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  1. 07 Jan, 2010 3 commits
  3. 30 Dec, 2009 3 commits
    • Jan Beulich's avatar
      x86-64: Modify memcpy()/memset() alternatives mechanism · 7269e881
      Jan Beulich authored 
      In order to avoid unnecessary chains of branches, rather than
implementing memcpy()/memset()'s access to their alternative
implementations via a jump, patch the (larger) original function
directly.

The memcpy() part of this is slightly subtle: while alternative
instruction patching does itself use memcpy(), with the
replacement block being less than 64-bytes in size the main loop
of the original function doesn't get used for copying memcpy_c()
over memcpy(), and hence we can safely write over its beginning.

Also note that the CFI annotations are fine for both variants of
each of the functions.
Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4B2BB8D30200007800026AF2@vpn.id2.novell.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      7269e881
    • Jan Beulich's avatar
      x86-64: Modify copy_user_generic() alternatives mechanism · 1b1d9258
      Jan Beulich authored 
      In order to avoid unnecessary chains of branches, rather than
implementing copy_user_generic() as a function consisting of
just a single (possibly patched) branch, instead properly deal
with patching call instructions in the alternative instructions
framework, and move the patching into the callers.

As a follow-on, one could also introduce something like
__EXPORT_SYMBOL_ALT() to avoid patching call sites in modules.
Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4B2BB8180200007800026AE7@vpn.id2.novell.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      1b1d9258
    • Jan Beulich's avatar
      x86: Lift restriction on the location of FIX_BTMAP_* · 499a5f1e
      Jan Beulich authored 
      The early ioremap fixmap entries cover half (or for 32-bit
non-PAE, a quarter) of a page table, yet they got
uncondtitionally aligned so far to a 256-entry boundary. This is
not necessary if the range of page table entries anyway falls
into a single page table.

This buys back, for (theoretically) 50% of all configurations
(25% of all non-PAE ones), at least some of the lowmem
necessarily lost with commit e621bd18.
Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4B2BB66F0200007800026AD6@vpn.id2.novell.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      499a5f1e
  5. 28 Dec, 2009 1 commit
    • Akinobu Mita's avatar
      x86, core: Optimize hweight32() · 39d997b5
      Akinobu Mita authored 
      Optimize hweight32 by using the same technique in hweight64.

The proof of this technique can be found in the commit log for
f9b41929 ("bitops: hweight()
speedup").

The userspace benchmark on x86_32 showed 20% speedup with
bitmap_weight() which uses hweight32 to count bits for each
unsigned long on 32bit architectures.

 int main(void)
 {
	#define SZ (1024 * 1024 * 512)

	static DECLARE_BITMAP(bitmap, SZ) = {
	        [0 ... 100] = 1,
	};

	return bitmap_weight(bitmap, SZ);
 }
Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1258603932-4590-1-git-send-email-akinobu.mita@gmail.com>
[ only x86 sets ARCH_HAS_FAST_MULTIPLIER so we do this via the x86 tree]
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      39d997b5
  7. 24 Dec, 2009 33 commits
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