linux-sg2042/include/asm-um
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
..
a.out-core.h aout: suppress A.OUT library support if !CONFIG_ARCH_SUPPORTS_AOUT 2008-02-08 09:22:30 -08:00
a.out.h aout: move STACK_TOP[_MAX] to asm/processor.h 2008-02-08 09:22:29 -08:00
alternative-asm.h x86: rename .i assembler includes to .h 2007-10-17 20:16:29 +02:00
alternative.h [PATCH] x86: SMP alternatives 2006-03-23 07:38:04 -08:00
apic.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
archparam-i386.h [PATCH] uml: s390 preparation, elf.h 2005-05-05 16:36:37 -07:00
archparam-ppc.h [PATCH] uml: remove some leftover PPC code 2006-10-20 10:26:36 -07:00
archparam-x86_64.h [PATCH] uml: s390 preparation, elf.h 2005-05-05 16:36:37 -07:00
asm.h uml: add asm-um/asm.h 2008-01-30 13:31:17 +01:00
atomic.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
auxvec.h [PATCH] auxiliary vector cleanups 2005-09-07 16:57:21 -07:00
bitops.h forbid asm/bitops.h direct inclusion 2007-10-19 11:53:41 -07:00
boot.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
bug.h uml: use generic BUG 2007-06-24 08:59:11 -07:00
bugs.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 Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
calling.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
checksum.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cmpxchg.h x86: create asm/cmpxchg.h 2007-05-08 11:15:20 -07:00
cobalt.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
common.lds.S uml: fix linker script alignment bugs 2007-08-31 01:42:22 -07:00
cpufeature.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 uml: current.h cleanup 2008-02-05 09:44:28 -08:00
delay.h [PATCH] uml: fix unreasonably long udelay 2007-04-02 10:06:08 -07:00
desc.h [PATCH] uml: implement {get,set}_thread_area for i386 2006-03-31 12:18:52 -08:00
device.h Driver core: add dev_archdata to struct device 2006-12-01 14:52:01 -08:00
div64.h [NET]: div64_64 consolidate (rev3) 2007-04-25 22:23:33 -07:00
dma-mapping.h [PATCH] Pass struct dev pointer to dma_cache_sync() 2006-12-07 08:39:41 -08:00
dma.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dwarf2.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
elf-i386.h uml: style cleanup 2008-02-05 09:44:28 -08:00
elf-ppc.h [PATCH] uml: fix apparent "CONFIG_64_BIT" typo. 2007-02-11 10:51:23 -08:00
elf-x86_64.h uml: header untangling 2008-02-05 09:44:28 -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
fcntl.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fixmap.h uml: runtime host VMSPLIT detection 2008-02-08 09:22:42 -08:00
floppy.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
frame.h x86: rename .i assembler includes to .h 2007-10-17 20:16:29 +02:00
futex.h [PATCH] consolidate asm/futex.h 2006-01-08 20:13:39 -08:00
hardirq.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
highmem.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
host_ldt-i386.h [PATCH] uml: split ldt.h in arch-independent and arch-dependant code 2006-03-31 12:18:51 -08:00
host_ldt-x86_64.h [PATCH] uml: split ldt.h in arch-independent and arch-dependant code 2006-03-31 12:18:51 -08:00
hw_irq.h [PATCH] genirq: add ->retrigger() irq op to consolidate hw_irq_resend() 2006-06-29 10:26:23 -07:00
ide.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
io.h [PATCH] uml: add __raw_writeq definition 2006-06-30 11:25:38 -07:00
ioctl.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
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
irq.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
irq_regs.h [PATCH] um: irq changes break build 2006-10-06 08:53:42 -07:00
irq_vectors.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
irqflags.h [PATCH] uml: add asm/irqflags.h 2006-06-05 12:29:17 -07:00
kdebug.h move die notifier handling to common code 2007-05-08 11:15:04 -07:00
keyboard.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
kmap_types.h [PATCH] uml: make copy_*_user atomic 2006-07-01 09:56:03 -07:00
kvm.h kvm: provide kvm.h for all architecture: fixes headers_install 2008-04-02 15:28:18 -07:00
ldt.h uml: LDT mutex conversion 2008-02-05 09:44:31 -08:00
linkage.h uml: get rid of asmlinkage 2008-02-05 09:44:25 -08:00
local.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
locks.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mca_dma.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mman.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mmu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mmu_context.h uml: cover stubs with a VMA 2008-02-05 09:44:29 -08:00
module-generic.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
module-i386.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
module-x86_64.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
msgbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mtrr.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 Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
nops.h git-x86: unbreak UML 2008-01-30 13:32:38 +01:00
page.h CONFIG_HIGHPTE vs. sub-page page tables. 2008-02-08 09:22:42 -08:00
page_offset.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
param.h uml: add back CONFIG_HZ 2008-02-05 09:44:31 -08:00
paravirt.h uml: add asm/paravirt.h 2007-06-24 08:59:11 -07:00
pci.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pda.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -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-2level.h uml: 64-bit tlb fixes 2008-02-05 09:44:29 -08:00
pgtable-3level.h uml: 64-bit tlb fixes 2008-02-05 09:44:29 -08:00
pgtable.h mm: introduce pte_special pte bit 2008-04-28 08:58:23 -07:00
poll.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
posix_types.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
prctl.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
processor-generic.h uml: runtime host VMSPLIT detection 2008-02-08 09:22:42 -08:00
processor-i386.h uml: remove xmm checking on x86 2008-02-05 09:44:24 -08:00
processor-ppc.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
processor-x86_64.h uml: x86_64 should copy %fs during fork 2008-02-08 09:22:43 -08:00
ptrace-generic.h uml: ptrace floating point fixes 2007-10-16 09:43:07 -07:00
ptrace-i386.h uml: ptrace floating point fixes 2007-10-16 09:43:07 -07:00
ptrace-x86_64.h uml: remove code made redundant by CHOOSE_MODE removal 2007-10-16 09:43:05 -07:00
required-features.h uml: fix build breakage 2007-05-09 12:30:48 -07:00
resource.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
rwlock.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
rwsem.h [PATCH] remove gcc-2 checks 2006-01-08 20:14:02 -08:00
scatterlist.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sections.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
segment.h [PATCH] uml: check for differences in host support 2006-03-31 12:18:52 -08:00
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.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
setup.h [PATCH] uml: command line handling cleanup 2005-05-06 22:09:29 -07:00
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-generic.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigcontext-i386.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigcontext-ppc.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigcontext-x86_64.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 Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
smp.h uml: fix inlines 2007-10-16 09:43:06 -07:00
socket.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sockios.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
spinlock.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
spinlock_types.h [PATCH] uml spinlock breakage 2005-09-10 16:50:01 -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-generic.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
system-i386.h [PATCH] uml: UML/i386 cmpxchg fix 2005-09-17 11:50:01 -07:00
system-ppc.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
system-x86_64.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
termbits.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
termios.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
thread_info.h uml: current.h cleanup 2008-02-05 09:44:28 -08:00
timex.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
tlb.h uml: compile error fix 2008-04-15 19:35:40 -07:00
tlbflush.h remove unused flush_tlb_pgtables 2007-10-19 11:53:34 -07:00
topology.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
types.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
uaccess.h uml: header untangling 2008-02-05 09:44:28 -08:00
ucontext.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unaligned.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unistd.h x86 merge fallout: uml 2007-10-29 07:41:32 -07:00
user.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vga.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vm-flags-i386.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vm-flags-x86_64.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vm86.h [PATCH] uml: vm86 compile fix 2005-07-28 21:46:03 -07:00
xor.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00