// SPDX-License-Identifier: GPL-2.0
/*
 * Disassemble s390 instructions.
 *
 * Copyright IBM Corp. 2007
 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/kallsyms.h>
#include <linux/reboot.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/uaccess.h>
#include <linux/atomic.h>
#include <asm/dis.h>
#include <asm/io.h>
#include <asm/cpcmd.h>
#include <asm/lowcore.h>
#include <asm/debug.h>
#include <asm/irq.h>

/* Type of operand */
#define OPERAND_GPR     0x1     /* Operand printed as %rx */
#define OPERAND_FPR     0x2     /* Operand printed as %fx */
#define OPERAND_AR      0x4     /* Operand printed as %ax */
#define OPERAND_CR      0x8     /* Operand printed as %cx */
#define OPERAND_VR      0x10    /* Operand printed as %vx */
#define OPERAND_DISP    0x20    /* Operand printed as displacement */
#define OPERAND_BASE    0x40    /* Operand printed as base register */
#define OPERAND_INDEX   0x80    /* Operand printed as index register */
#define OPERAND_PCREL   0x100   /* Operand printed as pc-relative symbol */
#define OPERAND_SIGNED  0x200   /* Operand printed as signed value */
#define OPERAND_LENGTH  0x400   /* Operand printed as length (+1) */

struct s390_operand {
        unsigned char bits;     /* The number of bits in the operand. */
        unsigned char shift;    /* The number of bits to shift. */
        unsigned short flags;   /* One bit syntax flags. */
};

struct s390_insn {
        union {
                const char name[5];
                struct {
                        unsigned char zero;
                        unsigned int offset;
                } __packed;
        };
        unsigned char opfrag;
        unsigned char format;
};

struct s390_opcode_offset {
        unsigned char opcode;
        unsigned char mask;
        unsigned char byte;
        unsigned short offset;
        unsigned short count;
} __packed;

enum {
        UNUSED,
        A_8,    /* Access reg. starting at position 8 */
        A_12,   /* Access reg. starting at position 12 */
        A_24,   /* Access reg. starting at position 24 */
        A_28,   /* Access reg. starting at position 28 */
        B_16,   /* Base register starting at position 16 */
        B_32,   /* Base register starting at position 32 */
        C_8,    /* Control reg. starting at position 8 */
        C_12,   /* Control reg. starting at position 12 */
        D20_20, /* 20 bit displacement starting at 20 */
        D_20,   /* Displacement starting at position 20 */
        D_36,   /* Displacement starting at position 36 */
        F_8,    /* FPR starting at position 8 */
        F_12,   /* FPR starting at position 12 */
        F_16,   /* FPR starting at position 16 */
        F_24,   /* FPR starting at position 24 */
        F_28,   /* FPR starting at position 28 */
        F_32,   /* FPR starting at position 32 */
        I8_8,   /* 8 bit signed value starting at 8 */
        I8_32,  /* 8 bit signed value starting at 32 */
        I16_16, /* 16 bit signed value starting at 16 */
        I16_32, /* 16 bit signed value starting at 32 */
        I32_16, /* 32 bit signed value starting at 16 */
        J12_12, /* 12 bit PC relative offset at 12 */
        J16_16, /* 16 bit PC relative offset at 16 */
        J16_32, /* 16 bit PC relative offset at 32 */
        J24_24, /* 24 bit PC relative offset at 24 */
        J32_16, /* 32 bit PC relative offset at 16 */
        L4_8,   /* 4 bit length starting at position 8 */
        L4_12,  /* 4 bit length starting at position 12 */
        L8_8,   /* 8 bit length starting at position 8 */
        R_8,    /* GPR starting at position 8 */
        R_12,   /* GPR starting at position 12 */
        R_16,   /* GPR starting at position 16 */
        R_24,   /* GPR starting at position 24 */
        R_28,   /* GPR starting at position 28 */
        U4_8,   /* 4 bit unsigned value starting at 8 */
        U4_12,  /* 4 bit unsigned value starting at 12 */
        U4_16,  /* 4 bit unsigned value starting at 16 */
        U4_20,  /* 4 bit unsigned value starting at 20 */
        U4_24,  /* 4 bit unsigned value starting at 24 */
        U4_28,  /* 4 bit unsigned value starting at 28 */
        U4_32,  /* 4 bit unsigned value starting at 32 */
        U4_36,  /* 4 bit unsigned value starting at 36 */
        U8_8,   /* 8 bit unsigned value starting at 8 */
        U8_16,  /* 8 bit unsigned value starting at 16 */
        U8_24,  /* 8 bit unsigned value starting at 24 */
        U8_28,  /* 8 bit unsigned value starting at 28 */
        U8_32,  /* 8 bit unsigned value starting at 32 */
        U12_16, /* 12 bit unsigned value starting at 16 */
        U16_16, /* 16 bit unsigned value starting at 16 */
        U16_32, /* 16 bit unsigned value starting at 32 */
        U32_16, /* 32 bit unsigned value starting at 16 */
        VX_12,  /* Vector index register starting at position 12 */
        V_8,    /* Vector reg. starting at position 8 */
        V_12,   /* Vector reg. starting at position 12 */
        V_16,   /* Vector reg. starting at position 16 */
        V_32,   /* Vector reg. starting at position 32 */
        X_12,   /* Index register starting at position 12 */
};

