BMC/Intel-BMC/linux.git/arch/x86/kernel/paravirt_patch_32.c, branch dev

locking/pvqspinlock, x86: Implement the paravirt qspinlock call patching

2015-05-08T10:37:09+00:00

We use the regular paravirt call patching to switch between: native_queued_spin_lock_slowpath() __pv_queued_spin_lock_slowpath() native_queued_spin_unlock() __pv_queued_spin_unlock() We use a callee saved call for the unlock function which reduces the i-cache footprint and allows 'inlining' of SPIN_UNLOCK functions again. We further optimize the unlock path by patching the direct call with a "movb $0,%arg1" if we are indeed using the native unlock code. This makes the unlock code almost as fast as the !PARAVIRT case. This significantly lowers the overhead of having CONFIG_PARAVIRT_SPINLOCKS enabled, even for native code. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Daniel J Blueman Cc: David Vrabel Cc: Douglas Hatch Cc: H. Peter Anvin Cc: Konrad Rzeszutek Wilk Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Paolo Bonzini Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Raghavendra K T Cc: Rik van Riel Cc: Scott J Norton Cc: Thomas Gleixner Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-10-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar

x86/pvops: add a paravirt_ident functions to allow special patching

2009-01-30T22:51:44+00:00

Impact: Optimization Several paravirt ops implementations simply return their arguments, the most obvious being the make_pte/pte_val class of operations on native. On 32-bit, the identity function is literally a no-op, as the calling convention uses the same registers for the first argument and return. On 64-bit, it can be implemented with a single "mov". This patch adds special identity functions for 32 and 64 bit argument, and machinery to recognize them and replace them with either nops or a mov as appropriate. At the moment, the only users for the identity functions are the pagetable entry conversion functions. The result is a measureable improvement on pagetable-heavy benchmarks (2-3%, reducing the pvops overhead from 5 to 2%). Signed-off-by: Jeremy Fitzhardinge Signed-off-by: H. Peter Anvin

x86: coding style fixes to arch/x86/kernel/paravirt_patch_32.c

2008-08-15T14:53:25+00:00

Before: total: 3 errors, 1 warnings, 49 lines checked After: total: 2 errors, 1 warnings, 49 lines checked paolo@paolo-desktop:~/linux.trees.git$ md5sum /tmp/paravirt_patch_32.o.* a78eea4264723e18c49dcfbe0ee0aae7 /tmp/paravirt_patch_32.o.after a78eea4264723e18c49dcfbe0ee0aae7 /tmp/paravirt_patch_32.o.before Signed-off-by: Paolo Ciarrocchi Signed-off-by: Ingo Molnar

x86/paravirt: split sysret and sysexit

2008-07-08T11:13:15+00:00

Don't conflate sysret and sysexit; they're different instructions with different semantics, and may be in use at the same time (at least within the same kernel, depending on whether its an Intel or AMD system). sysexit - just return to userspace, does no register restoration of any kind; must explicitly atomically enable interrupts. sysret - reloads flags from r11, so no need to explicitly enable interrupts on 64-bit, responsible for restoring usermode %gs Signed-off-by: Jeremy Fitzhardinge Cc: xen-devel Cc: Stephen Tweedie Cc: Eduardo Habkost Cc: Mark McLoughlin Signed-off-by: Ingo Molnar

x86: move patching code to arch-specific file.

2008-01-30T12:32:10+00:00

The core patching code for paravirt is sufficiently different among i386 and x86_64, and we move them to specific files. Signed-off-by: Glauber de Oliveira Costa Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner