From: Gerald Schaefer gerald.schaefer@de.ibm.com
commit ac49303d9ef0ad98b79867a380ef23480e48870b upstream.
Commit "bpf: Process in-kernel BTF" in linux-next introduced an undefined __weak symbol, which results in an R_390_GLOB_DAT relocation type. That is not yet handled by the KASLR relocation code, and the kernel stops with the message "Unknown relocation type".
Add code to detect and handle R_390_GLOB_DAT relocation types and undefined symbols.
Fixes: 805bc0bc238f ("s390/kernel: build a relocatable kernel") Cc: stable@vger.kernel.org # v5.2+ Acked-by: Heiko Carstens heiko.carstens@de.ibm.com Signed-off-by: Gerald Schaefer gerald.schaefer@de.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/s390/boot/startup.c | 14 +++++++++++--- arch/s390/kernel/machine_kexec_reloc.c | 1 + 2 files changed, 12 insertions(+), 3 deletions(-)
--- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -101,10 +101,18 @@ static void handle_relocs(unsigned long dynsym = (Elf64_Sym *) vmlinux.dynsym_start; for (rela = rela_start; rela < rela_end; rela++) { loc = rela->r_offset + offset; - val = rela->r_addend + offset; + val = rela->r_addend; r_sym = ELF64_R_SYM(rela->r_info); - if (r_sym) - val += dynsym[r_sym].st_value; + if (r_sym) { + if (dynsym[r_sym].st_shndx != SHN_UNDEF) + val += dynsym[r_sym].st_value + offset; + } else { + /* + * 0 == undefined symbol table index (STN_UNDEF), + * used for R_390_RELATIVE, only add KASLR offset + */ + val += offset; + } r_type = ELF64_R_TYPE(rela->r_info); rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0); if (rc) --- a/arch/s390/kernel/machine_kexec_reloc.c +++ b/arch/s390/kernel/machine_kexec_reloc.c @@ -27,6 +27,7 @@ int arch_kexec_do_relocs(int r_type, voi *(u32 *)loc = val; break; case R_390_64: /* Direct 64 bit. */ + case R_390_GLOB_DAT: *(u64 *)loc = val; break; case R_390_PC16: /* PC relative 16 bit. */