// SPDX-License-Identifier: GPL-2.0
/*
 * BPF Jit compiler for s390.
 *
 * Minimum build requirements:
 *
 *  - HAVE_MARCH_Z196_FEATURES: laal, laalg
 *  - HAVE_MARCH_Z10_FEATURES: msfi, cgrj, clgrj
 *  - HAVE_MARCH_Z9_109_FEATURES: alfi, llilf, clfi, oilf, nilf
 *  - PACK_STACK
 *  - 64BIT
 *
 * Copyright IBM Corp. 2012,2015
 *
 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 *            Michael Holzheu <holzheu@linux.vnet.ibm.com>
 */

#define KMSG_COMPONENT "bpf_jit"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/init.h>
#include <linux/bpf.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <asm/cacheflush.h>
#include <asm/dis.h>
#include <asm/facility.h>
#include <asm/nospec-branch.h>
#include <asm/set_memory.h>
#include "bpf_jit.h"

struct bpf_jit {
        u32 seen;               /* Flags to remember seen eBPF instructions */
        u32 seen_reg[16];       /* Array to remember which registers are used */
        u32 *addrs;             /* Array with relative instruction addresses */
        u8 *prg_buf;            /* Start of program */
        int size;               /* Size of program and literal pool */
        int size_prg;           /* Size of program */
        int prg;                /* Current position in program */
        int lit32_start;        /* Start of 32-bit literal pool */
        int lit32;              /* Current position in 32-bit literal pool */
        int lit64_start;        /* Start of 64-bit literal pool */
        int lit64;              /* Current position in 64-bit literal pool */
        int base_ip;            /* Base address for literal pool */
        int exit_ip;            /* Address of exit */
        int r1_thunk_ip;        /* Address of expoline thunk for 'br %r1' */
        int r14_thunk_ip;       /* Address of expoline thunk for 'br %r14' */
        int tail_call_start;    /* Tail call start offset */
        int labels[1];          /* Labels for local jumps */
};

#define SEEN_MEM        BIT(0)          /* use mem[] for temporary storage */
#define SEEN_LITERAL    BIT(1)          /* code uses literals */
#define SEEN_FUNC       BIT(2)          /* calls C functions */
#define SEEN_TAIL_CALL  BIT(3)          /* code uses tail calls */
#define SEEN_STACK      (SEEN_FUNC | SEEN_MEM)

/*
 * s390 registers
 */
#define REG_W0          (MAX_BPF_JIT_REG + 0)   /* Work register 1 (even) */
#define REG_W1          (MAX_BPF_JIT_REG + 1)   /* Work register 2 (odd) */
#define REG_L           (MAX_BPF_JIT_REG + 2)   /* Literal pool register */
#define REG_15          (MAX_BPF_JIT_REG + 3)   /* Register 15 */
#define REG_0           REG_W0                  /* Register 0 */
#define REG_1           REG_W1                  /* Register 1 */
#define REG_2           BPF_REG_1               /* Register 2 */
#define REG_14          BPF_REG_0               /* Register 14 */

/*
 * Mapping of BPF registers to s390 registers
 */
static const int reg2hex[] = {
        /* Return code */
        [BPF_REG_0]     = 14,
        /* Function parameters */
        [BPF_REG_1]     = 2,
        [BPF_REG_2]     = 3,
        [BPF_REG_3]     = 4,
        [BPF_REG_4]     = 5,
        [BPF_REG_5]     = 6,
        /* Call saved registers */
        [BPF_REG_6]     = 7,
        [BPF_REG_7]     = 8,
        [BPF_REG_8]     = 9,
        [BPF_REG_9]     = 10,
        /* BPF stack pointer */
        [BPF_REG_FP]    = 13,
        /* Register for blinding */
        [BPF_REG_AX]    = 12,
        /* Work registers for s390x backend */
        [REG_W0]        = 0,
        [REG_W1]        = 1,
        [REG_L]         = 11,
        [REG_15]        = 15,
};

static inline u32 reg(u32 dst_reg, u32 src_reg)
{
        return reg2hex[dst_reg] << 4 | reg2hex[src_reg];
}

static inline u32 reg_high(u32 reg)
{
        return reg2hex[reg] << 4;
}

static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
{
        u32 r1 = reg2hex[b1];

        if (!jit->seen_reg[r1] && r1 >= 6 && r1 <= 15)
                jit->seen_reg[r1] = 1;
}

#define REG_SET_SEEN(b1)                                        \
({                                                              \
        reg_set_seen(jit, b1);                                  \
})

#define REG_SEEN(b1) jit->seen_reg[reg2hex[(b1)]]

/*
 * EMIT macros for code generation
 */

#define _EMIT2(op)                                              \
({                                                              \
        if (jit->prg_buf)                                       \
                *(u16 *) (jit->prg_buf + jit->prg) = (op);      \
        jit->prg += 2;                                          \
})

#define EMIT2(op, b1, b2)                                       \
({                                                              \
        _EMIT2((op) | reg(b1, b2));                             \
        REG_SET_SEEN(b1);                                       \
        REG_SET_SEEN(b2);                                       \
})

#define _EMIT4(op)                                              \
({                                                              \
        if (jit->prg_buf)                                       \
                *(u32 *) (jit->prg_buf + jit->prg) = (op);      \
        jit->prg += 4;                                          \
})

#define EMIT4(op, b1, b2)                                       \
({                                                              \
        _EMIT4((op) | reg(b1, b2));                             \
        REG_SET_SEEN(b1);                                       \
        REG_SET_SEEN(b2);                                       \
})

#define EMIT4_RRF(op, b1, b2, b3)                               \
({                                                              \
        _EMIT4((op) | reg_high(b3) << 8 | reg(b1, b2));         \
        REG_SET_SEEN(b1);                                       \
        REG_SET_SEEN(b2);                                       \
        REG_SET_SEEN(b3);                                       \
})

#define _EMIT4_DISP(op, disp)                                   \
({                                                              \
        unsigned int __disp = (disp) & 0xfff;                   \
        _EMIT4((op) | __disp);                                  \
})

#define EMIT4_DISP(op, b1, b2, disp)                            \
({                                                              \
        _EMIT4_DISP((op) | reg_high(b1) << 16 |                 \
                    reg_high(b2) << 8, (disp));                 \
        REG_SET_SEEN(b1);                                       \
        REG_SET_SEEN(b2);                                       \
})

#define EMIT4_IMM(op, b1, imm)                                  \
({                                                              \
        unsigned int __imm = (imm) & 0xffff;                    \
        _EMIT4((op) | reg_high(b1) << 16 | __imm);              \
        REG_SET_SEEN(b1);                                       \
})

#define EMIT4_PCREL(op, pcrel)                                  \
({                                                              \
        long __pcrel = ((pcrel) >> 1) & 0xffff;                 \
        _EMIT4((op) | __pcrel);                                 \
})

#define EMIT4_PCREL_RIC(op, mask, target)                       \
({                                                              \
        int __rel = ((target) - jit->prg) / 2;                  \
        _EMIT4((op) | (mask) << 20 | (__rel & 0xffff));         \
})

#define _EMIT6(op1, op2)                                        \
({                                                              \
        if (jit->prg_buf) {                                     \
                *(u32 *) (jit->prg_buf + jit->prg) = (op1);     \
                *(u16 *) (jit->prg_buf + jit->prg + 4) = (op2); \
        }                                                       \
        jit->prg += 6;                                          \
})

#define _EMIT6_DISP(op1, op2, disp)                             \
({                                                              \
        unsigned int __disp = (disp) & 0xfff;                   \
        _EMIT6((op1) | __disp, op2);                            \
})

#define _EMIT6_DISP_LH(op1, op2, disp)                          \
({                                                              \
        u32 _disp = (u32) (disp);                               \
        unsigned int __disp_h = _disp & 0xff000;                \
        unsigned int __disp_l = _disp & 0x00fff;                \
        _EMIT6((op1) | __disp_l, (op2) | __disp_h >> 4);        \
})

#define EMIT6_DISP_LH(op1, op2, b1, b2, b3, disp)               \
({                                                              \
        _EMIT6_DISP_LH((op1) | reg(b1, b2) << 16 |              \
                       reg_high(b3) << 8, op2, disp);           \
        REG_SET_SEEN(b1);                                       \
        REG_SET_SEEN(b2);                                       \
        REG_SET_SEEN(b3);                                       \
})

#define EMIT6_PCREL_LABEL(op1, op2, b1, b2, label, mask)        \
({                                                              \
        int rel = (jit->labels[label] - jit->prg) >> 1;         \
        _EMIT6((op1) | reg(b1, b2) << 16 | (rel & 0xffff),      \
               (op2) | (mask) << 12);                           \
        REG_SET_SEEN(b1);                                       \
        REG_SET_SEEN(b2);                                       \
})

#define EMIT6_PCREL_IMM_LABEL(op1, op2, b1, imm, label, mask)   \
({                                                              \
        int rel = (jit->labels[label] - jit->prg) >> 1;         \
        _EMIT6((op1) | (reg_high(b1) | (mask)) << 16 |          \
                (rel & 0xffff), (op2) | ((imm) & 0xff) << 8);   \
        REG_SET_SEEN(b1);                                       \
        BUILD_BUG_ON(((unsigned long) (imm)) > 0xff);           \
})

#define EMIT6_PCREL(op1, op2, b1, b2, i, off, mask)             \
({                                                              \
        /* Branch instruction needs 6 bytes */                  \
        int rel = (addrs[(i) + (off) + 1] - (addrs[(i) + 1] - 6)) / 2;\
        _EMIT6((op1) | reg(b1, b2) << 16 | (rel & 0xffff), (op2) | (mask));\
        REG_SET_SEEN(b1);                                       \
        REG_SET_SEEN(b2);                                       \
})

#define EMIT6_PCREL_RILB(op, b, target)                         \
({                                                              \
        unsigned int rel = (int)((target) - jit->prg) / 2;      \
        _EMIT6((op) | reg_high(b) << 16 | rel >> 16, rel & 0xffff);\
        REG_SET_SEEN(b);                                        \
})

#define EMIT6_PCREL_RIL(op, target)                             \
({                                                              \
        unsigned int rel = (int)((target) - jit->prg) / 2;      \
        _EMIT6((op) | rel >> 16, rel & 0xffff);                 \
})

#define EMIT6_PCREL_RILC(op, mask, target)                      \
({                                                              \
        EMIT6_PCREL_RIL((op) | (mask) << 20, (target));         \
})

#define _EMIT6_IMM(op, imm)                                     \
({                                                              \
        unsigned int __imm = (imm);                             \
        _EMIT6((op) | (__imm >> 16), __imm & 0xffff);           \
})

#define EMIT6_IMM(op, b1, imm)                                  \
({                                                              \
        _EMIT6_IMM((op) | reg_high(b1) << 16, imm);             \
        REG_SET_SEEN(b1);                                       \
})

#define _EMIT_CONST_U32(val)                                    \
({                                                              \
        unsigned int ret;                                       \
        ret = jit->lit32;                                       \
        if (jit->prg_buf)                                       \
                *(u32 *)(jit->prg_buf + jit->lit32) = (u32)(val);\
        jit->lit32 += 4;                                        \
        ret;                                                    \
})

#define EMIT_CONST_U32(val)                                     \
({                                                              \
        jit->seen |= SEEN_LITERAL;                              \
        _EMIT_CONST_U32(val) - jit->base_ip;                    \
})

#define _EMIT_CONST_U64(val)                                    \
({                                                              \
        unsigned int ret;                                       \
        ret = jit->lit64;                                       \
        if (jit->prg_buf)                                       \
                *(u64 *)(jit->prg_buf + jit->lit64) = (u64)(val);\
        jit->lit64 += 8;                                        \
        ret;                                                    \
})

#define EMIT_CONST_U64(val)                                     \
({                                                              \
        jit->seen |= SEEN_LITERAL;                              \
        _EMIT_CONST_U64(val) - jit->base_ip;                    \
})

#define EMIT_ZERO(b1)                                           \
({                                                              \
        if (!fp->aux->verifier_zext) {                          \
                /* llgfr %dst,%dst (zero extend to 64 bit) */   \
                EMIT4(0xb9160000, b1, b1);                      \
                REG_SET_SEEN(b1);                               \
        }                                                       \
})

/*
 * Return whether this is the first pass. The first pass is special, since we
 * don't know any sizes yet, and thus must be conservative.
 */
static bool is_first_pass(struct bpf_jit *jit)
{
        return jit->size == 0;
}

/*
 * Return whether this is the code generation pass. The code generation pass is
 * special, since we should change as little as possible.
 */
static bool is_codegen_pass(struct bpf_jit *jit)
{
        return jit->prg_buf;
}

/*
 * Return whether "rel" can be encoded as a short PC-relative offset
 */
static bool is_valid_rel(int rel)
{
        return rel >= -65536 && rel <= 65534;
}

/*
 * Return whether "off" can be reached using a short PC-relative offset
 */
static bool can_use_rel(struct bpf_jit *jit, int off)
{
        return is_valid_rel(off - jit->prg);
}

/*
 * Return whether given displacement can be encoded using
 * Long-Displacement Facility
 */
static bool is_valid_ldisp(int disp)
{
        return disp >= -524288 && disp <= 524287;
}

/*
 * Return whether the next 32-bit literal pool entry can be referenced using
 * Long-Displacement Facility
 */
static bool can_use_ldisp_for_lit32(struct bpf_jit *jit)
{
        return is_valid_ldisp(jit->lit32 - jit->base_ip);
}

/*
 * Return whether the next 64-bit literal pool entry can be referenced using
 * Long-Displacement Facility
 */
static bool can_use_ldisp_for_lit64(struct bpf_jit *jit)
{
        return is_valid_ldisp(jit->lit64 - jit->base_ip);
}

/*
 * Fill whole space with illegal instructions
 */
static void jit_fill_hole(void *area, unsigned int size)
{
        memset(area, 0, size);
}

/*
 * Save registers from "rs" (register start) to "re" (register end) on stack
 */
static void save_regs(struct bpf_jit *jit, u32 rs, u32 re)
{
        u32 off = STK_OFF_R6 + (rs - 6) * 8;

        if (rs == re)
                /* stg %rs,off(%r15) */
                _EMIT6(0xe300f000 | rs << 20 | off, 0x0024);
        else
                /* stmg %rs,%re,off(%r15) */
                _EMIT6_DISP(0xeb00f000 | rs << 20 | re << 16, 0x0024, off);
}

/*
 * Restore registers from "rs" (register start) to "re" (register end) on stack
 */
static void restore_regs(struct bpf_jit *jit, u32 rs, u32 re, u32 stack_depth)
{
        u32 off = STK_OFF_R6 + (rs - 6) * 8;

        if (jit->seen & SEEN_STACK)
                off += STK_OFF + stack_depth;

        if (rs == re)
                /* lg %rs,off(%r15) */
                _EMIT6(0xe300f000 | rs << 20 | off, 0x0004);
        else
                /* lmg %rs,%re,off(%r15) */
                _EMIT6_DISP(0xeb00f000 | rs << 20 | re << 16, 0x0004, off);
}

/*
 * Return first seen register (from start)
 */
static int get_start(struct bpf_jit *jit, int start)
{
        int i;

        for (i = start; i <= 15; i++) {
                if (jit->seen_reg[i])
                        return i;
        }
        return 0;
}

/*
 * Return last seen register (from start) (gap >= 2)
 */
static int get_end(struct bpf_jit *jit, int start)
{
        int i;

        for (i = start; i < 15; i++) {
                if (!jit->seen_reg[i] && !jit->seen_reg[i + 1])
                        return i - 1;
        }
        return jit->seen_reg[15] ? 15 : 14;
}

#define REGS_SAVE       1
#define REGS_RESTORE    0
/*
 * Save and restore clobbered registers (6-15) on stack.
 * We save/restore registers in chunks with gap >= 2 registers.
 */
static void save_restore_regs(struct bpf_jit *jit, int op, u32 stack_depth)
{
        const int last = 15, save_restore_size = 6;
        int re = 6, rs;

        if (is_first_pass(jit)) {
                /*
                 * We don't know yet which registers are used. Reserve space
                 * conservatively.
                 */
                jit->prg += (last - re + 1) * save_restore_size;
                return;
        }

        do {
                rs = get_start(jit, re);
                if (!rs)
                        break;
                re = get_end(jit, rs + 1);
                if (op == REGS_SAVE)
                        save_regs(jit, rs, re);
                else
                        restore_regs(jit, rs, re, stack_depth);
                re++;
        } while (re <= last);
}

/*
 * Emit function prologue
 *
 * Save registers and create stack frame if necessary.
 * See stack frame layout desription in "bpf_jit.h"!
 */
static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth)
{
        if (jit->seen & SEEN_TAIL_CALL) {
                /* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */
                _EMIT6(0xd703f000 | STK_OFF_TCCNT, 0xf000 | STK_OFF_TCCNT);
        } else {
                /* j tail_call_start: NOP if no tail calls are used */
                EMIT4_PCREL(0xa7f40000, 6);
                /* bcr 0,%0 */
                EMIT2(0x0700, 0, REG_0);
        }
        /* Tail calls have to skip above initialization */
        jit->tail_call_start = jit->prg;
        /* Save registers */
        save_restore_regs(jit, REGS_SAVE, stack_depth);
        /* Setup literal pool */
        if (is_first_pass(jit) || (jit->seen & SEEN_LITERAL)) {
                if (!is_first_pass(jit) &&
                    is_valid_ldisp(jit->size - (jit->prg + 2))) {
                        /* basr %l,0 */
                        EMIT2(0x0d00, REG_L, REG_0);
                        jit->base_ip = jit->prg;
                } else {
                        /* larl %l,lit32_start */
                        EMIT6_PCREL_RILB(0xc0000000, REG_L, jit->lit32_start);
                        jit->base_ip = jit->lit32_start;
                }
        }
        /* Setup stack and backchain */
        if (is_first_pass(jit) || (jit->seen & SEEN_STACK)) {
                if (is_first_pass(jit) || (jit->seen & SEEN_FUNC))
                        /* lgr %w1,%r15 (backchain) */
                        EMIT4(0xb9040000, REG_W1, REG_15);
                /* la %bfp,STK_160_UNUSED(%r15) (BPF frame pointer) */
                EMIT4_DISP(0x41000000, BPF_REG_FP, REG_15, STK_160_UNUSED);
                /* aghi %r15,-STK_OFF */
                EMIT4_IMM(0xa70b0000, REG_15, -(STK_OFF + stack_depth));
                if (is_first_pass(jit) || (jit->seen & SEEN_FUNC))
                        /* stg %w1,152(%r15) (backchain) */
                        EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
                                      REG_15, 152);
        }
}

/*
 * Function epilogue
 */
static void bpf_jit_epilogue(struct bpf_jit *jit, u32 stack_depth)
{
        jit->exit_ip = jit->prg;
        /* Load exit code: lgr %r2,%b0 */
        EMIT4(0xb9040000, REG_2, BPF_REG_0);
        /* Restore registers */
        save_restore_regs(jit, REGS_RESTORE, stack_depth);
        if (__is_defined(CC_USING_EXPOLINE) && !nospec_disable) {
                jit->r14_thunk_ip = jit->prg;
                /* Generate __s390_indirect_jump_r14 thunk */
                if (test_facility(35)) {
                        /* exrl %r0,.+10 */
                        EMIT6_PCREL_RIL(0xc6000000, jit->prg + 10);
                } else {
                        /* larl %r1,.+14 */
                        EMIT6_PCREL_RILB(0xc0000000, REG_1, jit->prg + 14);
                        /* ex 0,0(%r1) */
                        EMIT4_DISP(0x44000000, REG_0, REG_1, 0);
                }
                /* j . */
                EMIT4_PCREL(0xa7f40000, 0);
        }
        /* br %r14 */
        _EMIT2(0x07fe);

        if (__is_defined(CC_USING_EXPOLINE) && !nospec_disable &&
            (is_first_pass(jit) || (jit->seen & SEEN_FUNC))) {
                jit->r1_thunk_ip = jit->prg;
                /* Generate __s390_indirect_jump_r1 thunk */
                if (test_facility(35)) {
                        /* exrl %r0,.+10 */
                        EMIT6_PCREL_RIL(0xc6000000, jit->prg + 10);
                        /* j . */
                        EMIT4_PCREL(0xa7f40000, 0);
                        /* br %r1 */
                        _EMIT2(0x07f1);
                } else {
                        /* ex 0,S390_lowcore.br_r1_tampoline */
                        EMIT4_DISP(0x44000000, REG_0, REG_0,
                                   offsetof(struct lowcore, br_r1_trampoline));
                        /* j . */
                        EMIT4_PCREL(0xa7f40000, 0);
                }
        }
}

/*
 * Compile one eBPF instruction into s390x code
 *
 * NOTE: Use noinline because for gcov (-fprofile-arcs) gcc allocates a lot of
 * stack space for the large switch statement.
 */
static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
                                 int i, bool extra_pass, u32 stack_depth)
{
        struct bpf_insn *insn = &fp->insnsi[i];
        u32 dst_reg = insn->dst_reg;
        u32 src_reg = insn->src_reg;
        int last, insn_count = 1;
        u32 *addrs = jit->addrs;
        s32 imm = insn->imm;
        s16 off = insn->off;
        unsigned int mask;

        switch (insn->code) {
        /*
         * BPF_MOV
         */
        case BPF_ALU | BPF_MOV | BPF_X: /* dst = (u32) src */
                /* llgfr %dst,%src */
                EMIT4(0xb9160000, dst_reg, src_reg);
                if (insn_is_zext(&insn[1]))
                        insn_count = 2;
                break;
        case BPF_ALU64 | BPF_MOV | BPF_X: /* dst = src */
                /* lgr %dst,%src */
                EMIT4(0xb9040000, dst_reg, src_reg);
                break;
        case BPF_ALU | BPF_MOV | BPF_K: /* dst = (u32) imm */
                /* llilf %dst,imm */
                EMIT6_IMM(0xc00f0000, dst_reg, imm);
                if (insn_is_zext(&insn[1]))
                        insn_count = 2;
                break;
        case BPF_ALU64 | BPF_MOV | BPF_K: /* dst = imm */
                /* lgfi %dst,imm */
                EMIT6_IMM(0xc0010000, dst_reg, imm);
                break;
        /*
         * BPF_LD 64
         */
        case BPF_LD | BPF_IMM | BPF_DW: /* dst = (u64) imm */
        {
                /* 16 byte instruction that uses two 'struct bpf_insn' */
                u64 imm64;

