From bf54eeb7bed7c0b9716c02efb5209e95b675b4fc Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen@gmail.com>
Date: Sun, 3 Apr 2022 07:54:57 +0100
Subject: [PATCH] New option to name reserved pages.

---
 CMakeLists.txt               |  3 +++
 src/snmalloc/pal/pal_linux.h | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index db1e5c54..b9b07b4e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,6 +24,7 @@ cmake_dependent_option(SNMALLOC_STATIC_LIBRARY "Build static libraries" ON "NOT
 cmake_dependent_option(SNMALLOC_MEMCPY_BOUNDS "Perform bounds checks on memcpy with heap objects" OFF "NOT SNMALLOC_HEADER_ONLY_LIBRARY" OFF)
 cmake_dependent_option(SNMALLOC_CHECK_LOADS "Perform bounds checks on the source argument to memcpy with heap objects" OFF "SNMALLOC_MEMCPY_BOUNDS" OFF)
 cmake_dependent_option(SNMALLOC_OPTIMISE_FOR_CURRENT_MACHINE "Compile for current machine architecture" Off "NOT SNMALLOC_HEADER_ONLY_LIBRARY" OFF)
+cmake_dependent_option(SNMALLOC_PAGEID "Set an id to memory regions" OFF "NOT SNMALLOC_PAGEID" OFF)
 if (NOT SNMALLOC_HEADER_ONLY_LIBRARY)
   # Pick a sensible default for the thread cleanup mechanism
   if (${CMAKE_SYSTEM_NAME} STREQUAL FreeBSD)
@@ -323,6 +324,8 @@ if(NOT SNMALLOC_HEADER_ONLY_LIBRARY)
 
     target_compile_definitions(${name} PRIVATE
       SNMALLOC_CHECK_LOADS=$<IF:$<BOOL:${SNMALLOC_CHECK_LOADS}>,true,false>)
+    target_compile_definitions(${name} PRIVATE
+      SNMALLOC_PAGEID=$<IF:$<BOOL:${SNMALLOC_PAGEID}>,true,false>)
 
     install(TARGETS ${name} EXPORT snmallocConfig)
 
diff --git a/src/snmalloc/pal/pal_linux.h b/src/snmalloc/pal/pal_linux.h
index 66240fab..3a06bf8e 100644
--- a/src/snmalloc/pal/pal_linux.h
+++ b/src/snmalloc/pal/pal_linux.h
@@ -6,6 +6,7 @@
 
 #  include <string.h>
 #  include <sys/mman.h>
+#  include <sys/prctl.h>
 #  include <syscall.h>
 
 extern "C" int puts(const char* str);
@@ -38,7 +39,32 @@ namespace snmalloc
     {
       void* p = PALPOSIX<PALLinux>::reserve(size);
       if (p)
+      {
         madvise(p, size, MADV_DONTDUMP);
+#  ifdef SNMALLOC_PAGEID
+#    ifndef PR_SET_VMA
+#      define PR_SET_VMA 0x53564d41
+#      define PR_SET_VMA_ANON_NAME 0
+#    endif
+
+        /**
+         *
+         * If the kernel is set with CONFIG_ANON_VMA_NAME
+         * the reserved pages would appear as follow
+         *
+         * 7fa5f0ceb000-7fa5f0e00000 rw-p 00000000 00:00 0 [anon:snmalloc]
+         * 7fa5f0e00000-7fa5f1800000 rw-p 00000000 00:00 0 [anon:snmalloc]
+         *
+         */
+
+        prctl(
+          PR_SET_VMA,
+          PR_SET_VMA_ANON_NAME,
+          (unsigned long)p,
+          size,
+          (unsigned long)"snmalloc");
+#  endif
+      }
       return p;
     }