s390/kprobes: add support for compare and branch instructions
The compare and branch instructions (not relative) all need special
handling when kprobed:
- if a branch was taken, the instruction pointer should be left alone
- if a branch was not taken, the instruction pointer must be adjusted
The compare and branch instructions family was introduced with the general
instruction extension facility (z10).
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 3388b2b..adbbe7f 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -105,14 +105,31 @@
fixup |= FIXUP_RETURN_REGISTER;
break;
case 0xeb:
- if ((insn[2] & 0xff) == 0x44 || /* bxhg */
- (insn[2] & 0xff) == 0x45) /* bxleg */
+ switch (insn[2] & 0xff) {
+ case 0x44: /* bxhg */
+ case 0x45: /* bxleg */
fixup = FIXUP_BRANCH_NOT_TAKEN;
+ break;
+ }
break;
case 0xe3: /* bctg */
if ((insn[2] & 0xff) == 0x46)
fixup = FIXUP_BRANCH_NOT_TAKEN;
break;
+ case 0xec:
+ switch (insn[2] & 0xff) {
+ case 0xe5: /* clgrb */
+ case 0xe6: /* cgrb */
+ case 0xf6: /* crb */
+ case 0xf7: /* clrb */
+ case 0xfc: /* cgib */
+ case 0xfd: /* cglib */
+ case 0xfe: /* cib */
+ case 0xff: /* clib */
+ fixup = FIXUP_BRANCH_NOT_TAKEN;
+ break;
+ }
+ break;
}
return fixup;
}