// SPDX-License-Identifier: GPL-2.0-only
/*
 * bpf_jit_comp64.c: eBPF JIT compiler
 *
 * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
 *                IBM Corporation
 *
 * Based on the powerpc classic BPF JIT compiler by Matt Evans
 */
#include <linux/moduleloader.h>
#include <asm/cacheflush.h>
#include <asm/asm-compat.h>
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/if_vlan.h>
#include <asm/kprobes.h>
#include <linux/bpf.h>

#include "bpf_jit64.h"

static inline bool bpf_has_stack_frame(struct codegen_context *ctx)
{
        /*
         * We only need a stack frame if:
         * - we call other functions (kernel helpers), or
         * - the bpf program uses its stack area
         * The latter condition is deduced from the usage of BPF_REG_FP
         */
        return ctx->seen & SEEN_FUNC || bpf_is_seen_register(ctx, b2p[BPF_REG_FP]);
}

/*
 * When not setting up our own stackframe, the redzone usage is:
 *
 *              [       prev sp         ] <-------------
 *              [         ...           ]               |
 * sp (r1) ---> [    stack pointer      ] --------------
 *              [   nv gpr save area    ] 6*8
 *              [    tail_call_cnt      ] 8
 *              [    local_tmp_var      ] 8
 *              [   unused red zone     ] 208 bytes protected
 */
static int bpf_jit_stack_local(struct codegen_context *ctx)
{
        if (bpf_has_stack_frame(ctx))
                return STACK_FRAME_MIN_SIZE + ctx->stack_size;
        else
                return -(BPF_PPC_STACK_SAVE + 16);
}

static int bpf_jit_stack_tailcallcnt(struct codegen_context *ctx)
{
        return bpf_jit_stack_local(ctx) + 8;
}

static int bpf_jit_stack_offsetof(struct codegen_context *ctx, int reg)
{
        if (reg >= BPF_PPC_NVR_MIN && reg < 32)
                return (bpf_has_stack_frame(ctx) ?
                        (BPF_PPC_STACKFRAME + ctx->stack_size) : 0)
                                - (8 * (32 - reg));

        pr_err("BPF JIT is asking about unknown registers");
        BUG();
}

void bpf_jit_realloc_regs(struct codegen_context *ctx)
{
}

void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx)
{
        int i;

        /*
         * Initialize tail_call_cnt if we do tail calls.
         * Otherwise, put in NOPs so that it can be skipped when we are
         * invoked through a tail call.
         */
        if (ctx->seen & SEEN_TAILCALL) {
                EMIT(PPC_RAW_LI(b2p[TMP_REG_1], 0));
                /* this goes in the redzone */
                PPC_BPF_STL(b2p[TMP_REG_1], 1, -(BPF_PPC_STACK_SAVE + 8));
        } else {
                EMIT(PPC_RAW_NOP());
                EMIT(PPC_RAW_NOP());
        }

#define BPF_TAILCALL_PROLOGUE_SIZE      8

        if (bpf_has_stack_frame(ctx)) {
                /*
                 * We need a stack frame, but we don't necessarily need to
                 * save/restore LR unless we call other functions
                 */
                if (ctx->seen & SEEN_FUNC) {
                        EMIT(PPC_RAW_MFLR(_R0));
                        PPC_BPF_STL(0, 1, PPC_LR_STKOFF);
                }

                PPC_BPF_STLU(1, 1, -(BPF_PPC_STACKFRAME + ctx->stack_size));
        }

        /*
         * Back up non-volatile regs -- BPF registers 6-10
         * If we haven't created our own stack frame, we save these
         * in the protected zone below the previous stack frame
         */
        for (i = BPF_REG_6; i <= BPF_REG_10; i++)
                if (bpf_is_seen_register(ctx, b2p[i]))
                        PPC_BPF_STL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));

        /* Setup frame pointer to point to the bpf stack area */
        if (bpf_is_seen_register(ctx, b2p[BPF_REG_FP]))
                EMIT(PPC_RAW_ADDI(b2p[BPF_REG_FP], 1,
                                STACK_FRAME_MIN_SIZE + ctx->stack_size));
}

static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx)
{
        int i;

        /* Restore NVRs */
        for (i = BPF_REG_6; i <= BPF_REG_10; i++)
                if (bpf_is_seen_register(ctx, b2p[i]))
                        PPC_BPF_LL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));