static const struct s390_operand operands[] = {
        [UNUSED] = {  0,  0, 0 },
        [A_8]    = {  4,  8, OPERAND_AR },
        [A_12]   = {  4, 12, OPERAND_AR },
        [A_24]   = {  4, 24, OPERAND_AR },
        [A_28]   = {  4, 28, OPERAND_AR },
        [B_16]   = {  4, 16, OPERAND_BASE | OPERAND_GPR },
        [B_32]   = {  4, 32, OPERAND_BASE | OPERAND_GPR },
        [C_8]    = {  4,  8, OPERAND_CR },
        [C_12]   = {  4, 12, OPERAND_CR },
        [D20_20] = { 20, 20, OPERAND_DISP | OPERAND_SIGNED },
        [D_20]   = { 12, 20, OPERAND_DISP },
        [D_36]   = { 12, 36, OPERAND_DISP },
        [F_8]    = {  4,  8, OPERAND_FPR },
        [F_12]   = {  4, 12, OPERAND_FPR },
        [F_16]   = {  4, 16, OPERAND_FPR },
        [F_24]   = {  4, 24, OPERAND_FPR },
        [F_28]   = {  4, 28, OPERAND_FPR },
        [F_32]   = {  4, 32, OPERAND_FPR },
        [I8_8]   = {  8,  8, OPERAND_SIGNED },
        [I8_32]  = {  8, 32, OPERAND_SIGNED },
        [I16_16] = { 16, 16, OPERAND_SIGNED },
        [I16_32] = { 16, 32, OPERAND_SIGNED },
        [I32_16] = { 32, 16, OPERAND_SIGNED },
        [J12_12] = { 12, 12, OPERAND_PCREL },
        [J16_16] = { 16, 16, OPERAND_PCREL },
        [J16_32] = { 16, 32, OPERAND_PCREL },
        [J24_24] = { 24, 24, OPERAND_PCREL },
        [J32_16] = { 32, 16, OPERAND_PCREL },
        [L4_8]   = {  4,  8, OPERAND_LENGTH },
        [L4_12]  = {  4, 12, OPERAND_LENGTH },
        [L8_8]   = {  8,  8, OPERAND_LENGTH },
        [R_8]    = {  4,  8, OPERAND_GPR },
        [R_12]   = {  4, 12, OPERAND_GPR },
        [R_16]   = {  4, 16, OPERAND_GPR },
        [R_24]   = {  4, 24, OPERAND_GPR },
        [R_28]   = {  4, 28, OPERAND_GPR },
        [U4_8]   = {  4,  8, 0 },
        [U4_12]  = {  4, 12, 0 },
        [U4_16]  = {  4, 16, 0 },
        [U4_20]  = {  4, 20, 0 },
        [U4_24]  = {  4, 24, 0 },
        [U4_28]  = {  4, 28, 0 },
        [U4_32]  = {  4, 32, 0 },
        [U4_36]  = {  4, 36, 0 },
        [U8_8]   = {  8,  8, 0 },
        [U8_16]  = {  8, 16, 0 },
        [U8_24]  = {  8, 24, 0 },
        [U8_28]  = {  8, 28, 0 },
        [U8_32]  = {  8, 32, 0 },
        [U12_16] = { 12, 16, 0 },
        [U16_16] = { 16, 16, 0 },
        [U16_32] = { 16, 32, 0 },
        [U32_16] = { 32, 16, 0 },
        [VX_12]  = {  4, 12, OPERAND_INDEX | OPERAND_VR },
        [V_8]    = {  4,  8, OPERAND_VR },
        [V_12]   = {  4, 12, OPERAND_VR },
        [V_16]   = {  4, 16, OPERAND_VR },
        [V_32]   = {  4, 32, OPERAND_VR },
        [X_12]   = {  4, 12, OPERAND_INDEX | OPERAND_GPR },
};

