linux-kernel - Re: [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup

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Message-ID: <20210109111259.GA4213@alpha.franken.de>
Date:   Sat, 9 Jan 2021 12:12:59 +0100
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Alexander Lobakin <alobakin@...me>
Cc:     Arnd Bergmann <arnd@...db.de>, Kees Cook <keescook@...omium.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Fangrui Song <maskray@...gle.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Pei Huang <huangpei@...ngson.cn>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Ingo Molnar <mingo@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Corey Minyard <cminyard@...sta.com>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, stable@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes &
 cleanup

On Thu, Jan 07, 2021 at 12:33:38PM +0000, Alexander Lobakin wrote:
> This series hunts the problems discovered after manual enabling of
> ARCH_WANT_LD_ORPHAN_WARN. Notably:
>  - adds the missing PAGE_ALIGNED_DATA() section affecting VDSO
>    placement (marked for stable);
>  - properly stops .eh_frame section generation.
> 
> Compile and runtime tested on MIPS32R2 CPS board with no issues
> using two different toolkits:
>  - Binutils 2.35.1, GCC 10.2.0;
>  - LLVM stack 11.0.0.
> 
> Since v3 [2]:
>  - fix the third patch as GNU stack emits .rel.dyn into VDSO for
>    some reason if .cfi_sections is specified.
> 
> Since v2 [1]:
>  - stop discarding .eh_frame and just prevent it from generating
>    (Kees);
>  - drop redundant sections assertions (Fangrui);
>  - place GOT table in .text instead of asserting as it's not empty
>    when building with LLVM (Nathan);
>  - catch compound literals in generic definitions when building with
>    LD_DEAD_CODE_DATA_ELIMINATION (Kees);
>  - collect two Reviewed-bys (Kees).
> 
> Since v1 [0]:
>  - catch .got entries too as LLD may produce it (Nathan);
>  - check for unwanted sections to be zero-sized instead of
>    discarding (Fangrui).
> 
> [0] https://lore.kernel.org/linux-mips/20210104121729.46981-1-alobakin@pm.me
> [1] https://lore.kernel.org/linux-mips/20210106200713.31840-1-alobakin@pm.me
> [2] https://lore.kernel.org/linux-mips/20210107115120.281008-1-alobakin@pm.me
> 
> Alexander Lobakin (7):
>   MIPS: vmlinux.lds.S: add missing PAGE_ALIGNED_DATA() section
>   MIPS: vmlinux.lds.S: add ".gnu.attributes" to DISCARDS
>   MIPS: properly stop .eh_frame generation
>   MIPS: vmlinux.lds.S: catch bad .rel.dyn at link time
>   MIPS: vmlinux.lds.S: explicitly declare .got table
>   vmlinux.lds.h: catch compound literals into data and BSS
>   MIPS: select ARCH_WANT_LD_ORPHAN_WARN

this breaks my builds:

  LD      vmlinux.o
  MODPOST vmlinux.symvers
  MODINFO modules.builtin.modinfo
  GEN     modules.builtin
  LD      .tmp_vmlinux.kallsyms1
mips64-linux-gnu-ld: Unexpected run-time relocations (.rel) detected!


$ mips64-linux-gnu-ld --version
GNU ld version 2.27-3.fc24

$ mips64-linux-gnu-gcc --version
mips64-linux-gnu-gcc (GCC) 6.1.1 20160621 (Red Hat Cross 6.1.1-2)

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]