Merge tag 'mtd/fixes-for-4.20-rc5' of git://git.infradead.org/linux-mtd

[sfrench/cifs-2.6.git] / arch / sparc / net / bpf_jit_comp_64.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/moduleloader.h>
#include <linux/workqueue.h>
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/bpf.h>
#include <linux/cache.h>
#include <linux/if_vlan.h>

#include <asm/cacheflush.h>
#include <asm/ptrace.h>

#include "bpf_jit_64.h"

static inline bool is_simm13(unsigned int value)
{
        return value + 0x1000 < 0x2000;
}

static inline bool is_simm10(unsigned int value)
{
        return value + 0x200 < 0x400;
}

static inline bool is_simm5(unsigned int value)
{
        return value + 0x10 < 0x20;
}

static inline bool is_sethi(unsigned int value)
{
        return (value & ~0x3fffff) == 0;
}

static void bpf_flush_icache(void *start_, void *end_)
{
        /* Cheetah's I-cache is fully coherent.  */
        if (tlb_type == spitfire) {
                unsigned long start = (unsigned long) start_;
                unsigned long end = (unsigned long) end_;

                start &= ~7UL;
                end = (end + 7UL) & ~7UL;
                while (start < end) {
                        flushi(start);
                        start += 32;
                }
        }
}

#define S13(X)          ((X) & 0x1fff)
#define S5(X)           ((X) & 0x1f)
#define IMMED           0x00002000
#define RD(X)           ((X) << 25)
#define RS1(X)          ((X) << 14)
#define RS2(X)          ((X))
#define OP(X)           ((X) << 30)
#define OP2(X)          ((X) << 22)
#define OP3(X)          ((X) << 19)
#define COND(X)         (((X) & 0xf) << 25)
#define CBCOND(X)       (((X) & 0x1f) << 25)
#define F1(X)           OP(X)
#define F2(X, Y)        (OP(X) | OP2(Y))
#define F3(X, Y)        (OP(X) | OP3(Y))
#define ASI(X)          (((X) & 0xff) << 5)

#define CONDN           COND(0x0)
#define CONDE           COND(0x1)
#define CONDLE          COND(0x2)
#define CONDL           COND(0x3)
#define CONDLEU         COND(0x4)
#define CONDCS          COND(0x5)
#define CONDNEG         COND(0x6)
#define CONDVC          COND(0x7)
#define CONDA           COND(0x8)
#define CONDNE          COND(0x9)
#define CONDG           COND(0xa)
#define CONDGE          COND(0xb)
#define CONDGU          COND(0xc)
#define CONDCC          COND(0xd)
#define CONDPOS         COND(0xe)
#define CONDVS          COND(0xf)

#define CONDGEU         CONDCC
#define CONDLU          CONDCS

#define WDISP22(X)      (((X) >> 2) & 0x3fffff)
#define WDISP19(X)      (((X) >> 2) & 0x7ffff)

/* The 10-bit branch displacement for CBCOND is split into two fields */
static u32 WDISP10(u32 off)
{
        u32 ret = ((off >> 2) & 0xff) << 5;

        ret |= ((off >> (2 + 8)) & 0x03) << 19;

        return ret;
}

#define CBCONDE         CBCOND(0x09)
#define CBCONDLE        CBCOND(0x0a)
#define CBCONDL         CBCOND(0x0b)
#define CBCONDLEU       CBCOND(0x0c)
#define CBCONDCS        CBCOND(0x0d)
#define CBCONDN         CBCOND(0x0e)
#define CBCONDVS        CBCOND(0x0f)
#define CBCONDNE        CBCOND(0x19)
#define CBCONDG         CBCOND(0x1a)
#define CBCONDGE        CBCOND(0x1b)
#define CBCONDGU        CBCOND(0x1c)
#define CBCONDCC        CBCOND(0x1d)
#define CBCONDPOS       CBCOND(0x1e)
#define CBCONDVC        CBCOND(0x1f)

#define CBCONDGEU       CBCONDCC
#define CBCONDLU        CBCONDCS

#define ANNUL           (1 << 29)
#define XCC             (1 << 21)

#define BRANCH          (F2(0, 1) | XCC)
#define CBCOND_OP       (F2(0, 3) | XCC)

#define BA              (BRANCH | CONDA)
#define BG              (BRANCH | CONDG)
#define BL              (BRANCH | CONDL)
#define BLE             (BRANCH | CONDLE)
#define BGU             (BRANCH | CONDGU)
#define BLEU            (BRANCH | CONDLEU)
#define BGE             (BRANCH | CONDGE)
#define BGEU            (BRANCH | CONDGEU)
#define BLU             (BRANCH | CONDLU)
#define BE              (BRANCH | CONDE)
#define BNE             (BRANCH | CONDNE)

#define SETHI(K, REG)   \
        (F2(0, 0x4) | RD(REG) | (((K) >> 10) & 0x3fffff))
#define OR_LO(K, REG)   \
        (F3(2, 0x02) | IMMED | RS1(REG) | ((K) & 0x3ff) | RD(REG))

#define ADD             F3(2, 0x00)
#define AND             F3(2, 0x01)
#define ANDCC           F3(2, 0x11)
#define OR              F3(2, 0x02)
#define XOR             F3(2, 0x03)
#define SUB             F3(2, 0x04)
#define SUBCC           F3(2, 0x14)
#define MUL             F3(2, 0x0a)
#define MULX            F3(2, 0x09)
#define UDIVX           F3(2, 0x0d)
#define DIV             F3(2, 0x0e)
#define SLL             F3(2, 0x25)
#define SLLX            (F3(2, 0x25)|(1<<12))
#define SRA             F3(2, 0x27)
#define SRAX            (F3(2, 0x27)|(1<<12))
#define SRL             F3(2, 0x26)
#define SRLX            (F3(2, 0x26)|(1<<12))
#define JMPL            F3(2, 0x38)
#define SAVE            F3(2, 0x3c)
#define RESTORE         F3(2, 0x3d)
#define CALL            F1(1)
#define BR              F2(0, 0x01)
#define RD_Y            F3(2, 0x28)
#define WR_Y            F3(2, 0x30)

#define LD32            F3(3, 0x00)
#define LD8             F3(3, 0x01)
#define LD16            F3(3, 0x02)
#define LD64            F3(3, 0x0b)
#define LD64A           F3(3, 0x1b)
#define ST8             F3(3, 0x05)
#define ST16            F3(3, 0x06)
#define ST32            F3(3, 0x04)
#define ST64            F3(3, 0x0e)

#define CAS             F3(3, 0x3c)
#define CASX            F3(3, 0x3e)

#define LDPTR           LD64
#define BASE_STACKFRAME 176

#define LD32I           (LD32 | IMMED)
#define LD8I            (LD8 | IMMED)
#define LD16I           (LD16 | IMMED)
#define LD64I           (LD64 | IMMED)
#define LDPTRI          (LDPTR | IMMED)
#define ST32I           (ST32 | IMMED)

struct jit_ctx {
        struct bpf_prog         *prog;
        unsigned int            *offset;
        int                     idx;
        int                     epilogue_offset;
        bool                    tmp_1_used;
        bool                    tmp_2_used;
        bool                    tmp_3_used;
        bool                    saw_frame_pointer;
        bool                    saw_call;
        bool                    saw_tail_call;
        u32                     *image;
};

