Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6b169ac9 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent bee5c286

arch/s390/kernel/kprobes.c

+19 −2
Original line number Diff line number Diff line
@@ -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;

}