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Commit 17128f6e authored by Barry Hayes's avatar Barry Hayes Committed by Carl Shapiro
Browse files

Break out create_contiguous_mspace_with_base 

This routine allows 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.
parent 32f51664

include/cutils/mspace.h

+6 −0
Original line number Diff line number Diff line
@@ -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

+67 −40
Original line number Diff line number Diff line
@@ -134,68 +134,47 @@ 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) {
@@ -203,9 +182,11 @@ mspace create_contiguous_mspace_with_name(size_t starting_capacity, 
     * 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;

  cs->magic = CONTIG_STATE_MAGIC;
@@ -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,