* Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote: > This implements text-relative kallsyms address tables. This was developed as > part of my series to implement KASLR/CONFIG_RELOCATABLE for arm64, but I think > it may be beneficial to other architectures as well, so I am presenting it as a > separate series. > > The idea is that on 64-bit builds, it is rather wasteful to use absolute > addressing for kernel symbols since they are all within a couple of MBs of each > other. On top of that, the absolute addressing implies that, when the kernel is > relocated at runtime, each address in the table needs to be fixed up > individually. > > Since all section-relative addresses are already emitted relative to _text, it > is quite straight-forward to record only the offset, and add the absolute > address of _text at runtime when referring to the address table. > > The reduction ranges from around 250 KB uncompressed vmlinux size and 10 KB > compressed size (s390) to 3 MB/500 KB for ppc64 (although, in the latter case, > the reduction in uncompressed size is primarily __init data) So since kallsyms is in unswappable kernel RAM, the uncompressed size reduction is what we care about mostly. How much bootloader load times are impacted is a third order concern. IOW a nice change! Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
