From ac49303d9ef0ad98b79867a380ef23480e48870b Mon Sep 17 00:00:00 2001 From: Gerald Schaefer Date: Mon, 21 Oct 2019 19:56:00 +0200 Subject: [PATCH] s390/kaslr: add support for R_390_GLOB_DAT relocation type 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: # v5.2+ Acked-by: Heiko Carstens Signed-off-by: Gerald Schaefer Signed-off-by: Vasily Gorbik --- arch/s390/boot/startup.c | 14 +++++++++++--- arch/s390/kernel/machine_kexec_reloc.c | 1 + 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index 596ca7cc4d7b..5367950510f6 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -101,10 +101,18 @@ static void handle_relocs(unsigned long offset) 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) diff --git a/arch/s390/kernel/machine_kexec_reloc.c b/arch/s390/kernel/machine_kexec_reloc.c index 3b664cb3ec4d..d5035de9020e 100644 --- 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, void *loc, unsigned long val, *(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. */