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Ensure that imports into per-domain kmem arenas are KVA_QUANTUM-aligned.

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The old code appears to assume that vmem_alloc() would import
size-aligned KVA chunks from the parent kernel_arena, but vmem doesn't
provide this guarantee.

Also remove the unused global RWX arena and add comments explaining why
we have per-domain arenas.

Reported by:	alc
Reviewed by:	alc, kib (previous version)
Approved by:	re (gjb)
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17249
This commit is contained in:
markj 2018-09-20 18:29:55 +00:00
parent 846a8dd029
commit c030a808b9
3 changed files with 21 additions and 27 deletions
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3
sys/kern/subr_vmem.c
View File

@ -241,9 +241,6 @@ static struct vmem buffer_arena_storage;
static struct vmem transient_arena_storage;
/* kernel and kmem arenas are aliased for backwards KPI compat. */
vmem_t *kernel_arena = &kernel_arena_storage;
#if VM_NRESERVLEVEL > 0
vmem_t *kernel_rwx_arena = NULL;
#endif
vmem_t *kmem_arena = &kernel_arena_storage;
vmem_t *buffer_arena = &buffer_arena_storage;
vmem_t *transient_arena = &transient_arena_storage;

44
sys/vm/vm_kern.c
View File

@ -669,7 +669,7 @@ kmem_init_zero_region(void)
}
/*
* Import kva into the kernel arena.
* Import KVA from the kernel map into the kernel arena.
*/
static int
kva_import(void *unused, vmem_size_t size, int flags, vmem_addr_t *addrp)
@ -691,22 +691,20 @@ kva_import(void *unused, vmem_size_t size, int flags, vmem_addr_t *addrp)
return (0);
}
#if VM_NRESERVLEVEL > 0
/*
* Import a superpage from the normal kernel arena into the special
* arena for allocations with different permissions.
* Import KVA from a parent arena into a per-domain arena. Imports must be
* KVA_QUANTUM-aligned and a multiple of KVA_QUANTUM in size.
*/
static int
kernel_rwx_alloc(void *arena, vmem_size_t size, int flags, vmem_addr_t *addrp)
kva_import_domain(void *arena, vmem_size_t size, int flags, vmem_addr_t *addrp)
{
KASSERT((size % KVA_QUANTUM) == 0,
("kernel_rwx_alloc: Size %jd is not a multiple of %d",
("kva_import_domain: Size %jd is not a multiple of %d",
(intmax_t)size, (int)KVA_QUANTUM));
return (vmem_xalloc(arena, size, KVA_QUANTUM, 0, 0, VMEM_ADDR_MIN,
VMEM_ADDR_MAX, flags, addrp));
}
#endif
/*
* kmem_init:
@ -744,30 +742,30 @@ kmem_init(vm_offset_t start, vm_offset_t end)
vmem_init(kernel_arena, "kernel arena", 0, 0, PAGE_SIZE, 0, 0);
vmem_set_import(kernel_arena, kva_import, NULL, NULL, KVA_QUANTUM);
#if VM_NRESERVLEVEL > 0
/*
* In an architecture with superpages, maintain a separate arena
* for allocations with permissions that differ from the "standard"
* read/write permissions used for memory in the kernel_arena.
*/
kernel_rwx_arena = vmem_create("kernel rwx arena", 0, 0, PAGE_SIZE,
0, M_WAITOK);
vmem_set_import(kernel_rwx_arena, kernel_rwx_alloc,
(vmem_release_t *)vmem_xfree, kernel_arena, KVA_QUANTUM);
#endif
for (domain = 0; domain < vm_ndomains; domain++) {
/*
* Initialize the per-domain arenas. These are used to color
* the KVA space in a way that ensures that virtual large pages
* are backed by memory from the same physical domain,
* maximizing the potential for superpage promotion.
*/
vm_dom[domain].vmd_kernel_arena = vmem_create(
"kernel arena domain", 0, 0, PAGE_SIZE, 0, M_WAITOK);
vmem_set_import(vm_dom[domain].vmd_kernel_arena,
(vmem_import_t *)vmem_alloc, NULL, kernel_arena,
KVA_QUANTUM);
kva_import_domain, NULL, kernel_arena, KVA_QUANTUM);
/*
* In architectures with superpages, maintain separate arenas
* for allocations with permissions that differ from the
* "standard" read/write permissions used for kernel memory,
* so as not to inhibit superpage promotion.
*/
#if VM_NRESERVLEVEL > 0
vm_dom[domain].vmd_kernel_rwx_arena = vmem_create(
"kernel rwx arena domain", 0, 0, PAGE_SIZE, 0, M_WAITOK);
vmem_set_import(vm_dom[domain].vmd_kernel_rwx_arena,
kernel_rwx_alloc, (vmem_release_t *)vmem_xfree,
vm_dom[domain].vmd_kernel_arena, KVA_QUANTUM);
kva_import_domain, (vmem_release_t *)vmem_xfree,
kernel_arena, KVA_QUANTUM);
#endif
}
}

1
sys/vm/vm_kern.h
View File

@ -70,7 +70,6 @@ extern vm_map_t kernel_map;
extern vm_map_t exec_map;
extern vm_map_t pipe_map;
extern struct vmem *kernel_arena;
extern struct vmem *kernel_rwx_arena;
extern struct vmem *kmem_arena;
extern struct vmem *buffer_arena;
extern struct vmem *transient_arena;