        /* Tear down our stack frame */
        if (bpf_has_stack_frame(ctx)) {
                EMIT(PPC_RAW_ADDI(1, 1, BPF_PPC_STACKFRAME + ctx->stack_size));
                if (ctx->seen & SEEN_FUNC) {
                        PPC_BPF_LL(0, 1, PPC_LR_STKOFF);
                        EMIT(PPC_RAW_MTLR(0));
                }
        }
}

void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
{
        bpf_jit_emit_common_epilogue(image, ctx);

        /* Move result to r3 */
        EMIT(PPC_RAW_MR(3, b2p[BPF_REG_0]));

        EMIT(PPC_RAW_BLR());
}

static void bpf_jit_emit_func_call_hlp(u32 *image, struct codegen_context *ctx,
                                       u64 func)
{
#ifdef PPC64_ELF_ABI_v1
        /* func points to the function descriptor */
        PPC_LI64(b2p[TMP_REG_2], func);
        /* Load actual entry point from function descriptor */
        PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_2], 0);
        /* ... and move it to CTR */
        EMIT(PPC_RAW_MTCTR(b2p[TMP_REG_1]));
        /*
         * Load TOC from function descriptor at offset 8.
         * We can clobber r2 since we get called through a
         * function pointer (so caller will save/restore r2)
         * and since we don't use a TOC ourself.
         */
        PPC_BPF_LL(2, b2p[TMP_REG_2], 8);
#else
        /* We can clobber r12 */
        PPC_FUNC_ADDR(12, func);
        EMIT(PPC_RAW_MTCTR(12));
#endif
        EMIT(PPC_RAW_BCTRL());
}

void bpf_jit_emit_func_call_rel(u32 *image, struct codegen_context *ctx, u64 func)
{
        unsigned int i, ctx_idx = ctx->idx;

        /* Load function address into r12 */
        PPC_LI64(12, func);

        /* For bpf-to-bpf function calls, the callee's address is unknown
         * until the last extra pass. As seen above, we use PPC_LI64() to
         * load the callee's address, but this may optimize the number of
         * instructions required based on the nature of the address.
         *
         * Since we don't want the number of instructions emitted to change,
         * we pad the optimized PPC_LI64() call with NOPs to guarantee that
         * we always have a five-instruction sequence, which is the maximum
         * that PPC_LI64() can emit.
         */
        for (i = ctx->idx - ctx_idx; i < 5; i++)
                EMIT(PPC_RAW_NOP());

#ifdef PPC64_ELF_ABI_v1
        /*
         * Load TOC from function descriptor at offset 8.
         * We can clobber r2 since we get called through a
         * function pointer (so caller will save/restore r2)
         * and since we don't use a TOC ourself.
         */
        PPC_BPF_LL(2, 12, 8);
        /* Load actual entry point from function descriptor */
        PPC_BPF_LL(12, 12, 0);
#endif

        EMIT(PPC_RAW_MTCTR(12));
        EMIT(PPC_RAW_BCTRL());
}

static void bpf_jit_emit_tail_call(u32 *image, struct codegen_context *ctx, u32 out)
{
        /*
         * By now, the eBPF program has already setup parameters in r3, r4 and r5
         * r3/BPF_REG_1 - pointer to ctx -- passed as is to the next bpf program
         * r4/BPF_REG_2 - pointer to bpf_array
         * r5/BPF_REG_3 - index in bpf_array
         */
        int b2p_bpf_array = b2p[BPF_REG_2];
        int b2p_index = b2p[BPF_REG_3];

        /*
         * if (index >= array->map.max_entries)
         *   goto out;
         */
        EMIT(PPC_RAW_LWZ(b2p[TMP_REG_1], b2p_bpf_array, offsetof(struct bpf_array, map.max_entries)));
        EMIT(PPC_RAW_RLWINM(b2p_index, b2p_index, 0, 0, 31));
        EMIT(PPC_RAW_CMPLW(b2p_index, b2p[TMP_REG_1]));
        PPC_BCC(COND_GE, out);

        /*
         * if (tail_call_cnt > MAX_TAIL_CALL_CNT)
         *   goto out;
         */
        PPC_BPF_LL(b2p[TMP_REG_1], 1, bpf_jit_stack_tailcallcnt(ctx));
        EMIT(PPC_RAW_CMPLWI(b2p[TMP_REG_1], MAX_TAIL_CALL_CNT));
        PPC_BCC(COND_GT, out);

        /*
         * tail_call_cnt++;
         */
        EMIT(PPC_RAW_ADDI(b2p[TMP_REG_1], b2p[TMP_REG_1], 1));
        PPC_BPF_STL(b2p[TMP_REG_1], 1, bpf_jit_stack_tailcallcnt(ctx));

        /* prog = array->ptrs[index]; */
        EMIT(PPC_RAW_MULI(b2p[TMP_REG_1], b2p_index, 8));
        EMIT(PPC_RAW_ADD(b2p[TMP_REG_1], b2p[TMP_REG_1], b2p_bpf_array));
        PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_1], offsetof(struct bpf_array, ptrs));

        /*
         * if (prog == NULL)
         *   goto out;
         */
        EMIT(PPC_RAW_CMPLDI(b2p[TMP_REG_1], 0));
        PPC_BCC(COND_EQ, out);

        /* goto *(prog->bpf_func + prologue_size); */
        PPC_BPF_LL(b2p[TMP_REG_1], b2p[TMP_REG_1], offsetof(struct bpf_prog, bpf_func));
#ifdef PPC64_ELF_ABI_v1
        /* skip past the function descriptor */
        EMIT(PPC_RAW_ADDI(b2p[TMP_REG_1], b2p[TMP_REG_1],
                        FUNCTION_DESCR_SIZE + BPF_TAILCALL_PROLOGUE_SIZE));
#else
        EMIT(PPC_RAW_ADDI(b2p[TMP_REG_1], b2p[TMP_REG_1], BPF_TAILCALL_PROLOGUE_SIZE));
#endif
        EMIT(PPC_RAW_MTCTR(b2p[TMP_REG_1]));

        /* tear down stack, restore NVRs, ... */
        bpf_jit_emit_common_epilogue(image, ctx);

        EMIT(PPC_RAW_BCTR());
        /* out: */
}

/* Assemble the body code between the prologue & epilogue */
int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *ctx,
                       u32 *addrs, bool extra_pass)
{
        const struct bpf_insn *insn = fp->insnsi;
        int flen = fp->len;
        int i, ret;

        /* Start of epilogue code - will only be valid 2nd pass onwards */
        u32 exit_addr = addrs[flen];

        for (i = 0; i < flen; i++) {
                u32 code = insn[i].code;
                u32 dst_reg = b2p[insn[i].dst_reg];
                u32 src_reg = b2p[insn[i].src_reg];
                s16 off = insn[i].off;
                s32 imm = insn[i].imm;
                bool func_addr_fixed;
                u64 func_addr;
                u64 imm64;
                u32 true_cond;
                u32 tmp_idx;

                /*
                 * addrs[] maps a BPF bytecode address into a real offset from
                 * the start of the body code.
                 */
                addrs[i] = ctx->idx * 4;

                /*
                 * As an optimization, we note down which non-volatile registers
                 * are used so that we can only save/restore those in our
                 * prologue and epilogue. We do this here regardless of whether
                 * the actual BPF instruction uses src/dst registers or not
                 * (for instance, BPF_CALL does not use them). The expectation
                 * is that those instructions will have src_reg/dst_reg set to
                 * 0. Even otherwise, we just lose some prologue/epilogue
                 * optimization but everything else should work without
                 * any issues.
                 */
                if (dst_reg >= BPF_PPC_NVR_MIN && dst_reg < 32)
                        bpf_set_seen_register(ctx, dst_reg);
                if (src_reg >= BPF_PPC_NVR_MIN && src_reg < 32)
                        bpf_set_seen_register(ctx, src_reg);

