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What is the first place of code, we enter in EDK2 after an SMI?

mzktsn@...
 

Hello, i would like to write code, right after an SMI occurs.
I have searched the functions such as SmiRendezvous,SmiManage etc, and finally
went to UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm file.

Is there any other file than this that the flow goes before reaching this file?
I have also read the document about EDK2 Topology : SMM of 2016 which points that
after a synchronous or asynchronous SMI the flow goeas to the SmiEntry.(n)asm file.


Thanks.

Guomin Jiang
 

As I know, the SMM flow as below:

1. Hardware trigger SMM signal (by IO trap, USB, PowerButton, and so on, detail in PI Spec)
2. CPU Save context and jump to the _SmiEntryPoint(SmiEntry.nasm)
3. _SmiEntryPoint()[SmiEntry.nasm]
-> SmiRendezvous()[MpService.c]
->BSPHandler()[MpService.c]
->gSmmCpuPrivate->SmmCoreEntry() == SmmEntryPoint()[PiSmmCore]
--> Registered Dispatcher(IO, USB, PowerButton, etc)

According to my knowledge, there are no pointer prior the SmiEntry.nasm.
And it is different to hack the SMM because it is transparent for OS.

-----Original Message-----
From: discuss@edk2.groups.io <discuss@edk2.groups.io> On Behalf Of
mzktsn@...
Sent: Wednesday, August 5, 2020 5:23 PM
To: discuss@edk2.groups.io
Subject: [edk2-discuss] What is the first place of code, we enter in EDK2 after
an SMI?

Hello, i would like to write code, right after an SMI occurs.
I have searched the functions such as SmiRendezvous,SmiManage etc, and
finally went to UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm file.

Is there any other file than this that the flow goes before reaching this file?
I have also read the document about EDK2 Topology : SMM of 2016 which
points that after a synchronous or asynchronous SMI the flow goeas to the
SmiEntry.(n)asm file.


Thanks.

Feng Libo <lbfeng@...>
 

Both AMD and Intel's Architectures Software Developer's Manual have the chapter to describe how to enter the SMM.


Yes, SMM is transparent for OS, so OS developers hate it. OS developers create SCI as equivalent.

From: "Guomin Jiang" <guomin.jiang@...>
Date: 2020-08-05 17:53:24
To: "discuss@edk2.groups.io" <discuss@edk2.groups.io>,"mzktsn@..." <mzktsn@...>
Subject: Re: [edk2-discuss] What is the first place of code, we enter in EDK2 after an SMI?>As I know, the SMM flow as below:


1. Hardware trigger SMM signal (by IO trap, USB, PowerButton, and so on, detail in PI Spec)
2. CPU Save context and jump to the _SmiEntryPoint(SmiEntry.nasm)
3. _SmiEntryPoint()[SmiEntry.nasm]
-> SmiRendezvous()[MpService.c]
->BSPHandler()[MpService.c]
->gSmmCpuPrivate->SmmCoreEntry() == SmmEntryPoint()[PiSmmCore]
--> Registered Dispatcher(IO, USB, PowerButton, etc)

According to my knowledge, there are no pointer prior the SmiEntry.nasm.
And it is different to hack the SMM because it is transparent for OS.

-----Original Message-----
From: discuss@edk2.groups.io <discuss@edk2.groups.io> On Behalf Of
mzktsn@...
Sent: Wednesday, August 5, 2020 5:23 PM
To: discuss@edk2.groups.io
Subject: [edk2-discuss] What is the first place of code, we enter in EDK2 after
an SMI?

Hello, i would like to write code, right after an SMI occurs.
I have searched the functions such as SmiRendezvous,SmiManage etc, and
finally went to UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmiEntry.nasm file.

Is there any other file than this that the flow goes before reaching this file?
I have also read the document about EDK2 Topology : SMM of 2016 which
points that after a synchronous or asynchronous SMI the flow goeas to the
SmiEntry.(n)asm file.


Thanks.



Feng Libo <lbfeng@...>
 

There is a functionality in AMD hardware debug tools, HDT, with which you can set a breakpoint at the SMM entry point, the very first piece of code. I believe Intel's debug tools has the same functionality as well.

Best Regards

Feng Libo

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