On Sat, 2020-01-25 at 22:16 -0500, Woody Suwalski wrote:

Trying to use an AMD64 3.16 kernel built on a new Debian system fails because most of the kernel modules can not be loaded.

I don't recommend using the latest toolchain for 3.16 (certainly gcc 9 won't work). But I will apply this since it's such a simple fix. Thanks for the backport.

Ben.

This patch handles the PLT32 relocation errors for kernels modules built with binutils newer then 2.31, similar to: [ 5.742485] module: autofs4: Unknown rela relocation: 4 [ 5.742536] systemd[1]: Failed to insert module 'autofs4': Exec format error

This patch is based on a mainline kernel patch b21ebf2fb4cde1618915a97cc773e287ff49173e From: "H.J. Lu" hjl.tools@gmail.com Date: Wed, 7 Feb 2018 14:20:09 -0800 Subject: x86: Treat R_X86_64_PLT32 as R_X86_64_PC32

Signed-off-by: Woody Suwalski terraluna977@gmail.com

--- a/arch/x86/tools/relocs.c 2020-01-24 18:48:09.477919152 -0500 +++ b/arch/x86/tools/relocs.c 2020-01-24 18:48:53.645612045 -0500 @@ -763,6 +763,7 @@ static int do_reloc64(struct section *se switch (r_type) { case R_X86_64_NONE: case R_X86_64_PC32:

• case R_X86_64_PLT32: /* * NONE can be ignored and PC relative relocations don't * need to be adjusted.

--- a/arch/x86/kernel/module.c 2020-01-24 18:46:54.922670590 -0500 +++ b/arch/x86/kernel/module.c 2020-01-24 18:47:46.714112016 -0500 @@ -180,6 +180,7 @@ int apply_relocate_add(Elf64_Shdr *sechd goto overflow; break; case R_X86_64_PC32:

•    case R_X86_64_PLT32:
          val -= (u64)loc;
          *(u32 *)loc = val;
  

  #if 0