                imm64 = (u64)(u32) insn[0].imm | ((u64)(u32) insn[1].imm) << 32;
                /* lgrl %dst,imm */
                EMIT6_PCREL_RILB(0xc4080000, dst_reg, _EMIT_CONST_U64(imm64));
                insn_count = 2;
                break;
        }
        /*
         * BPF_ADD
         */
        case BPF_ALU | BPF_ADD | BPF_X: /* dst = (u32) dst + (u32) src */
                /* ar %dst,%src */
                EMIT2(0x1a00, dst_reg, src_reg);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_ADD | BPF_X: /* dst = dst + src */
                /* agr %dst,%src */
                EMIT4(0xb9080000, dst_reg, src_reg);
                break;
        case BPF_ALU | BPF_ADD | BPF_K: /* dst = (u32) dst + (u32) imm */
                if (!imm)
                        break;
                /* alfi %dst,imm */
                EMIT6_IMM(0xc20b0000, dst_reg, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_ADD | BPF_K: /* dst = dst + imm */
                if (!imm)
                        break;
                /* agfi %dst,imm */
                EMIT6_IMM(0xc2080000, dst_reg, imm);
                break;
        /*
         * BPF_SUB
         */
        case BPF_ALU | BPF_SUB | BPF_X: /* dst = (u32) dst - (u32) src */
                /* sr %dst,%src */
                EMIT2(0x1b00, dst_reg, src_reg);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_SUB | BPF_X: /* dst = dst - src */
                /* sgr %dst,%src */
                EMIT4(0xb9090000, dst_reg, src_reg);
                break;
        case BPF_ALU | BPF_SUB | BPF_K: /* dst = (u32) dst - (u32) imm */
                if (!imm)
                        break;
                /* alfi %dst,-imm */
                EMIT6_IMM(0xc20b0000, dst_reg, -imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_SUB | BPF_K: /* dst = dst - imm */
                if (!imm)
                        break;
                /* agfi %dst,-imm */
                EMIT6_IMM(0xc2080000, dst_reg, -imm);
                break;
        /*
         * BPF_MUL
         */
        case BPF_ALU | BPF_MUL | BPF_X: /* dst = (u32) dst * (u32) src */
                /* msr %dst,%src */
                EMIT4(0xb2520000, dst_reg, src_reg);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_MUL | BPF_X: /* dst = dst * src */
                /* msgr %dst,%src */
                EMIT4(0xb90c0000, dst_reg, src_reg);
                break;
        case BPF_ALU | BPF_MUL | BPF_K: /* dst = (u32) dst * (u32) imm */
                if (imm == 1)
                        break;
                /* msfi %r5,imm */
                EMIT6_IMM(0xc2010000, dst_reg, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_MUL | BPF_K: /* dst = dst * imm */
                if (imm == 1)
                        break;
                /* msgfi %dst,imm */
                EMIT6_IMM(0xc2000000, dst_reg, imm);
                break;
        /*
         * BPF_DIV / BPF_MOD
         */
        case BPF_ALU | BPF_DIV | BPF_X: /* dst = (u32) dst / (u32) src */
        case BPF_ALU | BPF_MOD | BPF_X: /* dst = (u32) dst % (u32) src */
        {
                int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

                /* lhi %w0,0 */
                EMIT4_IMM(0xa7080000, REG_W0, 0);
                /* lr %w1,%dst */
                EMIT2(0x1800, REG_W1, dst_reg);
                /* dlr %w0,%src */
                EMIT4(0xb9970000, REG_W0, src_reg);
                /* llgfr %dst,%rc */
                EMIT4(0xb9160000, dst_reg, rc_reg);
                if (insn_is_zext(&insn[1]))
                        insn_count = 2;
                break;
        }
        case BPF_ALU64 | BPF_DIV | BPF_X: /* dst = dst / src */
        case BPF_ALU64 | BPF_MOD | BPF_X: /* dst = dst % src */
        {
                int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

                /* lghi %w0,0 */
                EMIT4_IMM(0xa7090000, REG_W0, 0);
                /* lgr %w1,%dst */
                EMIT4(0xb9040000, REG_W1, dst_reg);
                /* dlgr %w0,%dst */
                EMIT4(0xb9870000, REG_W0, src_reg);
                /* lgr %dst,%rc */
                EMIT4(0xb9040000, dst_reg, rc_reg);
                break;
        }
        case BPF_ALU | BPF_DIV | BPF_K: /* dst = (u32) dst / (u32) imm */
        case BPF_ALU | BPF_MOD | BPF_K: /* dst = (u32) dst % (u32) imm */
        {
                int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

                if (imm == 1) {
                        if (BPF_OP(insn->code) == BPF_MOD)
                                /* lhgi %dst,0 */
                                EMIT4_IMM(0xa7090000, dst_reg, 0);
                        break;
                }
                /* lhi %w0,0 */
                EMIT4_IMM(0xa7080000, REG_W0, 0);
                /* lr %w1,%dst */
                EMIT2(0x1800, REG_W1, dst_reg);
                if (!is_first_pass(jit) && can_use_ldisp_for_lit32(jit)) {
                        /* dl %w0,<d(imm)>(%l) */
                        EMIT6_DISP_LH(0xe3000000, 0x0097, REG_W0, REG_0, REG_L,
                                      EMIT_CONST_U32(imm));
                } else {
                        /* lgfrl %dst,imm */
                        EMIT6_PCREL_RILB(0xc40c0000, dst_reg,
                                         _EMIT_CONST_U32(imm));
                        jit->seen |= SEEN_LITERAL;
                        /* dlr %w0,%dst */
                        EMIT4(0xb9970000, REG_W0, dst_reg);
                }
                /* llgfr %dst,%rc */
                EMIT4(0xb9160000, dst_reg, rc_reg);
                if (insn_is_zext(&insn[1]))
                        insn_count = 2;
                break;
        }
        case BPF_ALU64 | BPF_DIV | BPF_K: /* dst = dst / imm */
        case BPF_ALU64 | BPF_MOD | BPF_K: /* dst = dst % imm */
        {
                int rc_reg = BPF_OP(insn->code) == BPF_DIV ? REG_W1 : REG_W0;

