From ac20919b13f82ea9f8d59fe1f34054b7060a96df Mon Sep 17 00:00:00 2001 From: Andreas Kling Date: Mon, 30 Sep 2019 17:21:45 +0200 Subject: [PATCH] Kernel: Make it possible to turn off VM guard pages at compile time This might be useful for debugging since guard pages introduce a fair amount of noise in the virtual address space. --- Kernel/VM/RangeAllocator.cpp | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/Kernel/VM/RangeAllocator.cpp b/Kernel/VM/RangeAllocator.cpp index 8330a798be..2273befaaf 100644 --- a/Kernel/VM/RangeAllocator.cpp +++ b/Kernel/VM/RangeAllocator.cpp @@ -3,6 +3,7 @@ #include //#define VRA_DEBUG +#define VM_GUARD_PAGES RangeAllocator::RangeAllocator(VirtualAddress base, size_t size) { @@ -59,14 +60,20 @@ void RangeAllocator::carve_at_index(int index, const Range& range) Range RangeAllocator::allocate_anywhere(size_t size) { +#ifdef VM_GUARD_PAGES // NOTE: We pad VM allocations with a guard page on each side. - size_t padded_size = size + PAGE_SIZE * 2; + size_t effective_size = size + PAGE_SIZE * 2; + size_t offset_from_effective_base = PAGE_SIZE; +#else + size_t effective_size = size; + size_t offset_from_effective_base = 0; +#endif for (int i = 0; i < m_available_ranges.size(); ++i) { auto& available_range = m_available_ranges[i]; - if (available_range.size() < padded_size) + if (available_range.size() < effective_size) continue; - Range allocated_range(available_range.base().offset(PAGE_SIZE), size); - if (available_range.size() == padded_size) { + Range allocated_range(available_range.base().offset(offset_from_effective_base), size); + if (available_range.size() == effective_size) { #ifdef VRA_DEBUG dbgprintf("VRA: Allocated perfect-fit anywhere(%u): %x\n", size, allocated_range.base().get()); #endif