Merge "Break out create_contiguous_mspace_with_base This routine allo…

…ws creating a contiguous mspace from raw mapped memory. In turn, this will enable preallocation of the 3 heap spaces, which will help remembered sets and zygote/app checks given pointer values."

include/cutils/mspace.h

@@ -80,6 +80,12 @@ mspace create_contiguous_mspace(size_t starting_capacity, size_t max_capacity,
 mspace create_contiguous_mspace_with_name(size_t starting_capacity,
     size_t max_capacity, int locked, const char *name);
 
+/*
+   Identical to create_contiguous_mspace, but uses previously mapped memory.
+*/
+mspace create_contiguous_mspace_with_base(size_t starting_capacity,
+    size_t max_capacity, int locked, void *base);
+
 size_t destroy_contiguous_mspace(mspace msp);
 #endif
 

libcutils/mspace.c

@@ -134,77 +134,58 @@ assert(nb >= 0);  //xxx deal with the trim case
   return oldbrk;
 }
 
-mspace create_contiguous_mspace_with_name(size_t starting_capacity,
-    size_t max_capacity, int locked, char const * name) {
-  int fd, ret;
+mspace create_contiguous_mspace_with_base(size_t starting_capacity,
+    size_t max_capacity, int locked, void *base) {
   struct mspace_contig_state *cs;
-  char buf[ASHMEM_NAME_LEN] = "mspace";
-  void *base;
   unsigned int pagesize;
   mstate m;
 
-  if (starting_capacity > max_capacity)
-    return (mspace)0;
-
   init_mparams();
   pagesize = PAGESIZE;
-
-  /* Create the anonymous memory that will back the mspace.
-   * This reserves all of the virtual address space we could
-   * ever need.  Physical pages will be mapped as the memory
-   * is touched.
-   *
-   * Align max_capacity to a whole page.
-   */
-  max_capacity = (size_t)ALIGN_UP(max_capacity, pagesize);
-
-  if (name)
-    snprintf(buf, sizeof(buf), "mspace/%s", name);
-  fd = ashmem_create_region(buf, max_capacity);
-  if (fd < 0)
-    return (mspace)0;
-
-  base = mmap(NULL, max_capacity, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
-  close(fd);
-  if (base == MAP_FAILED)
-    return (mspace)0;
-
-  /* Make sure that base is at the beginning of a page.
-   */
+  assert(starting_capacity <= max_capacity);
   assert(((uintptr_t)base & (pagesize-1)) == 0);
+  assert(((uintptr_t)max_capacity & (pagesize-1)) == 0);
+  starting_capacity = (size_t)ALIGN_UP(starting_capacity, pagesize);
 
-  /* Reserve some space for the information that our MORECORE needs.
+  /* Make the first page read/write. dlmalloc needs to use that page.
    */
-  cs = base;
+  if (mprotect(base, starting_capacity, PROT_READ | PROT_WRITE) < 0) {
+    goto error;
+  }
 
-  /* Create the mspace, pointing to the memory we just reserved.
+  /* Create the mspace, pointing to the memory given.
    */
   m = create_mspace_with_base((char *)base + sizeof(*cs), starting_capacity,
                               locked);
-  if (m == (mspace)0)
+  if (m == (mspace)0) {
     goto error;
-
-  /* Make sure that m is in the same page as cs.
+  }
+  /* Make sure that m is in the same page as base.
    */
   assert(((uintptr_t)m & (uintptr_t)~(pagesize-1)) == (uintptr_t)base);
+  /* Use some space for the information that our MORECORE needs.
+   */
+  cs = (struct mspace_contig_state *)base;
 
   /* Find out exactly how much of the memory the mspace
    * is using.
    */
   cs->brk = m->seg.base + m->seg.size;
   cs->top = (char *)base + max_capacity;
+
   assert((char *)base <= cs->brk);
   assert(cs->brk <= cs->top);
-
   /* Prevent access to the memory we haven't handed out yet.
    */
   if (cs->brk != cs->top) {
     /* mprotect() requires page-aligned arguments, but it's possible
      * for cs->brk not to be page-aligned at this point.
      */
     char *prot_brk = (char *)ALIGN_UP(cs->brk, pagesize);
-    if (mprotect(prot_brk, cs->top - prot_brk, PROT_NONE) < 0)
+    if ((mprotect(base, prot_brk - (char *)base, PROT_READ | PROT_WRITE) < 0) ||
+        (mprotect(prot_brk, cs->top - prot_brk, PROT_NONE) < 0)) {
       goto error;
+    }
   }
 
   cs->m = m;
@@ -213,10 +194,56 @@ mspace create_contiguous_mspace_with_name(size_t starting_capacity,
   return (mspace)m;
 
 error:
-  munmap(base, max_capacity);
   return (mspace)0;
 }
 
+
+mspace create_contiguous_mspace_with_name(size_t starting_capacity,
+    size_t max_capacity, int locked, char const *name) {
+  int fd, ret;
+  char buf[ASHMEM_NAME_LEN] = "mspace";
+  void *base;
+  unsigned int pagesize;
+  mstate m;
+
+  if (starting_capacity > max_capacity)
+    return (mspace)0;
+
+  init_mparams();
+  pagesize = PAGESIZE;
+
+  /* Create the anonymous memory that will back the mspace.
+   * This reserves all of the virtual address space we could
+   * ever need.  Physical pages will be mapped as the memory
+   * is touched.
+   *
+   * Align max_capacity to a whole page.
+   */
+  max_capacity = (size_t)ALIGN_UP(max_capacity, pagesize);
+
+  if (name)
+    snprintf(buf, sizeof(buf), "mspace/%s", name);
+  fd = ashmem_create_region(buf, max_capacity);
+  if (fd < 0)
+    return (mspace)0;
+
+  base = mmap(NULL, max_capacity, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+  close(fd);
+  if (base == MAP_FAILED)
+    return (mspace)0;
+
+  /* Make sure that base is at the beginning of a page.
+   */
+  assert(((uintptr_t)base & (pagesize-1)) == 0);
+
+  m = create_contiguous_mspace_with_base(starting_capacity, max_capacity,
+                                         locked, base);
+  if (m == 0) {
+    munmap(base, max_capacity);
+  }
+  return m;
+}
+
 mspace create_contiguous_mspace(size_t starting_capacity,
     size_t max_capacity, int locked) {
   return create_contiguous_mspace_with_name(starting_capacity,