Commit 69b67646 authored by Tyler Hall's avatar Tyler Hall Committed by Stefan Hajnoczi
Browse files

exec.c: Use subpages for large unaligned mappings 



Registering a multi-page memory region that is non-page-aligned results
in a subpage from the start to the page boundary, some number of full
pages, and possibly another subpage from the last page boundary to the
end. The full pages will have a value for offset_within_region that is
not a multiple of TARGET_PAGE_SIZE. Accesses through softmmu are unable
to handle this and will segfault.

Handling full pages through subpages is not optimal, but only
non-page-aligned mappings take the penalty.

Signed-off-by: default avatarTyler Hall <tylerwhall@gmail.com>
Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
parent adb2a9b5

exec.c

+9 −4
Original line number Diff line number Diff line
@@ -2305,10 +2305,15 @@ void cpu_register_physical_memory_log(MemoryRegionSection *section, 
        remain.offset_within_address_space += now.size;

        remain.offset_within_region += now.size;

    }

    while (remain.size >= TARGET_PAGE_SIZE) {

        now = remain;

        if (remain.offset_within_region & ~TARGET_PAGE_MASK) {

            now.size = TARGET_PAGE_SIZE;

            register_subpage(&now);

        } else {

            now.size &= TARGET_PAGE_MASK;

    if (now.size) {

            register_multipage(&now);

        }

        remain.size -= now.size;

        remain.offset_within_address_space += now.size;

        remain.offset_within_region += now.size;