Re: [Xen-devel] [PATCH v4 01/12] x86: infrastructure to allow converting certain indirect calls to direct ones

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 05/10/18 14:43, Jan Beulich wrote:
>>>> On 05.10.18 at 14:39, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 03/10/18 19:38, Andrew Cooper wrote:
>>> Finally, this series doesn't link with the default Debian toolchain.
>>>
>>> andrewcoop@andrewcoop:/local/xen.git/xen$ ld --version
>>> GNU ld (GNU Binutils for Debian) 2.25
>>>
>>> andrewcoop@andrewcoop:/local/xen.git/xen$ make -s build -j8 
>>> XEN_TARGET_ARCH=x86_64 KCONFIG_CONFIG=.config-release
>>>  __  __            _  _    _ ____                     _        _     _      
>>>  \ \/ /___ _ __   | || |  / |___ \    _   _ _ __  ___| |_ __ _| |__ | | ___ 
>>>   \  // _ \ '_ \  | || |_ | | __) |__| | | | '_ \/ __| __/ _` | '_ \| |/ _ \
>>>   /  \  __/ | | | |__   _|| |/ __/|__| |_| | | | \__ \ || (_| | |_) | |  __/
>>>  /_/\_\___|_| |_|    |_|(_)_|_____|   \__,_|_| |_|___/\__\__,_|_.__/|_|\___|
>>>                                                                             
>>> prelink.o:(.debug_aranges+0x3c94): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_info'
>>> prelink.o:(.debug_info+0x225fa): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x22b57): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x1b92da): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x21e976): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x21ec31): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x21f03b): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x2b2ac3): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_loc'
>>> prelink.o:(.debug_info+0x2b37f6): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x448fab): relocation truncated to fit: R_X86_64_32 
>>> against `.debug_str'
>>> prelink.o:(.debug_info+0x44b856): additional relocation overflows omitted 
>>> from the output
>>> ld: prelink.o: access beyond end of merged section (6617683)
>>> ld: prelink.o: access beyond end of merged section (6617630)
>>> ld: prelink.o: access beyond end of merged section (6617579)
>>> ld: prelink.o: access beyond end of merged section (6617558)
>>> ld: prelink.o: access beyond end of merged section (6617544)
>>> ld: prelink.o: access beyond end of merged section (6617605)
>>> ld: prelink.o: access beyond end of merged section (6617718)
>>> ld: prelink.o: access beyond end of merged section (6617570)
>>> ld: prelink.o: access beyond end of merged section (6617665)
>>> ld: prelink.o: access beyond end of merged section (6617671)
>>> ld: prelink.o: access beyond end of merged section (6617624)
>>> ld: prelink.o: access beyond end of merged section (6617748)
>>> ld: prelink.o: access beyond end of merged section (6617771)
>>> ld: prelink.o: access beyond end of merged section (6617592)
>>> ld: prelink.o: access beyond end of merged section (6617635)
>>> ld: prelink.o: access beyond end of merged section (6617652)
>>> ld: prelink.o: access beyond end of merged section (6617766)
>>> ld: prelink.o: access beyond end of merged section (6617742)
> Something along the lines of one or both of the above kinds I've
> happened to run into when using a gas producing compressed
> debug sections together with an objcopy which doesn't know
> about such section (iirc older objcopy silently dropped some
> section flag in this case).

I've tracked the issues down Olaf's DEBUG_INFO patch.  Having DEBUG_INFO
set when DEBUG is clear (which is the default for release builds)
results in this breakage.

Another diagnostic has come to light:

ld: Dwarf Error: found dwarf version '0', this reader only handles
version 2, 3 and 4 information.
prelink.o:(.debug_info+0x1bcee4): relocation truncated to fit:
R_X86_64_32 against `.debug_str'


