svn commit: r238998 - head/sys/vm
Alan Cox
alc at rice.edu
Fri Aug 3 02:04:16 UTC 2012
On 08/02/2012 20:48, Alan Cox wrote:
> Author: alc
> Date: Fri Aug 3 01:48:15 2012
> New Revision: 238998
> URL: http://svn.freebsd.org/changeset/base/238998
>
> Log:
> Inline vm_page_aflags_clear() and vm_page_aflags_set().
>
> Add comments stating that neither these functions nor the flags that they
> are used to manipulate are part of the KBI.
This should have also included:
Reviewed by: kib
> Modified:
> head/sys/vm/vm_page.c
> head/sys/vm/vm_page.h
>
> Modified: head/sys/vm/vm_page.c
> ==============================================================================
> --- head/sys/vm/vm_page.c Fri Aug 3 00:11:13 2012 (r238997)
> +++ head/sys/vm/vm_page.c Fri Aug 3 01:48:15 2012 (r238998)
> @@ -450,63 +450,6 @@ vm_page_startup(vm_offset_t vaddr)
> return (vaddr);
> }
>
> -
> -CTASSERT(offsetof(struct vm_page, aflags) % sizeof(uint32_t) == 0);
> -
> -void
> -vm_page_aflag_set(vm_page_t m, uint8_t bits)
> -{
> - uint32_t *addr, val;
> -
> - /*
> - * The PGA_WRITEABLE flag can only be set if the page is managed and
> - * VPO_BUSY. Currently, this flag is only set by pmap_enter().
> - */
> - KASSERT((bits& PGA_WRITEABLE) == 0 ||
> - (m->oflags& (VPO_UNMANAGED | VPO_BUSY)) == VPO_BUSY,
> - ("PGA_WRITEABLE and !VPO_BUSY"));
> -
> - /*
> - * We want to use atomic updates for m->aflags, which is a
> - * byte wide. Not all architectures provide atomic operations
> - * on the single-byte destination. Punt and access the whole
> - * 4-byte word with an atomic update. Parallel non-atomic
> - * updates to the fields included in the update by proximity
> - * are handled properly by atomics.
> - */
> - addr = (void *)&m->aflags;
> - MPASS(((uintptr_t)addr& (sizeof(uint32_t) - 1)) == 0);
> - val = bits;
> -#if BYTE_ORDER == BIG_ENDIAN
> - val<<= 24;
> -#endif
> - atomic_set_32(addr, val);
> -}
> -
> -void
> -vm_page_aflag_clear(vm_page_t m, uint8_t bits)
> -{
> - uint32_t *addr, val;
> -
> - /*
> - * The PGA_REFERENCED flag can only be cleared if the object
> - * containing the page is locked.
> - */
> - KASSERT((bits& PGA_REFERENCED) == 0 || VM_OBJECT_LOCKED(m->object),
> - ("PGA_REFERENCED and !VM_OBJECT_LOCKED"));
> -
> - /*
> - * See the comment in vm_page_aflag_set().
> - */
> - addr = (void *)&m->aflags;
> - MPASS(((uintptr_t)addr& (sizeof(uint32_t) - 1)) == 0);
> - val = bits;
> -#if BYTE_ORDER == BIG_ENDIAN
> - val<<= 24;
> -#endif
> - atomic_clear_32(addr, val);
> -}
> -
> void
> vm_page_reference(vm_page_t m)
> {
>
> Modified: head/sys/vm/vm_page.h
> ==============================================================================
> --- head/sys/vm/vm_page.h Fri Aug 3 00:11:13 2012 (r238997)
> +++ head/sys/vm/vm_page.h Fri Aug 3 01:48:15 2012 (r238998)
> @@ -239,13 +239,14 @@ extern struct vpglocks pa_lock[];
> #define vm_page_queue_free_mtx vm_page_queue_free_lock.data
>
> /*
> - * These are the flags defined for vm_page.
> - *
> - * aflags are updated by atomic accesses. Use the vm_page_aflag_set()
> - * and vm_page_aflag_clear() functions to set and clear the flags.
> + * The vm_page's aflags are updated using atomic operations. To set or clear
> + * these flags, the functions vm_page_aflag_set() and vm_page_aflag_clear()
> + * must be used. Neither these flags nor these functions are part of the KBI.
