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diff --git a/sys/vm/vm_extern.h b/sys/vm/vm_extern.h
--- a/sys/vm/vm_extern.h
+++ b/sys/vm/vm_extern.h
@@ -129,6 +129,8 @@
void vm_imgact_unmap_page(struct sf_buf *sf);
void vm_thread_dispose(struct thread *td);
int vm_thread_new(struct thread *td, int pages);
+vm_pindex_t vm_kstack_pindex(vm_offset_t ks, int npages);
+vm_object_t vm_thread_kstack_size_to_obj(int npages);
void vm_thread_stack_back(struct domainset *ds, vm_offset_t kaddr,
vm_page_t ma[], int npages, int req_class);
u_int vm_active_count(void);
diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -108,6 +108,15 @@
#include <machine/cpu.h>
+#if VM_NRESERVLEVEL > 0
+#define KVA_KSTACK_QUANTUM_SHIFT (VM_LEVEL_0_ORDER + PAGE_SHIFT)
+#else
+#define KVA_KSTACK_QUANTUM_SHIFT (8 + PAGE_SHIFT)
+#endif
+#define KVA_KSTACK_QUANTUM (1ul << KVA_KSTACK_QUANTUM_SHIFT)
+
+static vmem_t *kstack_arena = NULL;
+
/*
* MPSAFE
*
@@ -267,6 +276,7 @@
}
vm_object_t kstack_object;
+vm_object_t kstack_alt_object;
static uma_zone_t kstack_cache;
static int kstack_cache_size;
@@ -285,6 +295,114 @@
CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &kstack_cache_size, 0,
sysctl_kstack_cache_size, "IU", "Maximum number of cached kernel stacks");
+/*
+ * Allocate a virtual address range from the kstack arena.
+ */
+static vm_offset_t
+vm_thread_alloc_kstack_kva(vm_size_t size)
+{
+ vm_offset_t addr;
+
+ size = round_page(size);
+ /* Fall back to the kernel arena for non-standard kstack sizes */
+ if (size != (kstack_pages + KSTACK_GUARD_PAGES) * PAGE_SIZE) {
+ return (kva_alloc(size));
+ }
+
+ if (vmem_alloc(kstack_arena, size, M_BESTFIT | M_NOWAIT, &addr))
+ return (0);
+
+ return (addr);
+}
+
+/*
+ * Release a region of kernel virtual memory
+ * allocated from the kstack arena.
+ */
+static void
+vm_thread_free_kstack_kva(vm_offset_t addr, vm_size_t size)
+{
+ size = round_page(size);
+ if (size != (kstack_pages + KSTACK_GUARD_PAGES) * PAGE_SIZE) {
+ kva_free(addr, size);
+ } else {
+ vmem_free(kstack_arena, addr, size);
+ }
+}
+
+/*
+ * Import KVA from a parent arena into the kstack arena. Imports must be
+ * a multiple of kernel stack pages + guard pages in size.
+ *
+ * Kstack VA allocations need to be aligned so that the linear KVA pindex
+ * is divisible by the total number of kstack VA pages. This is necessary to
+ * make vm_kstack_pindex work properly.
+ *
+ * We allocate a KVA_KSTACK_QUANTUM-aligned VA region that is slightly
+ * larger than the requested size and adjust it until it is both
+ * properly aligned and of the requested size.
+ */
+static int
+vm_thread_kstack_arena_import(void *arena, vmem_size_t size, int flags,
+ vmem_addr_t *addrp)
+{
+ int error, rem;
+ size_t npages = kstack_pages + KSTACK_GUARD_PAGES;
+ vmem_size_t padding = npages * PAGE_SIZE;
+ vm_pindex_t lin_pidx;
+
+ KASSERT(atop(size) % npages == 0,
+ ("%s: Size %jd is not a multiple of kstack pages (%d)", __func__,
+ (intmax_t)size, (int)npages));
+
+ error = vmem_xalloc(arena, size + padding, KVA_KSTACK_QUANTUM, 0, 0,
+ VMEM_ADDR_MIN, VMEM_ADDR_MAX, flags, addrp);
+ if (error) {
+ return (error);
+ }
+
+ lin_pidx = atop(*addrp - VM_MIN_KERNEL_ADDRESS);
+ rem = lin_pidx % npages;
+ if (rem != 0) {
+ /* Bump addr to next aligned address */
+ *addrp = *addrp + (npages - rem) * PAGE_SIZE;
+ }
+
+ return (0);
+}
+
+/*
+ * Release KVA from a parent arena into the kstack arena. Released imports must
+ * be a multiple of kernel stack pages + guard pages in size.