static const unsigned char formats[][6] = {
        [INSTR_E]            = { 0, 0, 0, 0, 0, 0 },
        [INSTR_IE_UU]        = { U4_24, U4_28, 0, 0, 0, 0 },
        [INSTR_MII_UPP]      = { U4_8, J12_12, J24_24 },
        [INSTR_RIE_R0IU]     = { R_8, I16_16, U4_32, 0, 0, 0 },
        [INSTR_RIE_R0UU]     = { R_8, U16_16, U4_32, 0, 0, 0 },
        [INSTR_RIE_RRI0]     = { R_8, R_12, I16_16, 0, 0, 0 },
        [INSTR_RIE_RRP]      = { R_8, R_12, J16_16, 0, 0, 0 },
        [INSTR_RIE_RRPU]     = { R_8, R_12, U4_32, J16_16, 0, 0 },
        [INSTR_RIE_RRUUU]    = { R_8, R_12, U8_16, U8_24, U8_32, 0 },
        [INSTR_RIE_RUI0]     = { R_8, I16_16, U4_12, 0, 0, 0 },
        [INSTR_RIE_RUPI]     = { R_8, I8_32, U4_12, J16_16, 0, 0 },
        [INSTR_RIE_RUPU]     = { R_8, U8_32, U4_12, J16_16, 0, 0 },
        [INSTR_RIL_RI]       = { R_8, I32_16, 0, 0, 0, 0 },
        [INSTR_RIL_RP]       = { R_8, J32_16, 0, 0, 0, 0 },
        [INSTR_RIL_RU]       = { R_8, U32_16, 0, 0, 0, 0 },
        [INSTR_RIL_UP]       = { U4_8, J32_16, 0, 0, 0, 0 },
        [INSTR_RIS_RURDI]    = { R_8, I8_32, U4_12, D_20, B_16, 0 },
        [INSTR_RIS_RURDU]    = { R_8, U8_32, U4_12, D_20, B_16, 0 },
        [INSTR_RI_RI]        = { R_8, I16_16, 0, 0, 0, 0 },
        [INSTR_RI_RP]        = { R_8, J16_16, 0, 0, 0, 0 },
        [INSTR_RI_RU]        = { R_8, U16_16, 0, 0, 0, 0 },
        [INSTR_RI_UP]        = { U4_8, J16_16, 0, 0, 0, 0 },
        [INSTR_RRE_00]       = { 0, 0, 0, 0, 0, 0 },
        [INSTR_RRE_AA]       = { A_24, A_28, 0, 0, 0, 0 },
        [INSTR_RRE_AR]       = { A_24, R_28, 0, 0, 0, 0 },
        [INSTR_RRE_F0]       = { F_24, 0, 0, 0, 0, 0 },
        [INSTR_RRE_FF]       = { F_24, F_28, 0, 0, 0, 0 },
        [INSTR_RRE_FR]       = { F_24, R_28, 0, 0, 0, 0 },
        [INSTR_RRE_R0]       = { R_24, 0, 0, 0, 0, 0 },
        [INSTR_RRE_RA]       = { R_24, A_28, 0, 0, 0, 0 },
        [INSTR_RRE_RF]       = { R_24, F_28, 0, 0, 0, 0 },
        [INSTR_RRE_RR]       = { R_24, R_28, 0, 0, 0, 0 },
        [INSTR_RRF_0UFF]     = { F_24, F_28, U4_20, 0, 0, 0 },
        [INSTR_RRF_0URF]     = { R_24, F_28, U4_20, 0, 0, 0 },
        [INSTR_RRF_F0FF]     = { F_16, F_24, F_28, 0, 0, 0 },