                switch (code) {
                /*
                 * Arithmetic operations: ADD/SUB/MUL/DIV/MOD/NEG
                 */
                case BPF_ALU | BPF_ADD | BPF_X: /* (u32) dst += (u32) src */
                case BPF_ALU64 | BPF_ADD | BPF_X: /* dst += src */
                        EMIT(PPC_RAW_ADD(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_SUB | BPF_X: /* (u32) dst -= (u32) src */
                case BPF_ALU64 | BPF_SUB | BPF_X: /* dst -= src */
                        EMIT(PPC_RAW_SUB(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_ADD | BPF_K: /* (u32) dst += (u32) imm */
                case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
                case BPF_ALU64 | BPF_ADD | BPF_K: /* dst += imm */
                case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */
                        if (BPF_OP(code) == BPF_SUB)
                                imm = -imm;
                        if (imm) {
                                if (imm >= -32768 && imm < 32768)
                                        EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
                                else {
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
                                }
                        }
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_MUL | BPF_X: /* (u32) dst *= (u32) src */
                case BPF_ALU64 | BPF_MUL | BPF_X: /* dst *= src */
                        if (BPF_CLASS(code) == BPF_ALU)
                                EMIT(PPC_RAW_MULW(dst_reg, dst_reg, src_reg));
                        else
                                EMIT(PPC_RAW_MULD(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_MUL | BPF_K: /* (u32) dst *= (u32) imm */
                case BPF_ALU64 | BPF_MUL | BPF_K: /* dst *= imm */
                        if (imm >= -32768 && imm < 32768)
                                EMIT(PPC_RAW_MULI(dst_reg, dst_reg, IMM_L(imm)));
                        else {
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                if (BPF_CLASS(code) == BPF_ALU)
                                        EMIT(PPC_RAW_MULW(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]));
                                else
                                        EMIT(PPC_RAW_MULD(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]));
                        }
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_DIV | BPF_X: /* (u32) dst /= (u32) src */
                case BPF_ALU | BPF_MOD | BPF_X: /* (u32) dst %= (u32) src */
                        if (BPF_OP(code) == BPF_MOD) {
                                EMIT(PPC_RAW_DIVWU(b2p[TMP_REG_1], dst_reg, src_reg));
                                EMIT(PPC_RAW_MULW(b2p[TMP_REG_1], src_reg,
                                                b2p[TMP_REG_1]));
                                EMIT(PPC_RAW_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]));
                        } else
                                EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU64 | BPF_DIV | BPF_X: /* dst /= src */
                case BPF_ALU64 | BPF_MOD | BPF_X: /* dst %= src */
                        if (BPF_OP(code) == BPF_MOD) {
                                EMIT(PPC_RAW_DIVDU(b2p[TMP_REG_1], dst_reg, src_reg));
                                EMIT(PPC_RAW_MULD(b2p[TMP_REG_1], src_reg,
                                                b2p[TMP_REG_1]));
                                EMIT(PPC_RAW_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]));
                        } else
                                EMIT(PPC_RAW_DIVDU(dst_reg, dst_reg, src_reg));
                        break;
                case BPF_ALU | BPF_MOD | BPF_K: /* (u32) dst %= (u32) imm */
                case BPF_ALU | BPF_DIV | BPF_K: /* (u32) dst /= (u32) imm */
                case BPF_ALU64 | BPF_MOD | BPF_K: /* dst %= imm */
                case BPF_ALU64 | BPF_DIV | BPF_K: /* dst /= imm */
                        if (imm == 0)
                                return -EINVAL;
                        else if (imm == 1)
                                goto bpf_alu32_trunc;

                        PPC_LI32(b2p[TMP_REG_1], imm);
                        switch (BPF_CLASS(code)) {
                        case BPF_ALU:
                                if (BPF_OP(code) == BPF_MOD) {
                                        EMIT(PPC_RAW_DIVWU(b2p[TMP_REG_2],
                                                        dst_reg,
                                                        b2p[TMP_REG_1]));
                                        EMIT(PPC_RAW_MULW(b2p[TMP_REG_1],
                                                        b2p[TMP_REG_1],
                                                        b2p[TMP_REG_2]));
                                        EMIT(PPC_RAW_SUB(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]));
                                } else
                                        EMIT(PPC_RAW_DIVWU(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]));
                                break;
                        case BPF_ALU64:
                                if (BPF_OP(code) == BPF_MOD) {
                                        EMIT(PPC_RAW_DIVDU(b2p[TMP_REG_2],
                                                        dst_reg,
                                                        b2p[TMP_REG_1]));
                                        EMIT(PPC_RAW_MULD(b2p[TMP_REG_1],
                                                        b2p[TMP_REG_1],
                                                        b2p[TMP_REG_2]));
                                        EMIT(PPC_RAW_SUB(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]));
                                } else
                                        EMIT(PPC_RAW_DIVDU(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]));
                                break;
                        }
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_NEG: /* (u32) dst = -dst */
                case BPF_ALU64 | BPF_NEG: /* dst = -dst */
                        EMIT(PPC_RAW_NEG(dst_reg, dst_reg));
                        goto bpf_alu32_trunc;

                /*
                 * Logical operations: AND/OR/XOR/[A]LSH/[A]RSH
                 */
                case BPF_ALU | BPF_AND | BPF_X: /* (u32) dst = dst & src */
                case BPF_ALU64 | BPF_AND | BPF_X: /* dst = dst & src */
                        EMIT(PPC_RAW_AND(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_AND | BPF_K: /* (u32) dst = dst & imm */
                case BPF_ALU64 | BPF_AND | BPF_K: /* dst = dst & imm */
                        if (!IMM_H(imm))
                                EMIT(PPC_RAW_ANDI(dst_reg, dst_reg, IMM_L(imm)));
                        else {
                                /* Sign-extended */
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                EMIT(PPC_RAW_AND(dst_reg, dst_reg, b2p[TMP_REG_1]));
                        }
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_OR | BPF_X: /* dst = (u32) dst | (u32) src */
                case BPF_ALU64 | BPF_OR | BPF_X: /* dst = dst | src */
                        EMIT(PPC_RAW_OR(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_OR | BPF_K:/* dst = (u32) dst | (u32) imm */
                case BPF_ALU64 | BPF_OR | BPF_K:/* dst = dst | imm */
                        if (imm < 0 && BPF_CLASS(code) == BPF_ALU64) {
                                /* Sign-extended */
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                EMIT(PPC_RAW_OR(dst_reg, dst_reg, b2p[TMP_REG_1]));
                        } else {
                                if (IMM_L(imm))
                                        EMIT(PPC_RAW_ORI(dst_reg, dst_reg, IMM_L(imm)));
                                if (IMM_H(imm))
                                        EMIT(PPC_RAW_ORIS(dst_reg, dst_reg, IMM_H(imm)));
                        }
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_XOR | BPF_X: /* (u32) dst ^= src */
                case BPF_ALU64 | BPF_XOR | BPF_X: /* dst ^= src */
                        EMIT(PPC_RAW_XOR(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_XOR | BPF_K: /* (u32) dst ^= (u32) imm */
                case BPF_ALU64 | BPF_XOR | BPF_K: /* dst ^= imm */
                        if (imm < 0 && BPF_CLASS(code) == BPF_ALU64) {
                                /* Sign-extended */
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                EMIT(PPC_RAW_XOR(dst_reg, dst_reg, b2p[TMP_REG_1]));
                        } else {
                                if (IMM_L(imm))
                                        EMIT(PPC_RAW_XORI(dst_reg, dst_reg, IMM_L(imm)));
                                if (IMM_H(imm))
                                        EMIT(PPC_RAW_XORIS(dst_reg, dst_reg, IMM_H(imm)));
                        }
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_LSH | BPF_X: /* (u32) dst <<= (u32) src */
                        /* slw clears top 32 bits */
                        EMIT(PPC_RAW_SLW(dst_reg, dst_reg, src_reg));
                        /* skip zero extension move, but set address map. */
                        if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;
                case BPF_ALU64 | BPF_LSH | BPF_X: /* dst <<= src; */
                        EMIT(PPC_RAW_SLD(dst_reg, dst_reg, src_reg));
                        break;
                case BPF_ALU | BPF_LSH | BPF_K: /* (u32) dst <<== (u32) imm */
                        /* with imm 0, we still need to clear top 32 bits */
                        EMIT(PPC_RAW_SLWI(dst_reg, dst_reg, imm));
                        if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;
                case BPF_ALU64 | BPF_LSH | BPF_K: /* dst <<== imm */
                        if (imm != 0)
                                EMIT(PPC_RAW_SLDI(dst_reg, dst_reg, imm));
                        break;
                case BPF_ALU | BPF_RSH | BPF_X: /* (u32) dst >>= (u32) src */
                        EMIT(PPC_RAW_SRW(dst_reg, dst_reg, src_reg));
                        if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;
                case BPF_ALU64 | BPF_RSH | BPF_X: /* dst >>= src */
                        EMIT(PPC_RAW_SRD(dst_reg, dst_reg, src_reg));
                        break;
                case BPF_ALU | BPF_RSH | BPF_K: /* (u32) dst >>= (u32) imm */
                        EMIT(PPC_RAW_SRWI(dst_reg, dst_reg, imm));
                        if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;
                case BPF_ALU64 | BPF_RSH | BPF_K: /* dst >>= imm */
                        if (imm != 0)
                                EMIT(PPC_RAW_SRDI(dst_reg, dst_reg, imm));
                        break;
                case BPF_ALU | BPF_ARSH | BPF_X: /* (s32) dst >>= src */
                        EMIT(PPC_RAW_SRAW(dst_reg, dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU64 | BPF_ARSH | BPF_X: /* (s64) dst >>= src */
                        EMIT(PPC_RAW_SRAD(dst_reg, dst_reg, src_reg));
                        break;
                case BPF_ALU | BPF_ARSH | BPF_K: /* (s32) dst >>= imm */
                        EMIT(PPC_RAW_SRAWI(dst_reg, dst_reg, imm));
                        goto bpf_alu32_trunc;
                case BPF_ALU64 | BPF_ARSH | BPF_K: /* (s64) dst >>= imm */
                        if (imm != 0)
                                EMIT(PPC_RAW_SRADI(dst_reg, dst_reg, imm));
                        break;

                /*
                 * MOV
                 */
                case BPF_ALU | BPF_MOV | BPF_X: /* (u32) dst = src */
                case BPF_ALU64 | BPF_MOV | BPF_X: /* dst = src */
                        if (imm == 1) {
                                /* special mov32 for zext */
                                EMIT(PPC_RAW_RLWINM(dst_reg, dst_reg, 0, 0, 31));
                                break;
                        }
                        EMIT(PPC_RAW_MR(dst_reg, src_reg));
                        goto bpf_alu32_trunc;
                case BPF_ALU | BPF_MOV | BPF_K: /* (u32) dst = imm */
                case BPF_ALU64 | BPF_MOV | BPF_K: /* dst = (s64) imm */
                        PPC_LI32(dst_reg, imm);
                        if (imm < 0)
                                goto bpf_alu32_trunc;
                        else if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;

bpf_alu32_trunc:
                /* Truncate to 32-bits */
                if (BPF_CLASS(code) == BPF_ALU && !fp->aux->verifier_zext)
                        EMIT(PPC_RAW_RLWINM(dst_reg, dst_reg, 0, 0, 31));
                break;

                /*
                 * BPF_FROM_BE/LE
                 */
                case BPF_ALU | BPF_END | BPF_FROM_LE:
                case BPF_ALU | BPF_END | BPF_FROM_BE:
#ifdef __BIG_ENDIAN__
                        if (BPF_SRC(code) == BPF_FROM_BE)
                                goto emit_clear;
#else /* !__BIG_ENDIAN__ */
                        if (BPF_SRC(code) == BPF_FROM_LE)
                                goto emit_clear;
#endif
                        switch (imm) {
                        case 16:
                                /* Rotate 8 bits left & mask with 0x0000ff00 */
                                EMIT(PPC_RAW_RLWINM(b2p[TMP_REG_1], dst_reg, 8, 16, 23));
                                /* Rotate 8 bits right & insert LSB to reg */
                                EMIT(PPC_RAW_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 24, 31));
                                /* Move result back to dst_reg */
                                EMIT(PPC_RAW_MR(dst_reg, b2p[TMP_REG_1]));
                                break;
                        case 32:
                                /*
                                 * Rotate word left by 8 bits:
                                 * 2 bytes are already in their final position
                                 * -- byte 2 and 4 (of bytes 1, 2, 3 and 4)
                                 */
                                EMIT(PPC_RAW_RLWINM(b2p[TMP_REG_1], dst_reg, 8, 0, 31));
                                /* Rotate 24 bits and insert byte 1 */
                                EMIT(PPC_RAW_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 0, 7));
                                /* Rotate 24 bits and insert byte 3 */
                                EMIT(PPC_RAW_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 16, 23));
                                EMIT(PPC_RAW_MR(dst_reg, b2p[TMP_REG_1]));
                                break;
                        case 64:
                                /*
                                 * Way easier and faster(?) to store the value
                                 * into stack and then use ldbrx
                                 *
                                 * ctx->seen will be reliable in pass2, but
                                 * the instructions generated will remain the
                                 * same across all passes
                                 */
                                PPC_BPF_STL(dst_reg, 1, bpf_jit_stack_local(ctx));
                                EMIT(PPC_RAW_ADDI(b2p[TMP_REG_1], 1, bpf_jit_stack_local(ctx)));
                                EMIT(PPC_RAW_LDBRX(dst_reg, 0, b2p[TMP_REG_1]));
                                break;
                        }
                        break;

