diff options
Diffstat (limited to 'sys/uvm/uvm_map.c')
| -rw-r--r-- | sys/uvm/uvm_map.c | 41 |
1 files changed, 40 insertions, 1 deletions
diff --git a/sys/uvm/uvm_map.c b/sys/uvm/uvm_map.c index a13a7ce92a6..338ec1fc99e 100644 --- a/sys/uvm/uvm_map.c +++ b/sys/uvm/uvm_map.c @@ -1,4 +1,4 @@ -/* $OpenBSD: uvm_map.c,v 1.100 2008/06/09 20:30:23 miod Exp $ */ +/* $OpenBSD: uvm_map.c,v 1.101 2008/07/18 16:40:17 kurt Exp $ */ /* $NetBSD: uvm_map.c,v 1.86 2000/11/27 08:40:03 chs Exp $ */ /* @@ -1100,6 +1100,45 @@ uvm_map_spacefits(struct vm_map *map, vaddr_t *phint, vsize_t length, } /* + * uvm_map_pie: return a random load address for a PIE executable + * properly aligned. + */ + +#ifndef VM_PIE_MAX_ADDR +#define VM_PIE_MAX_ADDR (VM_MAXUSER_ADDRESS / 4) +#endif + +#ifndef VM_PIE_MIN_ADDR +#define VM_PIE_MIN_ADDR VM_MIN_ADDRESS +#endif + +#ifndef VM_PIE_MIN_ALIGN +#define VM_PIE_MIN_ALIGN PAGE_SIZE +#endif + +vaddr_t +uvm_map_pie(vaddr_t align) +{ + vaddr_t addr, space, min; + + align = MAX(align, VM_PIE_MIN_ALIGN); + + /* round up to next alignment */ + min = (VM_PIE_MIN_ADDR + align - 1) & ~(align - 1); + + if (align >= VM_PIE_MAX_ADDR || min >= VM_PIE_MAX_ADDR) + return (align); + + space = (VM_PIE_MAX_ADDR - min) / align; + space = MIN(space, (u_int32_t)-1); + + addr = (vaddr_t)arc4random_uniform((u_int32_t)space) * align; + addr += min; + + return (addr); +} + +/* * uvm_map_hint: return the beginning of the best area suitable for * creating a new mapping with "prot" protection. */ |