        [INSTR_RRF_F0FF2]    = { F_24, F_16, F_28, 0, 0, 0 },
        [INSTR_RRF_F0FR]     = { F_24, F_16, R_28, 0, 0, 0 },
        [INSTR_RRF_FFRU]     = { F_24, F_16, R_28, U4_20, 0, 0 },
        [INSTR_RRF_FUFF]     = { F_24, F_16, F_28, U4_20, 0, 0 },
        [INSTR_RRF_FUFF2]    = { F_24, F_28, F_16, U4_20, 0, 0 },
        [INSTR_RRF_R0RR]     = { R_24, R_16, R_28, 0, 0, 0 },
        [INSTR_RRF_R0RR2]    = { R_24, R_28, R_16, 0, 0, 0 },
        [INSTR_RRF_RURR]     = { R_24, R_28, R_16, U4_20, 0, 0 },
        [INSTR_RRF_RURR2]    = { R_24, R_16, R_28, U4_20, 0, 0 },
        [INSTR_RRF_U0FF]     = { F_24, U4_16, F_28, 0, 0, 0 },
        [INSTR_RRF_U0RF]     = { R_24, U4_16, F_28, 0, 0, 0 },
        [INSTR_RRF_U0RR]     = { R_24, R_28, U4_16, 0, 0, 0 },
        [INSTR_RRF_URR]      = { R_24, R_28, U8_16, 0, 0, 0 },
        [INSTR_RRF_UUFF]     = { F_24, U4_16, F_28, U4_20, 0, 0 },
        [INSTR_RRF_UUFR]     = { F_24, U4_16, R_28, U4_20, 0, 0 },
        [INSTR_RRF_UURF]     = { R_24, U4_16, F_28, U4_20, 0, 0 },
        [INSTR_RRS_RRRDU]    = { R_8, R_12, U4_32, D_20, B_16 },
        [INSTR_RR_FF]        = { F_8, F_12, 0, 0, 0, 0 },
        [INSTR_RR_R0]        = { R_8,  0, 0, 0, 0, 0 },
        [INSTR_RR_RR]        = { R_8, R_12, 0, 0, 0, 0 },
        [INSTR_RR_U0]        = { U8_8,  0, 0, 0, 0, 0 },
        [INSTR_RR_UR]        = { U4_8, R_12, 0, 0, 0, 0 },
        [INSTR_RSI_RRP]      = { R_8, R_12, J16_16, 0, 0, 0 },
        [INSTR_RSL_LRDFU]    = { F_32, D_20, L8_8, B_16, U4_36, 0 },
        [INSTR_RSL_R0RD]     = { D_20, L4_8, B_16, 0, 0, 0 },
        [INSTR_RSY_AARD]     = { A_8, A_12, D20_20, B_16, 0, 0 },
        [INSTR_RSY_CCRD]     = { C_8, C_12, D20_20, B_16, 0, 0 },
        [INSTR_RSY_RDRU]     = { R_8, D20_20, B_16, U4_12, 0, 0 },
        [INSTR_RSY_RRRD]     = { R_8, R_12, D20_20, B_16, 0, 0 },
        [INSTR_RSY_RURD]     = { R_8, U4_12, D20_20, B_16, 0, 0 },
        [INSTR_RSY_RURD2]    = { R_8, D20_20, B_16, U4_12, 0, 0 },
        [INSTR_RS_AARD]      = { A_8, A_12, D_20, B_16, 0, 0 },
        [INSTR_RS_CCRD]      = { C_8, C_12, D_20, B_16, 0, 0 },
        [INSTR_RS_R0RD]      = { R_8, D_20, B_16, 0, 0, 0 },
        [INSTR_RS_RRRD]      = { R_8, R_12, D_20, B_16, 0, 0 },
