On 5/17/24 08:27, Jürgen Groß wrote:
On 17.05.24 17:16, Dave Hansen wrote:
On 5/17/24 07:44, Juergen Gross wrote:
Just another data point: Before using this machine I was testing on
another one with older firmware. That one really didn't support
NOM_RBP_MOD
and I needed to build the kernel with CONFIG_FRAME_POINTER enabled to
get
past the check you are mentioning above.
For all intents and purposes, the modules that intentionally clobber RBP
don't support Linux. If buggy modules are accidentally clobbering RBP,
we can debate how much the kernel should bend over to accommodate them,
but my preference would be to ignore them.
I'd much rather put a deny list in the kernel than try to tolerate RBP
clobbering universally.
Would you be fine with adding a new X86_FEATURE (or BUG?) allowing
to switch RBP save/restore via ALTERNATIVE, controlled by a command
line option?
Or maybe by adding a new CONFIG_TDX_MODULE_CAN_CLOBBER_RBP (probably
using a shorter name) option?
As a last resort maybe.
TBH I'm slightly puzzled that the firmware I'm using could make it
outside Intel. I'm fearing this might happen again.
You're puzzled that the firmware is either old buggy or both? Huh.
Intel ships all kinds of crazy pre-production stuff as development
platforms. Let's make sure we know what you've got before we go tearing
up mainline for it.
Because if the options are:
1. Maintain code in mainline until the day I die^Wretire
or
2. Get Jürgen a BIOS update so he stops sending patches
.. it's kinda an easy choice. ;)
Attachment:
OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key
Attachment:
OpenPGP_signature.asc
Description: OpenPGP digital signature