From: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
commit f3b7e73b2c6619884351a3a0a7468642f852b8a2 upstream.
If the size of the PLT entries generated by apply_rela() exceeds
64KiB, the first ones can no longer reach __jump_r1 with brc. Fix by
using brcl. An alternative solution is to add a __jump_r1 copy after
every 64KiB, however, the space savings are quite small and do not
justify the additional complexity.
Fixes: f19fbd5ed642 ("s390: introduce execute-trampolines for branches")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Reviewed-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/kernel/module.c | 37 ++++++++++++++++++-------------------
1 file changed, 18 insertions(+), 19 deletions(-)
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -33,7 +33,7 @@
#define DEBUGP(fmt , ...)
#endif
-#define PLT_ENTRY_SIZE 20
+#define PLT_ENTRY_SIZE 22
void *module_alloc(unsigned long size)
{
@@ -341,27 +341,26 @@ static int apply_rela(Elf_Rela *rela, El
case R_390_PLTOFF32: /* 32 bit offset from GOT to PLT. */
case R_390_PLTOFF64: /* 16 bit offset from GOT to PLT. */
if (info->plt_initialized == 0) {
- unsigned int insn[5];
- unsigned int *ip = me->core_layout.base +
- me->arch.plt_offset +
- info->plt_offset;
-
- insn[0] = 0x0d10e310; /* basr 1,0 */
- insn[1] = 0x100a0004; /* lg 1,10(1) */
+ unsigned char insn[PLT_ENTRY_SIZE];
+ char *plt_base;
+ char *ip;
+
+ plt_base = me->core_layout.base + me->arch.plt_offset;
+ ip = plt_base + info->plt_offset;
+ *(int *)insn = 0x0d10e310; /* basr 1,0 */
+ *(int *)&insn[4] = 0x100c0004; /* lg 1,12(1) */
if (IS_ENABLED(CONFIG_EXPOLINE) && !nospec_disable) {
- unsigned int *ij;
- ij = me->core_layout.base +
- me->arch.plt_offset +
- me->arch.plt_size - PLT_ENTRY_SIZE;
- insn[2] = 0xa7f40000 + /* j __jump_r1 */
- (unsigned int)(u16)
- (((unsigned long) ij - 8 -
- (unsigned long) ip) / 2);
+ char *jump_r1;
+
+ jump_r1 = plt_base + me->arch.plt_size -
+ PLT_ENTRY_SIZE;
+ /* brcl 0xf,__jump_r1 */
+ *(short *)&insn[8] = 0xc0f4;
+ *(int *)&insn[10] = (jump_r1 - (ip + 8)) / 2;
} else {
- insn[2] = 0x07f10000; /* br %r1 */
+ *(int *)&insn[8] = 0x07f10000; /* br %r1 */
}
- insn[3] = (unsigned int) (val >> 32);
- insn[4] = (unsigned int) val;
+ *(long *)&insn[14] = val;
write(ip, insn, sizeof(insn));
info->plt_initialized = 1;
