Subject: Missing operand for tlbie instruction on Power7

From: Laura Abbott <[email-masked]>
Date: Fri, 2 Oct 2015 08:43:31 -0700

Hi,

We received a report (https://bugzilla.redhat.com/show_bug.cgi?id=1267395) of bad assembly
when compiling on powerpc with little endian

[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 problem started happening after a binutils update:

[labbott@labbott-redhat-machine linux_upstream]$ powerpc64-linux-gnu-as --version
GNU assembler version 2.25.1-1.fc22
Copyright (C) 2014 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
This assembler was configured for a target of `powerpc64-linux-gnu'.
[labbott@labbott-redhat-machine linux_upstream]$

After some discussion with the binutils folks, it turns out that the tlbie
instruction actually requires another operand and binutils was updated to
check for this https://sourceware.org/ml/binutils/2015-05/msg00133.html .

The code sequence in arch/powerpc/include/asm/ppc_asm.h now needs to be updated:

#if !defined(CONFIG_4xx) && !defined(CONFIG_8xx)
#define tlbia                                   \
         li      r4,1024;                        \
         mtctr   r4;                             \
         lis     r4,KERNELBASE@h;                \
0:      tlbie   r4;                             \
         addi    r4,r4,0x1000;                   \
         bdnz    0b
#endif

I don't know enough ppc assembly to properly fix this but I can test.

Thanks,
Laura