Re: [PATCH v3 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup

From: Alexander Lobakin <alobakin@pm.me>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Alexander Lobakin <alobakin@pm.me>, 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 v3 mips-next 0/7] MIPS: vmlinux.lds.S sections fixes & cleanup
Date: Thu, 07 Jan 2021 12:30:08 +0000	[thread overview]
Message-ID: <20210107122944.353565-1-alobakin@pm.me> (raw)
In-Reply-To: <20210107115120.281008-1-alobakin@pm.me>

> 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 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
> 
> 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

Well, GNU fails to build VDSO with this patch... Sorry, sending
v4 now.

>   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
> 
>  arch/mips/Kconfig                 |  1 +
>  arch/mips/include/asm/asm.h       | 18 ++++++++++++++++++
>  arch/mips/kernel/vmlinux.lds.S    | 15 ++++++++++++++-
>  include/asm-generic/vmlinux.lds.h |  6 +++---
>  4 files changed, 36 insertions(+), 4 deletions(-)
> 
> --
> 2.30.0

Al