Re: Missing operand for tlbie instruction on Power7

[Laura Abbott]

On 10/02/2015 03:00 PM, Segher Boessenkool wrote:
> On Sat, Oct 03, 2015 at 12:37:35AM +0300, Denis Kirjanov wrote:
> > > > -0:     tlbie   r4;                             \
> > > > +0:     tlbie   r4, 0;                          \
> > >
> > > This isn't correct.  With POWER7 and later (which this compile
> > > is, since it's on LE), the tlbie instruction takes two register
> > > operands:
> > >
> > >      tlbie RB, RS
> > >
> > > The tlbie instruction on pre POWER7 cpus had one required register
> > > operand (RB) and an optional second L operand, where if you omitted
> > > it, it was the same as using "0":
> > >
> > >      tlbie RB, L
> > >
> > > This is a POWER7 and later build, so your change which adds the "0"
> > > above is really adding r0 for RS.  The new tlbie instruction doesn't
> > > treat r0 specially, so you'll be using whatever random bits which
> > > happen to be in r0 which I don't think that is what you want.
> >
> > Ok, than we can just zero out r5 for example and use it in tlbie as RS,
> > right?
>
> That won't assemble _unless_ your assembler is in POWER7 mode.  It also
> won't do the right thing at run time on older machines.
>
> Where is this tlbia macro used at all, for 64-bit machines?


[labbott@labbott-redhat-machine linux_upstream]$ make ARCH=powerpc CROSS_COMPILE=powerpc64-linux-gnu-
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/bounds.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  CALL    arch/powerpc/kernel/systbl_chk.sh
  AS      arch/powerpc/kernel/swsusp_asm64.o
arch/powerpc/kernel/swsusp_asm64.S: Assembler messages:
arch/powerpc/kernel/swsusp_asm64.S:188: Error: missing operand
scripts/Makefile.build:294: recipe for target 'arch/powerpc/kernel/swsusp_asm64.o' failed
make[1]: *** [arch/powerpc/kernel/swsusp_asm64.o] Error 1
Makefile:941: recipe for target 'arch/powerpc/kernel' failed
make: *** [arch/powerpc/kernel] Error 2

This is piece of code protected by CONFIG_PPC_BOOK3S_64.
 
> Segher

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