Re: include/linux/atomic-arch-fallback.h:60:32: error: implicit declaration of function 'arch_cmpxchg64'; did you mean 'arch_cmpxchg'?

From: Mark Rutland
Date: Mon Jul 12 2021 - 10:31:58 EST


On Sun, Jul 11, 2021 at 06:44:47AM +0800, kernel test robot wrote:
> Hi Mark,
>
> FYI, the error/warning still remains.

I thought we'd already identified that this was an existing bug, and all that
has changed is the specific error that manifests.

In v5.13 this would fail with:

| CC drivers/iommu/io-pgtable-arm.o
| In file included from ./include/linux/atomic.h:84,
| from drivers/iommu/io-pgtable-arm.c:12:
| drivers/iommu/io-pgtable-arm.c: In function 'arm_lpae_install_table':
| ./include/linux/atomic-fallback.h:60:27: error: implicit declaration of function 'cmpxchg64'; did you mean 'cmpxchg'? [-Werror=implicit-function-declaration]
| 60 | #define cmpxchg64_relaxed cmpxchg64
| | ^~~~~~~~~
| drivers/iommu/io-pgtable-arm.c:320:8: note: in expansion of macro 'cmpxchg64_relaxed'
| 320 | old = cmpxchg64_relaxed(ptep, curr, new);
| | ^~~~~~~~~~~~~~~~~

... which has the same underlying problem -- the architecture has not provided
a cmpxchg64() implementation, but the IO pagetable code depends upon
cmpxchg64().

Thanks,
Mark.

>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 1e16624d7b4376797ede36e3c955375cf0f23298
> commit: bccf1ec369ac126b0997d01a6e1deae00e2cf6b3 locking/atomics: atomic-instrumented: simplify ifdeffery
> date: 6 weeks ago
> config: arc-allyesconfig (attached as .config)
> compiler: arceb-elf-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bccf1ec369ac126b0997d01a6e1deae00e2cf6b3
> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> git fetch --no-tags linus master
> git checkout bccf1ec369ac126b0997d01a6e1deae00e2cf6b3
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arc
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
> All errors (new ones prefixed by >>):
>
> In file included from include/linux/atomic.h:80,
> from drivers/iommu/io-pgtable-arm.c:12:
> drivers/iommu/io-pgtable-arm.c: In function 'arm_lpae_install_table':
> >> include/linux/atomic-arch-fallback.h:60:32: error: implicit declaration of function 'arch_cmpxchg64'; did you mean 'arch_cmpxchg'? [-Werror=implicit-function-declaration]
> 60 | #define arch_cmpxchg64_relaxed arch_cmpxchg64
> | ^~~~~~~~~~~~~~
> include/asm-generic/atomic-instrumented.h:1261:2: note: in expansion of macro 'arch_cmpxchg64_relaxed'
> 1261 | arch_cmpxchg64_relaxed(__ai_ptr, __VA_ARGS__); \
> | ^~~~~~~~~~~~~~~~~~~~~~
> drivers/iommu/io-pgtable-arm.c:320:8: note: in expansion of macro 'cmpxchg64_relaxed'
> 320 | old = cmpxchg64_relaxed(ptep, curr, new);
> | ^~~~~~~~~~~~~~~~~
> cc1: some warnings being treated as errors
>
>
> vim +60 include/linux/atomic-arch-fallback.h
>
> 37f8173dd84936 Peter Zijlstra 2020-01-24 56
> 37f8173dd84936 Peter Zijlstra 2020-01-24 57 #ifndef arch_cmpxchg64_relaxed
> 37f8173dd84936 Peter Zijlstra 2020-01-24 58 #define arch_cmpxchg64_acquire arch_cmpxchg64
> 37f8173dd84936 Peter Zijlstra 2020-01-24 59 #define arch_cmpxchg64_release arch_cmpxchg64
> 29f006fdefe6f8 Peter Zijlstra 2020-08-29 @60 #define arch_cmpxchg64_relaxed arch_cmpxchg64
> 37f8173dd84936 Peter Zijlstra 2020-01-24 61 #else /* arch_cmpxchg64_relaxed */
> 37f8173dd84936 Peter Zijlstra 2020-01-24 62
>
> :::::: The code at line 60 was first introduced by commit
> :::::: 29f006fdefe6f88abde973a0b0f20d2704e93fd4 asm-generic/atomic: Add try_cmpxchg() fallbacks
>
> :::::: TO: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> :::::: CC: Ingo Molnar <mingo@xxxxxxxxxx>
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx