Re: [edk2-devel] ovmf miscompiles with gcc-12

[Jiri Slaby <jirislaby@kernel.org>]

Hi,

On 07. 06. 22, 12:31, Gerd Hoffmann wrote:
>> The reason is TemporaryRamMigration() overwrites rbp unconditionally -- it
>> adds an offset to rbp even if rbp is NOT used as a frame pointer
> 
>> Now, what is the right way to fix this? Do the SetJump/LongJump in assembly
>> and wrap it into push rbp/pop rbp?
> 
> push/pop rbp will break in case frame pointers are used, no?

Yes, see the downstream bug at:

https://bugzilla.suse.com/show_bug.cgi?id=1199597#c45

and read further.

> I think essentially the code needs to know whenever frame pointers are
> used or not and then update (or not) rbp depending on that.  Update
> compiler flags to explicitly set -f(no-)omit-frame-pointer, also add
> -D OMIT_FRAME_POINTER=1, the compile conditionally on OMIT_FRAME_POINTER?

Yes, the comment above mentions this too (cf. CONFIG_FRAME_POINTER in 
the kernel). So see the downstream bugzilla for discussion.

The upstream bugzilla needs an account which I don't have and cannot 
create automatically. It needs manual intervention and I am too lazy to 
do so. So I didn't comment there:
https://bugzilla.tianocore.org/show_bug.cgi?id=3934

thanks,
-- 
js