        [INSTR_RS_RURD]      = { R_8, U4_12, D_20, B_16, 0, 0 },
        [INSTR_RXE_FRRD]     = { F_8, D_20, X_12, B_16, 0, 0 },
        [INSTR_RXE_RRRDU]    = { R_8, D_20, X_12, B_16, U4_32, 0 },
        [INSTR_RXF_FRRDF]    = { F_32, F_8, D_20, X_12, B_16, 0 },
        [INSTR_RXY_FRRD]     = { F_8, D20_20, X_12, B_16, 0, 0 },
        [INSTR_RXY_RRRD]     = { R_8, D20_20, X_12, B_16, 0, 0 },
        [INSTR_RXY_URRD]     = { U4_8, D20_20, X_12, B_16, 0, 0 },
        [INSTR_RX_FRRD]      = { F_8, D_20, X_12, B_16, 0, 0 },
        [INSTR_RX_RRRD]      = { R_8, D_20, X_12, B_16, 0, 0 },
        [INSTR_RX_URRD]      = { U4_8, D_20, X_12, B_16, 0, 0 },
        [INSTR_SIL_RDI]      = { D_20, B_16, I16_32, 0, 0, 0 },
        [INSTR_SIL_RDU]      = { D_20, B_16, U16_32, 0, 0, 0 },
        [INSTR_SIY_IRD]      = { D20_20, B_16, I8_8, 0, 0, 0 },
        [INSTR_SIY_URD]      = { D20_20, B_16, U8_8, 0, 0, 0 },
        [INSTR_SI_RD]        = { D_20, B_16, 0, 0, 0, 0 },
        [INSTR_SI_URD]       = { D_20, B_16, U8_8, 0, 0, 0 },
        [INSTR_SMI_U0RDP]    = { U4_8, J16_32, D_20, B_16, 0, 0 },
        [INSTR_SSE_RDRD]     = { D_20, B_16, D_36, B_32, 0, 0 },
        [INSTR_SSF_RRDRD]    = { D_20, B_16, D_36, B_32, R_8, 0 },
        [INSTR_SSF_RRDRD2]   = { R_8, D_20, B_16, D_36, B_32, 0 },
        [INSTR_SS_L0RDRD]    = { D_20, L8_8, B_16, D_36, B_32, 0 },
        [INSTR_SS_L2RDRD]    = { D_20, B_16, D_36, L8_8, B_32, 0 },
        [INSTR_SS_LIRDRD]    = { D_20, L4_8, B_16, D_36, B_32, U4_12 },
        [INSTR_SS_LLRDRD]    = { D_20, L4_8, B_16, D_36, L4_12, B_32 },
        [INSTR_SS_RRRDRD]    = { D_20, R_8, B_16, D_36, B_32, R_12 },
        [INSTR_SS_RRRDRD2]   = { R_8, D_20, B_16, R_12, D_36, B_32 },
        [INSTR_SS_RRRDRD3]   = { R_8, R_12, D_20, B_16, D_36, B_32 },
        [INSTR_S_00]         = { 0, 0, 0, 0, 0, 0 },
        [INSTR_S_RD]         = { D_20, B_16, 0, 0, 0, 0 },
        [INSTR_VRI_V0IU]     = { V_8, I16_16, U4_32, 0, 0, 0 },
        [INSTR_VRI_V0U]      = { V_8, U16_16, 0, 0, 0, 0 },
        [INSTR_VRI_V0UU2]    = { V_8, U16_16, U4_32, 0, 0, 0 },
        [INSTR_VRI_V0UUU]    = { V_8, U8_16, U8_24, U4_32, 0, 0 },
        [INSTR_VRI_VR0UU]    = { V_8, R_12, U8_28, U4_24, 0, 0 },
