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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: Tyler Hall <tylerwhall@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
This commit is contained in:
Tyler Hall 2012-07-25 18:45:04 -04:00 committed by Stefan Hajnoczi
parent adb2a9b5d4
commit 69b67646bc
1 changed files with 9 additions and 4 deletions
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13
exec.c
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@ -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;
}
now = remain;
now.size &= TARGET_PAGE_MASK;
if (now.size) {
register_multipage(&now);
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;
register_multipage(&now);
}
remain.size -= now.size;
remain.offset_within_address_space += now.size;
remain.offset_within_region += now.size;