From 35a8552605be4fcbded961bf2dcbee5655401575 Mon Sep 17 00:00:00 2001
From: David CARLIER <devnexen@gmail.com>
Date: Tue, 26 Jan 2021 21:49:08 +0000
Subject: [PATCH] Mac OS: Tag mapped pages.

This can be used to help profiling tools (e.g. vmmap) identify the
sources of mappings more specifically.
---
 configure.ac                                         | 12 ++++++++++++
 .../jemalloc/internal/jemalloc_internal_defs.h.in    |  3 +++
 src/pages.c                                          |  9 +++++++--
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 53ac7cce..34613feb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -926,6 +926,18 @@ if test "x${je_cv_cold}" = "xyes" ; then
   AC_DEFINE([JEMALLOC_HAVE_ATTR_COLD], [ ])
 fi
 
+dnl Check for VM_MAKE_TAG for mmap support.
+JE_COMPILABLE([vm_make_tag],
+	      [#include <sys/mman.h>
+	       #include <mach/vm_statistics.h>],
+	      [void *p;
+	       p = mmap(0, 16, PROT_READ, MAP_ANON|MAP_PRIVATE, VM_MAKE_TAG(1), 0);
+	       munmap(p, 16);],
+	      [je_cv_vm_make_tag])
+if test "x${je_cv_vm_make_tag}" = "xyes" ; then
+  AC_DEFINE([JEMALLOC_HAVE_VM_MAKE_TAG], [ ])
+fi
+
 dnl Support optional additions to rpath.
 AC_ARG_WITH([rpath],
   [AS_HELP_STRING([--with-rpath=<rpath>], [Colon-separated rpath (ELF systems only)])],
diff --git a/include/jemalloc/internal/jemalloc_internal_defs.h.in b/include/jemalloc/internal/jemalloc_internal_defs.h.in
index dc4f01fb..093c8be0 100644
--- a/include/jemalloc/internal/jemalloc_internal_defs.h.in
+++ b/include/jemalloc/internal/jemalloc_internal_defs.h.in
@@ -404,4 +404,7 @@
 /* Performs additional size checks when defined. */
 #undef JEMALLOC_OPT_SIZE_CHECKS
 
+/* Darwin VM_MAKE_TAG support */
+#undef JEMALLOC_HAVE_VM_MAKE_TAG
+
 #endif /* JEMALLOC_INTERNAL_DEFS_H_ */
diff --git a/src/pages.c b/src/pages.c
index 6984d2a0..42618858 100644
--- a/src/pages.c
+++ b/src/pages.c
@@ -16,6 +16,11 @@
 #ifdef __NetBSD__
 #include <sys/bitops.h>	/* ilog2 */
 #endif
+#ifdef JEMALLOC_HAVE_VM_MAKE_TAG
+#define PAGES_FD_TAG VM_MAKE_TAG(101U)
+#else
+#define PAGES_FD_TAG -1
+#endif
 
 /******************************************************************************/
 /* Data. */
@@ -141,7 +146,7 @@ os_pages_map(void *addr, size_t size, size_t alignment, bool *commit) {
 #endif
 		int prot = *commit ? PAGES_PROT_COMMIT : PAGES_PROT_DECOMMIT;
 
-		ret = mmap(addr, size, prot, mmap_flags, -1, 0);
+		ret = mmap(addr, size, prot, mmap_flags, PAGES_FD_TAG, 0);
 	}
 	assert(ret != NULL);
 
@@ -326,7 +331,7 @@ pages_commit_impl(void *addr, size_t size, bool commit) {
 	{
 		int prot = commit ? PAGES_PROT_COMMIT : PAGES_PROT_DECOMMIT;
 		void *result = mmap(addr, size, prot, mmap_flags | MAP_FIXED,
-		    -1, 0);
+		    PAGES_FD_TAG, 0);
 		if (result == MAP_FAILED) {
 			return true;
 		}