diff options
Diffstat (limited to 'linux-user/mmap.c')
| -rw-r--r-- | linux-user/mmap.c | 102 |
1 files changed, 78 insertions, 24 deletions
diff --git a/linux-user/mmap.c b/linux-user/mmap.c index 65fdc33c26..ad00b6f555 100644 --- a/linux-user/mmap.c +++ b/linux-user/mmap.c @@ -264,12 +264,15 @@ static int mmap_frag(abi_ulong real_start, return 0; } -#if defined(__CYGWIN__) +#if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64 +# define TASK_UNMAPPED_BASE (1ul << 38) +#elif defined(__CYGWIN__) /* Cygwin doesn't have a whole lot of address space. */ -static abi_ulong mmap_next_start = 0x18000000; +# define TASK_UNMAPPED_BASE 0x18000000 #else -static abi_ulong mmap_next_start = 0x40000000; +# define TASK_UNMAPPED_BASE 0x40000000 #endif +static abi_ulong mmap_next_start = TASK_UNMAPPED_BASE; unsigned long last_brk; @@ -281,19 +284,24 @@ unsigned long last_brk; */ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) { - void *ptr; + void *ptr, *prev; abi_ulong addr; - - size = HOST_PAGE_ALIGN(size); - start &= qemu_host_page_mask; + int wrapped, repeat; /* If 'start' == 0, then a default start address is used. */ - if (start == 0) + if (start == 0) { start = mmap_next_start; + } else { + start &= qemu_host_page_mask; + } + + size = HOST_PAGE_ALIGN(size); addr = start; + wrapped = repeat = 0; + prev = 0; - for(;;) { + for (;; prev = ptr) { /* * Reserve needed memory area to avoid a race. * It should be discarded using: @@ -301,31 +309,77 @@ abi_ulong mmap_find_vma(abi_ulong start, abi_ulong size) * - mremap() with MREMAP_FIXED flag * - shmat() with SHM_REMAP flag */ - ptr = mmap((void *)(unsigned long)addr, size, PROT_NONE, + 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) + if (ptr == MAP_FAILED) { return (abi_ulong)-1; + } - /* If address fits target address space we've found what we need */ - if ((unsigned long)ptr + size - 1 <= (abi_ulong)-1) - break; + /* 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); - /* Unmap and try again with new page */ + 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); - addr += qemu_host_page_size; - /* ENOMEM if we check whole of target address space */ - if (addr == start) + /* ENOMEM if we checked the whole of the target address space. */ + if (addr == -1ul) { 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 truely 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; + } } - - /* Update default start address */ - if (start == mmap_next_start) - mmap_next_start = (unsigned long)ptr + size; - - return h2g(ptr); } /* NOTE: all the constants are the HOST ones */ |