPRAMINIT_OFFSETPcdFSPTBase的值是:

gPlatformModuleTokenSpaceGuid.PcdFSPTBase | $(FSP_T_BASE)

FSP_T_BASE表示的是FSP-T.bin的开始位置,094h在前面也已经介绍过,其前面的内容是FV Header,该地址开始是FSP Header,而FSP_HEADER_TEMPRAMINIT_OFFSET是FSP Header的偏移,该位置对应成员是TempRamInitEntryOffset,到这里就对应起来了,FspTempRamInit()即是该位置的值。

不过对于FSP_T_BASE的值,它是FSP-T放到系统内存中位置的地址,可以在BootloaderCorePkg\Platform.dsc中找到:

DEFINE FSP_T_BASE = 0xFFFF0000

这个值也跟SBL二进制产生关系:

Flash Map Information: +------------------------------------------------------------------------+ | FLASH MAP | | (RomSize = 0x00721000) | +------------------------------------------------------------------------+ | NAME | OFFSET (BASE) | SIZE | FLAGS | +----------+------------------------+------------+-----------------------+ +------------------------------------------------------------------------+ | TOP SWAP A | +------------------------------------------------------------------------+ | SG1A | 0x711000(0xFFFF0000) | 0x010000 | Uncompressed, TS_A | +------------------------------------------------------------------------+ | TOP SWAP B | +------------------------------------------------------------------------+ | SG1A | 0x701000(0xFFFE0000) | 0x010000 | Uncompressed, TS_B | +------------------------------------------------------------------------+ | REDUNDANT A | +------------------------------------------------------------------------+ | KEYH | 0x700000(0xFFFDF000) | 0x001000 | Uncompressed, R_A | | CNFG | 0x6ff000(0xFFFDE000) | 0x001000 | Uncompressed, R_A | | FWUP | 0x6e7000(0xFFFC6000) | 0x018000 | Compressed , R_A | | SG1B | 0x6b7000(0xFFF96000) | 0x030000 | Compressed , R_A | | SG02 | 0x69f000(0xFFF7E000) | 0x018000 | Compressed , R_A | | EMTY | 0x681000(0xFFF60000) | 0x01e000 | Uncompressed, R_A | +------------------------------------------------------------------------+ | REDUNDANT B | +------------------------------------------------------------------------+ | KEYH | 0x680000(0xFFF5F000) | 0x001000 | Uncompressed, R_B | | CNFG | 0x67f000(0xFFF5E000) | 0x001000 | Uncompressed, R_B | | FWUP | 0x667000(0xFFF46000) | 0x018000 | Compressed , R_B | | SG1B | 0x637000(0xFFF16000) | 0x030000 | Compressed , R_B | | SG02 | 0x61f000(0xFFEFE000) | 0x018000 | Compressed , R_B | | EMTY | 0x601000(0xFFEE0000) | 0x01e000 | Uncompressed, R_B | +------------------------------------------------------------------------+ | NON REDUNDANT | +------------------------------------------------------------------------+ | PTES | 0x600000(0xFFEDF000) | 0x001000 | Uncompressed, NR | | IPFW | 0x5f0000(0xFFECF000) | 0x010000 | Uncompressed, NR | | EPLD | 0x3e3000(0xFFCC2000) | 0x20d000 | Uncompressed, NR | | PYLD | 0x2e3000(0xFFBC2000) | 0x100000 | Compressed , NR | | VARS | 0x2e1000(0xFFBC0000) | 0x002000 | Uncompressed, NR | | EMTY | 0x001000(0xFF8E0000) | 0x2e0000 | Uncompressed, NR | +------------------------------------------------------------------------+ | NON VOLATILE | +------------------------------------------------------------------------+ | RSVD | 0x000000(0xFF8DF000) | 0x001000 | Uncompressed, NV | +----------+------------------------+------------+-----------------------+Flash Map Information:
        +------------------------------------------------------------------------+
        |                              FLASH  MAP                                |
        |                         (RomSize = 0x00721000)                         |
        +------------------------------------------------------------------------+
        |   NAME   |     OFFSET  (BASE)     |    SIZE    |         FLAGS         |
