microwatt_defconfig broken: fined reference to `hash__tlb_flush'

[Christophe Leroy]

Hi Jan-Benedict,

Le 17/02/2023 à 21:41, Jan-Benedict Glaw a écrit :
> Hi Christophe!
> 
> On Fri, 2023-02-17 21:00:43 +0100, Jan-Benedict Glaw <jbglaw at lug-owl.de> wrote:
>> On Fri, 2023-02-17 19:44:27 +0000, Christophe Leroy <christophe.leroy at csgroup.eu> wrote:
>>> Le 17/02/2023 à 18:14, Jan-Benedict Glaw a écrit :
>>>> My CI builds showed that the microwatt_defconfig broke somewhere between
>>>> (upstream Linus) 6d796c50f84ca79f1722bb131799e5a5710c4700 (last known good, log
>>>> at [1]) and 033c40a89f55525139fd5b6342281b09b97d05bf (first known bad, log at
>>>> [2]) with this:
>>>>
>>>> [...]
>>>> make V=1 ARCH=powerpc CROSS_COMPILE=powerpc64le-linux- INSTALL_MOD_PATH=/var/lib/laminar/run/linux-powerpc-microwatt_defconfig/28/linux-powerpc-microwatt_defconfig INSTALL_DTBS_PATH=/var/lib/laminar/run/linux-powerpc-microwatt_defconfig/28/linux-powerpc-microwatt_defconfig all
>>>> [...]
>>>> [mk all 2023-02-17 01:42:27] + powerpc64le-linux-ld -EL -z noexecstack --no-warn-rwx-segments -Bstatic --build-id=sha1 --orphan-handling=warn --script=./arch/powerpc/kernel/vmlinux.lds --strip-debug -o .tmp_vmlinux.kallsyms1 --whole-archive vmlinux.a init/version-timestamp.o --no-whole-archive --start-group lib/lib.a --end-group
>>>> [mk all 2023-02-17 01:42:28] powerpc64le-linux-ld: mm/memory.o: in function `tlb_flush_mmu_tlbonly':
>>>> [mk all 2023-02-17 01:42:28] memory.c:(.text+0x320): undefined reference to `hash__tlb_flush'
>>>> [mk all 2023-02-17 01:42:28] powerpc64le-linux-ld: mm/mmu_gather.o: in function `tlb_flush_mmu_tlbonly':
>>>> [mk all 2023-02-17 01:42:28] mmu_gather.c:(.text+0xe0): undefined reference to `hash__tlb_flush'
>>>> [mk all 2023-02-17 01:42:28] powerpc64le-linux-ld: mm/mprotect.o: in function `change_protection':
>>>> [mk all 2023-02-17 01:42:28] mprotect.c:(.text+0x59c): undefined reference to `hash__tlb_flush'
>>>> [mk all 2023-02-17 01:42:28] powerpc64le-linux-ld: mm/madvise.o: in function `tlb_end_vma.isra.0':
>>>> [mk all 2023-02-17 01:42:28] madvise.c:(.text+0x1f0): undefined reference to `hash__tlb_flush'
>>>> [mk all 2023-02-17 01:42:28] make[1]: *** [scripts/Makefile.vmlinux:35: vmlinux] Error 1
>>>> [mk all 2023-02-17 01:42:28] make: *** [Makefile:1264: vmlinux] Error 2
>>>
>>>
>>> The fix is available here :
>>> https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id=4302abc628fc0dc08e5855f21bbfaed407a72bc3
>>
>> I can give that patch a try, but on the first glimpse, it won't help:
> [...]
>> The patch handles a return-type issue. My above issue is a linkage
>> issue, the linker cannot find hash__tlb_flush(). Or am I mistaken?
> 
> I stand corrected: That patch fixes the linker issue. (Build log at
> http://toolchain.lug-owl.de/laminar/jobs/linux-powerpc-microwatt_defconfig/69)
> Just ftr: How does this work?
> 

On microwatt_defconfig, radix_enabled() is always true so the compiler 
eliminates the else branch.

Christophe