From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Date: Sat, 9 Jan 2021 12:12:59 +0100

On Thu, Jan 07, 2021 at 12:33:38PM +0000, Alexander Lobakin wrote:

quoted

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 (local)
[1] https://lore.kernel.org/linux-mips/20210106200713.31840-1-alobakin@pm.me (local)
[2] https://lore.kernel.org/linux-mips/20210107115120.281008-1-alobakin@pm.me (local)

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!

I think they should be handled as it's done for ARM64 [0]. Will do v5
soon.

[0] https://elixir.bootlin.com/linux/v5.11-rc2/source/arch/arm64/kernel/vmlinux.lds.S#L219

$ 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.

Thanks,
Alex

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