        +----------+------------------------+------------+-----------------------+
        +------------------------------------------------------------------------+
        |                               TOP SWAP A                               |
        +------------------------------------------------------------------------+
        |   SG1A   |  0x711000(0xFFFF0000)  |  0x010000  |  Uncompressed, TS_A   |
        +------------------------------------------------------------------------+
        |                               TOP SWAP B                               |
        +------------------------------------------------------------------------+
        |   SG1A   |  0x701000(0xFFFE0000)  |  0x010000  |  Uncompressed, TS_B   |
        +------------------------------------------------------------------------+
        |                              REDUNDANT A                               |
        +------------------------------------------------------------------------+
        |   KEYH   |  0x700000(0xFFFDF000)  |  0x001000  |  Uncompressed, R_A    |
        |   CNFG   |  0x6ff000(0xFFFDE000)  |  0x001000  |  Uncompressed, R_A    |
        |   FWUP   |  0x6e7000(0xFFFC6000)  |  0x018000  |  Compressed  , R_A    |
        |   SG1B   |  0x6b7000(0xFFF96000)  |  0x030000  |  Compressed  , R_A    |
        |   SG02   |  0x69f000(0xFFF7E000)  |  0x018000  |  Compressed  , R_A    |
        |   EMTY   |  0x681000(0xFFF60000)  |  0x01e000  |  Uncompressed, R_A    |
        +------------------------------------------------------------------------+
        |                              REDUNDANT B                               |
        +------------------------------------------------------------------------+
        |   KEYH   |  0x680000(0xFFF5F000)  |  0x001000  |  Uncompressed, R_B    |
        |   CNFG   |  0x67f000(0xFFF5E000)  |  0x001000  |  Uncompressed, R_B    |
        |   FWUP   |  0x667000(0xFFF46000)  |  0x018000  |  Compressed  , R_B    |
        |   SG1B   |  0x637000(0xFFF16000)  |  0x030000  |  Compressed  , R_B    |
        |   SG02   |  0x61f000(0xFFEFE000)  |  0x018000  |  Compressed  , R_B    |
        |   EMTY   |  0x601000(0xFFEE0000)  |  0x01e000  |  Uncompressed, R_B    |
        +------------------------------------------------------------------------+
        |                             NON REDUNDANT                              |
        +------------------------------------------------------------------------+
        |   PTES   |  0x600000(0xFFEDF000)  |  0x001000  |  Uncompressed,  NR    |
        |   IPFW   |  0x5f0000(0xFFECF000)  |  0x010000  |  Uncompressed,  NR    |
        |   EPLD   |  0x3e3000(0xFFCC2000)  |  0x20d000  |  Uncompressed,  NR    |
        |   PYLD   |  0x2e3000(0xFFBC2000)  |  0x100000  |  Compressed  ,  NR    |
        |   VARS   |  0x2e1000(0xFFBC0000)  |  0x002000  |  Uncompressed,  NR    |
        |   EMTY   |  0x001000(0xFF8E0000)  |  0x2e0000  |  Uncompressed,  NR    |
        +------------------------------------------------------------------------+
        |                              NON VOLATILE                              |
        +------------------------------------------------------------------------+
        |   RSVD   |  0x000000(0xFF8DF000)  |  0x001000  |  Uncompressed,  NV    |
        +----------+------------------------+------------+-----------------------+

由于SBL会放到4G以下的空间,而FSP-T.Fv放在了SG1A中,大小是0x10000,所以位置就是0xFFFF0000。通过下述命令能够更清楚的看出来:

F:\Gitee\sbl>BootloaderCorePkg\Tools\IfwiUtility.py view -i Outputs\qemu\SlimBootloader.bin
IFWI                     [O:0x00000000  L:0x00721000]
  BIOS                   [O:0x00000000  L:0x00721000]
    NVS                  [O:0x00000000  L:0x00001000]
      RSVD               [O:0x00000000  L:0x00001000]
    NRD                  [O:0x00001000  L:0x00600000]
      EMTY               [O:0x00001000  L:0x002E0000]
      VARS               [O:0x002E1000  L:0x00002000]
      PYLD               [O:0x002E3000  L:0x00100000]
      EPLD               [O:0x003E3000  L:0x0020D000]
      IPFW               [O:0x005F0000  L:0x00010000]
      PTES               [O:0x00600000  L:0x00001000]
    RD1                  [O:0x00601000  L:0x00080000]
      EMTY               [O:0x00601000  L:0x0001E000]
      SG02               [O:0x0061F000  L:0x00018000]
      SG1B               [O:0x00637000  L:0x00030000]
      FWUP               [O:0x00667000  L:0x00018000]
      CNFG               [O:0x0067F000  L:0x00001000]
      KEYH               [O:0x00680000  L:0x00001000]
    RD0                  [O:0x00681000  L:0x00080000]
      EMTY               [O:0x00681000  L:0x0001E000]
      SG02               [O:0x0069F000  L:0x00018000]
      SG1B               [O:0x006B7000  L:0x00030000]
      FWUP               [O:0x006E7000  L:0x00018000]
      CNFG               [O:0x006FF000  L:0x00001000]
      KEYH               [O:0x00700000  L:0x00001000]
    TS1                  [O:0x00701000  L:0x00010000]
      SG1A               [O:0x00701000  L:0x00010000]
    TS0                  [O:0x00711000  L:0x00010000]
      SG1A               [O:0x00711000  L:0x00010000] ---- 这里的最后就是0x100000000的位置

SBL二进制和FSP-T.bin的对应关系:

最终可以查看到PcdGet32(PcdFSPTBase)+ 094h + FSP_HEADER_TEMPRAMINIT_OFFSET处的值是0x473(位于0x7110C4),这也跟编译FSP时的Patch对应:

Patched offset 0x000370C4:[00000000] with value 0x00000473 # TempRamInit API

从上图可以看到该位置的值是EB 0B 90 90 90等等,可以确定这些就是代码了,但是它对应到的是哪个模块呢?其实可以从QemuFspPkg\QemuFspPkg.fdf中找到答案:

[FV.FSP-T]
BlockSize          = $(FLASH_BLOCK_SIZE)
FvAlignment        = 16
ERASE_POLARITY     = 1
MEMORY_MAPPED      = TRUE
STICKY_WRITE       = TRUE
LOCK_CAP           = TRUE
LOCK_STATUS        = TRUE
WRITE_DISABLED_CAP = TRUE
WRITE_ENABLED_CAP  = TRUE
WRITE_STATUS       = TRUE
WRITE_LOCK_CAP     = TRUE
WRITE_LOCK_STATUS  = TRUE
READ_DISABLED_CAP  = TRUE
READ_ENABLED_CAP   = TRUE
READ_STATUS        = TRUE
READ_LOCK_CAP      = TRUE
READ_LOCK_STATUS   = TRUE
FvNameGuid         = 52F1AFB6-78A6-448f-8274-F370549AC5D0
#
# FSP header
#
INF  RuleOverride = FSPHEADER   $(FSP_PACKAGE)/FspHeader/FspHeader.inf
#
# Project specific configuration data files
#
!ifndef $(CFG_PREBUILD)
FILE RAW = $(FSP_T_UPD_FFS_GUID) {
    SECTION RAW = $(OUTPUT_DIRECTORY)/$(TARGET)_$(TOOL_CHAIN_TAG)/FV/$(FSP_T_UPD_TOOL_GUID).bin
}
!endif
INF RuleOverride = RELOC   IntelFsp2Pkg/FspSecCore/FspSecCoreT.inf

根据前面的介绍,FspHeader.inf是FSP Header,$(FSP_T_UPD_TOOL_GUID).bin是UPD配置文件,那么FspSecCoreT.inf就应该是包含FspTempRamInit()函数代码的模块了。

这里直接找对应的模块,它被编译成一个二进制FspSecCoreT.efi,efi文件符合的是《Microsoft Portable Executable and Common Object File Format Specification》(后称Spec)规范。文档可以点击下载。在这个文档中描述了efi二进制头部的格式如下:

通过它可以找到真正的代码入口位置,不过也不需要一一计算,可以通过对应的map文件(这里就是Build\QemuFspPkg\DEBUG_VS2019\IA32\IntelFsp2Pkg\FspSecCore\FspSecCoreT\DEBUG\FspSecCoreT.map)找到需要的入口:

  Address         Publics by Value              Rva+Base       Lib:Object
 0001:000001fb       _TempRamInitApi            0000041b     FspSecCoreT:FspApiEntryT.obj

可以看到地址是0000041b,查看FspSecCoreT.efi二进制:

可以看到数据已经对应上了。再进一步分析这些数据的话,会发现EB实际上是一个跳转指令(注意之类是16位的代码,所以是近跳转),可以参考《64-ia-32-architectures-software-developer-instruction-set-reference-manual.pdf》中的“JMP—Jump”章节:

cb表示的是跳转偏移,这里的值是0xB,对应的代码在IntelFsp2Pkg\FspSecCore\Ia32\SaveRestoreSseNasm.inc:

%macro ENABLE_SSE   0
            ;
            ; Initialize floating point units
            ;
            jmp     NextAddress
align 4 	; 需要4字节对齐,所以后面补充了90,表示的是nop指令,总共3个字节
            ;
            ; Float control word initial value:
            ; all exceptions masked, double-precision, round-to-nearest
            ;
FpuControlWord       DW      027Fh	; 占据2个字节
            ;
            ; Multimedia-extensions control word:
            ; all exceptions masked, round-to-nearest, flush to zero for masked underflow
            ;
MmxControlWord       DD      01F80h	; 占据2个字节
SseError:
            ;
            ; Processor has to support SSE
            ;
            jmp     SseError	; 对应的机器码是EB FE,因为是循环执行,相当于跳转回去执行同一条命令,而该命令是2个字节,所以就是-2,等于0xFE
NextAddress:	; 理论上到这里只有9个字节,但是代码中跳转了0xB,也就是有11个字节,多出来的2个字节用0补上了,应该也是为了4字节对齐

到这里整个调用流程就完整了。

Stage1B

本阶段SBL会调用FSP中的FspMemoryInit(),对应的代码在BootloaderCorePkg\Stage1B\Stage1B.c:

  // Initialize memory
  HobList = NULL;
  DEBUG ((DEBUG_INIT, "Memory Init\n"));
  AddMeasurePoint (0x2020);
  Status = CallFspMemoryInit (PCD_GET32_WITH_ADJUST (PcdFSPMBase), &HobList);
  AddMeasurePoint (0x2030);

CallFspMemoryInit()执行的最重要的代码如下:

  FspMemoryInit = (FSP_MEMORY_INIT)(UINTN)(FspHeader->ImageBase + \
                                           FspHeader->FspMemoryInitEntryOffset);
  Status = FspMemoryInit (&FspmUpd, HobList);

从这里可以看到这就是一个跳转的动作,而跳转的位置就是FSP_INFO_HEADER中的成员FspMemoryInitEntryOffset,这个在前面已经说明过。

FSP中对应的模块主要有:

#
# It is important to keep the proper order for these PEIMs
# for this implementation
#
INF RuleOverride = RELOC   IntelFsp2Pkg/FspSecCore/FspSecCoreM.inf
INF MdeModulePkg/Core/Pei/PeiMain.inf
INF MdeModulePkg/Universal/PCD/Pei/Pcd.inf
#
# Project specific PEIMs
#
INF $(FSP_PACKAGE)/FspmInit/FspmInit.inf

FspSecCoreM.inf可以认为是一个伪SEC代码,主要的目的就是为了进入之后的PEI阶段,即PeiMain.inf,它跟UEFI中的PEI没有本质的区别,不过能够Dispatch的模块仅有后面的两个,Pcd.inf只是功能模块在这里并不重要,而FspmInit.inf就是内存初始化的主体。下面会简单介绍其中的主要模块。