                if (imm == 1) {
                        if (BPF_OP(insn->code) == BPF_MOD)
                                /* lhgi %dst,0 */
                                EMIT4_IMM(0xa7090000, dst_reg, 0);
                        break;
                }
                /* lghi %w0,0 */
                EMIT4_IMM(0xa7090000, REG_W0, 0);
                /* lgr %w1,%dst */
                EMIT4(0xb9040000, REG_W1, dst_reg);
                if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
                        /* dlg %w0,<d(imm)>(%l) */
                        EMIT6_DISP_LH(0xe3000000, 0x0087, REG_W0, REG_0, REG_L,
                                      EMIT_CONST_U64(imm));
                } else {
                        /* lgrl %dst,imm */
                        EMIT6_PCREL_RILB(0xc4080000, dst_reg,
                                         _EMIT_CONST_U64(imm));
                        jit->seen |= SEEN_LITERAL;
                        /* dlgr %w0,%dst */
                        EMIT4(0xb9870000, REG_W0, dst_reg);
                }
                /* lgr %dst,%rc */
                EMIT4(0xb9040000, dst_reg, rc_reg);
                break;
        }
        /*
         * BPF_AND
         */
        case BPF_ALU | BPF_AND | BPF_X: /* dst = (u32) dst & (u32) src */
                /* nr %dst,%src */
                EMIT2(0x1400, dst_reg, src_reg);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_AND | BPF_X: /* dst = dst & src */
                /* ngr %dst,%src */
                EMIT4(0xb9800000, dst_reg, src_reg);
                break;
        case BPF_ALU | BPF_AND | BPF_K: /* dst = (u32) dst & (u32) imm */
                /* nilf %dst,imm */
                EMIT6_IMM(0xc00b0000, dst_reg, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_AND | BPF_K: /* dst = dst & imm */
                if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
                        /* ng %dst,<d(imm)>(%l) */
                        EMIT6_DISP_LH(0xe3000000, 0x0080,
                                      dst_reg, REG_0, REG_L,
                                      EMIT_CONST_U64(imm));
                } else {
                        /* lgrl %w0,imm */
                        EMIT6_PCREL_RILB(0xc4080000, REG_W0,
                                         _EMIT_CONST_U64(imm));
                        jit->seen |= SEEN_LITERAL;
                        /* ngr %dst,%w0 */
                        EMIT4(0xb9800000, dst_reg, REG_W0);
                }
                break;
        /*
         * BPF_OR
         */
        case BPF_ALU | BPF_OR | BPF_X: /* dst = (u32) dst | (u32) src */
                /* or %dst,%src */
                EMIT2(0x1600, dst_reg, src_reg);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_OR | BPF_X: /* dst = dst | src */
                /* ogr %dst,%src */
                EMIT4(0xb9810000, dst_reg, src_reg);
                break;
        case BPF_ALU | BPF_OR | BPF_K: /* dst = (u32) dst | (u32) imm */
                /* oilf %dst,imm */
                EMIT6_IMM(0xc00d0000, dst_reg, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_OR | BPF_K: /* dst = dst | imm */
                if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
                        /* og %dst,<d(imm)>(%l) */
                        EMIT6_DISP_LH(0xe3000000, 0x0081,
                                      dst_reg, REG_0, REG_L,
                                      EMIT_CONST_U64(imm));
                } else {
                        /* lgrl %w0,imm */
                        EMIT6_PCREL_RILB(0xc4080000, REG_W0,
                                         _EMIT_CONST_U64(imm));
                        jit->seen |= SEEN_LITERAL;
                        /* ogr %dst,%w0 */
                        EMIT4(0xb9810000, dst_reg, REG_W0);
                }
                break;
        /*
         * BPF_XOR
         */
        case BPF_ALU | BPF_XOR | BPF_X: /* dst = (u32) dst ^ (u32) src */
                /* xr %dst,%src */
                EMIT2(0x1700, dst_reg, src_reg);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_XOR | BPF_X: /* dst = dst ^ src */
                /* xgr %dst,%src */
                EMIT4(0xb9820000, dst_reg, src_reg);
                break;
        case BPF_ALU | BPF_XOR | BPF_K: /* dst = (u32) dst ^ (u32) imm */
                if (!imm)
                        break;
                /* xilf %dst,imm */
                EMIT6_IMM(0xc0070000, dst_reg, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_XOR | BPF_K: /* dst = dst ^ imm */
                if (!is_first_pass(jit) && can_use_ldisp_for_lit64(jit)) {
                        /* xg %dst,<d(imm)>(%l) */
                        EMIT6_DISP_LH(0xe3000000, 0x0082,
                                      dst_reg, REG_0, REG_L,
                                      EMIT_CONST_U64(imm));
                } else {
                        /* lgrl %w0,imm */
                        EMIT6_PCREL_RILB(0xc4080000, REG_W0,
                                         _EMIT_CONST_U64(imm));
                        jit->seen |= SEEN_LITERAL;
                        /* xgr %dst,%w0 */
                        EMIT4(0xb9820000, dst_reg, REG_W0);
                }
                break;
        /*
         * BPF_LSH
         */
        case BPF_ALU | BPF_LSH | BPF_X: /* dst = (u32) dst << (u32) src */
                /* sll %dst,0(%src) */
                EMIT4_DISP(0x89000000, dst_reg, src_reg, 0);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_LSH | BPF_X: /* dst = dst << src */
                /* sllg %dst,%dst,0(%src) */
                EMIT6_DISP_LH(0xeb000000, 0x000d, dst_reg, dst_reg, src_reg, 0);
                break;
        case BPF_ALU | BPF_LSH | BPF_K: /* dst = (u32) dst << (u32) imm */
                if (imm == 0)
                        break;
                /* sll %dst,imm(%r0) */
                EMIT4_DISP(0x89000000, dst_reg, REG_0, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_LSH | BPF_K: /* dst = dst << imm */
                if (imm == 0)
                        break;
                /* sllg %dst,%dst,imm(%r0) */
                EMIT6_DISP_LH(0xeb000000, 0x000d, dst_reg, dst_reg, REG_0, imm);
                break;
        /*
         * BPF_RSH
         */
        case BPF_ALU | BPF_RSH | BPF_X: /* dst = (u32) dst >> (u32) src */
                /* srl %dst,0(%src) */
                EMIT4_DISP(0x88000000, dst_reg, src_reg, 0);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_RSH | BPF_X: /* dst = dst >> src */
                /* srlg %dst,%dst,0(%src) */
                EMIT6_DISP_LH(0xeb000000, 0x000c, dst_reg, dst_reg, src_reg, 0);
                break;
        case BPF_ALU | BPF_RSH | BPF_K: /* dst = (u32) dst >> (u32) imm */
                if (imm == 0)
                        break;
                /* srl %dst,imm(%r0) */
                EMIT4_DISP(0x88000000, dst_reg, REG_0, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_RSH | BPF_K: /* dst = dst >> imm */
                if (imm == 0)
                        break;
                /* srlg %dst,%dst,imm(%r0) */
                EMIT6_DISP_LH(0xeb000000, 0x000c, dst_reg, dst_reg, REG_0, imm);
                break;
        /*
         * BPF_ARSH
         */
        case BPF_ALU | BPF_ARSH | BPF_X: /* ((s32) dst) >>= src */
                /* sra %dst,%dst,0(%src) */
                EMIT4_DISP(0x8a000000, dst_reg, src_reg, 0);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_ARSH | BPF_X: /* ((s64) dst) >>= src */
                /* srag %dst,%dst,0(%src) */
                EMIT6_DISP_LH(0xeb000000, 0x000a, dst_reg, dst_reg, src_reg, 0);
                break;
        case BPF_ALU | BPF_ARSH | BPF_K: /* ((s32) dst >> imm */
                if (imm == 0)
                        break;
                /* sra %dst,imm(%r0) */
                EMIT4_DISP(0x8a000000, dst_reg, REG_0, imm);
                EMIT_ZERO(dst_reg);
                break;
        case BPF_ALU64 | BPF_ARSH | BPF_K: /* ((s64) dst) >>= imm */
                if (imm == 0)
                        break;
                /* srag %dst,%dst,imm(%r0) */
                EMIT6_DISP_LH(0xeb000000, 0x000a, dst_reg, dst_reg, REG_0, imm);
                break;
        /*
         * BPF_NEG
         */
        case BPF_ALU | BPF_NEG: /* dst = (u32) -dst */
                /* lcr %dst,%dst */
                EMIT2(0x1300, dst_reg, dst_reg);
                EMIT_ZERO(dst_reg);

                break;
        case BPF_ALU64 | BPF_NEG: /* dst = -dst */
                /* lcgr %dst,%dst */
                EMIT4(0xb9030000, dst_reg, dst_reg);
                break;
        /*
         * BPF_FROM_BE/LE
         */
        case BPF_ALU | BPF_END | BPF_FROM_BE:
                /* s390 is big endian, therefore only clear high order bytes */
                switch (imm) {
                case 16: /* dst = (u16) cpu_to_be16(dst) */
                        /* llghr %dst,%dst */
                        EMIT4(0xb9850000, dst_reg, dst_reg);
                        if (insn_is_zext(&insn[1]))
                                insn_count = 2;
                        break;
                case 32: /* dst = (u32) cpu_to_be32(dst) */
                        if (!fp->aux->verifier_zext)
                                /* llgfr %dst,%dst */
                                EMIT4(0xb9160000, dst_reg, dst_reg);
                        break;
                case 64: /* dst = (u64) cpu_to_be64(dst) */
                        break;
                }
                break;
        case BPF_ALU | BPF_END | BPF_FROM_LE:
                switch (imm) {
                case 16: /* dst = (u16) cpu_to_le16(dst) */
                        /* lrvr %dst,%dst */
                        EMIT4(0xb91f0000, dst_reg, dst_reg);
                        /* srl %dst,16(%r0) */
                        EMIT4_DISP(0x88000000, dst_reg, REG_0, 16);
                        /* llghr %dst,%dst */
                        EMIT4(0xb9850000, dst_reg, dst_reg);
                        if (insn_is_zext(&insn[1]))
                                insn_count = 2;
                        break;
                case 32: /* dst = (u32) cpu_to_le32(dst) */
                        /* lrvr %dst,%dst */
                        EMIT4(0xb91f0000, dst_reg, dst_reg);
                        if (!fp->aux->verifier_zext)
                                /* llgfr %dst,%dst */
                                EMIT4(0xb9160000, dst_reg, dst_reg);
                        break;
                case 64: /* dst = (u64) cpu_to_le64(dst) */
                        /* lrvgr %dst,%dst */
                        EMIT4(0xb90f0000, dst_reg, dst_reg);
                        break;
                }
                break;
        /*
         * BPF_ST(X)
         */
        case BPF_STX | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = src_reg */
                /* stcy %src,off(%dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0072, src_reg, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_STX | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = src */
                /* sthy %src,off(%dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0070, src_reg, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_STX | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = src */
                /* sty %src,off(%dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0050, src_reg, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_STX | BPF_MEM | BPF_DW: /* (u64 *)(dst + off) = src */
                /* stg %src,off(%dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0024, src_reg, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_ST | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = imm */
                /* lhi %w0,imm */
                EMIT4_IMM(0xa7080000, REG_W0, (u8) imm);
                /* stcy %w0,off(dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0072, REG_W0, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_ST | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = imm */
                /* lhi %w0,imm */
                EMIT4_IMM(0xa7080000, REG_W0, (u16) imm);
                /* sthy %w0,off(dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0070, REG_W0, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_ST | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = imm */
                /* llilf %w0,imm  */
                EMIT6_IMM(0xc00f0000, REG_W0, (u32) imm);
                /* sty %w0,off(%dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0050, REG_W0, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_ST | BPF_MEM | BPF_DW: /* *(u64 *)(dst + off) = imm */
                /* lgfi %w0,imm */
                EMIT6_IMM(0xc0010000, REG_W0, imm);
                /* stg %w0,off(%dst) */
                EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W0, dst_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                break;
        /*
         * BPF_STX XADD (atomic_add)
         */
        case BPF_STX | BPF_XADD | BPF_W: /* *(u32 *)(dst + off) += src */
                /* laal %w0,%src,off(%dst) */
                EMIT6_DISP_LH(0xeb000000, 0x00fa, REG_W0, src_reg,
                              dst_reg, off);
                jit->seen |= SEEN_MEM;
                break;
        case BPF_STX | BPF_XADD | BPF_DW: /* *(u64 *)(dst + off) += src */
                /* laalg %w0,%src,off(%dst) */
                EMIT6_DISP_LH(0xeb000000, 0x00ea, REG_W0, src_reg,
                              dst_reg, off);
                jit->seen |= SEEN_MEM;
                break;
        /*
         * BPF_LDX
         */
        case BPF_LDX | BPF_MEM | BPF_B: /* dst = *(u8 *)(ul) (src + off) */
                /* llgc %dst,0(off,%src) */
                EMIT6_DISP_LH(0xe3000000, 0x0090, dst_reg, src_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                if (insn_is_zext(&insn[1]))
                        insn_count = 2;
                break;
        case BPF_LDX | BPF_MEM | BPF_H: /* dst = *(u16 *)(ul) (src + off) */
                /* llgh %dst,0(off,%src) */
                EMIT6_DISP_LH(0xe3000000, 0x0091, dst_reg, src_reg, REG_0, off);
                jit->seen |= SEEN_MEM;
                if (insn_is_zext(&insn[1]))
                        insn_count = 2;
                break;
        case BPF_LDX | BPF_MEM | BPF_W: /* dst = *(u32 *)(ul) (src + off) */
                /* llgf %dst,off(%src) */
                jit->seen |= SEEN_MEM;
                EMIT6_DISP_LH(0xe3000000, 0x0016, dst_reg, src_reg, REG_0, off);
                if (insn_is_zext(&insn[1]))
                        insn_count = 2;
                break;
        case BPF_LDX | BPF_MEM | BPF_DW: /* dst = *(u64 *)(ul) (src + off) */
                /* lg %dst,0(off,%src) */
                jit->seen |= SEEN_MEM;
                EMIT6_DISP_LH(0xe3000000, 0x0004, dst_reg, src_reg, REG_0, off);
                break;
        /*
         * BPF_JMP / CALL
         */
        case BPF_JMP | BPF_CALL:
        {
                u64 func;
                bool func_addr_fixed;
                int ret;

