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s390/kprobes: add support for compare and branch instructions

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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>
This commit is contained in:
Heiko Carstens 2013-08-01 10:16:27 +02:00 committed by Martin Schwidefsky
parent bee5c2863e
commit 6b169ac9b4
1 changed files with 19 additions and 2 deletions
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21
arch/s390/kernel/kprobes.c
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@ -105,14 +105,31 @@ static int __kprobes get_fixup_type(kprobe_opcode_t *insn)
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;
}