#define TMP_REG_1       (MAX_BPF_JIT_REG + 0)
#define TMP_REG_2       (MAX_BPF_JIT_REG + 1)
#define TMP_REG_3       (MAX_BPF_JIT_REG + 2)

/* Map BPF registers to SPARC registers */
static const int bpf2sparc[] = {
        /* return value from in-kernel function, and exit value from eBPF */
        [BPF_REG_0] = O5,

        /* arguments from eBPF program to in-kernel function */
        [BPF_REG_1] = O0,
        [BPF_REG_2] = O1,
        [BPF_REG_3] = O2,
        [BPF_REG_4] = O3,
        [BPF_REG_5] = O4,

        /* callee saved registers that in-kernel function will preserve */
        [BPF_REG_6] = L0,
        [BPF_REG_7] = L1,
        [BPF_REG_8] = L2,
        [BPF_REG_9] = L3,

        /* read-only frame pointer to access stack */
        [BPF_REG_FP] = L6,

        [BPF_REG_AX] = G7,

        /* temporary register for internal BPF JIT */
        [TMP_REG_1] = G1,
        [TMP_REG_2] = G2,
        [TMP_REG_3] = G3,
};

static void emit(const u32 insn, struct jit_ctx *ctx)
{
        if (ctx->image != NULL)
                ctx->image[ctx->idx] = insn;

        ctx->idx++;
}

static void emit_call(u32 *func, struct jit_ctx *ctx)
{
        if (ctx->image != NULL) {
                void *here = &ctx->image[ctx->idx];
                unsigned int off;

                off = (void *)func - here;
                ctx->image[ctx->idx] = CALL | ((off >> 2) & 0x3fffffff);
        }
        ctx->idx++;
}

static void emit_nop(struct jit_ctx *ctx)
{
        emit(SETHI(0, G0), ctx);
}

static void emit_reg_move(u32 from, u32 to, struct jit_ctx *ctx)
{
        emit(OR | RS1(G0) | RS2(from) | RD(to), ctx);
}

/* Emit 32-bit constant, zero extended. */
static void emit_set_const(s32 K, u32 reg, struct jit_ctx *ctx)
{
        emit(SETHI(K, reg), ctx);
        emit(OR_LO(K, reg), ctx);
}

/* Emit 32-bit constant, sign extended. */
static void emit_set_const_sext(s32 K, u32 reg, struct jit_ctx *ctx)
{
        if (K >= 0) {
                emit(SETHI(K, reg), ctx);
                emit(OR_LO(K, reg), ctx);
        } else {
                u32 hbits = ~(u32) K;
                u32 lbits = -0x400 | (u32) K;

                emit(SETHI(hbits, reg), ctx);
                emit(XOR | IMMED | RS1(reg) | S13(lbits) | RD(reg), ctx);
        }
}

static void emit_alu(u32 opcode, u32 src, u32 dst, struct jit_ctx *ctx)
{
        emit(opcode | RS1(dst) | RS2(src) | RD(dst), ctx);
}

static void emit_alu3(u32 opcode, u32 a, u32 b, u32 c, struct jit_ctx *ctx)
{
        emit(opcode | RS1(a) | RS2(b) | RD(c), ctx);
}

static void emit_alu_K(unsigned int opcode, unsigned int dst, unsigned int imm,
                       struct jit_ctx *ctx)
{
        bool small_immed = is_simm13(imm);
        unsigned int insn = opcode;

        insn |= RS1(dst) | RD(dst);
        if (small_immed) {
                emit(insn | IMMED | S13(imm), ctx);
        } else {
                unsigned int tmp = bpf2sparc[TMP_REG_1];

                ctx->tmp_1_used = true;

                emit_set_const_sext(imm, tmp, ctx);
                emit(insn | RS2(tmp), ctx);
        }
}

static void emit_alu3_K(unsigned int opcode, unsigned int src, unsigned int imm,
                        unsigned int dst, struct jit_ctx *ctx)
{
        bool small_immed = is_simm13(imm);
        unsigned int insn = opcode;

        insn |= RS1(src) | RD(dst);
        if (small_immed) {
                emit(insn | IMMED | S13(imm), ctx);
        } else {
                unsigned int tmp = bpf2sparc[TMP_REG_1];

                ctx->tmp_1_used = true;

                emit_set_const_sext(imm, tmp, ctx);
                emit(insn | RS2(tmp), ctx);
        }
}

static void emit_loadimm32(s32 K, unsigned int dest, struct jit_ctx *ctx)
{
        if (K >= 0 && is_simm13(K)) {
                /* or %g0, K, DEST */
                emit(OR | IMMED | RS1(G0) | S13(K) | RD(dest), ctx);
        } else {
                emit_set_const(K, dest, ctx);
        }
}

static void emit_loadimm(s32 K, unsigned int dest, struct jit_ctx *ctx)
{
        if (is_simm13(K)) {
                /* or %g0, K, DEST */
                emit(OR | IMMED | RS1(G0) | S13(K) | RD(dest), ctx);
        } else {
                emit_set_const(K, dest, ctx);
        }
}

static void emit_loadimm_sext(s32 K, unsigned int dest, struct jit_ctx *ctx)
{
        if (is_simm13(K)) {
                /* or %g0, K, DEST */
                emit(OR | IMMED | RS1(G0) | S13(K) | RD(dest), ctx);
        } else {
                emit_set_const_sext(K, dest, ctx);
        }
}

static void analyze_64bit_constant(u32 high_bits, u32 low_bits,
                                   int *hbsp, int *lbsp, int *abbasp)
{
        int lowest_bit_set, highest_bit_set, all_bits_between_are_set;
        int i;

        lowest_bit_set = highest_bit_set = -1;
        i = 0;
        do {
                if ((lowest_bit_set == -1) && ((low_bits >> i) & 1))
                        lowest_bit_set = i;
                if ((highest_bit_set == -1) && ((high_bits >> (32 - i - 1)) & 1))
                        highest_bit_set = (64 - i - 1);
        }  while (++i < 32 && (highest_bit_set == -1 ||
                               lowest_bit_set == -1));
        if (i == 32) {
                i = 0;
                do {
                        if (lowest_bit_set == -1 && ((high_bits >> i) & 1))
                                lowest_bit_set = i + 32;
                        if (highest_bit_set == -1 &&
                            ((low_bits >> (32 - i - 1)) & 1))
                                highest_bit_set = 32 - i - 1;
                } while (++i < 32 && (highest_bit_set == -1 ||
                                      lowest_bit_set == -1));
        }

        all_bits_between_are_set = 1;
        for (i = lowest_bit_set; i <= highest_bit_set; i++) {
                if (i < 32) {
                        if ((low_bits & (1 << i)) != 0)
                                continue;
                } else {
                        if ((high_bits & (1 << (i - 32))) != 0)
                                continue;
                }
                all_bits_between_are_set = 0;
                break;
        }
        *hbsp = highest_bit_set;
        *lbsp = lowest_bit_set;
        *abbasp = all_bits_between_are_set;
}