+ */
+static void
+vm_thread_kstack_arena_release(void *arena, vmem_addr_t addr, vmem_size_t size)
+{
+ int rem;
+ size_t npages = kstack_pages + KSTACK_GUARD_PAGES;
+ vmem_size_t padding = npages * PAGE_SIZE;
+
+ KASSERT(size % npages == 0,
+ ("%s: Size %jd is not a multiple of kstack pages (%d)", __func__,
+ (intmax_t)size, (int)npages));
+ KASSERT(addr % npages == 0,
+ ("%s: Address %p is not a multiple of kstack pages (%d)", __func__,
+ (void *)addr, (int)npages));
+
+ /*
+ * If the address is not KVA_KSTACK_QUANTUM-aligned we have to decrement
+ * it to account for the shift in kva_import_kstack.
+ */
+ rem = addr % KVA_KSTACK_QUANTUM;
+ if (rem) {
+ KASSERT(rem <= (npages * PAGE_SIZE),
+ ("%s: rem > npages (%d), (%d)", __func__, rem,
+ (int)npages));
+ addr -= rem;
+ }
+ vmem_xfree(arena, addr, size + padding);
+}
+
/*
* Create the kernel stack (including pcb for i386) for a new thread.
*/
@@ -298,7 +416,8 @@
/*
* Get a kernel virtual address for this thread's kstack.
*/
- ks = kva_alloc((pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
+ ks = vm_thread_alloc_kstack_kva(
+ (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
if (ks == 0) {
printf("%s: kstack allocation failed\n", __func__);
return (0);
@@ -326,22 +445,23 @@
vm_page_t m;
vm_pindex_t pindex;
int i;
+ vm_object_t obj = vm_thread_kstack_size_to_obj(pages);
- pindex = atop(ks - VM_MIN_KERNEL_ADDRESS);
+ pindex = vm_kstack_pindex(ks, pages);
pmap_qremove(ks, pages);
- VM_OBJECT_WLOCK(kstack_object);
+ VM_OBJECT_WLOCK(obj);
for (i = 0; i < pages; i++) {
- m = vm_page_lookup(kstack_object, pindex + i);
+ m = vm_page_lookup(obj, pindex + i);
if (m == NULL)
panic("%s: kstack already missing?", __func__);
vm_page_xbusy_claim(m);
vm_page_unwire_noq(m);
vm_page_free(m);
}
- VM_OBJECT_WUNLOCK(kstack_object);
+ VM_OBJECT_WUNLOCK(obj);
kasan_mark((void *)ks, ptoa(pages), ptoa(pages), 0);
- kva_free(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
+ vm_thread_free_kstack_kva(ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
(pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
}
@@ -400,6 +520,28 @@
vm_thread_stack_dispose(ks, pages);
}
+/*
+ * Calculate kstack pindex.
+
+ * Uses a non-linear mapping if guard pages are
+ * active to avoid pindex holes in the kstack object.
+ */
+vm_pindex_t
+vm_kstack_pindex(vm_offset_t ks, int npages)
+{
+ vm_pindex_t pindex = atop(ks - VM_MIN_KERNEL_ADDRESS);
+
+ /* Return the linear pindex if guard pages aren't active or if we are
+ * allocating a non-standard kstack size. */
+ if (KSTACK_GUARD_PAGES == 0 || npages != kstack_pages) {
+ return (pindex);
+ }
+ KASSERT(pindex % (npages + KSTACK_GUARD_PAGES) != 0,
+ ("%s: Attempting to calculate kstack guard page pindex", __func__));
+
+ return (pindex - ((pindex / (npages + KSTACK_GUARD_PAGES)) + 1));
+}
+
/*
* Allocate physical pages, following the specified NUMA policy, to back a
* kernel stack.
@@ -410,23 +552,29 @@
{
vm_pindex_t pindex;
int n;
+ vm_object_t obj = vm_thread_kstack_size_to_obj(npages);
+ pindex = vm_kstack_pindex(ks, npages);
- pindex = atop(ks - VM_MIN_KERNEL_ADDRESS);
-
- VM_OBJECT_WLOCK(kstack_object);
+ VM_OBJECT_WLOCK(obj);
for (n = 0; n < npages;) {
if (vm_ndomains > 1)
- kstack_object->domain.dr_policy = ds;
+ obj->domain.dr_policy = ds;
/*
* Use WAITFAIL to force a reset of the domain selection policy
* if we had to sleep for pages.
*/
- n += vm_page_grab_pages(kstack_object, pindex + n,
- req_class | VM_ALLOC_WIRED | VM_ALLOC_WAITFAIL,
- &ma[n], npages - n);
+ n += vm_page_grab_pages(obj, pindex + n,
+ req_class | VM_ALLOC_WIRED | VM_ALLOC_WAITFAIL, &ma[n],
+ npages - n);
}
- VM_OBJECT_WUNLOCK(kstack_object);
+ VM_OBJECT_WUNLOCK(obj);
+}
+
+vm_object_t
+vm_thread_kstack_size_to_obj(int npages)
+{
+ return (npages == kstack_pages ? kstack_object : kstack_alt_object);
}
static int
@@ -463,6 +611,8 @@
static void
kstack_cache_init(void *null)
{
+ vm_size_t kstack_quantum;
+
kstack_object = vm_object_allocate(OBJT_SWAP,
atop(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS));
kstack_cache = uma_zcache_create("kstack_cache",
@@ -471,6 +621,30 @@
UMA_ZONE_FIRSTTOUCH);
kstack_cache_size = imax(128, mp_ncpus * 4);
uma_zone_set_maxcache(kstack_cache, kstack_cache_size);
+
+ kstack_alt_object = vm_object_allocate(OBJT_SWAP,
+ atop(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS));
+
+ kstack_quantum = KVA_KSTACK_QUANTUM;
+#ifdef __ILP32__
+ /* Adjust kstack quantum size. */
+ kstack_quantum -= kstack_quantum %
+ ((kstack_pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
+#else
+ /* The kstack_quantum is larger than KVA_QUANTUM to account
+ for holes induced by guard pages. */
+ kstack_quantum *= kstack_pages + KSTACK_GUARD_PAGES;
+#endif
+
+ /*
+ * Create the kstack_arena and set kernel_arena as parent.