FspSecCoreM.inf对应的入口:

;----------------------------------------------------------------------------
; FspMemoryInit API
;
; This FSP API is called after TempRamInit and initializes the memory.
;
;----------------------------------------------------------------------------
global ASM_PFX(FspMemoryInitApi)
ASM_PFX(FspMemoryInitApi):
  mov    eax,  3 ; FSP_API_INDEX.FspMemoryInitApiIndex
  jmp    ASM_PFX(FspApiCommon)

对应的调用路径:

调用路径中大部分是汇编,不过有几个是C函数,因为在Stage1A中已经可以使用C函数了。SecStartup()位于UefiCpuPkg\SecCore\SecMain.c,是SEC的C函数入口,之后转入执行PeiMain,这个PEI阶段Dispatch的模块主要是FspmInit.inf,它完成真正的内存初始化操作。

FspmInit.inf模块中完成内存初始化的代码这里不多做介绍,因为真正的Intel平台中的代码要复杂的多,这里只是虚拟机的内存初始化,本身的意义不大,不过需要注意的是其中的某些代码:

EFI_PEI_NOTIFY_DESCRIPTOR mMemoryDiscoveredNotifyList = {
  (EFI_PEI_PPI_DESCRIPTOR_NOTIFY_DISPATCH | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST),
  &gEfiPeiMemoryDiscoveredPpiGuid,
  MemoryDiscoveredPpiNotifyCallback
};
//
// Now that all of the pre-permanent memory activities have
// been taken care of, post a call-back for the permanent-memory
// resident services, such as HOB construction.
// PEI Core will switch stack after this PEIM exit.  After that the MTRR
// can be set.
//
Status = PeiServicesNotifyPpi (&mMemoryDiscoveredNotifyList);

这个操作在gEfiPeiMemoryDiscoveredPpiGuid被安装后被调用,而安装动作在PeiCore()中完成:

    //
    // Alert any listeners that there is permanent memory available
    //
    PERF_INMODULE_BEGIN ("DisMem");
    Status = PeiServicesInstallPpi (&mMemoryDiscoveredPpi);

gEfiPeiMemoryDiscoveredPpiGuid对应的回调函数有很多个,这里关注的是FspmInit.inf模块中的。原因是这里有两层的跳转,其中有如下的代码:

EFI_STATUS
EFIAPI
MemoryDiscoveredPpiNotifyCallback (
  IN EFI_PEI_SERVICES           **PeiServices,
  IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
  IN VOID                       *Ppi
  )
{
  //
  // Migrate FSP-M UPD data before destroying CAR
  //
  MigrateFspmUpdData ();
  //
  // Give control back after MemoryInitApi
  //
  FspMemoryInitDone (HobListPtr);
  if (GetFspApiCallingIndex() == TempRamExitApiIndex) {
    DEBUG ((DEBUG_INFO | DEBUG_INIT, "Memory Discovered Notify completed ...\n"));
    //
    // Give control back after TempRamExitApi
    //
    FspTempRamExitDone ();
  }
}

这里的FspMemoryInitDone()执行之后,CPU又会跳转到SBL代码中去执行,直到SBL中再次调用FSP中的TempRamExit()这个API,对应SBL中的代码:

Status = CallFspTempRamExit (PCD_GET32_WITH_ADJUST (PcdFSPMBase), NULL);

然后会再次开始执行FspMemoryInitDone()之后的代码,直到FspTempRamExitDone()退出。

Stage1B中调用的两个API到这里就都介绍完毕了。

Stage2

本阶段SBL会调用FSP中FspSiliconInit(),对应的代码在BootloaderCorePkg\Stage2\Stage2.c:

  DEBUG ((DEBUG_INIT, "Silicon Init\n"));
  AddMeasurePoint (0x3020);
  Status = CallFspSiliconInit ();
  AddMeasurePoint (0x3030);
  FspResetHandler (Status);
  ASSERT_EFI_ERROR (Status);

跟Stage1B中调用FSP中的API一样,这里也是一个跳转:

  FspSiliconInit = (FSP_SILICON_INIT)(UINTN)(FspHeader->ImageBase + \
                                             FspHeader->FspSiliconInitEntryOffset)
  Status = FspSiliconInit (FspsUpdptr);

对应的FSP-S的执行过程跟FSP-M差不多,也有一个伪SEC模块,对应的模块如下所示:

#
# It is important to keep the proper order for these PEIMs
# for this implementation
#
INF RuleOverride = RELOC   IntelFsp2Pkg/FspSecCore/FspSecCoreS.inf
INF MdeModulePkg/Core/DxeIplPeim/DxeIpl.inf
INF RuleOverride = PE32  $(FSP_PACKAGE)/FspsInit/FspsInit.inf
INF RuleOverride = PE32  $(FSP_PACKAGE)/QemuVideo/QemuVideo.inf
INF RuleOverride = PE32    IntelFsp2Pkg/FspNotifyPhase/FspNotifyPhasePeim.inf

不过实际上,当调用FspSiliconInit()之后,代码还是从Stage1B中的FSP退出的位置开始执行的,即QemuFspPkg\FspmInit\FspmInit.c中的FspTempRamExitDone ()之后开始执行代码,其对应的函数是ReportAndInstallNewFv (),也就是说,Stage2调用FSP-S之后,还是从PeiMain开始执行,当前述的函数安装了FV之后,就又开始Dispatch,完成上述模块的执行。

Stage2还是调用FSP中的NotifyPhase(),对应SBL中的代码:

EFI_STATUS
EFIAPI
CallFspNotifyPhase (
  FSP_INIT_PHASE  Phase
  )
{
  FSP_INFO_HEADER            *FspHeader;
  FSP_NOTIFY_PHASE            NotifyPhase;
  NOTIFY_PHASE_PARAMS         NotifyPhaseParams;
  EFI_STATUS                  Status;
  FspHeader = (FSP_INFO_HEADER *)(UINTN)(PcdGet32 (PcdFSPSBase) + FSP_INFO_HEADER_OFF);
  ASSERT (FspHeader->Signature == FSP_INFO_HEADER_SIGNATURE);
  ASSERT (FspHeader->ImageBase == PcdGet32 (PcdFSPSBase));
  if (FspHeader->NotifyPhaseEntryOffset == 0) {
    return EFI_UNSUPPORTED;
  }
  NotifyPhase = (FSP_NOTIFY_PHASE)(UINTN)(FspHeader->ImageBase +
                                          FspHeader->NotifyPhaseEntryOffset);
  NotifyPhaseParams.Phase = Phase;
  DEBUG ((DEBUG_INFO, "Call FspNotifyPhase(%02X) ... ", Phase));
  if (IS_X64) {
    Status = Execute32BitCode ((UINTN)NotifyPhase, (UINTN)&NotifyPhaseParams, (UINTN)0, FALSE);
    Status = (UINTN)LShiftU64 (Status & ((UINTN)MAX_INT32 + 1), 32) | (Status & MAX_INT32);
  } else {
    Status = NotifyPhase (&NotifyPhaseParams);
  }
  DEBUG ((DEBUG_INFO, "%r\n", Status));
  return Status;
}

可以看到也只是一个简单的跳转。这里的参数FSP_INIT_PHASE对应的值:

///
/// Enumeration of FSP_INIT_PHASE for NOTIFY_PHASE.
///
typedef enum {
  ///
  /// This stage is notified when the bootloader completes the
  /// PCI enumeration and the resource allocation for the
  /// PCI devices is complete.
  ///
  EnumInitPhaseAfterPciEnumeration = 0x20,
  ///
  /// This stage is notified just before the bootloader hand-off
  /// to the OS loader.
  ///
  EnumInitPhaseReadyToBoot         = 0x40,
  ///
  /// This stage is notified just before the firmware/Preboot
  /// environment transfers management of all system resources
  /// to the OS or next level execution environment.
  ///
  EnumInitPhaseEndOfFirmware       = 0xF0
} FSP_INIT_PHASE;

标明了调用NotifyPhase()的具体位置。

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