linux/include/asm-m32r
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
..
m32104ut [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
m32700ut m32r: remove dead config symbols from M32R code 2008-02-05 09:44:08 -08:00
mappi2 [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
mappi3 [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
opsput [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
a.out.h aout: move STACK_TOP[_MAX] to asm/processor.h 2008-02-08 09:22:29 -08:00
addrspace.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
assembler.h m32r: Rename STI/CLI macros 2007-09-06 11:10:56 +09:00
atomic.h atomic.h: atomic_add_unless as inline. Remove system.h atomic.h circular dependency 2007-05-08 11:15:20 -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
bug.h
bugs.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
byteorder.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
cache.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
cachectl.h
cacheflush.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
checksum.h [NET]: M32R checksum annotations and cleanups. 2006-12-02 21:23:06 -08:00
cputime.h
current.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
delay.h Fix __const_udelay declaration and definition mismatches 2008-02-06 10:41:06 -08:00
device.h Driver core: add dev_archdata to struct device 2006-12-01 14:52:01 -08:00
div64.h
dma.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
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
errno.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
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
flat.h Binfmt_flat: Add minimum support for the Blackfin relocations 2007-10-03 23:41:43 +08:00
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
hw_irq.h [PATCH] genirq: add ->retrigger() irq op to consolidate hw_irq_resend() 2006-06-29 10:26:23 -07:00
ide.h ide: remove ide_init_default_irq() macro 2008-04-18 00:46:35 +02:00
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 m32r: enable arbitary speed tty rate setting 2007-07-16 09:05:38 -07:00
ipcbuf.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
irq_regs.h [PATCH] m32r pt_regs fixes 2006-10-07 10:51:15 -07:00
irq.h m32r: remove dead config symbols from M32R code 2008-02-05 09:44:08 -08:00
Kbuild Add empty Kbuild files for 'make headers_install' in remaining arches. 2006-06-18 12:58:53 +01:00
kdebug.h move die notifier handling to common code 2007-05-08 11:15:04 -07:00
kmap_types.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
kvm.h kvm: provide kvm.h for all architecture: fixes headers_install 2008-04-02 15:28:18 -07:00
linkage.h
local.h local_t m32r use architecture specific cmpxchg_local 2008-02-07 08:42:32 -08:00
m32r_mp_fpga.h
m32r.h m32r: Define symbols to unify platform-dependent ICU checks 2007-09-03 11:30:18 +09:00
m32102.h [PATCH] m32r: support a synthesizable M32700 core 2006-12-08 08:28:37 -08:00
mc146818rtc.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
mman.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
mmu_context.h [PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction 2007-05-02 19:27:14 +02:00
mmu.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
mmzone.h [PATCH] unify pfn_to_page: m32r pfn_to_page 2006-03-27 08:44:45 -08:00
module.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
msgbuf.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
mutex.h [PATCH] mutex subsystem, add default include/asm-*/mutex.h files 2006-01-09 15:59:19 -08:00
namei.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
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 [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
percpu.h
pgalloc.h CONFIG_HIGHPTE vs. sub-page page tables. 2008-02-08 09:22:42 -08:00
pgtable-2level.h m32r: fix pte_to_pgoff(), pgoff_to_pte() and __swp_type() macros 2007-05-11 08:29:33 -07:00
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 aout: move STACK_TOP[_MAX] to asm/processor.h 2008-02-08 09:22:29 -08:00
ptrace.h m32r: convert to generic sys_ptrace 2007-10-16 09:43:04 -07:00
resource.h
rtc.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
s1d13806.h
scatterlist.h Add CONFIG_DEBUG_SG sg validation 2007-10-22 21:20:03 +02:00
sections.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
segment.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
semaphore.h Generic semaphore implementation 2008-04-17 10:42:34 -04:00
sembuf.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
serial.h Don't include linux/config.h from anywhere else in include/ 2006-04-26 12:56:16 +01:00
setup.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
shmbuf.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
shmparam.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
sigcontext.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
siginfo.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
signal.h core: remove last users of empty FASTCALL macro 2008-01-30 13:31:17 +01:00
smp.h Remove hardcoding of hard_smp_processor_id on UP systems 2007-05-09 12:30:48 -07:00
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_types.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
spinlock.h [PATCH] Directed yield: cpu_relax variants for spinlocks and rw-locks 2006-10-01 00:39:21 -07:00
stat.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
statfs.h
string.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
syscall.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
system.h Fix m32r __xchg 2008-02-07 08:42:32 -08:00
termbits.h m32r: enable arbitary speed tty rate setting 2007-07-16 09:05:38 -07:00
termios.h m32r: enable arbitary speed tty rate setting 2007-07-16 09:05:38 -07:00
thread_info.h m32r: Update sys_rt_sigsuspend 2007-11-28 01:24:04 +09:00
timex.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
tlb.h
tlbflush.h remove unused flush_tlb_pgtables 2007-10-19 11:53:34 -07:00
topology.h
types.h remove strict ansi check from __u64 in asm/types.h 2007-10-17 08:42:53 -07:00
uaccess.h [PATCH] fix sparse warnings from {asm,net}/checksum.h 2007-02-11 10:51:31 -08:00
ucontext.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
unaligned.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
unistd.h timerfd: fix remaining architectures 2008-02-05 14:37:15 -08:00
user.h Sanitize the type of struct user.u_ar0 2008-02-07 08:42:30 -08:00
vga.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00
xor.h [PATCH] m32r: cosmetic updates and trivial fixes 2007-02-11 10:51:20 -08:00