static unsigned long create_simple_focus_bits(unsigned long high_bits,
                                              unsigned long low_bits,
                                              int lowest_bit_set, int shift)
{
        long hi, lo;

        if (lowest_bit_set < 32) {
                lo = (low_bits >> lowest_bit_set) << shift;
                hi = ((high_bits << (32 - lowest_bit_set)) << shift);
        } else {
                lo = 0;
                hi = ((high_bits >> (lowest_bit_set - 32)) << shift);
        }
        return hi | lo;
}

static bool const64_is_2insns(unsigned long high_bits,
                              unsigned long low_bits)
{
        int highest_bit_set, lowest_bit_set, all_bits_between_are_set;

        if (high_bits == 0 || high_bits == 0xffffffff)
                return true;

        analyze_64bit_constant(high_bits, low_bits,
                               &highest_bit_set, &lowest_bit_set,
                               &all_bits_between_are_set);

        if ((highest_bit_set == 63 || lowest_bit_set == 0) &&
            all_bits_between_are_set != 0)
                return true;

        if (highest_bit_set - lowest_bit_set < 21)
                return true;

        return false;
}

static void sparc_emit_set_const64_quick2(unsigned long high_bits,
                                          unsigned long low_imm,
                                          unsigned int dest,
                                          int shift_count, struct jit_ctx *ctx)
{
        emit_loadimm32(high_bits, dest, ctx);

        /* Now shift it up into place.  */
        emit_alu_K(SLLX, dest, shift_count, ctx);

        /* If there is a low immediate part piece, finish up by
         * putting that in as well.
         */
        if (low_imm != 0)
                emit(OR | IMMED | RS1(dest) | S13(low_imm) | RD(dest), ctx);
}

static void emit_loadimm64(u64 K, unsigned int dest, struct jit_ctx *ctx)
{
        int all_bits_between_are_set, lowest_bit_set, highest_bit_set;
        unsigned int tmp = bpf2sparc[TMP_REG_1];
        u32 low_bits = (K & 0xffffffff);
        u32 high_bits = (K >> 32);

        /* These two tests also take care of all of the one
         * instruction cases.
         */
        if (high_bits == 0xffffffff && (low_bits & 0x80000000))
                return emit_loadimm_sext(K, dest, ctx);
        if (high_bits == 0x00000000)
                return emit_loadimm32(K, dest, ctx);

        analyze_64bit_constant(high_bits, low_bits, &highest_bit_set,
                               &lowest_bit_set, &all_bits_between_are_set);

        /* 1) mov       -1, %reg
         *    sllx      %reg, shift, %reg
         * 2) mov       -1, %reg
         *    srlx      %reg, shift, %reg
         * 3) mov       some_small_const, %reg
         *    sllx      %reg, shift, %reg
         */
        if (((highest_bit_set == 63 || lowest_bit_set == 0) &&
             all_bits_between_are_set != 0) ||
            ((highest_bit_set - lowest_bit_set) < 12)) {
                int shift = lowest_bit_set;
                long the_const = -1;

                if ((highest_bit_set != 63 && lowest_bit_set != 0) ||
                    all_bits_between_are_set == 0) {
                        the_const =
                                create_simple_focus_bits(high_bits, low_bits,
                                                         lowest_bit_set, 0);
                } else if (lowest_bit_set == 0)
                        shift = -(63 - highest_bit_set);

                emit(OR | IMMED | RS1(G0) | S13(the_const) | RD(dest), ctx);
                if (shift > 0)
                        emit_alu_K(SLLX, dest, shift, ctx);
                else if (shift < 0)
                        emit_alu_K(SRLX, dest, -shift, ctx);

                return;
        }

        /* Now a range of 22 or less bits set somewhere.
         * 1) sethi     %hi(focus_bits), %reg
         *    sllx      %reg, shift, %reg
         * 2) sethi     %hi(focus_bits), %reg
         *    srlx      %reg, shift, %reg
         */
        if ((highest_bit_set - lowest_bit_set) < 21) {
                unsigned long focus_bits =
                        create_simple_focus_bits(high_bits, low_bits,
                                                 lowest_bit_set, 10);

                emit(SETHI(focus_bits, dest), ctx);

                /* If lowest_bit_set == 10 then a sethi alone could
                 * have done it.
                 */
                if (lowest_bit_set < 10)
                        emit_alu_K(SRLX, dest, 10 - lowest_bit_set, ctx);
                else if (lowest_bit_set > 10)
                        emit_alu_K(SLLX, dest, lowest_bit_set - 10, ctx);
                return;
        }

        /* Ok, now 3 instruction sequences.  */
        if (low_bits == 0) {
                emit_loadimm32(high_bits, dest, ctx);
                emit_alu_K(SLLX, dest, 32, ctx);
                return;
        }

        /* We may be able to do something quick
         * when the constant is negated, so try that.
         */
        if (const64_is_2insns((~high_bits) & 0xffffffff,
                              (~low_bits) & 0xfffffc00)) {
                /* NOTE: The trailing bits get XOR'd so we need the
                 * non-negated bits, not the negated ones.
                 */
                unsigned long trailing_bits = low_bits & 0x3ff;

                if ((((~high_bits) & 0xffffffff) == 0 &&
                     ((~low_bits) & 0x80000000) == 0) ||
                    (((~high_bits) & 0xffffffff) == 0xffffffff &&
                     ((~low_bits) & 0x80000000) != 0)) {
                        unsigned long fast_int = (~low_bits & 0xffffffff);

                        if ((is_sethi(fast_int) &&
                             (~high_bits & 0xffffffff) == 0)) {
                                emit(SETHI(fast_int, dest), ctx);
                        } else if (is_simm13(fast_int)) {
                                emit(OR | IMMED | RS1(G0) | S13(fast_int) | RD(dest), ctx);
                        } else {
                                emit_loadimm64(fast_int, dest, ctx);
                        }
                } else {
                        u64 n = ((~low_bits) & 0xfffffc00) |
                                (((unsigned long)((~high_bits) & 0xffffffff))<<32);
                        emit_loadimm64(n, dest, ctx);
                }

                low_bits = -0x400 | trailing_bits;

                emit(XOR | IMMED | RS1(dest) | S13(low_bits) | RD(dest), ctx);
                return;
        }

        /* 1) sethi     %hi(xxx), %reg
         *    or        %reg, %lo(xxx), %reg
         *    sllx      %reg, yyy, %reg
         */
        if ((highest_bit_set - lowest_bit_set) < 32) {
                unsigned long focus_bits =
                        create_simple_focus_bits(high_bits, low_bits,
                                                 lowest_bit_set, 0);

                /* So what we know is that the set bits straddle the
                 * middle of the 64-bit word.
                 */
                sparc_emit_set_const64_quick2(focus_bits, 0, dest,
                                              lowest_bit_set, ctx);
                return;
        }

