// SPDX-License-Identifier: GPL-2.0
/*
 *    Common helper functions for kprobes and uprobes
 *
 *    Copyright IBM Corp. 2014
 */

#include <linux/errno.h>
#include <asm/kprobes.h>
#include <asm/dis.h>

int probe_is_prohibited_opcode(u16 *insn)
{
        if (!is_known_insn((unsigned char *)insn))
                return -EINVAL;
        switch (insn[0] >> 8) {
        case 0x0c:      /* bassm */
        case 0x0b:      /* bsm   */
        case 0x83:      /* diag  */
        case 0x44:      /* ex    */
        case 0xac:      /* stnsm */
        case 0xad:      /* stosm */
                return -EINVAL;
        case 0xc6:
                switch (insn[0] & 0x0f) {
                case 0x00: /* exrl   */
                        return -EINVAL;
                }
        }
        switch (insn[0]) {
        case 0x0101:    /* pr    */
        case 0xb25a:    /* bsa   */
        case 0xb240:    /* bakr  */
        case 0xb258:    /* bsg   */
        case 0xb218:    /* pc    */
        case 0xb228:    /* pt    */
        case 0xb98d:    /* epsw  */
        case 0xe560:    /* tbegin */
        case 0xe561:    /* tbeginc */
        case 0xb2f8:    /* tend  */
                return -EINVAL;
        }
        return 0;
}

int probe_get_fixup_type(u16 *insn)
{
        /* default fixup method */
        int fixup = FIXUP_PSW_NORMAL;

        switch (insn[0] >> 8) {
        case 0x05:      /* balr */
        case 0x0d:      /* basr */
                fixup = FIXUP_RETURN_REGISTER;
                /* if r2 = 0, no branch will be taken */
                if ((insn[0] & 0x0f) == 0)
                        fixup |= FIXUP_BRANCH_NOT_TAKEN;
                break;
        case 0x06:      /* bctr */
        case 0x07:      /* bcr  */
                fixup = FIXUP_BRANCH_NOT_TAKEN;
                break;
        case 0x45:      /* bal  */
        case 0x4d:      /* bas  */
                fixup = FIXUP_RETURN_REGISTER;
                break;
        case 0x47:      /* bc   */
        case 0x46:      /* bct  */
        case 0x86:      /* bxh  */
        case 0x87:      /* bxle */
                fixup = FIXUP_BRANCH_NOT_TAKEN;
                break;
        case 0x82:      /* lpsw */
                fixup = FIXUP_NOT_REQUIRED;
                break;
        case 0xb2:      /* lpswe */
                if ((insn[0] & 0xff) == 0xb2)
                        fixup = FIXUP_NOT_REQUIRED;
                break;
        case 0xa7:      /* bras */
                if ((insn[0] & 0x0f) == 0x05)
                        fixup |= FIXUP_RETURN_REGISTER;
                break;
        case 0xc0:
                if ((insn[0] & 0x0f) == 0x05)   /* brasl */
                        fixup |= FIXUP_RETURN_REGISTER;
                break;
        case 0xeb:
                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;
}

int probe_is_insn_relative_long(u16 *insn)
{
        /* Check if we have a RIL-b or RIL-c format instruction which
         * we need to modify in order to avoid instruction emulation. */
        switch (insn[0] >> 8) {
        case 0xc0:
                if ((insn[0] & 0x0f) == 0x00) /* larl */
                        return true;
                break;
        case 0xc4:
                switch (insn[0] & 0x0f) {
                case 0x02: /* llhrl  */
                case 0x04: /* lghrl  */
                case 0x05: /* lhrl   */
                case 0x06: /* llghrl */
                case 0x07: /* sthrl  */
                case 0x08: /* lgrl   */
                case 0x0b: /* stgrl  */
                case 0x0c: /* lgfrl  */
                case 0x0d: /* lrl    */
                case 0x0e: /* llgfrl */
                case 0x0f: /* strl   */
                        return true;
                }
                break;
        case 0xc6:
                switch (insn[0] & 0x0f) {
                case 0x02: /* pfdrl  */
                case 0x04: /* cghrl  */
                case 0x05: /* chrl   */
                case 0x06: /* clghrl */
                case 0x07: /* clhrl  */
                case 0x08: /* cgrl   */
                case 0x0a: /* clgrl  */
                case 0x0c: /* cgfrl  */
                case 0x0d: /* crl    */
                case 0x0e: /* clgfrl */
                case 0x0f: /* clrl   */
                        return true;
                }
                break;
        }
        return false;
}