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| author | Konstantin Belousov <kib@FreeBSD.org> | 2023-07-28 00:40:53 +0000 |
|---|---|---|
| committer | Konstantin Belousov <kib@FreeBSD.org> | 2023-08-12 06:28:14 +0000 |
| commit | 90049eabcfadf229e3983f04310a8ea28fe3d2b1 (patch) | |
| tree | fcac96ca69badfbb1d419b2afa75b54b76e2309c | |
| parent | b6037edbd17dd3144aa1a7b0814cd5ebe98d765a (diff) | |
| download | src-90049eabcfadf229e3983f04310a8ea28fe3d2b1.tar.gz src-90049eabcfadf229e3983f04310a8ea28fe3d2b1.zip | |
vm_map_protect(): add VM_MAP_PROTECT_GROWSDOWN flag
which requests to propagate lowest stack segment protection to the grow gap.
This seems to be required for Linux emulation.
Reported by: dchagin
Reviewed by: alc, markj
Tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D41099
| -rw-r--r-- | sys/vm/vm_map.c | 19 | ||||
| -rw-r--r-- | sys/vm/vm_map.h | 1 |
2 files changed, 20 insertions, 0 deletions
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c index 1c806d6cae34..8d98af7709cd 100644 --- a/sys/vm/vm_map.c +++ b/sys/vm/vm_map.c @@ -2758,6 +2758,7 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, vm_map_entry_t entry, first_entry, in_tran, prev_entry; vm_object_t obj; struct ucred *cred; + vm_offset_t orig_start; vm_prot_t check_prot, max_prot, old_prot; int rv; @@ -2769,8 +2770,10 @@ vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, !CONTAINS_BITS(new_maxprot, new_prot)) return (KERN_OUT_OF_BOUNDS); + orig_start = start; again: in_tran = NULL; + start = orig_start; vm_map_lock(map); if ((map->flags & MAP_WXORX) != 0 && @@ -2793,6 +2796,22 @@ again: if (!vm_map_lookup_entry(map, start, &first_entry)) first_entry = vm_map_entry_succ(first_entry); + if ((flags & VM_MAP_PROTECT_GROWSDOWN) != 0 && + (first_entry->eflags & MAP_ENTRY_GROWS_DOWN) != 0) { + /* + * Handle Linux's PROT_GROWSDOWN flag. + * It means that protection is applied down to the + * whole stack, including the specified range of the + * mapped region, and the grow down region (AKA + * guard). + */ + while (!CONTAINS_BITS(first_entry->eflags, + MAP_ENTRY_GUARD | MAP_ENTRY_STACK_GAP_DN) && + first_entry != vm_map_entry_first(map)) + first_entry = vm_map_entry_pred(first_entry); + start = first_entry->start; + } + /* * Make a first pass to check for protection violations. */ diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h index 08bc6532b8b8..e41516477af4 100644 --- a/sys/vm/vm_map.h +++ b/sys/vm/vm_map.h @@ -522,6 +522,7 @@ vm_map_entry_succ(vm_map_entry_t entry) #define VM_MAP_PROTECT_SET_PROT 0x0001 #define VM_MAP_PROTECT_SET_MAXPROT 0x0002 +#define VM_MAP_PROTECT_GROWSDOWN 0x0004 int vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, vm_prot_t new_prot, vm_prot_t new_maxprot, int flags); |