        /* 1) sethi     %hi(high_bits), %reg
         *    or        %reg, %lo(high_bits), %reg
         *    sllx      %reg, 32, %reg
         *    or        %reg, low_bits, %reg
         */
        if (is_simm13(low_bits) && ((int)low_bits > 0)) {
                sparc_emit_set_const64_quick2(high_bits, low_bits,
                                              dest, 32, ctx);
                return;
        }

        /* Oh well, we tried... Do a full 64-bit decomposition.  */
        ctx->tmp_1_used = true;

        emit_loadimm32(high_bits, tmp, ctx);
        emit_loadimm32(low_bits, dest, ctx);
        emit_alu_K(SLLX, tmp, 32, ctx);
        emit(OR | RS1(dest) | RS2(tmp) | RD(dest), ctx);
}

static void emit_branch(unsigned int br_opc, unsigned int from_idx, unsigned int to_idx,
                        struct jit_ctx *ctx)
{
        unsigned int off = to_idx - from_idx;

        if (br_opc & XCC)
                emit(br_opc | WDISP19(off << 2), ctx);
        else
                emit(br_opc | WDISP22(off << 2), ctx);
}

static void emit_cbcond(unsigned int cb_opc, unsigned int from_idx, unsigned int to_idx,
                        const u8 dst, const u8 src, struct jit_ctx *ctx)
{
        unsigned int off = to_idx - from_idx;

        emit(cb_opc | WDISP10(off << 2) | RS1(dst) | RS2(src), ctx);
}

static void emit_cbcondi(unsigned int cb_opc, unsigned int from_idx, unsigned int to_idx,
                         const u8 dst, s32 imm, struct jit_ctx *ctx)
{
        unsigned int off = to_idx - from_idx;

        emit(cb_opc | IMMED | WDISP10(off << 2) | RS1(dst) | S5(imm), ctx);
}

#define emit_read_y(REG, CTX)   emit(RD_Y | RD(REG), CTX)
#define emit_write_y(REG, CTX)  emit(WR_Y | IMMED | RS1(REG) | S13(0), CTX)

#define emit_cmp(R1, R2, CTX)                           \
        emit(SUBCC | RS1(R1) | RS2(R2) | RD(G0), CTX)

#define emit_cmpi(R1, IMM, CTX)                         \
        emit(SUBCC | IMMED | RS1(R1) | S13(IMM) | RD(G0), CTX)

#define emit_btst(R1, R2, CTX)                          \
        emit(ANDCC | RS1(R1) | RS2(R2) | RD(G0), CTX)

#define emit_btsti(R1, IMM, CTX)                        \
        emit(ANDCC | IMMED | RS1(R1) | S13(IMM) | RD(G0), CTX)

static int emit_compare_and_branch(const u8 code, const u8 dst, u8 src,
                                   const s32 imm, bool is_imm, int branch_dst,
                                   struct jit_ctx *ctx)
{
        bool use_cbcond = (sparc64_elf_hwcap & AV_SPARC_CBCOND) != 0;
        const u8 tmp = bpf2sparc[TMP_REG_1];

        branch_dst = ctx->offset[branch_dst];

        if (!is_simm10(branch_dst - ctx->idx) ||
            BPF_OP(code) == BPF_JSET)
                use_cbcond = false;

        if (is_imm) {
                bool fits = true;

                if (use_cbcond) {
                        if (!is_simm5(imm))
                                fits = false;
                } else if (!is_simm13(imm)) {
                        fits = false;
                }
                if (!fits) {
                        ctx->tmp_1_used = true;
                        emit_loadimm_sext(imm, tmp, ctx);
                        src = tmp;
                        is_imm = false;
                }
        }

        if (!use_cbcond) {
                u32 br_opcode;

                if (BPF_OP(code) == BPF_JSET) {
                        if (is_imm)
                                emit_btsti(dst, imm, ctx);
                        else
                                emit_btst(dst, src, ctx);
                } else {
                        if (is_imm)
                                emit_cmpi(dst, imm, ctx);
                        else
                                emit_cmp(dst, src, ctx);
                }
                switch (BPF_OP(code)) {
                case BPF_JEQ:
                        br_opcode = BE;
                        break;
                case BPF_JGT:
                        br_opcode = BGU;
                        break;
                case BPF_JLT:
                        br_opcode = BLU;
                        break;
                case BPF_JGE:
                        br_opcode = BGEU;
                        break;
                case BPF_JLE:
                        br_opcode = BLEU;
                        break;
                case BPF_JSET:
                case BPF_JNE:
                        br_opcode = BNE;
                        break;
                case BPF_JSGT:
                        br_opcode = BG;
                        break;
                case BPF_JSLT:
                        br_opcode = BL;
                        break;
                case BPF_JSGE:
                        br_opcode = BGE;
                        break;
                case BPF_JSLE:
                        br_opcode = BLE;
                        break;
                default:
                        /* Make sure we dont leak kernel information to the
                         * user.
                         */
                        return -EFAULT;
                }
                emit_branch(br_opcode, ctx->idx, branch_dst, ctx);
                emit_nop(ctx);
        } else {
                u32 cbcond_opcode;

                switch (BPF_OP(code)) {
                case BPF_JEQ:
                        cbcond_opcode = CBCONDE;
                        break;
                case BPF_JGT:
                        cbcond_opcode = CBCONDGU;
                        break;
                case BPF_JLT:
                        cbcond_opcode = CBCONDLU;
                        break;
                case BPF_JGE:
                        cbcond_opcode = CBCONDGEU;
                        break;
                case BPF_JLE:
                        cbcond_opcode = CBCONDLEU;
                        break;
                case BPF_JNE:
                        cbcond_opcode = CBCONDNE;
                        break;
                case BPF_JSGT:
                        cbcond_opcode = CBCONDG;
                        break;
                case BPF_JSLT:
                        cbcond_opcode = CBCONDL;
                        break;
                case BPF_JSGE:
                        cbcond_opcode = CBCONDGE;
                        break;
                case BPF_JSLE:
                        cbcond_opcode = CBCONDLE;
                        break;
                default:
                        /* Make sure we dont leak kernel information to the
                         * user.
                         */
                        return -EFAULT;
                }
                cbcond_opcode |= CBCOND_OP;
                if (is_imm)
                        emit_cbcondi(cbcond_opcode, ctx->idx, branch_dst,
                                     dst, imm, ctx);
                else
                        emit_cbcond(cbcond_opcode, ctx->idx, branch_dst,
                                    dst, src, ctx);
        }
        return 0;
}

/* Just skip the save instruction and the ctx register move.  */
#define BPF_TAILCALL_PROLOGUE_SKIP      32
#define BPF_TAILCALL_CNT_SP_OFF         (STACK_BIAS + 128)

static void build_prologue(struct jit_ctx *ctx)
{
        s32 stack_needed = BASE_STACKFRAME;

        if (ctx->saw_frame_pointer || ctx->saw_tail_call) {
                struct bpf_prog *prog = ctx->prog;
                u32 stack_depth;

                stack_depth = prog->aux->stack_depth;
                stack_needed += round_up(stack_depth, 16);
        }

        if (ctx->saw_tail_call)
                stack_needed += 8;

