linux/include/asm-frv
Nick Piggin 7e675137a8 mm: introduce pte_special pte bit
s390 for one, cannot implement VM_MIXEDMAP with pfn_valid, due to their memory
model (which is more dynamic than most).  Instead, they had proposed to
implement it with an additional path through vm_normal_page(), using a bit in
the pte to determine whether or not the page should be refcounted:

vm_normal_page()
{
	...
        if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
                if (vma->vm_flags & VM_MIXEDMAP) {
#ifdef s390
			if (!mixedmap_refcount_pte(pte))
				return NULL;
#else
                        if (!pfn_valid(pfn))
                                return NULL;
#endif
                        goto out;
                }
	...
}

This is fine, however if we are allowed to use a bit in the pte to determine
refcountedness, we can use that to _completely_ replace all the vma based
schemes.  So instead of adding more cases to the already complex vma-based
scheme, we can have a clearly seperate and simple pte-based scheme (and get
slightly better code generation in the process):

vm_normal_page()
{
#ifdef s390
	if (!mixedmap_refcount_pte(pte))
		return NULL;
	return pte_page(pte);
#else
	...
#endif
}

And finally, we may rather make this concept usable by any architecture rather
than making it s390 only, so implement a new type of pte state for this.
Unfortunately the old vma based code must stay, because some architectures may
not be able to spare pte bits.  This makes vm_normal_page a little bit more
ugly than we would like, but the 2 cases are clearly seperate.

So introduce a pte_special pte state, and use it in mm/memory.c.  It is
currently a noop for all architectures, so this doesn't actually result in any
compiled code changes to mm/memory.o.

BTW:
I haven't put vm_normal_page() into arch code as-per an earlier suggestion.
The reason is that, regardless of where vm_normal_page is actually
implemented, the *abstraction* is still exactly the same. Also, while it
depends on whether the architecture has pte_special or not, that is the
only two possible cases, and it really isn't an arch specific function --
the role of the arch code should be to provide primitive functions and
accessors with which to build the core code; pte_special does that. We do
not want architectures to know or care about vm_normal_page itself, and
we definitely don't want them being able to invent something new there
out of sight of mm/ code. If we made vm_normal_page an arch function, then
we have to make vm_insert_mixed (next patch) an arch function too. So I
don't think moving it to arch code fundamentally improves any abstractions,
while it does practically make the code more difficult to follow, for both
mm and arch developers, and easier to misuse.

