On Tue, Oct 1, 2019 at 9:42 AM Raul Rangel <rran...@chromium.org> wrote:
> That's exciting. That means we can finally catch stack overflows in SMM. > Because of paging? > > 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 >
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