                ret = bpf_jit_get_func_addr(fp, insn, extra_pass,
                                            &func, &func_addr_fixed);
                if (ret < 0)
                        return -1;

                REG_SET_SEEN(BPF_REG_5);
                jit->seen |= SEEN_FUNC;
                /* lgrl %w1,func */
                EMIT6_PCREL_RILB(0xc4080000, REG_W1, _EMIT_CONST_U64(func));
                if (__is_defined(CC_USING_EXPOLINE) && !nospec_disable) {
                        /* brasl %r14,__s390_indirect_jump_r1 */
                        EMIT6_PCREL_RILB(0xc0050000, REG_14, jit->r1_thunk_ip);
                } else {
                        /* basr %r14,%w1 */
                        EMIT2(0x0d00, REG_14, REG_W1);
                }
                /* lgr %b0,%r2: load return value into %b0 */
                EMIT4(0xb9040000, BPF_REG_0, REG_2);
                break;
        }
        case BPF_JMP | BPF_TAIL_CALL:
                /*
                 * Implicit input:
                 *  B1: pointer to ctx
                 *  B2: pointer to bpf_array
                 *  B3: index in bpf_array
                 */
                jit->seen |= SEEN_TAIL_CALL;

                /*
                 * if (index >= array->map.max_entries)
                 *         goto out;
                 */

                /* llgf %w1,map.max_entries(%b2) */
                EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_2,
                              offsetof(struct bpf_array, map.max_entries));
                /* if ((u32)%b3 >= (u32)%w1) goto out; */
                if (!is_first_pass(jit) && can_use_rel(jit, jit->labels[0])) {
                        /* clrj %b3,%w1,0xa,label0 */
                        EMIT6_PCREL_LABEL(0xec000000, 0x0077, BPF_REG_3,
                                          REG_W1, 0, 0xa);
                } else {
                        /* clr %b3,%w1 */
                        EMIT2(0x1500, BPF_REG_3, REG_W1);
                        /* brcl 0xa,label0 */
                        EMIT6_PCREL_RILC(0xc0040000, 0xa, jit->labels[0]);
                }

                /*
                 * if (tail_call_cnt++ > MAX_TAIL_CALL_CNT)
                 *         goto out;
                 */

                if (jit->seen & SEEN_STACK)
                        off = STK_OFF_TCCNT + STK_OFF + stack_depth;
                else
                        off = STK_OFF_TCCNT;
                /* lhi %w0,1 */
                EMIT4_IMM(0xa7080000, REG_W0, 1);
                /* laal %w1,%w0,off(%r15) */
                EMIT6_DISP_LH(0xeb000000, 0x00fa, REG_W1, REG_W0, REG_15, off);
                if (!is_first_pass(jit) && can_use_rel(jit, jit->labels[0])) {
                        /* clij %w1,MAX_TAIL_CALL_CNT,0x2,label0 */
                        EMIT6_PCREL_IMM_LABEL(0xec000000, 0x007f, REG_W1,
                                              MAX_TAIL_CALL_CNT, 0, 0x2);
                } else {
                        /* clfi %w1,MAX_TAIL_CALL_CNT */
                        EMIT6_IMM(0xc20f0000, REG_W1, MAX_TAIL_CALL_CNT);
                        /* brcl 0x2,label0 */
                        EMIT6_PCREL_RILC(0xc0040000, 0x2, jit->labels[0]);
                }

                /*
                 * prog = array->ptrs[index];
                 * if (prog == NULL)
                 *         goto out;
                 */

                /* llgfr %r1,%b3: %r1 = (u32) index */
                EMIT4(0xb9160000, REG_1, BPF_REG_3);
                /* sllg %r1,%r1,3: %r1 *= 8 */
                EMIT6_DISP_LH(0xeb000000, 0x000d, REG_1, REG_1, REG_0, 3);
                /* ltg %r1,prog(%b2,%r1) */
                EMIT6_DISP_LH(0xe3000000, 0x0002, REG_1, BPF_REG_2,
                              REG_1, offsetof(struct bpf_array, ptrs));
                if (!is_first_pass(jit) && can_use_rel(jit, jit->labels[0])) {
                        /* brc 0x8,label0 */
                        EMIT4_PCREL_RIC(0xa7040000, 0x8, jit->labels[0]);
                } else {
                        /* brcl 0x8,label0 */
                        EMIT6_PCREL_RILC(0xc0040000, 0x8, jit->labels[0]);
                }

                /*
                 * Restore registers before calling function
                 */
                save_restore_regs(jit, REGS_RESTORE, stack_depth);

                /*
                 * goto *(prog->bpf_func + tail_call_start);
                 */

