From c0deafe457450b896a3951d0ce40bd35a72e750e Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sun, 21 Nov 2021 12:28:01 +0100
Subject: [PATCH] Kernel: Avoid repeated memory zeroing while generating
 coredumps

Reuse the same buffer-full-of-zeroes for every un-paged-in page that we
dump out.
---
 Kernel/Coredump.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Kernel/Coredump.cpp b/Kernel/Coredump.cpp
index 85fda720fd4..d2014a72f13 100644
--- a/Kernel/Coredump.cpp
+++ b/Kernel/Coredump.cpp
@@ -167,6 +167,8 @@ ErrorOr<void> Coredump::write_program_headers(size_t notes_size)
 
 ErrorOr<void> Coredump::write_regions()
 {
+    u8 zero_buffer[PAGE_SIZE] = {};
+
     for (auto& region : m_process->address_space().regions()) {
         VERIFY(!region->is_kernel());
 
@@ -180,8 +182,6 @@ ErrorOr<void> Coredump::write_regions()
 
         for (size_t i = 0; i < region->page_count(); i++) {
             auto* page = region->physical_page(i);
-
-            uint8_t zero_buffer[PAGE_SIZE] = {};
             auto src_buffer = [&]() -> ErrorOr<UserOrKernelBuffer> {
                 if (page)
                     return UserOrKernelBuffer::for_user_buffer(reinterpret_cast<uint8_t*>((region->vaddr().as_ptr() + (i * PAGE_SIZE))), PAGE_SIZE);