void *qemu_vmalloc(size_t size)
{
void *p;
mmap_lock();
/* Use map and mark the pages as used. */
p = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (h2g_valid(p)) {
/* Allocated region overlaps guest address space. This may recurse. */
abi_ulong addr = h2g(p);
page_set_flags(addr & TARGET_PAGE_MASK, TARGET_PAGE_ALIGN(addr + size),
PAGE_RESERVED);
}
mmap_unlock();
return p;
}
/*
* Find and reserve a free memory area of size 'size'. The search
* starts at 'start'.
* It must be called with mmap_lock() held.
* Return -1 if error.
*/
abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size)
{
void *ptr, *prev;
abi_ulong addr;
int wrapped, repeat;
/* If 'start' == 0, then a default start address is used. */
if (start == 0) {
start = mmap_next_start;
} else {
start &= qemu_host_page_mask;
}
size = HOST_PAGE_ALIGN(size);
#ifdef CONFIG_USE_GUEST_BASE
if (RESERVED_VA) {
return mmap_find_vma_reserved(start, size);
}
#endif
addr = start;
wrapped = repeat = 0;
prev = 0;
for (;; prev = ptr) {
/*
* Reserve needed memory area to avoid a race.
* It should be discarded using:
* - mmap() with MAP_FIXED flag
* - mremap() with MREMAP_FIXED flag
* - shmat() with SHM_REMAP flag
*/
ptr = mmap(g2h(addr), size, PROT_NONE,
MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, -1, 0);
/* ENOMEM, if host address space has no memory */
if (ptr == MAP_FAILED) {
return (abi_ulong)-1;
}
/* Count the number of sequential returns of the same address.
This is used to modify the search algorithm below. */
repeat = (ptr == prev ? repeat + 1 : 0);
if (h2g_valid(ptr + size - 1)) {
addr = h2g(ptr);
if ((addr & ~TARGET_PAGE_MASK) == 0) {
/* Success. */
if (start == mmap_next_start && addr >= TASK_UNMAPPED_BASE) {
mmap_next_start = addr + size;
}
return addr;
}
/* The address is not properly aligned for the target. */
switch (repeat) {
case 0:
/* Assume the result that the kernel gave us is the
first with enough free space, so start again at the
next higher target page. */
addr = TARGET_PAGE_ALIGN(addr);
break;
case 1:
/* Sometimes the kernel decides to perform the allocation
at the top end of memory instead. */
addr &= TARGET_PAGE_MASK;
break;
case 2:
/* Start over at low memory. */
addr = 0;
break;
default:
/* Fail. This unaligned block must the last. */
addr = -1;
break;
}
} else {
/* Since the result the kernel gave didn't fit, start
again at low memory. If any repetition, fail. */
addr = (repeat ? -1 : 0);
}
/* Unmap and try again. */
munmap(ptr, size);
/* ENOMEM if we checked the whole of the target address space. */
if (addr == (abi_ulong)-1) {
return (abi_ulong)-1;
} else if (addr == 0) {
if (wrapped) {
return (abi_ulong)-1;
}
wrapped = 1;
/* Don't actually use 0 when wrapping, instead indicate
that we'd truly like an allocation in low memory. */
addr = (mmap_min_addr > TARGET_PAGE_SIZE
? TARGET_PAGE_ALIGN(mmap_min_addr)
: TARGET_PAGE_SIZE);
} else if (wrapped && addr >= start) {
return (abi_ulong)-1;
}
}
}