        /* save %sp, -176, %sp */
        emit(SAVE | IMMED | RS1(SP) | S13(-stack_needed) | RD(SP), ctx);

        /* tail_call_cnt = 0 */
        if (ctx->saw_tail_call) {
                u32 off = BPF_TAILCALL_CNT_SP_OFF;

                emit(ST32 | IMMED | RS1(SP) | S13(off) | RD(G0), ctx);
        } else {
                emit_nop(ctx);
        }
        if (ctx->saw_frame_pointer) {
                const u8 vfp = bpf2sparc[BPF_REG_FP];

                emit(ADD | IMMED | RS1(FP) | S13(STACK_BIAS) | RD(vfp), ctx);
        } else {
                emit_nop(ctx);
        }

        emit_reg_move(I0, O0, ctx);
        emit_reg_move(I1, O1, ctx);
        emit_reg_move(I2, O2, ctx);
        emit_reg_move(I3, O3, ctx);
        emit_reg_move(I4, O4, ctx);
        /* If you add anything here, adjust BPF_TAILCALL_PROLOGUE_SKIP above. */
}

static void build_epilogue(struct jit_ctx *ctx)
{
        ctx->epilogue_offset = ctx->idx;

        /* ret (jmpl %i7 + 8, %g0) */
        emit(JMPL | IMMED | RS1(I7) | S13(8) | RD(G0), ctx);

        /* restore %i5, %g0, %o0 */
        emit(RESTORE | RS1(bpf2sparc[BPF_REG_0]) | RS2(G0) | RD(O0), ctx);
}

static void emit_tail_call(struct jit_ctx *ctx)
{
        const u8 bpf_array = bpf2sparc[BPF_REG_2];
        const u8 bpf_index = bpf2sparc[BPF_REG_3];
        const u8 tmp = bpf2sparc[TMP_REG_1];
        u32 off;

        ctx->saw_tail_call = true;

        off = offsetof(struct bpf_array, map.max_entries);
        emit(LD32 | IMMED | RS1(bpf_array) | S13(off) | RD(tmp), ctx);
        emit_cmp(bpf_index, tmp, ctx);
#define OFFSET1 17
        emit_branch(BGEU, ctx->idx, ctx->idx + OFFSET1, ctx);
        emit_nop(ctx);

        off = BPF_TAILCALL_CNT_SP_OFF;
        emit(LD32 | IMMED | RS1(SP) | S13(off) | RD(tmp), ctx);
        emit_cmpi(tmp, MAX_TAIL_CALL_CNT, ctx);
#define OFFSET2 13
        emit_branch(BGU, ctx->idx, ctx->idx + OFFSET2, ctx);
        emit_nop(ctx);

        emit_alu_K(ADD, tmp, 1, ctx);
        off = BPF_TAILCALL_CNT_SP_OFF;
        emit(ST32 | IMMED | RS1(SP) | S13(off) | RD(tmp), ctx);

        emit_alu3_K(SLL, bpf_index, 3, tmp, ctx);
        emit_alu(ADD, bpf_array, tmp, ctx);
        off = offsetof(struct bpf_array, ptrs);
        emit(LD64 | IMMED | RS1(tmp) | S13(off) | RD(tmp), ctx);

        emit_cmpi(tmp, 0, ctx);
#define OFFSET3 5
        emit_branch(BE, ctx->idx, ctx->idx + OFFSET3, ctx);
        emit_nop(ctx);

        off = offsetof(struct bpf_prog, bpf_func);
        emit(LD64 | IMMED | RS1(tmp) | S13(off) | RD(tmp), ctx);

        off = BPF_TAILCALL_PROLOGUE_SKIP;
        emit(JMPL | IMMED | RS1(tmp) | S13(off) | RD(G0), ctx);
        emit_nop(ctx);
}

static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx)
{
        const u8 code = insn->code;
        const u8 dst = bpf2sparc[insn->dst_reg];
        const u8 src = bpf2sparc[insn->src_reg];
        const int i = insn - ctx->prog->insnsi;
        const s16 off = insn->off;
        const s32 imm = insn->imm;

        if (insn->src_reg == BPF_REG_FP)
                ctx->saw_frame_pointer = true;

        switch (code) {
        /* dst = src */
        case BPF_ALU | BPF_MOV | BPF_X:
                emit_alu3_K(SRL, src, 0, dst, ctx);
                break;
        case BPF_ALU64 | BPF_MOV | BPF_X:
                emit_reg_move(src, dst, ctx);
                break;
        /* dst = dst OP src */
        case BPF_ALU | BPF_ADD | BPF_X:
        case BPF_ALU64 | BPF_ADD | BPF_X:
                emit_alu(ADD, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_SUB | BPF_X:
        case BPF_ALU64 | BPF_SUB | BPF_X:
                emit_alu(SUB, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_AND | BPF_X:
        case BPF_ALU64 | BPF_AND | BPF_X:
                emit_alu(AND, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_OR | BPF_X:
        case BPF_ALU64 | BPF_OR | BPF_X:
                emit_alu(OR, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_XOR | BPF_X:
        case BPF_ALU64 | BPF_XOR | BPF_X:
                emit_alu(XOR, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_MUL | BPF_X:
                emit_alu(MUL, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU64 | BPF_MUL | BPF_X:
                emit_alu(MULX, src, dst, ctx);
                break;
        case BPF_ALU | BPF_DIV | BPF_X:
                emit_write_y(G0, ctx);
                emit_alu(DIV, src, dst, ctx);
                break;
        case BPF_ALU64 | BPF_DIV | BPF_X:
                emit_alu(UDIVX, src, dst, ctx);
                break;
        case BPF_ALU | BPF_MOD | BPF_X: {
                const u8 tmp = bpf2sparc[TMP_REG_1];

                ctx->tmp_1_used = true;

                emit_write_y(G0, ctx);
                emit_alu3(DIV, dst, src, tmp, ctx);
                emit_alu3(MULX, tmp, src, tmp, ctx);
                emit_alu3(SUB, dst, tmp, dst, ctx);
                goto do_alu32_trunc;
        }
        case BPF_ALU64 | BPF_MOD | BPF_X: {
                const u8 tmp = bpf2sparc[TMP_REG_1];

                ctx->tmp_1_used = true;

                emit_alu3(UDIVX, dst, src, tmp, ctx);
                emit_alu3(MULX, tmp, src, tmp, ctx);
                emit_alu3(SUB, dst, tmp, dst, ctx);
                break;
        }
        case BPF_ALU | BPF_LSH | BPF_X:
                emit_alu(SLL, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU64 | BPF_LSH | BPF_X:
                emit_alu(SLLX, src, dst, ctx);
                break;
        case BPF_ALU | BPF_RSH | BPF_X:
                emit_alu(SRL, src, dst, ctx);
                break;
        case BPF_ALU64 | BPF_RSH | BPF_X:
                emit_alu(SRLX, src, dst, ctx);
                break;
        case BPF_ALU | BPF_ARSH | BPF_X:
                emit_alu(SRA, src, dst, ctx);
                goto do_alu32_trunc;
        case BPF_ALU64 | BPF_ARSH | BPF_X:
                emit_alu(SRAX, src, dst, ctx);
                break;

        /* dst = -dst */
        case BPF_ALU | BPF_NEG:
        case BPF_ALU64 | BPF_NEG:
                emit(SUB | RS1(0) | RS2(dst) | RD(dst), ctx);
                goto do_alu32_trunc;

        case BPF_ALU | BPF_END | BPF_FROM_BE:
                switch (imm) {
                case 16:
                        emit_alu_K(SLL, dst, 16, ctx);
                        emit_alu_K(SRL, dst, 16, ctx);
                        break;
                case 32:
                        emit_alu_K(SRL, dst, 0, ctx);
                        break;
                case 64:
                        /* nop */
                        break;

                }
                break;

        /* dst = BSWAP##imm(dst) */
        case BPF_ALU | BPF_END | BPF_FROM_LE: {
                const u8 tmp = bpf2sparc[TMP_REG_1];
                const u8 tmp2 = bpf2sparc[TMP_REG_2];

                ctx->tmp_1_used = true;
                switch (imm) {
                case 16:
                        emit_alu3_K(AND, dst, 0xff, tmp, ctx);
                        emit_alu3_K(SRL, dst, 8, dst, ctx);
                        emit_alu3_K(AND, dst, 0xff, dst, ctx);
                        emit_alu3_K(SLL, tmp, 8, tmp, ctx);
                        emit_alu(OR, tmp, dst, ctx);
                        break;

                case 32:
                        ctx->tmp_2_used = true;
                        emit_alu3_K(SRL, dst, 24, tmp, ctx);    /* tmp  = dst >> 24 */
                        emit_alu3_K(SRL, dst, 16, tmp2, ctx);   /* tmp2 = dst >> 16 */
                        emit_alu3_K(AND, tmp2, 0xff, tmp2, ctx);/* tmp2 = tmp2 & 0xff */
                        emit_alu3_K(SLL, tmp2, 8, tmp2, ctx);   /* tmp2 = tmp2 << 8 */
                        emit_alu(OR, tmp2, tmp, ctx);           /* tmp  = tmp | tmp2 */
                        emit_alu3_K(SRL, dst, 8, tmp2, ctx);    /* tmp2 = dst >> 8 */
                        emit_alu3_K(AND, tmp2, 0xff, tmp2, ctx);/* tmp2 = tmp2 & 0xff */
                        emit_alu3_K(SLL, tmp2, 16, tmp2, ctx);  /* tmp2 = tmp2 << 16 */
                        emit_alu(OR, tmp2, tmp, ctx);           /* tmp  = tmp | tmp2 */
                        emit_alu3_K(AND, dst, 0xff, dst, ctx);  /* dst  = dst & 0xff */
                        emit_alu3_K(SLL, dst, 24, dst, ctx);    /* dst  = dst << 24 */
                        emit_alu(OR, tmp, dst, ctx);            /* dst  = dst | tmp */
                        break;

                case 64:
                        emit_alu3_K(ADD, SP, STACK_BIAS + 128, tmp, ctx);
                        emit(ST64 | RS1(tmp) | RS2(G0) | RD(dst), ctx);
                        emit(LD64A | ASI(ASI_PL) | RS1(tmp) | RS2(G0) | RD(dst), ctx);
                        break;
                }
                break;
        }
        /* dst = imm */
        case BPF_ALU | BPF_MOV | BPF_K:
                emit_loadimm32(imm, dst, ctx);
                break;
        case BPF_ALU64 | BPF_MOV | BPF_K:
                emit_loadimm_sext(imm, dst, ctx);
                break;
        /* dst = dst OP imm */
        case BPF_ALU | BPF_ADD | BPF_K:
        case BPF_ALU64 | BPF_ADD | BPF_K:
                emit_alu_K(ADD, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_SUB | BPF_K:
        case BPF_ALU64 | BPF_SUB | BPF_K:
                emit_alu_K(SUB, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_AND | BPF_K:
        case BPF_ALU64 | BPF_AND | BPF_K:
                emit_alu_K(AND, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_OR | BPF_K:
        case BPF_ALU64 | BPF_OR | BPF_K:
                emit_alu_K(OR, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_XOR | BPF_K:
        case BPF_ALU64 | BPF_XOR | BPF_K:
                emit_alu_K(XOR, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU | BPF_MUL | BPF_K:
                emit_alu_K(MUL, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU64 | BPF_MUL | BPF_K:
                emit_alu_K(MULX, dst, imm, ctx);
                break;
        case BPF_ALU | BPF_DIV | BPF_K:
                if (imm == 0)
                        return -EINVAL;

                emit_write_y(G0, ctx);
                emit_alu_K(DIV, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU64 | BPF_DIV | BPF_K:
                if (imm == 0)
                        return -EINVAL;

                emit_alu_K(UDIVX, dst, imm, ctx);
                break;
        case BPF_ALU64 | BPF_MOD | BPF_K:
        case BPF_ALU | BPF_MOD | BPF_K: {
                const u8 tmp = bpf2sparc[TMP_REG_2];
                unsigned int div;

                if (imm == 0)
                        return -EINVAL;

                div = (BPF_CLASS(code) == BPF_ALU64) ? UDIVX : DIV;

                ctx->tmp_2_used = true;

                if (BPF_CLASS(code) != BPF_ALU64)
                        emit_write_y(G0, ctx);
                if (is_simm13(imm)) {
                        emit(div | IMMED | RS1(dst) | S13(imm) | RD(tmp), ctx);
                        emit(MULX | IMMED | RS1(tmp) | S13(imm) | RD(tmp), ctx);
                        emit(SUB | RS1(dst) | RS2(tmp) | RD(dst), ctx);
                } else {
                        const u8 tmp1 = bpf2sparc[TMP_REG_1];

                        ctx->tmp_1_used = true;

                        emit_set_const_sext(imm, tmp1, ctx);
                        emit(div | RS1(dst) | RS2(tmp1) | RD(tmp), ctx);
                        emit(MULX | RS1(tmp) | RS2(tmp1) | RD(tmp), ctx);
                        emit(SUB | RS1(dst) | RS2(tmp) | RD(dst), ctx);
                }
                goto do_alu32_trunc;
        }
        case BPF_ALU | BPF_LSH | BPF_K:
                emit_alu_K(SLL, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU64 | BPF_LSH | BPF_K:
                emit_alu_K(SLLX, dst, imm, ctx);
                break;
        case BPF_ALU | BPF_RSH | BPF_K:
                emit_alu_K(SRL, dst, imm, ctx);
                break;
        case BPF_ALU64 | BPF_RSH | BPF_K:
                emit_alu_K(SRLX, dst, imm, ctx);
                break;
        case BPF_ALU | BPF_ARSH | BPF_K:
                emit_alu_K(SRA, dst, imm, ctx);
                goto do_alu32_trunc;
        case BPF_ALU64 | BPF_ARSH | BPF_K:
                emit_alu_K(SRAX, dst, imm, ctx);
                break;

        do_alu32_trunc:
                if (BPF_CLASS(code) == BPF_ALU)
                        emit_alu_K(SRL, dst, 0, ctx);
                break;

        /* JUMP off */
        case BPF_JMP | BPF_JA:
                emit_branch(BA, ctx->idx, ctx->offset[i + off], ctx);
                emit_nop(ctx);
                break;
        /* IF (dst COND src) JUMP off */
        case BPF_JMP | BPF_JEQ | BPF_X:
        case BPF_JMP | BPF_JGT | BPF_X:
        case BPF_JMP | BPF_JLT | BPF_X:
        case BPF_JMP | BPF_JGE | BPF_X:
        case BPF_JMP | BPF_JLE | BPF_X:
        case BPF_JMP | BPF_JNE | BPF_X:
        case BPF_JMP | BPF_JSGT | BPF_X:
        case BPF_JMP | BPF_JSLT | BPF_X:
        case BPF_JMP | BPF_JSGE | BPF_X:
        case BPF_JMP | BPF_JSLE | BPF_X:
        case BPF_JMP | BPF_JSET | BPF_X: {
                int err;

                err = emit_compare_and_branch(code, dst, src, 0, false, i + off, ctx);
                if (err)
                        return err;
                break;
        }
        /* IF (dst COND imm) JUMP off */
        case BPF_JMP | BPF_JEQ | BPF_K:
        case BPF_JMP | BPF_JGT | BPF_K:
        case BPF_JMP | BPF_JLT | BPF_K:
        case BPF_JMP | BPF_JGE | BPF_K:
        case BPF_JMP | BPF_JLE | BPF_K:
        case BPF_JMP | BPF_JNE | BPF_K:
        case BPF_JMP | BPF_JSGT | BPF_K:
        case BPF_JMP | BPF_JSLT | BPF_K:
        case BPF_JMP | BPF_JSGE | BPF_K:
        case BPF_JMP | BPF_JSLE | BPF_K:
        case BPF_JMP | BPF_JSET | BPF_K: {
                int err;

                err = emit_compare_and_branch(code, dst, 0, imm, true, i + off, ctx);
                if (err)
                        return err;
                break;
        }

        /* function call */
        case BPF_JMP | BPF_CALL:
        {
                u8 *func = ((u8 *)__bpf_call_base) + imm;

                ctx->saw_call = true;

                emit_call((u32 *)func, ctx);
                emit_nop(ctx);

                emit_reg_move(O0, bpf2sparc[BPF_REG_0], ctx);
                break;
        }

        /* tail call */
        case BPF_JMP | BPF_TAIL_CALL:
                emit_tail_call(ctx);
                break;

        /* function return */
        case BPF_JMP | BPF_EXIT:
                /* Optimization: when last instruction is EXIT,
                   simply fallthrough to epilogue. */
                if (i == ctx->prog->len - 1)
                        break;
                emit_branch(BA, ctx->idx, ctx->epilogue_offset, ctx);
                emit_nop(ctx);
                break;

        /* dst = imm64 */
        case BPF_LD | BPF_IMM | BPF_DW:
        {
                const struct bpf_insn insn1 = insn[1];
                u64 imm64;

                imm64 = (u64)insn1.imm << 32 | (u32)imm;
                emit_loadimm64(imm64, dst, ctx);

                return 1;
        }

        /* LDX: dst = *(size *)(src + off) */
        case BPF_LDX | BPF_MEM | BPF_W:
        case BPF_LDX | BPF_MEM | BPF_H:
        case BPF_LDX | BPF_MEM | BPF_B:
        case BPF_LDX | BPF_MEM | BPF_DW: {
                const u8 tmp = bpf2sparc[TMP_REG_1];
                u32 opcode = 0, rs2;

                ctx->tmp_1_used = true;
                switch (BPF_SIZE(code)) {
                case BPF_W:
                        opcode = LD32;
                        break;
                case BPF_H:
                        opcode = LD16;
                        break;
                case BPF_B:
                        opcode = LD8;
                        break;
                case BPF_DW:
                        opcode = LD64;
                        break;
                }

                if (is_simm13(off)) {
                        opcode |= IMMED;
                        rs2 = S13(off);
                } else {
                        emit_loadimm(off, tmp, ctx);
                        rs2 = RS2(tmp);
                }
                emit(opcode | RS1(src) | rs2 | RD(dst), ctx);
                break;
        }
        /* ST: *(size *)(dst + off) = imm */
        case BPF_ST | BPF_MEM | BPF_W:
        case BPF_ST | BPF_MEM | BPF_H:
        case BPF_ST | BPF_MEM | BPF_B:
        case BPF_ST | BPF_MEM | BPF_DW: {
                const u8 tmp = bpf2sparc[TMP_REG_1];
                const u8 tmp2 = bpf2sparc[TMP_REG_2];
                u32 opcode = 0, rs2;

                if (insn->dst_reg == BPF_REG_FP)
                        ctx->saw_frame_pointer = true;

                ctx->tmp_2_used = true;
                emit_loadimm(imm, tmp2, ctx);

                switch (BPF_SIZE(code)) {
                case BPF_W:
                        opcode = ST32;
                        break;
                case BPF_H:
                        opcode = ST16;
                        break;
                case BPF_B:
                        opcode = ST8;
                        break;
                case BPF_DW:
                        opcode = ST64;
                        break;
                }

                if (is_simm13(off)) {
                        opcode |= IMMED;
                        rs2 = S13(off);
                } else {
                        ctx->tmp_1_used = true;
                        emit_loadimm(off, tmp, ctx);
                        rs2 = RS2(tmp);
                }
                emit(opcode | RS1(dst) | rs2 | RD(tmp2), ctx);
                break;
        }

        /* STX: *(size *)(dst + off) = src */
        case BPF_STX | BPF_MEM | BPF_W:
        case BPF_STX | BPF_MEM | BPF_H:
        case BPF_STX | BPF_MEM | BPF_B:
        case BPF_STX | BPF_MEM | BPF_DW: {
                const u8 tmp = bpf2sparc[TMP_REG_1];
                u32 opcode = 0, rs2;

                if (insn->dst_reg == BPF_REG_FP)
                        ctx->saw_frame_pointer = true;

                switch (BPF_SIZE(code)) {
                case BPF_W:
                        opcode = ST32;
                        break;
                case BPF_H:
                        opcode = ST16;
                        break;
                case BPF_B:
                        opcode = ST8;
                        break;
                case BPF_DW:
                        opcode = ST64;
                        break;
                }
                if (is_simm13(off)) {
                        opcode |= IMMED;
                        rs2 = S13(off);
                } else {
                        ctx->tmp_1_used = true;
                        emit_loadimm(off, tmp, ctx);
                        rs2 = RS2(tmp);
                }
                emit(opcode | RS1(dst) | rs2 | RD(src), ctx);
                break;
        }

        /* STX XADD: lock *(u32 *)(dst + off) += src */
        case BPF_STX | BPF_XADD | BPF_W: {
                const u8 tmp = bpf2sparc[TMP_REG_1];
                const u8 tmp2 = bpf2sparc[TMP_REG_2];
                const u8 tmp3 = bpf2sparc[TMP_REG_3];

                if (insn->dst_reg == BPF_REG_FP)
                        ctx->saw_frame_pointer = true;

                ctx->tmp_1_used = true;
                ctx->tmp_2_used = true;
                ctx->tmp_3_used = true;
                emit_loadimm(off, tmp, ctx);
                emit_alu3(ADD, dst, tmp, tmp, ctx);

                emit(LD32 | RS1(tmp) | RS2(G0) | RD(tmp2), ctx);
                emit_alu3(ADD, tmp2, src, tmp3, ctx);
                emit(CAS | ASI(ASI_P) | RS1(tmp) | RS2(tmp2) | RD(tmp3), ctx);
                emit_cmp(tmp2, tmp3, ctx);
                emit_branch(BNE, 4, 0, ctx);
                emit_nop(ctx);
                break;
        }
        /* STX XADD: lock *(u64 *)(dst + off) += src */
        case BPF_STX | BPF_XADD | BPF_DW: {
                const u8 tmp = bpf2sparc[TMP_REG_1];
                const u8 tmp2 = bpf2sparc[TMP_REG_2];
                const u8 tmp3 = bpf2sparc[TMP_REG_3];

                if (insn->dst_reg == BPF_REG_FP)
                        ctx->saw_frame_pointer = true;

                ctx->tmp_1_used = true;
                ctx->tmp_2_used = true;
                ctx->tmp_3_used = true;
                emit_loadimm(off, tmp, ctx);
                emit_alu3(ADD, dst, tmp, tmp, ctx);

                emit(LD64 | RS1(tmp) | RS2(G0) | RD(tmp2), ctx);
                emit_alu3(ADD, tmp2, src, tmp3, ctx);
                emit(CASX | ASI(ASI_P) | RS1(tmp) | RS2(tmp2) | RD(tmp3), ctx);
                emit_cmp(tmp2, tmp3, ctx);
                emit_branch(BNE, 4, 0, ctx);
                emit_nop(ctx);
                break;
        }

        default:
                pr_err_once("unknown opcode %02x\n", code);
                return -EINVAL;
        }

        return 0;
}

static int build_body(struct jit_ctx *ctx)
{
        const struct bpf_prog *prog = ctx->prog;
        int i;

        for (i = 0; i < prog->len; i++) {
                const struct bpf_insn *insn = &prog->insnsi[i];
                int ret;

                ret = build_insn(insn, ctx);

                if (ret > 0) {
                        i++;
                        ctx->offset[i] = ctx->idx;
                        continue;
                }
                ctx->offset[i] = ctx->idx;
                if (ret)
                        return ret;
        }
        return 0;
}

static void jit_fill_hole(void *area, unsigned int size)
{
        u32 *ptr;
        /* We are guaranteed to have aligned memory. */
        for (ptr = area; size >= sizeof(u32); size -= sizeof(u32))
                *ptr++ = 0x91d02005; /* ta 5 */
}

struct sparc64_jit_data {
        struct bpf_binary_header *header;
        u8 *image;
        struct jit_ctx ctx;
};

struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
        struct bpf_prog *tmp, *orig_prog = prog;
        struct sparc64_jit_data *jit_data;
        struct bpf_binary_header *header;
        u32 prev_image_size, image_size;
        bool tmp_blinded = false;
        bool extra_pass = false;
        struct jit_ctx ctx;
        u8 *image_ptr;
        int pass, i;

        if (!prog->jit_requested)
                return orig_prog;

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

        jit_data = prog->aux->jit_data;
        if (!jit_data) {
                jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
                if (!jit_data) {
                        prog = orig_prog;
                        goto out;
                }
                prog->aux->jit_data = jit_data;
        }
        if (jit_data->ctx.offset) {
                ctx = jit_data->ctx;
                image_ptr = jit_data->image;
                header = jit_data->header;
                extra_pass = true;
                image_size = sizeof(u32) * ctx.idx;
                prev_image_size = image_size;
                pass = 1;
                goto skip_init_ctx;
        }

        memset(&ctx, 0, sizeof(ctx));
        ctx.prog = prog;

        ctx.offset = kmalloc_array(prog->len, sizeof(unsigned int), GFP_KERNEL);
        if (ctx.offset == NULL) {
                prog = orig_prog;
                goto out_off;
        }

        /* Longest sequence emitted is for bswap32, 12 instructions.  Pre-cook
         * the offset array so that we converge faster.
         */
        for (i = 0; i < prog->len; i++)
                ctx.offset[i] = i * (12 * 4);

        prev_image_size = ~0U;
        for (pass = 1; pass < 40; pass++) {
                ctx.idx = 0;

                build_prologue(&ctx);
                if (build_body(&ctx)) {
                        prog = orig_prog;
                        goto out_off;
                }
                build_epilogue(&ctx);

                if (bpf_jit_enable > 1)
                        pr_info("Pass %d: size = %u, seen = [%c%c%c%c%c%c]\n", pass,
                                ctx.idx * 4,
                                ctx.tmp_1_used ? '1' : ' ',
                                ctx.tmp_2_used ? '2' : ' ',
                                ctx.tmp_3_used ? '3' : ' ',
                                ctx.saw_frame_pointer ? 'F' : ' ',
                                ctx.saw_call ? 'C' : ' ',
                                ctx.saw_tail_call ? 'T' : ' ');

                if (ctx.idx * 4 == prev_image_size)
                        break;
                prev_image_size = ctx.idx * 4;
                cond_resched();
        }

        /* Now we know the actual image size. */
        image_size = sizeof(u32) * ctx.idx;
        header = bpf_jit_binary_alloc(image_size, &image_ptr,
                                      sizeof(u32), jit_fill_hole);
        if (header == NULL) {
                prog = orig_prog;
                goto out_off;
        }

        ctx.image = (u32 *)image_ptr;
skip_init_ctx:
        ctx.idx = 0;

        build_prologue(&ctx);

        if (build_body(&ctx)) {
                bpf_jit_binary_free(header);
                prog = orig_prog;
                goto out_off;
        }

        build_epilogue(&ctx);

        if (ctx.idx * 4 != prev_image_size) {
                pr_err("bpf_jit: Failed to converge, prev_size=%u size=%d\n",
                       prev_image_size, ctx.idx * 4);
                bpf_jit_binary_free(header);
                prog = orig_prog;
                goto out_off;
        }

        if (bpf_jit_enable > 1)
                bpf_jit_dump(prog->len, image_size, pass, ctx.image);

        bpf_flush_icache(header, (u8 *)header + (header->pages * PAGE_SIZE));

        if (!prog->is_func || extra_pass) {
                bpf_jit_binary_lock_ro(header);
        } else {
                jit_data->ctx = ctx;
                jit_data->image = image_ptr;
                jit_data->header = header;
        }

        prog->bpf_func = (void *)ctx.image;
        prog->jited = 1;
        prog->jited_len = image_size;

        if (!prog->is_func || extra_pass) {
out_off:
                kfree(ctx.offset);
                kfree(jit_data);
                prog->aux->jit_data = NULL;
        }
out:
        if (tmp_blinded)
                bpf_jit_prog_release_other(prog, prog == orig_prog ?
                                           tmp : orig_prog);
        return prog;
}