[PATCH 1/5] powerpc/64s: Guarded Userspace Access Prevention

[kbuild test robot]

Hi Russell,

I love your patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on next-20181019]
[cannot apply to v4.19]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Russell-Currey/Guarded-Userspace-Access-Prevention-on-Radix/20181026-145017
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-allyesconfig (attached as .config)
compiler: powerpc64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.2.0 make.cross ARCH=powerpc 

All error/warnings (new ones prefixed by >>):

   arch/powerpc/kernel/entry_64.S: Assembler messages:
>> arch/powerpc/kernel/entry_64.S:304: Error: junk at end of line: `9452:.pushsection __ftr_alt_945,"a"'
>> arch/powerpc/kernel/entry_64.S:304: Warning: .popsection without corresponding .pushsection; ignored
>> arch/powerpc/kernel/entry_64.S:304: Error: backward ref to unknown label "9452:"
>> arch/powerpc/kernel/entry_64.S:304: Error: backward ref to unknown label "9452:"
>> arch/powerpc/kernel/entry_64.S:304: Error: non-constant expression in ".if" statement
   arch/powerpc/kernel/entry_64.S:997: Error: junk at end of line: `9452:.pushsection __ftr_alt_945,"a"'
   arch/powerpc/kernel/entry_64.S:997: Warning: .popsection without corresponding .pushsection; ignored
   arch/powerpc/kernel/entry_64.S:997: Error: backward ref to unknown label "9452:"
   arch/powerpc/kernel/entry_64.S:997: Error: backward ref to unknown label "9452:"
   arch/powerpc/kernel/entry_64.S:997: Error: non-constant expression in ".if" statement

vim +304 arch/powerpc/kernel/entry_64.S

   288	
   289		ld	r13,GPR13(r1)	/* only restore r13 if returning to usermode */
   290		ld	r2,GPR2(r1)
   291		ld	r1,GPR1(r1)
   292		mtlr	r4
   293		mtcr	r5
   294		mtspr	SPRN_SRR0,r7
   295		mtspr	SPRN_SRR1,r8
   296		RFI_TO_USER
   297		b	.	/* prevent speculative execution */
   298	
   299		/* exit to kernel */
   300	1:	/* if the AMR was unlocked before, unlock it again */
   301		lbz	r2,PACA_USER_ACCESS_ALLOWED(r13)
   302		cmpwi	cr1,0
   303		bne	2f
 > 304		UNLOCK_USER_ACCESS(r2)
   305	2:	ld	r2,GPR2(r1)
   306		ld	r1,GPR1(r1)
   307		mtlr	r4
   308		mtcr	r5
   309		mtspr	SPRN_SRR0,r7
   310		mtspr	SPRN_SRR1,r8
   311		RFI_TO_KERNEL
   312		b	.	/* prevent speculative execution */
   313	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
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