malloc: Decorate malloc maps

Add anonymous mmap annotations on loader malloc, malloc when it
allocates memory with mmap, and on malloc arena.  The /proc/self/maps
will now print:

   [anon: glibc: malloc arena]
   [anon: glibc: malloc]
   [anon: glibc: loader malloc]

On arena allocation, glibc annotates only the read/write mapping.

Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>

malloc/arena.c

@@ -17,6 +17,7 @@
    not, see <https://www.gnu.org/licenses/>.  */
 
 #include <stdbool.h>
+#include <setvmaname.h>
 
 #define TUNABLE_NAMESPACE malloc
 #include <elf/dl-tunables.h>
@@ -436,6 +437,9 @@ alloc_new_heap  (size_t size, size_t top_pad, size_t pagesize,
       return 0;
     }
 
+  /* Only considere the actual usable range.  */
+  __set_vma_name (p2, size, " glibc: malloc arena");
+
   madvise_thp (p2, size);
 
   h = (heap_info *) p2;

malloc/malloc.c

@@ -218,6 +218,7 @@
 #include <sys/sysinfo.h>
 
 #include <ldsodefs.h>
+#include <setvmaname.h>
 
 #include <unistd.h>
 #include <stdio.h>    /* needed for malloc_stats */
@@ -2428,6 +2429,8 @@ sysmalloc_mmap (INTERNAL_SIZE_T nb, size_t pagesize, int extra_flags, mstate av)
     madvise_thp (mm, size);
 #endif
 
+  __set_vma_name (mm, size, " glibc: malloc");
+
   /*
     The offset to the start of the mmapped region is stored in the prev_size
     field of the chunk.  This allows us to adjust returned start address to
@@ -2513,6 +2516,8 @@ sysmalloc_mmap_fallback (long int *s, INTERNAL_SIZE_T nb,
     madvise_thp (mbrk, size);
 #endif
 
+  __set_vma_name (mbrk, size, " glibc: malloc");
+
   /* Record that we no longer have a contiguous sbrk region.  After the first
      time mmap is used as backup, we do not ever rely on contiguous space
      since this could incorrectly bridge regions.  */