>
>>> ld: prelink.o(.debug_info+0xc962ed): reloc against `.debug_loc': error 2
>>> Makefile:134: recipe for target '/local/xen.git/xen/xen-syms' failed
>>> make[2]: *** [/local/xen.git/xen/xen-syms] Error 1
>>> make[2]: *** Waiting for unfinished jobs....
>>> /local/xen.git/xen/.xen.efi.0s.S: Assembler messages:
>>> /local/xen.git/xen/.xen.efi.0s.S:21: Warning: value 0x7d2f80000544 
>>> truncated to 0x80000544
>>> /local/xen.git/xen/.xen.efi.0s.S:22: Warning: value 0x7d2f800008dc 
>>> truncated to 0x800008dc
>>> /local/xen.git/xen/.xen.efi.0s.S:23: Warning: value 0x7d2f800008de 
>>> truncated to 0x800008de
>>> /local/xen.git/xen/.xen.efi.0s.S:24: Warning: value 0x7d2f800008e3 
>>> truncated to 0x800008e3
>>> /local/xen.git/xen/.xen.efi.0s.S:25: Warning: value 0x7d2f80001086 
>>> truncated to 0x80001086
>>> /local/xen.git/xen/.xen.efi.0s.S:26: Warning: value 0x7d2f8000108a 
>>> truncated to 0x8000108a
>>> /local/xen.git/xen/.xen.efi.0s.S:27: Warning: value 0x7d2f8000108e 
>>> truncated to 0x8000108e
>>> /local/xen.git/xen/.xen.efi.0s.S:28: Warning: value 0x7d2f800010dc 
>>> truncated to 0x800010dc
>>> /local/xen.git/xen/.xen.efi.0s.S:29: Warning: value 0x7d2f80001172 
>>> truncated to 0x80001172
>>> /local/xen.git/xen/.xen.efi.1s.S: Assembler messages:
>>> /local/xen.git/xen/.xen.efi.1s.S:21: Warning: value 0x7d2f80000544 
>>> truncated to 0x80000544
>>> /local/xen.git/xen/.xen.efi.1s.S:22: Warning: value 0x7d2f800008dc 
>>> truncated to 0x800008dc
>>> /local/xen.git/xen/.xen.efi.1s.S:23: Warning: value 0x7d2f800008de 
>>> truncated to 0x800008de
>>> /local/xen.git/xen/.xen.efi.1s.S:24: Warning: value 0x7d2f800008e3 
>>> truncated to 0x800008e3
>>> /local/xen.git/xen/.xen.efi.1s.S:25: Warning: value 0x7d2f80001086 
>>> truncated to 0x80001086
>>> /local/xen.git/xen/.xen.efi.1s.S:26: Warning: value 0x7d2f8000108a 
>>> truncated to 0x8000108a
>>> /local/xen.git/xen/.xen.efi.1s.S:27: Warning: value 0x7d2f8000108e 
>>> truncated to 0x8000108e
>>> /local/xen.git/xen/.xen.efi.1s.S:28: Warning: value 0x7d2f800010dc 
>>> truncated to 0x800010dc
>>> /local/xen.git/xen/.xen.efi.1s.S:29: Warning: value 0x7d2f80001172 
>>> truncated to 0x80001172
> These are just warnings, and I vaguely recall looking into this once (I
> don't see these myself, so I supposed I had asked you or someone
> else to send my some object files), finding that gas is right to warn,
> but the effect on the embedded symbol table should be benign. What
> I don't understand though is why I've never seen these myself.

This happens when you've got CONFIG_LIVEPATCH enabled and use the
default debian toolchain.

>
>>> Makefile:136: recipe for target '/local/xen.git/xen/xen' failed
>>> make[1]: *** [/local/xen.git/xen/xen] Error 2
>>> Makefile:45: recipe for target 'build' failed
>>> make: *** [build] Error 2
>>>
>>> Using LD 2.30 built from source is fine, but I'm not sure exactly what
>>> is going on here.
>> Actually, I've just encountered this failure to link on staging as well,
>> so it is clearly not related to this series.  Sorry for the noise (but
>> I'm still non-the-wiser as to what is actually broken).
> Could you try 2.31.1? Of course I did use 2.30 until 2.31 went out,
> and still didn't see this. Yet then again my variant is not exactly
> vanilla.

I could (when I've got time to recompile my non-default compilers), but
what is this going to demonstrate?  I wouldn't expect 2.31 to be broken
when 2.30 works fine.

~Andrew

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