                /* lg %r1,bpf_func(%r1) */
                EMIT6_DISP_LH(0xe3000000, 0x0004, REG_1, REG_1, REG_0,
                              offsetof(struct bpf_prog, bpf_func));
                /* bc 0xf,tail_call_start(%r1) */
                _EMIT4(0x47f01000 + jit->tail_call_start);
                /* out: */
                jit->labels[0] = jit->prg;
                break;
        case BPF_JMP | BPF_EXIT: /* return b0 */
                last = (i == fp->len - 1) ? 1 : 0;
                if (last)
                        break;
                /* j <exit> */
                EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
                break;
        /*
         * Branch relative (number of skipped instructions) to offset on
         * condition.
         *
         * Condition code to mask mapping:
         *
         * CC | Description        | Mask
         * ------------------------------
         * 0  | Operands equal     |    8
         * 1  | First operand low  |    4
         * 2  | First operand high |    2
         * 3  | Unused             |    1
         *
         * For s390x relative branches: ip = ip + off_bytes
         * For BPF relative branches:   insn = insn + off_insns + 1
         *
         * For example for s390x with offset 0 we jump to the branch
         * instruction itself (loop) and for BPF with offset 0 we
         * branch to the instruction behind the branch.
         */
        case BPF_JMP | BPF_JA: /* if (true) */
                mask = 0xf000; /* j */
                goto branch_oc;
        case BPF_JMP | BPF_JSGT | BPF_K: /* ((s64) dst > (s64) imm) */
        case BPF_JMP32 | BPF_JSGT | BPF_K: /* ((s32) dst > (s32) imm) */
                mask = 0x2000; /* jh */
                goto branch_ks;
        case BPF_JMP | BPF_JSLT | BPF_K: /* ((s64) dst < (s64) imm) */
        case BPF_JMP32 | BPF_JSLT | BPF_K: /* ((s32) dst < (s32) imm) */
                mask = 0x4000; /* jl */
                goto branch_ks;
        case BPF_JMP | BPF_JSGE | BPF_K: /* ((s64) dst >= (s64) imm) */
        case BPF_JMP32 | BPF_JSGE | BPF_K: /* ((s32) dst >= (s32) imm) */
                mask = 0xa000; /* jhe */
                goto branch_ks;
        case BPF_JMP | BPF_JSLE | BPF_K: /* ((s64) dst <= (s64) imm) */
        case BPF_JMP32 | BPF_JSLE | BPF_K: /* ((s32) dst <= (s32) imm) */
                mask = 0xc000; /* jle */
                goto branch_ks;
        case BPF_JMP | BPF_JGT | BPF_K: /* (dst_reg > imm) */
        case BPF_JMP32 | BPF_JGT | BPF_K: /* ((u32) dst_reg > (u32) imm) */
                mask = 0x2000; /* jh */
                goto branch_ku;
        case BPF_JMP | BPF_JLT | BPF_K: /* (dst_reg < imm) */
        case BPF_JMP32 | BPF_JLT | BPF_K: /* ((u32) dst_reg < (u32) imm) */
                mask = 0x4000; /* jl */
                goto branch_ku;
        case BPF_JMP | BPF_JGE | BPF_K: /* (dst_reg >= imm) */
        case BPF_JMP32 | BPF_JGE | BPF_K: /* ((u32) dst_reg >= (u32) imm) */
                mask = 0xa000; /* jhe */
                goto branch_ku;
        case BPF_JMP | BPF_JLE | BPF_K: /* (dst_reg <= imm) */
        case BPF_JMP32 | BPF_JLE | BPF_K: /* ((u32) dst_reg <= (u32) imm) */
                mask = 0xc000; /* jle */
                goto branch_ku;
        case BPF_JMP | BPF_JNE | BPF_K: /* (dst_reg != imm) */
        case BPF_JMP32 | BPF_JNE | BPF_K: /* ((u32) dst_reg != (u32) imm) */
                mask = 0x7000; /* jne */
                goto branch_ku;
        case BPF_JMP | BPF_JEQ | BPF_K: /* (dst_reg == imm) */
        case BPF_JMP32 | BPF_JEQ | BPF_K: /* ((u32) dst_reg == (u32) imm) */
                mask = 0x8000; /* je */
                goto branch_ku;
        case BPF_JMP | BPF_JSET | BPF_K: /* (dst_reg & imm) */
        case BPF_JMP32 | BPF_JSET | BPF_K: /* ((u32) dst_reg & (u32) imm) */
                mask = 0x7000; /* jnz */
                if (BPF_CLASS(insn->code) == BPF_JMP32) {
                        /* llilf %w1,imm (load zero extend imm) */
                        EMIT6_IMM(0xc00f0000, REG_W1, imm);
                        /* nr %w1,%dst */
                        EMIT2(0x1400, REG_W1, dst_reg);
                } else {
                        /* lgfi %w1,imm (load sign extend imm) */
                        EMIT6_IMM(0xc0010000, REG_W1, imm);
                        /* ngr %w1,%dst */
                        EMIT4(0xb9800000, REG_W1, dst_reg);
                }
                goto branch_oc;

        case BPF_JMP | BPF_JSGT | BPF_X: /* ((s64) dst > (s64) src) */
        case BPF_JMP32 | BPF_JSGT | BPF_X: /* ((s32) dst > (s32) src) */
                mask = 0x2000; /* jh */
                goto branch_xs;
        case BPF_JMP | BPF_JSLT | BPF_X: /* ((s64) dst < (s64) src) */
        case BPF_JMP32 | BPF_JSLT | BPF_X: /* ((s32) dst < (s32) src) */
                mask = 0x4000; /* jl */
                goto branch_xs;
        case BPF_JMP | BPF_JSGE | BPF_X: /* ((s64) dst >= (s64) src) */
        case BPF_JMP32 | BPF_JSGE | BPF_X: /* ((s32) dst >= (s32) src) */
                mask = 0xa000; /* jhe */
                goto branch_xs;
        case BPF_JMP | BPF_JSLE | BPF_X: /* ((s64) dst <= (s64) src) */
        case BPF_JMP32 | BPF_JSLE | BPF_X: /* ((s32) dst <= (s32) src) */
                mask = 0xc000; /* jle */
                goto branch_xs;
        case BPF_JMP | BPF_JGT | BPF_X: /* (dst > src) */
        case BPF_JMP32 | BPF_JGT | BPF_X: /* ((u32) dst > (u32) src) */
                mask = 0x2000; /* jh */
                goto branch_xu;
        case BPF_JMP | BPF_JLT | BPF_X: /* (dst < src) */
        case BPF_JMP32 | BPF_JLT | BPF_X: /* ((u32) dst < (u32) src) */
                mask = 0x4000; /* jl */
                goto branch_xu;
        case BPF_JMP | BPF_JGE | BPF_X: /* (dst >= src) */
        case BPF_JMP32 | BPF_JGE | BPF_X: /* ((u32) dst >= (u32) src) */
                mask = 0xa000; /* jhe */
                goto branch_xu;
        case BPF_JMP | BPF_JLE | BPF_X: /* (dst <= src) */
        case BPF_JMP32 | BPF_JLE | BPF_X: /* ((u32) dst <= (u32) src) */
                mask = 0xc000; /* jle */
                goto branch_xu;
        case BPF_JMP | BPF_JNE | BPF_X: /* (dst != src) */
        case BPF_JMP32 | BPF_JNE | BPF_X: /* ((u32) dst != (u32) src) */
                mask = 0x7000; /* jne */
                goto branch_xu;
        case BPF_JMP | BPF_JEQ | BPF_X: /* (dst == src) */
        case BPF_JMP32 | BPF_JEQ | BPF_X: /* ((u32) dst == (u32) src) */
                mask = 0x8000; /* je */
                goto branch_xu;
        case BPF_JMP | BPF_JSET | BPF_X: /* (dst & src) */
        case BPF_JMP32 | BPF_JSET | BPF_X: /* ((u32) dst & (u32) src) */
        {
                bool is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;

