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s390/kaslr: add support for R_390_GLOB_DAT relocation type

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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: 805bc0bc23 ("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>
This commit is contained in:
Gerald Schaefer 2019-10-21 19:56:00 +02:00 committed by Vasily Gorbik
parent 388bb19be8
commit ac49303d9e
2 changed files with 12 additions and 3 deletions
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14
arch/s390/boot/startup.c
View File

@ -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)

1
arch/s390/kernel/machine_kexec_reloc.c
View File

@ -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. */