| Message ID | 1343256304-32029-2-git-send-email-tylerwhall@gmail.com |
|---|---|
| State | New |
| Headers | show |
On 07/26/2012 01:45 AM, Tyler Hall wrote: > 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. Reviewed-by: Avi Kivity <avi@redhat.com>
diff --git a/exec.c b/exec.c index 27b100c..e6ac3e7 100644 --- a/exec.c +++ b/exec.c @@ -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;
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> --- exec.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)