That's exciting. That means we can finally catch stack overflows in SMM. On Sun, Sep 29, 2019 at 5:42 AM Patrick Rudolph <s...@das-labor.org> wrote:
> Dear coreboot community, > Please test and review the patch series [1]. > > It adds support for x86 long mode on qemu and allows to build test > most of coreboot's common code using the x86_64 toolchain. > It serves as reference implementation to migrate real hardware to long > mode. > > Here some technical details, that can also be found in the > Documentation/ folder: > > A new tool called pgtblgen create static page tables for a known > physical > memory address. The page tables are placed in CBFS at the given address. > Due to the fixed and known address, they can easily be loaded in > assembly code. > It only works on platforms that memory map the SPI flash, which are > almost all > modern x86 platforms. > > The advantage of page tables in ROM are: > * No runtime (assembly) code to generate page tables > * No need to find a (4K aligned) place in heap to store them > * Improved security for SMM, as page tables are always immutable > > The page tables are loaded in bootblock and SMM and persist until > control is handed > over to the payload. > > For the Proof-of-Concept only 4GiB are identity mapped, thus no stage > can't access > memory over 4GiB. That's not a problem for now as no coreboot code make > use of memory > above 4GiB yet. > > I haven't done further tests on long mode. > It will be interesting to see if there are improvements on boot speed, > code size or > faster firmware decompression speeds. > > Regards, > Patrick > > 1: > > https://review.coreboot.org/q/topic:%22x86_64_support2%22+(status:open%20OR%20status:merged) > _______________________________________________ > coreboot mailing list -- coreboot@coreboot.org > To unsubscribe send an email to coreboot-le...@coreboot.org >
_______________________________________________ coreboot mailing list -- coreboot@coreboot.org To unsubscribe send an email to coreboot-le...@coreboot.org