        [INSTR_VRI_VVUU]     = { V_8, V_12, U16_16, U4_32, 0, 0 },
        [INSTR_VRI_VVUUU]    = { V_8, V_12, U12_16, U4_32, U4_28, 0 },
        [INSTR_VRI_VVUUU2]   = { V_8, V_12, U8_28, U8_16, U4_24, 0 },
        [INSTR_VRI_VVV0U]    = { V_8, V_12, V_16, U8_24, 0, 0 },
        [INSTR_VRI_VVV0UU]   = { V_8, V_12, V_16, U8_24, U4_32, 0 },
        [INSTR_VRI_VVV0UU2]  = { V_8, V_12, V_16, U8_28, U4_24, 0 },
        [INSTR_VRR_0V]       = { V_12, 0, 0, 0, 0, 0 },
        [INSTR_VRR_0VV0U]    = { V_12, V_16, U4_24, 0, 0, 0 },
        [INSTR_VRR_RV0UU]    = { R_8, V_12, U4_24, U4_28, 0, 0 },
        [INSTR_VRR_VRR]      = { V_8, R_12, R_16, 0, 0, 0 },
        [INSTR_VRR_VV]       = { V_8, V_12, 0, 0, 0, 0 },
        [INSTR_VRR_VV0U]     = { V_8, V_12, U4_32, 0, 0, 0 },
        [INSTR_VRR_VV0U0U]   = { V_8, V_12, U4_32, U4_24, 0, 0 },
        [INSTR_VRR_VV0UU2]   = { V_8, V_12, U4_32, U4_28, 0, 0 },
        [INSTR_VRR_VV0UUU]   = { V_8, V_12, U4_32, U4_28, U4_24, 0 },
        [INSTR_VRR_VVV]      = { V_8, V_12, V_16, 0, 0, 0 },
        [INSTR_VRR_VVV0U]    = { V_8, V_12, V_16, U4_32, 0, 0 },
        [INSTR_VRR_VVV0U0U]  = { V_8, V_12, V_16, U4_32, U4_24, 0 },
        [INSTR_VRR_VVV0UU]   = { V_8, V_12, V_16, U4_32, U4_28, 0 },
        [INSTR_VRR_VVV0UUU]  = { V_8, V_12, V_16, U4_32, U4_28, U4_24 },
        [INSTR_VRR_VVV0V]    = { V_8, V_12, V_16, V_32, 0, 0 },
        [INSTR_VRR_VVVU0UV]  = { V_8, V_12, V_16, V_32, U4_28, U4_20 },
        [INSTR_VRR_VVVU0V]   = { V_8, V_12, V_16, V_32, U4_20, 0 },
        [INSTR_VRR_VVVUU0V]  = { V_8, V_12, V_16, V_32, U4_20, U4_24 },
        [INSTR_VRS_RRDV]     = { V_32, R_12, D_20, B_16, 0, 0 },
        [INSTR_VRS_RVRDU]    = { R_8, V_12, D_20, B_16, U4_32, 0 },
        [INSTR_VRS_VRRD]     = { V_8, R_12, D_20, B_16, 0, 0 },
        [INSTR_VRS_VRRDU]    = { V_8, R_12, D_20, B_16, U4_32, 0 },
        [INSTR_VRS_VVRDU]    = { V_8, V_12, D_20, B_16, U4_32, 0 },
        [INSTR_VRV_VVXRDU]   = { V_8, D_20, VX_12, B_16, U4_32, 0 },
        [INSTR_VRX_VRRDU]    = { V_8, D_20, X_12, B_16, U4_32, 0 },
        [INSTR_VRX_VV]       = { V_8, V_12, 0, 0, 0, 0 },
        [INSTR_VSI_URDV]     = { V_32, D_20, B_16, U8_8, 0, 0 },
};