[akpm@linux-foundation.org: build fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Carsten Otte <cotte@de.ibm.com>
Cc: Jared Hulbert <jaredeh@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-28 08:58:23 -07:00
..
Kbuild Unexport asm/page.h 2008-02-07 08:42:30 -08:00
atomic.h Fix FRV cmpxchg_local 2008-02-08 15:33:32 -08:00
auxvec.h [PATCH] auxiliary vector cleanups 2005-09-07 16:57:21 -07:00
ax88796.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
bitops.h Fix FRV cmpxchg_local 2008-02-08 15:33:32 -08:00
bug.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
bugs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
busctl-regs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
byteorder.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cache.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
cacheflush.h include/asm-frv/: Spelling fixes 2008-02-03 17:34:55 +02:00
checksum.h [NET]: FRV checksum annotations. 2006-12-02 21:23:03 -08:00
cpu-irqs.h [PATCH] FRV: Use the generic IRQ stuff 2006-09-26 08:48:53 -07:00
cpumask.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cputime.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
current.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
delay.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
device.h Driver core: add dev_archdata to struct device 2006-12-01 14:52:01 -08:00
div64.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dm9000.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dma-mapping.h FRV: move DMA macros to scatterlist.h for consistency. 2008-02-05 09:44:20 -08:00
dma.h IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
elf.h Cleanup asm/{elf,page,user}.h: #ifdef __KERNEL__ is no longer needed 2008-02-07 08:42:30 -08:00
emergency-restart.h [PATCH] Add emergency_restart() 2005-07-26 14:35:41 -07:00
errno.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fb.h fbdev: detect primary display device 2007-07-17 10:23:11 -07:00
fcntl.h [PATCH] Clean up struct flock64 definitions 2005-09-07 16:57:38 -07:00
fpu.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
futex.h [PATCH] lightweight robust futexes updates 2006-03-27 08:44:49 -08:00
gdb-stub.h [PATCH] FRV: Introduce asm-offsets for FRV arch 2006-07-10 13:24:22 -07:00
gpio-regs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
hardirq.h [PATCH] FRV: Use the generic IRQ stuff 2006-09-26 08:48:53 -07:00
highmem.h move frv docs one level up 2008-02-03 15:54:28 +02:00
hw_irq.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ide.h ide: remove stale ide.h "configuration options" 2008-01-25 22:17:08 +01:00
init.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
io.h [PATCH] Consolidate check_signature 2006-10-11 11:14:23 -07:00
ioctl.h [PATCH] Generic ioctl.h 2006-01-10 08:01:34 -08:00
ioctls.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ipcbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
irc-regs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
irq.h frv: Remove bogus NO_IRQ = -1 define 2007-11-09 15:11:44 -08:00
irq_regs.h IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 2006-10-05 15:10:12 +01:00
kdebug.h move die notifier handling to common code 2007-05-08 11:15:04 -07:00
kmap_types.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
kvm.h kvm: provide kvm.h for all architecture: fixes headers_install 2008-04-02 15:28:18 -07:00
linkage.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
local.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
math-emu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mb-regs.h [PATCH] frv: basic __iomem annotations 2006-06-23 07:42:54 -07:00
mb86943a.h FRV: Enable the MB86943 PCI arbiter correctly 2007-08-01 20:48:17 -07:00
mb93091-fpga-irqs.h [PATCH] FRV: Use the generic IRQ stuff 2006-09-26 08:48:53 -07:00
mb93093-fpga-irqs.h [PATCH] FRV: Use the generic IRQ stuff 2006-09-26 08:48:53 -07:00
mb93493-irqs.h [PATCH] FRV: Use the generic IRQ stuff 2006-09-26 08:48:53 -07:00
mb93493-regs.h [PATCH] FRV: Use the generic IRQ stuff 2006-09-26 08:48:53 -07:00
mc146818rtc.h [PATCH] frv: miscellaneous changes 2006-01-08 20:13:38 -08:00
mem-layout.h FRV: Move STACK_TOP_MAX up [try #2] 2008-04-10 13:41:28 -07:00
mman.h [PATCH] add asm-generic/mman.h 2006-02-15 15:32:22 -08:00
mmu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mmu_context.h [PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction 2007-05-02 19:27:14 +02:00
module.h [PATCH] frv: add module support stubs 2006-01-08 20:13:37 -08:00
msgbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mutex.h [PATCH] mutex subsystem, add default include/asm-*/mutex.h files 2006-01-09 15:59:19 -08:00
namei.h fix file specification in comments 2006-10-03 23:01:26 +02:00
page.h CONFIG_HIGHPTE vs. sub-page page tables. 2008-02-08 09:22:42 -08:00
param.h avoid overflows in kernel/time.c 2008-02-08 09:22:39 -08:00
pci.h PCI: remove pci_dac_dma_... APIs 2007-07-11 16:02:11 -07:00
percpu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pgalloc.h CONFIG_HIGHPTE vs. sub-page page tables. 2008-02-08 09:22:42 -08:00
pgtable.h mm: introduce pte_special pte bit 2008-04-28 08:58:23 -07:00
poll.h Consolidate asm/poll.h 2007-05-11 08:29:34 -07:00
posix_types.h asm-*/posix_types.h: scrub __GLIBC__ 2008-02-08 09:22:34 -08:00
processor.h [PATCH] Make cpu_relax() imply barrier() on all arches 2006-07-12 12:56:45 -07:00
ptrace.h [PATCH] fix frv headers_check 2007-02-01 16:17:05 -08:00
registers.h [PATCH] FRV: Introduce asm-offsets for FRV arch 2006-07-10 13:24:22 -07:00
resource.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
scatterlist.h FRV: move DMA macros to scatterlist.h for consistency. 2008-02-05 09:44:20 -08:00
sections.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
segment.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
semaphore.h Generic semaphore implementation 2008-04-17 10:42:34 -04:00
sembuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
serial-regs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
serial.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
setup.h [PATCH] cleanup asm/setup.h userspace visibility 2006-12-07 08:39:46 -08:00
shmbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
shmparam.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigcontext.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
siginfo.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
signal.h [PATCH] irq-flags: FRV: Use the new IRQF_ constants 2006-07-02 13:58:46 -07:00
smp.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
socket.h [NET]: Introducing socket mark socket option. 2008-01-31 19:27:19 -08:00
sockios.h [NET]: Introduce SIOCGSTAMPNS ioctl to get timestamps with nanosec resolution 2007-04-25 22:24:04 -07:00
spinlock.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
spr-regs.h FRV: Add support for emulation of userspace atomic ops [try #2] 2008-04-10 13:41:29 -07:00
stat.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
statfs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
string.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
suspend.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
system.h frv: remove HARD_RESET_NOW() 2008-04-21 16:03:13 -07:00
termbits.h lots-of-architectures: enable arbitary speed tty support 2007-07-10 17:51:13 -07:00
termios.h [PATCH] consolidate line discipline number definitions 2007-02-11 10:51:26 -08:00
thread_info.h include/asm-frv/thread_info.h: kmalloc + memset conversion to kzalloc 2007-10-16 09:43:03 -07:00
timer-regs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
timex.h [PATCH] ntp: cleanup defines and comments 2006-10-01 00:39:27 -07:00
tlb.h FRV: Replace pgd management via slabs through quicklists 2007-05-09 12:30:46 -07:00
tlbflush.h remove unused flush_tlb_pgtables 2007-10-19 11:53:34 -07:00
topology.h asm-generic: add node_to_cpumask_ptr macro 2008-04-19 19:44:58 +02:00
types.h remove strict ansi check from __u64 in asm/types.h 2007-10-17 08:42:53 -07:00
uaccess.h frv: missing __clear_user() 2007-07-15 16:40:52 -07:00
ucontext.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unaligned.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
unistd.h FRV: Change the timerfd syscalls to be the same as i386 2008-02-20 19:58:16 -08:00
user.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vga.h [PATCH] frv: miscellaneous changes 2006-01-08 20:13:38 -08:00
virtconvert.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
xor.h [PATCH] frv: miscellaneous changes 2006-01-08 20:13:38 -08:00