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path: root/arch/x86/lib/rwsem_64.S
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2011-02-28x86-64: Add CFI annotations to lib/rwsem_64.SJan Beulich
These weren't part of the initial commit of this code. Signed-off-by: Jan Beulich <jbeulich@novell.com> Cc: Alexander van Heukelum <heukelum@fastmail.fm> LKML-Reference: <4D6BCDFF02000078000341B0@vpn.id2.novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-05-04Fix the x86_64 implementation of call_rwsem_wait()David Howells
The x86_64 call_rwsem_wait() treats the active state counter part of the R/W semaphore state as being 16-bit when it's actually 32-bit (it's half of the 64-bit state). It should do "decl %edx" not "decw %dx". Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-01-13x86-64: support native xadd rwsem implementationLinus Torvalds
This one is much faster than the spinlock based fallback rwsem code, with certain artifical benchmarks having shown 300%+ improvement on threaded page faults etc. Again, note the 32767-thread limit here. So this really does need that whole "make rwsem_count_t be 64-bit and fix the BIAS values to match" extension on top of it, but that is conceptually a totally independent issue. NOT TESTED! The original patch that this all was based on were tested by KAMEZAWA Hiroyuki, but maybe I screwed up something when I created the cleaned-up series, so caveat emptor.. Also note that it _may_ be a good idea to mark some more registers clobbered on x86-64 in the inline asms instead of saving/restoring them. They are inline functions, but they are only used in places where there are not a lot of live registers _anyway_, so doing for example the clobbers of %r8-%r11 in the asm wouldn't make the fast-path code any worse, and would make the slow-path code smaller. (Not that the slow-path really matters to that degree. Saving a few unnecessary registers is the _least_ of our problems when we hit the slow path. The instruction/cycle counting really only matters in the fast path). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> LKML-Reference: <alpine.LFD.2.00.1001121810410.17145@localhost.localdomain> Signed-off-by: H. Peter Anvin <hpa@zytor.com>