static char long_insn_name[][7] = LONG_INSN_INITIALIZER;
static struct s390_insn opcode[] = OPCODE_TABLE_INITIALIZER;
static struct s390_opcode_offset opcode_offset[] = OPCODE_OFFSET_INITIALIZER;

/* Extracts an operand value from an instruction.  */
static unsigned int extract_operand(unsigned char *code,
                                    const struct s390_operand *operand)
{
        unsigned char *cp;
        unsigned int val;
        int bits;

        /* Extract fragments of the operand byte for byte.  */
        cp = code + operand->shift / 8;
        bits = (operand->shift & 7) + operand->bits;
        val = 0;
        do {
                val <<= 8;
                val |= (unsigned int) *cp++;
                bits -= 8;
        } while (bits > 0);
        val >>= -bits;
        val &= ((1U << (operand->bits - 1)) << 1) - 1;

        /* Check for special long displacement case.  */
        if (operand->bits == 20 && operand->shift == 20)
                val = (val & 0xff) << 12 | (val & 0xfff00) >> 8;

        /* Check for register extensions bits for vector registers. */
        if (operand->flags & OPERAND_VR) {
                if (operand->shift == 8)
                        val |= (code[4] & 8) << 1;
                else if (operand->shift == 12)
                        val |= (code[4] & 4) << 2;
                else if (operand->shift == 16)
                        val |= (code[4] & 2) << 3;
                else if (operand->shift == 32)
                        val |= (code[4] & 1) << 4;
        }

        /* Sign extend value if the operand is signed or pc relative.  */
        if ((operand->flags & (OPERAND_SIGNED | OPERAND_PCREL)) &&
            (val & (1U << (operand->bits - 1))))
                val |= (-1U << (operand->bits - 1)) << 1;

        /* Double value if the operand is pc relative.  */
        if (operand->flags & OPERAND_PCREL)
                val <<= 1;

        /* Length x in an instructions has real length x + 1.  */
        if (operand->flags & OPERAND_LENGTH)
                val++;
        return val;
}

struct s390_insn *find_insn(unsigned char *code)
{
        struct s390_opcode_offset *entry;
        struct s390_insn *insn;
        unsigned char opfrag;
        int i;

        /* Search the opcode offset table to find an entry which
         * matches the beginning of the opcode. If there is no match
         * the last entry will be used, which is the default entry for
         * unknown instructions as well as 1-byte opcode instructions.
         */
        for (i = 0; i < ARRAY_SIZE(opcode_offset); i++) {
                entry = &opcode_offset[i];
                if (entry->opcode == code[0])
                        break;
        }

        opfrag = *(code + entry->byte) & entry->mask;

        insn = &opcode[entry->offset];
        for (i = 0; i < entry->count; i++) {
                if (insn->opfrag == opfrag)
                        return insn;
                insn++;
        }
        return NULL;
}

static int print_insn(char *buffer, unsigned char *code, unsigned long addr)
{
        struct s390_insn *insn;
        const unsigned char *ops;
        const struct s390_operand *operand;
        unsigned int value;
        char separator;
        char *ptr;
        int i;

        ptr = buffer;
        insn = find_insn(code);
        if (insn) {
                if (insn->zero == 0)
                        ptr += sprintf(ptr, "%.7s\t",
                                       long_insn_name[insn->offset]);
                else
                        ptr += sprintf(ptr, "%.5s\t", insn->name);
                /* Extract the operands. */
                separator = 0;
                for (ops = formats[insn->format], i = 0;
                     *ops != 0 && i < 6; ops++, i++) {
                        operand = operands + *ops;
                        value = extract_operand(code, operand);
                        if ((operand->flags & OPERAND_INDEX)  && value == 0)
                                continue;
                        if ((operand->flags & OPERAND_BASE) &&
                            value == 0 && separator == '(') {
                                separator = ',';
                                continue;
                        }
                        if (separator)
                                ptr += sprintf(ptr, "%c", separator);
                        if (operand->flags & OPERAND_GPR)
                                ptr += sprintf(ptr, "%%r%i", value);
                        else if (operand->flags & OPERAND_FPR)
                                ptr += sprintf(ptr, "%%f%i", value);
                        else if (operand->flags & OPERAND_AR)
                                ptr += sprintf(ptr, "%%a%i", value);
                        else if (operand->flags & OPERAND_CR)
                                ptr += sprintf(ptr, "%%c%i", value);
                        else if (operand->flags & OPERAND_VR)
                                ptr += sprintf(ptr, "%%v%i", value);
                        else if (operand->flags & OPERAND_PCREL)
                                ptr += sprintf(ptr, "%lx", (signed int) value
                                                                      + addr);
                        else if (operand->flags & OPERAND_SIGNED)
                                ptr += sprintf(ptr, "%i", value);
                        else
                                ptr += sprintf(ptr, "%u", value);
                        if (operand->flags & OPERAND_DISP)
                                separator = '(';
                        else if (operand->flags & OPERAND_BASE) {
                                ptr += sprintf(ptr, ")");
                                separator = ',';
                        } else
                                separator = ',';
                }
        } else
                ptr += sprintf(ptr, "unknown");
        return (int) (ptr - buffer);
}

