linux.git/arch/powerpc/kernel/vdso.c, branch v2.6.26

Reinstate ZERO_PAGE optimization in 'get_user_pages()' and fix XIP

2008-06-20T18:18:25+00:00

KAMEZAWA Hiroyuki and Oleg Nesterov point out that since the commit
557ed1fa2620dc119adb86b34c614e152a629a80 ("remove ZERO_PAGE") removed
the ZERO_PAGE from the VM mappings, any users of get_user_pages() will
generally now populate the VM with real empty pages needlessly.

We used to get the ZERO_PAGE when we did the "handle_mm_fault()", but
since fault handling no longer uses ZERO_PAGE for new anonymous pages,
we now need to handle that special case in follow_page() instead.

In particular, the removal of ZERO_PAGE effectively removed the core
file writing optimization where we would skip writing pages that had not
been populated at all, and increased memory pressure a lot by allocating
all those useless newly zeroed pages.

This reinstates the optimization by making the unmapped PTE case the
same as for a non-existent page table, which already did this correctly.

While at it, this also fixes the XIP case for follow_page(), where the
caller could not differentiate between the case of a page that simply
could not be used (because it had no "struct page" associated with it)
and a page that just wasn't mapped.

We do that by simply returning an error pointer for pages that could not
be turned into a "struct page *".  The error is arbitrarily picked to be
EFAULT, since that was what get_user_pages() already used for the
equivalent IO-mapped page case.

[ Also removed an impossible test for pte_offset_map_lock() failing:
  that's not how that function works ]

Acked-by: Oleg Nesterov 
Acked-by: Nick Piggin 
Cc: KAMEZAWA Hiroyuki 
Cc: Hugh Dickins 
Cc: Andrew Morton 
Cc: Ingo Molnar 
Cc: Roland McGrath 
Signed-off-by: Linus Torvalds

Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/lmb-2.6

2008-02-26T10:08:45+00:00

[POWERPC] vdso_do_func_patch{32,64}() must be __init

2008-02-14T11:11:02+00:00

This fixes the following section mismatches:

<--  snip  -->

...
WARNING: vmlinux.o(.text+0xe49c): Section mismatch in reference from the function .vdso_do_func_patch64() to the function .init.text:.find_symbol64()
WARNING: vmlinux.o(.text+0xe4d0): Section mismatch in reference from the function .vdso_do_func_patch64() to the function .init.text:.find_symbol64()
WARNING: vmlinux.o(.text+0xe56c): Section mismatch in reference from the function .vdso_do_func_patch32() to the function .init.text:.find_symbol32()
WARNING: vmlinux.o(.text+0xe5a0): Section mismatch in reference from the function .vdso_do_func_patch32() to the function .init.text:.find_symbol32()
...

<--  snip  -->

Signed-off-by: Adrian Bunk 
Signed-off-by: Paul Mackerras

[LIB]: Make PowerPC LMB code generic so sparc64 can use it too.

2008-02-14T00:56:49+00:00

Signed-off-by: David S. Miller

[POWERPC] vdso: Fixes for cache block sizes

2007-11-20T02:56:31+00:00

The current VDSO implementation is hardcoded to 128 byte cache blocks,
which are only used on IBM's 64-bit processors.

Convert it to get the cache block sizes out of vdso_data instead,
similar to how the ppc64 in-kernel cache flush does it.

Signed-off-by: Olof Johansson 
Signed-off-by: Paul Mackerras

[POWERPC] Disable vDSO support for ARCH=ppc where it's not implemented

2007-10-11T10:25:25+00:00

Signed-off-by: Wolfgang Denk 
Signed-off-by: Paul Mackerras

[POWERPC] Don't expose clock vDSO functions when CPU has no timebase

2007-09-19T05:26:34+00:00

We forgot to remove the clock_gettime, clock_getres and get_tbfreq vDSO
calls on CPUs that have no timebase such as 601 or 403 (old CPUs that have
different mechanisms and for which the vDSO code will not work properly).
This fixes it.

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Paul Mackerras

[POWERPC] Fix VDSO compile warning

2007-06-14T12:29:55+00:00

Maybe the type should have been char[] instead of __u8[]
in the first place, but this will do.

Signed-off-by: Segher Boessenkool 
Signed-off-by: Paul Mackerras

header cleaning: don't include smp_lock.h when not used

2007-05-08T18:15:07+00:00

Remove includes of  where it is not used/needed.
Suggested by Al Viro.

Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc,
sparc64, and arm (all 59 defconfigs).

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[POWERPC] Fix vDSO page count calculation

2007-02-13T04:35:52+00:00

The recent vDSO consolidation patches broke powerpc due to a mistake
in the definition of MAXPAGES constants. This fixes it by moving to
a dynamically allocated array of pages instead as I don't like much
hard coded size limits. Also move the vdso initialisation to an initcall
since it doesn't really need to be done -that- early.

Applogies for not catching the breakage earlier, Roland _did_ CC me on
his patches a while ago, I got busy with other things and forgot to test
them.

Signed-off-by: Benjamin Herrenschmidt 
Signed-off-by: Paul Mackerras