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2d1bcce34a
The fault was happening when retrieving a current backtrace for the SystemServer process. To generate a backtrace, we go into the paging scope of the process, meaning we temporarily switch to using its page directory as our own. Because kernel VM is allocated on demand, it's possible for a process's mappings above the 3GB mark to be out-of-date. Normally this just gets fixed up transparently by the page fault handler (which simply copies the PDE from the canonical MM.kernel_page_directory() into the current process.) However, if the current kernel *stack* is in a piece of memory that the backtraced process lacks up-to-date PDE's for, we still get a page fault, but are unable to handle it, since the CPU wants to push to the stack as part of calling the page fault handler. So we're screwed and it's a triple-fault. Fix this by always updating the kernel VM mappings before switching into a paging scope. In practical terms, this is a 1KB memcpy() that happens when generating a backtrace, or doing exec(). |
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| .. | ||
| AnonymousVMObject.cpp | ||
| AnonymousVMObject.h | ||
| InodeVMObject.cpp | ||
| InodeVMObject.h | ||
| MemoryManager.cpp | ||
| MemoryManager.h | ||
| PageDirectory.cpp | ||
| PageDirectory.h | ||
| PhysicalAddress.h | ||
| PhysicalPage.cpp | ||
| PhysicalPage.h | ||
| PhysicalRegion.cpp | ||
| PhysicalRegion.h | ||
| RangeAllocator.cpp | ||
| RangeAllocator.h | ||
| Region.cpp | ||
| Region.h | ||
| VirtualAddress.h | ||
| VMObject.cpp | ||
| VMObject.h | ||