Re: Missing operand for tlbie instruction on Power7

On 10/02/2015 03:00 PM, Segher Boessenkool wrote:

On Sat, Oct 03, 2015 at 12:37:35AM +0300, Denis Kirjanov wrote:

quoted

quoted

quoted

-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