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Kernel: Don't trigger page faults during profiling stack walk

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The kernel sampling profiler will walk thread stacks during the timer
tick handler. Since it's not safe to trigger page faults during IRQ's,
we now avoid this by checking the page tables manually before accessing
each stack location.
This commit is contained in:
Andreas Kling 2020-02-21 13:05:39 +01:00
parent f9a138aa4b
commit 59b9e49bcd
4 changed files with 31 additions and 1 deletions
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2
Kernel/Thread.cpp
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@ -813,7 +813,7 @@ Vector<uintptr_t> Thread::raw_backtrace(uintptr_t ebp) const
ProcessPagingScope paging_scope(process);
Vector<uintptr_t, Profiling::max_stack_frame_count> backtrace;
backtrace.append(ebp);
for (uintptr_t* stack_ptr = (uintptr_t*)ebp; process.validate_read_from_kernel(VirtualAddress(stack_ptr), sizeof(uintptr_t) * 2); stack_ptr = (uintptr_t*)*stack_ptr) {
for (uintptr_t* stack_ptr = (uintptr_t*)ebp; MM.can_read_without_faulting(process, VirtualAddress(stack_ptr), sizeof(uintptr_t) * 2); stack_ptr = (uintptr_t*)*stack_ptr) {
uintptr_t retaddr = stack_ptr[1];
backtrace.append(retaddr);
if (backtrace.size() == Profiling::max_stack_frame_count)