On 17/11/17 20:42, Josh Poimboeuf wrote: > On Fri, Nov 17, 2017 at 08:10:13PM +0100, Juergen Gross wrote: >> On 17/11/17 19:07, Borislav Petkov wrote: >>> On Wed, Oct 04, 2017 at 10:58:24AM -0500, Josh Poimboeuf wrote: >>>> Convert the hard-coded native patch assembly code strings to macros to >>>> facilitate sharing common code between 32-bit and 64-bit. >>>> >>>> These macros will also be used by a future patch which requires the GCC >>>> extended asm syntax of two '%' characters instead of one when specifying >>>> a register name. >>>> >>>> Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com> >>>> --- >>>> arch/x86/include/asm/special_insns.h | 24 ++++++++++++++++++++++++ >>>> arch/x86/kernel/paravirt_patch_32.c | 21 +++++++++++---------- >>>> arch/x86/kernel/paravirt_patch_64.c | 29 +++++++++++++++-------------- >>>> 3 files changed, 50 insertions(+), 24 deletions(-) >>>> >>>> diff --git a/arch/x86/include/asm/special_insns.h >>>> b/arch/x86/include/asm/special_insns.h >>>> index ac402c6fc24b..0549c5f2c1b3 100644 >>>> --- a/arch/x86/include/asm/special_insns.h >>>> +++ b/arch/x86/include/asm/special_insns.h >>>> @@ -6,6 +6,30 @@ >>>> >>>> #include <asm/nops.h> >>>> >>>> +#ifdef CONFIG_X86_64 >>>> +# define _REG_ARG1 "%rdi" >>>> +# define NATIVE_IDENTITY_32 "mov %edi, %eax" >>> >>> Yeah, that "identity" looks strange. How about NATIVE_NOOP and >>> NATIVE_NOOP_32 ? >> >> Those are not NOPs. They return the identical value which was passed to >> them. So identity isn't a bad name after all. > > Right, like the math identity function: > > https://en.wikipedia.org/wiki/Identity_function > >>>> +# define NATIVE_USERGS_SYSRET64 "swapgs; sysretq" >>>> +#else >>>> +# define _REG_ARG1 "%eax" >>>> +#endif >>>> + >>>> +#define _REG_RET "%" _ASM_AX >>>> + >>>> +#define NATIVE_ZERO "xor " _REG_ARG1 ", " _REG_ARG1 >>> >>> NATIVE_ZERO_OUT >>> >>> I guess. NATIVE_ZERO reads like the native representation of 0 :-) >> >> NATIVE_ZERO_ARG1? > > On a slight tangent, does anybody know why it zeros the arg?
Why are _you_ asking? You've introduced it. > The only place it's used is here: > > #if defined(CONFIG_PARAVIRT_SPINLOCKS) > DEF_NATIVE(pv_lock_ops, queued_spin_unlock, > NATIVE_QUEUED_SPIN_UNLOCK); > DEF_NATIVE(pv_lock_ops, vcpu_is_preempted, NATIVE_ZERO); > #endif > > Isn't that a bug? Seems like it should _return_ zero. Zeroing the arg > shouldn't have any effect. Right. Before that patch it _did_ return zero instead of zeroing arg1. > If I'm right, we could call it NATIVE_FALSE. I'd prefer NATIVE_ZERO, as it will be usable for non-boolean cases, too. Juergen _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