+ */
+ kstack_arena = vmem_create("kstack arena", 0, 0, PAGE_SIZE, 0,
+ M_WAITOK);
+ KASSERT(kstack_arena != NULL,
+ ("%s: failed to create kstack_arena", __func__));
+ vmem_set_import(kstack_arena, vm_thread_kstack_arena_import,
+ vm_thread_kstack_arena_release, kernel_arena, kstack_quantum);
}
SYSINIT(vm_kstacks, SI_SUB_KMEM, SI_ORDER_ANY, kstack_cache_init, NULL);
diff --git a/sys/vm/vm_kern.h b/sys/vm/vm_kern.h
--- a/sys/vm/vm_kern.h
+++ b/sys/vm/vm_kern.h
@@ -80,6 +80,4 @@
extern u_long vm_kmem_size;
extern u_int exec_map_entries;
extern u_int exec_map_entry_size;
-extern vm_object_t kstack_object;
-
#endif /* _VM_VM_KERN_H_ */
diff --git a/sys/vm/vm_swapout.c b/sys/vm/vm_swapout.c
--- a/sys/vm/vm_swapout.c
+++ b/sys/vm/vm_swapout.c
@@ -534,22 +534,24 @@
vm_offset_t kaddr;
vm_pindex_t pindex;
int i, pages;
+ vm_object_t obj;
cpu_thread_swapout(td);
kaddr = td->td_kstack;
pages = td->td_kstack_pages;
- pindex = atop(kaddr - VM_MIN_KERNEL_ADDRESS);
+ obj = vm_thread_kstack_size_to_obj(pages);
+ pindex = vm_kstack_pindex(kaddr, pages);
pmap_qremove(kaddr, pages);
- VM_OBJECT_WLOCK(kstack_object);
+ VM_OBJECT_WLOCK(obj);
for (i = 0; i < pages; i++) {
- m = vm_page_lookup(kstack_object, pindex + i);
+ m = vm_page_lookup(obj, pindex + i);
if (m == NULL)
panic("vm_thread_swapout: kstack already missing?");
vm_page_dirty(m);
vm_page_xunbusy_unchecked(m);
vm_page_unwire(m, PQ_LAUNDRY);
}
- VM_OBJECT_WUNLOCK(kstack_object);
+ VM_OBJECT_WUNLOCK(obj);
}
/*
@@ -560,10 +562,12 @@
{
vm_page_t ma[KSTACK_MAX_PAGES];
vm_offset_t kaddr;
+ vm_object_t obj;
int a, count, i, j, pages, rv __diagused;
kaddr = td->td_kstack;
pages = td->td_kstack_pages;
+ obj = vm_thread_kstack_size_to_obj(pages);
vm_thread_stack_back(td->td_domain.dr_policy, kaddr, ma, pages,
oom_alloc);
for (i = 0; i < pages;) {
@@ -572,19 +576,19 @@
i++;
continue;
}
- vm_object_pip_add(kstack_object, 1);
+ vm_object_pip_add(obj, 1);
for (j = i + 1; j < pages; j++)
if (vm_page_all_valid(ma[j]))
break;
- VM_OBJECT_WLOCK(kstack_object);
- rv = vm_pager_has_page(kstack_object, ma[i]->pindex, NULL, &a);
- VM_OBJECT_WUNLOCK(kstack_object);
+ VM_OBJECT_WLOCK(obj);
+ rv = vm_pager_has_page(obj, ma[i]->pindex, NULL, &a);
+ VM_OBJECT_WUNLOCK(obj);
KASSERT(rv == 1, ("%s: missing page %p", __func__, ma[i]));
count = min(a + 1, j - i);
- rv = vm_pager_get_pages(kstack_object, ma + i, count, NULL, NULL);
+ rv = vm_pager_get_pages(obj, ma + i, count, NULL, NULL);
KASSERT(rv == VM_PAGER_OK, ("%s: cannot get kstack for proc %d",
__func__, td->td_proc->p_pid));
- vm_object_pip_wakeup(kstack_object);
+ vm_object_pip_wakeup(obj);
i += count;
}
pmap_qenter(kaddr, ma, pages);

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