linux/arch/s390/kernel/machine_kexec_reloc.c
Gerald Schaefer 4c1cbcbd6c s390/kaslr: add support for R_390_JMP_SLOT relocation type
With certain kernel configurations, the R_390_JMP_SLOT relocation type
might be generated, which is not expected by the KASLR relocation code,
and the kernel stops with the message "Unknown relocation type".

This was found with a zfcpdump kernel config, where CONFIG_MODULES=n
and CONFIG_VFIO=n. In that case, symbol_get() is used on undefined
__weak symbols in virt/kvm/vfio.c, which results in the generation
of R_390_JMP_SLOT relocation types.

Fix this by handling R_390_JMP_SLOT similar to R_390_GLOB_DAT.

Fixes: 805bc0bc23 ("s390/kernel: build a relocatable kernel")
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2020-05-20 10:13:27 +02:00

57 lines
1.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/elf.h>
#include <asm/kexec.h>
int arch_kexec_do_relocs(int r_type, void *loc, unsigned long val,
unsigned long addr)
{
switch (r_type) {
case R_390_NONE:
break;
case R_390_8: /* Direct 8 bit. */
*(u8 *)loc = val;
break;
case R_390_12: /* Direct 12 bit. */
*(u16 *)loc &= 0xf000;
*(u16 *)loc |= val & 0xfff;
break;
case R_390_16: /* Direct 16 bit. */
*(u16 *)loc = val;
break;
case R_390_20: /* Direct 20 bit. */
*(u32 *)loc &= 0xf00000ff;
*(u32 *)loc |= (val & 0xfff) << 16; /* DL */
*(u32 *)loc |= (val & 0xff000) >> 4; /* DH */
break;
case R_390_32: /* Direct 32 bit. */
*(u32 *)loc = val;
break;
case R_390_64: /* Direct 64 bit. */
case R_390_GLOB_DAT:
case R_390_JMP_SLOT:
*(u64 *)loc = val;
break;
case R_390_PC16: /* PC relative 16 bit. */
*(u16 *)loc = (val - addr);
break;
case R_390_PC16DBL: /* PC relative 16 bit shifted by 1. */
*(u16 *)loc = (val - addr) >> 1;
break;
case R_390_PC32DBL: /* PC relative 32 bit shifted by 1. */
*(u32 *)loc = (val - addr) >> 1;
break;
case R_390_PC32: /* PC relative 32 bit. */
*(u32 *)loc = (val - addr);
break;
case R_390_PC64: /* PC relative 64 bit. */
*(u64 *)loc = (val - addr);
break;
case R_390_RELATIVE:
*(unsigned long *) loc = val;
break;
default:
return 1;
}
return 0;
}