void show_code(struct pt_regs *regs)
{
        char *mode = user_mode(regs) ? "User" : "Krnl";
        unsigned char code[64];
        char buffer[128], *ptr;
        mm_segment_t old_fs;
        unsigned long addr;
        int start, end, opsize, hops, i;

        /* Get a snapshot of the 64 bytes surrounding the fault address. */
        old_fs = get_fs();
        set_fs(user_mode(regs) ? USER_DS : KERNEL_DS);
        for (start = 32; start && regs->psw.addr >= 34 - start; start -= 2) {
                addr = regs->psw.addr - 34 + start;
                if (__copy_from_user(code + start - 2,
                                     (char __user *) addr, 2))
                        break;
        }
        for (end = 32; end < 64; end += 2) {
                addr = regs->psw.addr + end - 32;
                if (__copy_from_user(code + end,
                                     (char __user *) addr, 2))
                        break;
        }
        set_fs(old_fs);
        /* Code snapshot useable ? */
        if ((regs->psw.addr & 1) || start >= end) {
                printk("%s Code: Bad PSW.\n", mode);
                return;
        }
        /* Find a starting point for the disassembly. */
        while (start < 32) {
                for (i = 0, hops = 0; start + i < 32 && hops < 3; hops++) {
                        if (!find_insn(code + start + i))
                                break;
                        i += insn_length(code[start + i]);
                }
                if (start + i == 32)
                        /* Looks good, sequence ends at PSW. */
                        break;
                start += 2;
        }
        /* Decode the instructions. */
        ptr = buffer;
        ptr += sprintf(ptr, "%s Code:", mode);
        hops = 0;
        while (start < end && hops < 8) {
                opsize = insn_length(code[start]);
                if  (start + opsize == 32)
                        *ptr++ = '#';
                else if (start == 32)
                        *ptr++ = '>';
                else
                        *ptr++ = ' ';
                addr = regs->psw.addr + start - 32;
                ptr += sprintf(ptr, "%016lx: ", addr);
                if (start + opsize >= end)
                        break;
                for (i = 0; i < opsize; i++)
                        ptr += sprintf(ptr, "%02x", code[start + i]);
                *ptr++ = '\t';
                if (i < 6)
                        *ptr++ = '\t';
                ptr += print_insn(ptr, code + start, addr);
                start += opsize;
                pr_cont("%s", buffer);
                ptr = buffer;
                ptr += sprintf(ptr, "\n          ");
                hops++;
        }
        pr_cont("\n");
}

void print_fn_code(unsigned char *code, unsigned long len)
{
        char buffer[64], *ptr;
        int opsize, i;

        while (len) {
                ptr = buffer;
                opsize = insn_length(*code);
                if (opsize > len)
                        break;
                ptr += sprintf(ptr, "%p: ", code);
                for (i = 0; i < opsize; i++)
                        ptr += sprintf(ptr, "%02x", code[i]);
                *ptr++ = '\t';
                if (i < 4)
                        *ptr++ = '\t';
                ptr += print_insn(ptr, code, (unsigned long) code);
                *ptr++ = '\n';
                *ptr++ = 0;
                printk("%s", buffer);
                code += opsize;
                len -= opsize;
        }
}