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kernel/vm: also honor page protections on copy-on-write

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this fixes #17895

Change-Id: Ide6cb044cf96213b4bae7eb62235f988b73c0fb1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5601
Tested-by: Commit checker robot <[email protected]>
Reviewed-by: waddlesplash <[email protected]>
This commit is contained in:
Jérôme Duval
2022-08-30 16:43:41 +00:00
committed by waddlesplash
parent 90d62fd900
commit 8045bb174e
1 changed files with 31 additions and 5 deletions
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src/system/kernel/vm/vm.cpp
+31 -5
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@@ -2510,15 +2510,18 @@ vm_copy_on_write_area(VMCache* lowerCache,
tempArea = tempArea->cache_next) { tempArea = tempArea->cache_next) {
// The area must be readable in the same way it was // The area must be readable in the same way it was
// previously writable. // previously writable.
uint32 protection = B_KERNEL_READ_AREA; addr_t address = virtual_page_address(tempArea, page);
if ((tempArea->protection & B_READ_AREA) != 0) uint32 protection = 0;
uint32 pageProtection = get_area_page_protection(tempArea, address);
if ((pageProtection & B_KERNEL_READ_AREA) != 0)
protection |= B_KERNEL_READ_AREA;
if ((pageProtection & B_READ_AREA) != 0)
protection |= B_READ_AREA; protection |= B_READ_AREA;
VMTranslationMap* map VMTranslationMap* map
= tempArea->address_space->TranslationMap(); = tempArea->address_space->TranslationMap();
map->Lock(); map->Lock();
map->ProtectPage(tempArea, map->ProtectPage(tempArea, address, protection);
virtual_page_address(tempArea, page), protection);
map->Unlock(); map->Unlock();
} }
} }
@@ -2529,9 +2532,32 @@ vm_copy_on_write_area(VMCache* lowerCache,
// just change the protection of all areas // just change the protection of all areas
for (VMArea* tempArea = upperCache->areas; tempArea != NULL; for (VMArea* tempArea = upperCache->areas; tempArea != NULL;
tempArea = tempArea->cache_next) { tempArea = tempArea->cache_next) {
if (tempArea->page_protections != NULL) {
// Change the protection of all pages in this area.
VMTranslationMap* map = tempArea->address_space->TranslationMap();
map->Lock();
for (VMCachePagesTree::Iterator it = lowerCache->pages.GetIterator();
vm_page* page = it.Next();) {
// The area must be readable in the same way it was
// previously writable.
addr_t address = virtual_page_address(tempArea, page);
uint32 protection = 0;
uint32 pageProtection = get_area_page_protection(tempArea, address);
if ((pageProtection & B_KERNEL_READ_AREA) != 0)
protection |= B_KERNEL_READ_AREA;
if ((pageProtection & B_READ_AREA) != 0)
protection |= B_READ_AREA;
map->ProtectPage(tempArea, address, protection);
}
map->Unlock();
continue;
}
// The area must be readable in the same way it was previously // The area must be readable in the same way it was previously
// writable. // writable.
uint32 protection = B_KERNEL_READ_AREA; uint32 protection = 0;
if ((tempArea->protection & B_KERNEL_READ_AREA) != 0)
protection |= B_KERNEL_READ_AREA;
if ((tempArea->protection & B_READ_AREA) != 0) if ((tempArea->protection & B_READ_AREA) != 0)
protection |= B_READ_AREA; protection |= B_READ_AREA;