diff options
| -rw-r--r-- | lib/libc/sys/mmap.2 | 33 | ||||
| -rw-r--r-- | sys/sys/mman.h | 1 | ||||
| -rw-r--r-- | sys/vm/vm_map.c | 3 | ||||
| -rw-r--r-- | sys/vm/vm_map.h | 1 | ||||
| -rw-r--r-- | sys/vm/vm_mmap.c | 4 |
5 files changed, 35 insertions, 7 deletions
diff --git a/lib/libc/sys/mmap.2 b/lib/libc/sys/mmap.2 index 01cde0e..3dd8303 100644 --- a/lib/libc/sys/mmap.2 +++ b/lib/libc/sys/mmap.2 @@ -28,7 +28,7 @@ .\" @(#)mmap.2 8.4 (Berkeley) 5/11/95 .\" $FreeBSD$ .\" -.Dd September 9, 2013 +.Dd June 19, 2014 .Dt MMAP 2 .Os .Sh NAME @@ -141,6 +141,12 @@ argument must be 0. This flag is identical to .Dv MAP_ANON and is provided for compatibility. +.It Dv MAP_EXCL +This flag can only be used in combination with +.Dv MAP_FIXED . +Please see the definition of +.Dv MAP_FIXED +for the description of its effect. .It Dv MAP_FIXED Do not permit the system to select a different address than the one specified. @@ -152,17 +158,21 @@ If is specified, .Fa addr must be a multiple of the pagesize. -If a +If +.Dv MAP_EXCL +is not specified, a successfull .Dv MAP_FIXED -request is successful, the mapping established by -.Fn mmap -replaces any previous mappings for the process' pages in the range from +request replaces any previous mappings for the process' +pages in the range from .Fa addr to .Fa addr + .Fa len . -Use of this option is discouraged. +In contrast, if +.Dv MAP_EXCL +is specified, the request will fail if a mapping +already exists within the range. .It Dv MAP_HASSEMAPHORE Notify the kernel that the region may contain semaphores and that special handling may be necessary. @@ -393,6 +403,17 @@ argument was not -1. was specified and the .Fa offset argument was not 0. +.It Bq Er EINVAL +Both +.Dv MAP_FIXED +and +.Dv MAP_EXCL +were specified, but the requested region is already used by a mapping. +.It Bq Er EINVAL +.Dv MAP_EXCL +was specified, but +.Dv MAP_FIXED +was not. .It Bq Er ENODEV .Dv MAP_ANON has not been specified and diff --git a/sys/sys/mman.h b/sys/sys/mman.h index eaea818..e89bee3 100644 --- a/sys/sys/mman.h +++ b/sys/sys/mman.h @@ -89,6 +89,7 @@ /* * Extended flags */ +#define MAP_EXCL 0x00004000 /* for MAP_FIXED, fail if address is used */ #define MAP_NOCORE 0x00020000 /* dont include these pages in a coredump */ #define MAP_PREFAULT_READ 0x00040000 /* prefault mapping for reading */ #ifdef __LP64__ diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c index 35f2147..fabc022 100644 --- a/sys/vm/vm_map.c +++ b/sys/vm/vm_map.c @@ -1393,7 +1393,8 @@ vm_map_fixed(vm_map_t map, vm_object_t object, vm_ooffset_t offset, ("vm_map_fixed: non-NULL backing object for stack")); vm_map_lock(map); VM_MAP_RANGE_CHECK(map, start, end); - (void) vm_map_delete(map, start, end); + if ((cow & MAP_CHECK_EXCL) == 0) + vm_map_delete(map, start, end); if ((cow & (MAP_STACK_GROWS_DOWN | MAP_STACK_GROWS_UP)) != 0) { result = vm_map_stack_locked(map, start, length, sgrowsiz, prot, max, cow); diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h index 850bf25..8cced05 100644 --- a/sys/vm/vm_map.h +++ b/sys/vm/vm_map.h @@ -315,6 +315,7 @@ long vmspace_resident_count(struct vmspace *vmspace); #define MAP_PREFAULT 0x0008 #define MAP_PREFAULT_PARTIAL 0x0010 #define MAP_DISABLE_SYNCER 0x0020 +#define MAP_CHECK_EXCL 0x0040 #define MAP_DISABLE_COREDUMP 0x0100 #define MAP_PREFAULT_MADVISE 0x0200 /* from (user) madvise request */ #define MAP_VN_WRITECOUNT 0x0400 diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c index 0fc5bb4..a524839 100644 --- a/sys/vm/vm_mmap.c +++ b/sys/vm/vm_mmap.c @@ -245,6 +245,8 @@ sys_mmap(td, uap) flags |= MAP_ANON; pos = 0; } + if ((flags & (MAP_EXCL | MAP_FIXED)) == MAP_EXCL) + return (EINVAL); /* * Align the file position to a page boundary, @@ -1626,6 +1628,8 @@ vm_mmap(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot, return (EINVAL); docow |= MAP_STACK_GROWS_DOWN; } + if ((flags & MAP_EXCL) != 0) + docow |= MAP_CHECK_EXCL; if (fitit) { if ((flags & MAP_ALIGNMENT_MASK) == MAP_ALIGNED_SUPER) |
