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

From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Alexander Lobakin <alobakin@pm.me>
Cc: Arnd Bergmann <arnd@arndb.de>, Kees Cook <keescook@chromium.org>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Fangrui Song <maskray@google.com>,
	Huacai Chen <chenhuacai@kernel.org>,
	Pei Huang <huangpei@loongson.cn>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Ingo Molnar <mingo@kernel.org>,
	Ralf Baechle <ralf@linux-mips.org>,
	Corey Minyard <cminyard@mvista.com>,
	linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arch@vger.kernel.org, stable@vger.kernel.org,
	clang-built-linux@googlegroups.com
Subject: Re: [PATCH v4 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup
Date: Sat, 9 Jan 2021 12:12:59 +0100	[thread overview]
Message-ID: <20210109111259.GA4213@alpha.franken.de> (raw)
In-Reply-To: <20210107123331.354075-1-alobakin@pm.me>

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
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