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.
diff --git a/include/cutils/mspace.h b/include/cutils/mspace.h
index 33410c1..e6e4047 100644
--- a/include/cutils/mspace.h
+++ b/include/cutils/mspace.h
@@ -80,6 +80,12 @@
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
diff --git a/libcutils/mspace.c b/libcutils/mspace.c
index 2110b43..63b199d 100644
--- a/libcutils/mspace.c
+++ b/libcutils/mspace.c
@@ -134,10 +134,73 @@
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;
+ unsigned int pagesize;
+ mstate m;
+
+ init_mparams();
+ pagesize = PAGESIZE;
+ 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);
+
+ /* Make the first page read/write. dlmalloc needs to use that page.
+ */
+ if (mprotect(base, starting_capacity, PROT_READ | PROT_WRITE) < 0) {
+ goto error;
+ }
+
+ /* Create the mspace, pointing to the memory given.
+ */
+ m = create_mspace_with_base((char *)base + sizeof(*cs), starting_capacity,
+ locked);
+ if (m == (mspace)0) {
+ goto error;
+ }
+ /* 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(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;
+
+ return (mspace)m;
+
+error:
+ 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;
@@ -173,48 +236,12 @@
*/
assert(((uintptr_t)base & (pagesize-1)) == 0);
- /* Reserve some space for the information that our MORECORE needs.
- */
- cs = base;
-
- /* Create the mspace, pointing to the memory we just reserved.
- */
- m = create_mspace_with_base((char *)base + sizeof(*cs), starting_capacity,
- locked);
- if (m == (mspace)0)
- goto error;
-
- /* Make sure that m is in the same page as cs.
- */
- assert(((uintptr_t)m & (uintptr_t)~(pagesize-1)) == (uintptr_t)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)
- goto error;
+ m = create_contiguous_mspace_with_base(starting_capacity, max_capacity,
+ locked, base);
+ if (m == 0) {
+ munmap(base, max_capacity);
}
-
- cs->m = m;
- cs->magic = CONTIG_STATE_MAGIC;
-
- return (mspace)m;
-
-error:
- munmap(base, max_capacity);
- return (mspace)0;
+ return m;
}
mspace create_contiguous_mspace(size_t starting_capacity,