                mask = 0x7000; /* jnz */
                /* nrk or ngrk %w1,%dst,%src */
                EMIT4_RRF((is_jmp32 ? 0xb9f40000 : 0xb9e40000),
                          REG_W1, dst_reg, src_reg);
                goto branch_oc;
branch_ks:
                is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
                /* cfi or cgfi %dst,imm */
                EMIT6_IMM(is_jmp32 ? 0xc20d0000 : 0xc20c0000,
                          dst_reg, imm);
                if (!is_first_pass(jit) &&
                    can_use_rel(jit, addrs[i + off + 1])) {
                        /* brc mask,off */
                        EMIT4_PCREL_RIC(0xa7040000,
                                        mask >> 12, addrs[i + off + 1]);
                } else {
                        /* brcl mask,off */
                        EMIT6_PCREL_RILC(0xc0040000,
                                         mask >> 12, addrs[i + off + 1]);
                }
                break;
branch_ku:
                is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
                /* clfi or clgfi %dst,imm */
                EMIT6_IMM(is_jmp32 ? 0xc20f0000 : 0xc20e0000,
                          dst_reg, imm);
                if (!is_first_pass(jit) &&
                    can_use_rel(jit, addrs[i + off + 1])) {
                        /* brc mask,off */
                        EMIT4_PCREL_RIC(0xa7040000,
                                        mask >> 12, addrs[i + off + 1]);
                } else {
                        /* brcl mask,off */
                        EMIT6_PCREL_RILC(0xc0040000,
                                         mask >> 12, addrs[i + off + 1]);
                }
                break;
branch_xs:
                is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
                if (!is_first_pass(jit) &&
                    can_use_rel(jit, addrs[i + off + 1])) {
                        /* crj or cgrj %dst,%src,mask,off */
                        EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0076 : 0x0064),
                                    dst_reg, src_reg, i, off, mask);
                } else {
                        /* cr or cgr %dst,%src */
                        if (is_jmp32)
                                EMIT2(0x1900, dst_reg, src_reg);
                        else
                                EMIT4(0xb9200000, dst_reg, src_reg);
                        /* brcl mask,off */
                        EMIT6_PCREL_RILC(0xc0040000,
                                         mask >> 12, addrs[i + off + 1]);
                }
                break;
branch_xu:
                is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
                if (!is_first_pass(jit) &&
                    can_use_rel(jit, addrs[i + off + 1])) {
                        /* clrj or clgrj %dst,%src,mask,off */
                        EMIT6_PCREL(0xec000000, (is_jmp32 ? 0x0077 : 0x0065),
                                    dst_reg, src_reg, i, off, mask);
                } else {
                        /* clr or clgr %dst,%src */
                        if (is_jmp32)
                                EMIT2(0x1500, dst_reg, src_reg);
                        else
                                EMIT4(0xb9210000, dst_reg, src_reg);
                        /* brcl mask,off */
                        EMIT6_PCREL_RILC(0xc0040000,
                                         mask >> 12, addrs[i + off + 1]);
                }
                break;
branch_oc:
                if (!is_first_pass(jit) &&
                    can_use_rel(jit, addrs[i + off + 1])) {
                        /* brc mask,off */
                        EMIT4_PCREL_RIC(0xa7040000,
                                        mask >> 12, addrs[i + off + 1]);
                } else {
                        /* brcl mask,off */
                        EMIT6_PCREL_RILC(0xc0040000,
                                         mask >> 12, addrs[i + off + 1]);
                }
                break;
        }
        default: /* too complex, give up */
                pr_err("Unknown opcode %02x\n", insn->code);
                return -1;
        }
        return insn_count;
}

/*
 * Return whether new i-th instruction address does not violate any invariant
 */
static bool bpf_is_new_addr_sane(struct bpf_jit *jit, int i)
{
        /* On the first pass anything goes */
        if (is_first_pass(jit))
                return true;

        /* The codegen pass must not change anything */
        if (is_codegen_pass(jit))
                return jit->addrs[i] == jit->prg;

        /* Passes in between must not increase code size */
        return jit->addrs[i] >= jit->prg;
}

/*
 * Update the address of i-th instruction
 */
static int bpf_set_addr(struct bpf_jit *jit, int i)
{
        if (!bpf_is_new_addr_sane(jit, i))
                return -1;
        jit->addrs[i] = jit->prg;
        return 0;
}

/*
 * Compile eBPF program into s390x code
 */
static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp,
                        bool extra_pass, u32 stack_depth)
{
        int i, insn_count, lit32_size, lit64_size;

        jit->lit32 = jit->lit32_start;
        jit->lit64 = jit->lit64_start;
        jit->prg = 0;

        bpf_jit_prologue(jit, stack_depth);
        if (bpf_set_addr(jit, 0) < 0)
                return -1;
        for (i = 0; i < fp->len; i += insn_count) {
                insn_count = bpf_jit_insn(jit, fp, i, extra_pass, stack_depth);
                if (insn_count < 0)
                        return -1;
                /* Next instruction address */
                if (bpf_set_addr(jit, i + insn_count) < 0)
                        return -1;
        }
        bpf_jit_epilogue(jit, stack_depth);

        lit32_size = jit->lit32 - jit->lit32_start;
        lit64_size = jit->lit64 - jit->lit64_start;
        jit->lit32_start = jit->prg;
        if (lit32_size)
                jit->lit32_start = ALIGN(jit->lit32_start, 4);
        jit->lit64_start = jit->lit32_start + lit32_size;
        if (lit64_size)
                jit->lit64_start = ALIGN(jit->lit64_start, 8);
        jit->size = jit->lit64_start + lit64_size;
        jit->size_prg = jit->prg;
        return 0;
}

bool bpf_jit_needs_zext(void)
{
        return true;
}

struct s390_jit_data {
        struct bpf_binary_header *header;
        struct bpf_jit ctx;
        int pass;
};

/*
 * Compile eBPF program "fp"
 */
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
{
        u32 stack_depth = round_up(fp->aux->stack_depth, 8);
        struct bpf_prog *tmp, *orig_fp = fp;
        struct bpf_binary_header *header;
        struct s390_jit_data *jit_data;
        bool tmp_blinded = false;
        bool extra_pass = false;
        struct bpf_jit jit;
        int pass;

        if (!fp->jit_requested)
                return orig_fp;

        tmp = bpf_jit_blind_constants(fp);
        /*
         * If blinding was requested and we failed during blinding,
         * we must fall back to the interpreter.
         */
        if (IS_ERR(tmp))
                return orig_fp;
        if (tmp != fp) {
                tmp_blinded = true;
                fp = tmp;
        }

        jit_data = fp->aux->jit_data;
        if (!jit_data) {
                jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
                if (!jit_data) {
                        fp = orig_fp;
                        goto out;
                }
                fp->aux->jit_data = jit_data;
        }
        if (jit_data->ctx.addrs) {
                jit = jit_data->ctx;
                header = jit_data->header;
                extra_pass = true;
                pass = jit_data->pass + 1;
                goto skip_init_ctx;
        }

        memset(&jit, 0, sizeof(jit));
        jit.addrs = kvcalloc(fp->len + 1, sizeof(*jit.addrs), GFP_KERNEL);
        if (jit.addrs == NULL) {
                fp = orig_fp;
                goto out;
        }
        /*
         * Three initial passes:
         *   - 1/2: Determine clobbered registers
         *   - 3:   Calculate program size and addrs arrray
         */
        for (pass = 1; pass <= 3; pass++) {
                if (bpf_jit_prog(&jit, fp, extra_pass, stack_depth)) {
                        fp = orig_fp;
                        goto free_addrs;
                }
        }
        /*
         * Final pass: Allocate and generate program
         */
        header = bpf_jit_binary_alloc(jit.size, &jit.prg_buf, 8, jit_fill_hole);
        if (!header) {
                fp = orig_fp;
                goto free_addrs;
        }
skip_init_ctx:
        if (bpf_jit_prog(&jit, fp, extra_pass, stack_depth)) {
                bpf_jit_binary_free(header);
                fp = orig_fp;
                goto free_addrs;
        }
        if (bpf_jit_enable > 1) {
                bpf_jit_dump(fp->len, jit.size, pass, jit.prg_buf);
                print_fn_code(jit.prg_buf, jit.size_prg);
        }
        if (!fp->is_func || extra_pass) {
                bpf_jit_binary_lock_ro(header);
        } else {
                jit_data->header = header;
                jit_data->ctx = jit;
                jit_data->pass = pass;
        }
        fp->bpf_func = (void *) jit.prg_buf;
        fp->jited = 1;
        fp->jited_len = jit.size;

        if (!fp->is_func || extra_pass) {
                bpf_prog_fill_jited_linfo(fp, jit.addrs + 1);
free_addrs:
                kvfree(jit.addrs);
                kfree(jit_data);
                fp->aux->jit_data = NULL;
        }
out:
        if (tmp_blinded)
                bpf_jit_prog_release_other(fp, fp == orig_fp ?
                                           tmp : orig_fp);
        return fp;
}