> *
> * PGA_REFERENCED may be cleared only if the object containing the page is
> - * locked. It is set by both the MI and MD VM layers.
> + * locked. It is set by both the MI and MD VM layers. However, kernel
> + * loadable modules should not directly set this flag. They should call
> + * vm_page_reference() instead.
> *
> * PGA_WRITEABLE is set exclusively on managed pages by pmap_enter(). When it
> * does so, the page must be VPO_BUSY. The MI VM layer must never access this
> @@ -281,8 +282,12 @@ extern struct vpglocks pa_lock[];
>
> #ifdef _KERNEL
>
> +#include<sys/systm.h>
> +
> #include<vm/vm_param.h>
>
> +#include<machine/atomic.h>
> +
> /*
> * Each pageable resident page falls into one of five lists:
> *
> @@ -349,8 +354,6 @@ extern struct vpglocks vm_page_queue_loc
> #define VM_ALLOC_COUNT_SHIFT 16
> #define VM_ALLOC_COUNT(count) ((count)<< VM_ALLOC_COUNT_SHIFT)
>
> -void vm_page_aflag_set(vm_page_t m, uint8_t bits);
> -void vm_page_aflag_clear(vm_page_t m, uint8_t bits);
> void vm_page_busy(vm_page_t m);
> void vm_page_flash(vm_page_t m);
> void vm_page_io_start(vm_page_t m);
> @@ -428,6 +431,75 @@ void vm_page_object_lock_assert(vm_page_
> #endif
>
> /*
> + * We want to use atomic updates for the aflags field, which is 8 bits wide.
> + * However, not all architectures support atomic operations on 8-bit
> + * destinations. In order that we can easily use a 32-bit operation, we
> + * require that the aflags field be 32-bit aligned.
> + */
> +CTASSERT(offsetof(struct vm_page, aflags) % sizeof(uint32_t) == 0);
> +
> +/*
> + * Clear the given bits in the specified page.
> + */
> +static inline void
> +vm_page_aflag_clear(vm_page_t m, uint8_t bits)
> +{
> + uint32_t *addr, val;
> +
> + /*
> + * The PGA_REFERENCED flag can only be cleared if the object
> + * containing the page is locked.
> + */
> + if ((bits& PGA_REFERENCED) != 0)
> + VM_PAGE_OBJECT_LOCK_ASSERT(m);
> +
> + /*
> + * Access the whole 32-bit word containing the aflags field with an
> + * atomic update. Parallel non-atomic updates to the other fields
> + * within this word are handled properly by the atomic update.
> + */
> + addr = (void *)&m->aflags;
> + KASSERT(((uintptr_t)addr& (sizeof(uint32_t) - 1)) == 0,
> + ("vm_page_aflag_clear: aflags is misaligned"));
> + val = bits;
> +#if BYTE_ORDER == BIG_ENDIAN
> + val<<= 24;
> +#endif
> + atomic_clear_32(addr, val);
> +}
> +
> +/*
> + * Set the given bits in the specified page.
> + */
> +static inline void
> +vm_page_aflag_set(vm_page_t m, uint8_t bits)
> +{
> + uint32_t *addr, val;
> +
> + /*
> + * The PGA_WRITEABLE flag can only be set if the page is managed and
> + * VPO_BUSY. Currently, this flag is only set by pmap_enter().
> + */
> + KASSERT((bits& PGA_WRITEABLE) == 0 ||
> + (m->oflags& (VPO_UNMANAGED | VPO_BUSY)) == VPO_BUSY,
> + ("vm_page_aflag_set: PGA_WRITEABLE and !VPO_BUSY"));
> +
> + /*
> + * Access the whole 32-bit word containing the aflags field with an
> + * atomic update. Parallel non-atomic updates to the other fields
> + * within this word are handled properly by the atomic update.
> + */
> + addr = (void *)&m->aflags;
> + KASSERT(((uintptr_t)addr& (sizeof(uint32_t) - 1)) == 0,
> + ("vm_page_aflag_set: aflags is misaligned"));
> + val = bits;
> +#if BYTE_ORDER == BIG_ENDIAN
> + val<<= 24;
> +#endif
> + atomic_set_32(addr, val);
> +}
> +
> +/*
> * vm_page_dirty:
> *
> * Set all bits in the page's dirty field.
>
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