On Sat, Dec 26, 2015 at 10:57 PM, Tony Luck <tony.l...@gmail.com> wrote: > On Sat, Dec 26, 2015 at 6:16 PM, Andy Lutomirski <l...@amacapital.net> wrote: >>>> We could make one of them 31-bits (since even an "allyesconfig" kernel >>>> is still much smaller than a gigabyte) to free a bit for a flag. But there >>>> are those external tools to pre-sort exception tables that would all >>>> need to be fixed too. >> >> Wait, why? The external tools sort by source address, and we'd >> squeeze the flag into the target address, no? > > I was thinking that we'd need to recompute the fixup when we move > the entry to its new sorted location. So that: > > ex_fixup_addr(const struct exception_table_entry *x) > { > return (unsigned long)&x->fixup + x->fixup; > } > > will get the right value. Maybe this would still work out > if the fixup is a 31-bit value plus a flag, but the external > tool thinks it is a 32-bit value? I'd have to ponder that.
I think I can save you some pondering. This old patch gives two flag bits. Feel free to borrow the patch, but you'll probably want to change the _EXTABLE_CLASS_XYZ macros: https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=strict_uaccess_fixups/patch_v1&id=16644d9460fc6531456cf510d5efc57f89e5cd34 --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/