Date: Sat, 12 Aug 2023 07:56:48 GMT From: Alan Cox <alc@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 37e5d49e1e5e - main - vm: Fix address hints of 0 with MAP_32BIT Message-ID: <202308120756.37C7umYi075084@gitrepo.freebsd.org>
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The branch main has been updated by alc: URL: https://cgit.FreeBSD.org/src/commit/?id=37e5d49e1e5e750bf2a200ef2e117d14c4e9a578 commit 37e5d49e1e5e750bf2a200ef2e117d14c4e9a578 Author: Alan Cox <alc@FreeBSD.org> AuthorDate: 2023-08-03 07:07:14 +0000 Commit: Alan Cox <alc@FreeBSD.org> CommitDate: 2023-08-12 07:35:21 +0000 vm: Fix address hints of 0 with MAP_32BIT Also, rename min_addr to default_addr, which better reflects what it represents. The min_addr is not a minimum address in the same way that max_addr is actually a maximum address that can be allocated. For example, a non-zero hint can be less than min_addr and be allocated. Reported by: dchagin Reviewed by: dchagin, kib, markj Fixes: d8e6f4946cec0 "vm: Fix anonymous memory clustering under ASLR" Differential Revision: https://reviews.freebsd.org/D41397 --- sys/vm/vm_map.c | 16 ++++++++-------- sys/vm/vm_mmap.c | 14 ++++++++++---- 2 files changed, 18 insertions(+), 12 deletions(-) diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c index 8d98af7709cd..c77c00b8b5c6 100644 --- a/sys/vm/vm_map.c +++ b/sys/vm/vm_map.c @@ -2255,19 +2255,19 @@ done: /* * vm_map_find_min() is a variant of vm_map_find() that takes an - * additional parameter (min_addr) and treats the given address - * (*addr) differently. Specifically, it treats *addr as a hint + * additional parameter ("default_addr") and treats the given address + * ("*addr") differently. Specifically, it treats "*addr" as a hint * and not as the minimum address where the mapping is created. * * This function works in two phases. First, it tries to * allocate above the hint. If that fails and the hint is - * greater than min_addr, it performs a second pass, replacing - * the hint with min_addr as the minimum address for the + * greater than "default_addr", it performs a second pass, replacing + * the hint with "default_addr" as the minimum address for the * allocation. */ int vm_map_find_min(vm_map_t map, vm_object_t object, vm_ooffset_t offset, - vm_offset_t *addr, vm_size_t length, vm_offset_t min_addr, + vm_offset_t *addr, vm_size_t length, vm_offset_t default_addr, vm_offset_t max_addr, int find_space, vm_prot_t prot, vm_prot_t max, int cow) { @@ -2277,14 +2277,14 @@ vm_map_find_min(vm_map_t map, vm_object_t object, vm_ooffset_t offset, hint = *addr; if (hint == 0) { cow |= MAP_NO_HINT; - *addr = hint = min_addr; + *addr = hint = default_addr; } for (;;) { rv = vm_map_find(map, object, offset, addr, length, max_addr, find_space, prot, max, cow); - if (rv == KERN_SUCCESS || min_addr >= hint) + if (rv == KERN_SUCCESS || default_addr >= hint) return (rv); - *addr = hint = min_addr; + *addr = hint = default_addr; } } diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c index 7876a055ca91..d904c4f38e40 100644 --- a/sys/vm/vm_mmap.c +++ b/sys/vm/vm_mmap.c @@ -1555,7 +1555,7 @@ vm_mmap_object(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot, vm_prot_t maxprot, int flags, vm_object_t object, vm_ooffset_t foff, boolean_t writecounted, struct thread *td) { - vm_offset_t max_addr; + vm_offset_t default_addr, max_addr; int docow, error, findspace, rv; bool curmap, fitit; @@ -1630,10 +1630,16 @@ vm_mmap_object(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot, max_addr = MAP_32BIT_MAX_ADDR; #endif if (curmap) { - rv = vm_map_find_min(map, object, foff, addr, size, + default_addr = round_page((vm_offset_t)td->td_proc->p_vmspace-> - vm_daddr + lim_max(td, RLIMIT_DATA)), max_addr, - findspace, prot, maxprot, docow); + vm_daddr + lim_max(td, RLIMIT_DATA)); +#ifdef MAP_32BIT + if ((flags & MAP_32BIT) != 0) + default_addr = 0; +#endif + rv = vm_map_find_min(map, object, foff, addr, size, + default_addr, max_addr, findspace, prot, maxprot, + docow); } else { rv = vm_map_find(map, object, foff, addr, size, max_addr, findspace, prot, maxprot, docow);
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