Re: [peterz-queue:sched/urgent 4/5] ld.lld: error: section .text at 0xFFFFFFFF80200000 of size 0x1E8915C exceeds available address space

[Fangrui Song <maskray@google.com>]

On 2020-04-04, Philip Li wrote:
>On Fri, Apr 03, 2020 at 12:20:58PM -0700, Nathan Chancellor wrote:
>> On Fri, Apr 03, 2020 at 09:37:57AM -0700, 'Nick Desaulniers' via Clang Built Linux wrote:
>> > + Fangrui, Rui, George
>> > The below errors from LLD look new to me, thoughts?
>> >
>> > On Fri, Apr 3, 2020 at 8:42 AM kbuild test robot <lkp@intel.com> wrote:
>> > >
>> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/urgent
>> > > head:   59d4dade8ccbaa299f5f5dcd775f7a9b7277fb5a
>> > > commit: ae1177617ed17157f29959b0fe4d60f532a5b36e [4/5] workqueue: Remove the warning in wq_worker_sleeping()
>> > > config: mips-randconfig-a001-20200403 (attached as .config)
>> > > compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project f68cc2a7ed766965028b8b0f0d9300a0460c3cf1)
>> > > reproduce:
>> > >         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>> > >         chmod +x ~/bin/make.cross
>> > >         git checkout ae1177617ed17157f29959b0fe4d60f532a5b36e
>> > >         # save the attached .config to linux build tree
>> > >         COMPILER=clang make.cross ARCH=mips
>> > >
>> > > If you fix the issue, kindly add following tag
>> > > Reported-by: kbuild test robot <lkp@intel.com>
>> > >
>> > > All errors (new ones prefixed by >>):
>> > >
>> > > >> ld.lld: error: section .text at 0xFFFFFFFF80200000 of size 0x1E8915C exceeds available address space
>> > > >> ld.lld: error: section __ex_table at 0xFFFFFFFF82089160 of size 0x27B0 exceeds available address space
>> > > >> ld.lld: error: section __dbe_table at 0xFFFFFFFF8208B910 of size 0x0 exceeds available address space
>> > >    ld.lld: error: section .rodata at 0xFFFFFFFF8208C000 of size 0x480F81 exceeds available address space
>> > >    ld.lld: error: section .data..page_aligned at 0xFFFFFFFF8250D000 of size 0x2000 exceeds available address space
>> > >    ld.lld: error: section .got at 0xFFFFFFFF8250F000 of size 0x8 exceeds available address space
>> > >    ld.lld: error: section .rodata1 at 0xFFFFFFFF8250F008 of size 0x0 exceeds available address space
>> > >    ld.lld: error: section .pci_fixup at 0xFFFFFFFF8250F008 of size 0x0 exceeds available address space
>> > >    ld.lld: error: section .builtin_fw at 0xFFFFFFFF8250F008 of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __ksymtab at 0xFFFFFFFF8250F008 of size 0x145EC exceeds available address space
>> > >    ld.lld: error: section __ksymtab_gpl at 0xFFFFFFFF825235F4 of size 0x12378 exceeds available address space
>> > >    ld.lld: error: section __ksymtab_unused at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __ksymtab_unused_gpl at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __ksymtab_gpl_future at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __kcrctab at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __kcrctab_gpl at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __kcrctab_unused at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __kcrctab_unused_gpl at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __kcrctab_gpl_future at 0xFFFFFFFF8253596C of size 0x0 exceeds available address space
>> > >    ld.lld: error: section __ksymtab_strings at 0xFFFFFFFF8253596C of size 0x40CB3 exceeds available address space
>> > >    ld.lld: error: too many errors emitted, stopping now (use -error-limit=0 to see all errors)
>> > >
>> > > ---
>> > > 0-DAY CI Kernel Test Service, Intel Corporation
>> > > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>> > >
>> >
>> >
>> >
>> > --
>> > Thanks,
>> > ~Nick Desaulniers
>> >
>>
>> This is an open issue on our issue tracker:
>>
>> https://github.com/ClangBuiltLinux/linux/issues/786
>>
>> Note that this is a mips-randconfig.
>Thanks, we will temporarily blacklist this error.

Reproduce for a clang/lld developer:

make -j$(nproc) ARCH=mips CC=clang CROSS_COMPILE=mipsel-linux-gnu- LD=ld.lld O=/tmp/out/mipsel distclean malta_defconfig vmlinux
(Requires mipsel-linux-gnu-as and clang in PATH)

I have noticed multiple problems.

% file .tmp_vmlinux.kallsyms1
.tmp_vmlinux.kallsyms1: ELF 32-bit LSB executable, MIPS, MIPS32 rel2 version 1 (SYSV), statically linked, BuildID[sha1]=ff348ad92c80e525b3f14149e57e8987de66e041, not stripped

In arch/mips/kernel/vmlinux.lds.S, VMLINUX_LOAD_ADDRESS (from load-y) is 0xffffffff8010000.
GNU ld seems to allow 64-bit addresses when linking an ELFCLASS32 file.
The addresses will be truncated to 32-bit. This behavior seems error-prone to me.

lld does the right thing by erroring out. I do notice a display problem
of lld -Map and I have a patch to address that: https://reviews.llvm.org/D77445

For 32-bit linux-mips, the right approach seems to be make VMLINUX_LOAD_ADDRESS fit into 32-bit.
However, my Linux-fu and MIPS-fu is not strong enough to do this :/