emit_clear:
                        switch (imm) {
                        case 16:
                                /* zero-extend 16 bits into 64 bits */
                                EMIT(PPC_RAW_RLDICL(dst_reg, dst_reg, 0, 48));
                                if (insn_is_zext(&insn[i + 1]))
                                        addrs[++i] = ctx->idx * 4;
                                break;
                        case 32:
                                if (!fp->aux->verifier_zext)
                                        /* zero-extend 32 bits into 64 bits */
                                        EMIT(PPC_RAW_RLDICL(dst_reg, dst_reg, 0, 32));
                                break;
                        case 64:
                                /* nop */
                                break;
                        }
                        break;

                /*
                 * BPF_ST NOSPEC (speculation barrier)
                 */
                case BPF_ST | BPF_NOSPEC:
                        break;

                /*
                 * BPF_ST(X)
                 */
                case BPF_STX | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = src */
                case BPF_ST | BPF_MEM | BPF_B: /* *(u8 *)(dst + off) = imm */
                        if (BPF_CLASS(code) == BPF_ST) {
                                EMIT(PPC_RAW_LI(b2p[TMP_REG_1], imm));
                                src_reg = b2p[TMP_REG_1];
                        }
                        EMIT(PPC_RAW_STB(src_reg, dst_reg, off));
                        break;
                case BPF_STX | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = src */
                case BPF_ST | BPF_MEM | BPF_H: /* (u16 *)(dst + off) = imm */
                        if (BPF_CLASS(code) == BPF_ST) {
                                EMIT(PPC_RAW_LI(b2p[TMP_REG_1], imm));
                                src_reg = b2p[TMP_REG_1];
                        }
                        EMIT(PPC_RAW_STH(src_reg, dst_reg, off));
                        break;
                case BPF_STX | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = src */
                case BPF_ST | BPF_MEM | BPF_W: /* *(u32 *)(dst + off) = imm */
                        if (BPF_CLASS(code) == BPF_ST) {
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                src_reg = b2p[TMP_REG_1];
                        }
                        EMIT(PPC_RAW_STW(src_reg, dst_reg, off));
                        break;
                case BPF_STX | BPF_MEM | BPF_DW: /* (u64 *)(dst + off) = src */
                case BPF_ST | BPF_MEM | BPF_DW: /* *(u64 *)(dst + off) = imm */
                        if (BPF_CLASS(code) == BPF_ST) {
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                src_reg = b2p[TMP_REG_1];
                        }
                        PPC_BPF_STL(src_reg, dst_reg, off);
                        break;

                /*
                 * BPF_STX ATOMIC (atomic ops)
                 */
                case BPF_STX | BPF_ATOMIC | BPF_W:
                        if (imm != BPF_ADD) {
                                pr_err_ratelimited(
                                        "eBPF filter atomic op code %02x (@%d) unsupported\n",
                                        code, i);
                                return -ENOTSUPP;
                        }

                        /* *(u32 *)(dst + off) += src */

                        /* Get EA into TMP_REG_1 */
                        EMIT(PPC_RAW_ADDI(b2p[TMP_REG_1], dst_reg, off));
                        tmp_idx = ctx->idx * 4;
                        /* load value from memory into TMP_REG_2 */
                        EMIT(PPC_RAW_LWARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0));
                        /* add value from src_reg into this */
                        EMIT(PPC_RAW_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg));
                        /* store result back */
                        EMIT(PPC_RAW_STWCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]));
                        /* we're done if this succeeded */
                        PPC_BCC_SHORT(COND_NE, tmp_idx);
                        break;
                case BPF_STX | BPF_ATOMIC | BPF_DW:
                        if (imm != BPF_ADD) {
                                pr_err_ratelimited(
                                        "eBPF filter atomic op code %02x (@%d) unsupported\n",
                                        code, i);
                                return -ENOTSUPP;
                        }
                        /* *(u64 *)(dst + off) += src */

                        EMIT(PPC_RAW_ADDI(b2p[TMP_REG_1], dst_reg, off));
                        tmp_idx = ctx->idx * 4;
                        EMIT(PPC_RAW_LDARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0));
                        EMIT(PPC_RAW_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg));
                        EMIT(PPC_RAW_STDCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]));
                        PPC_BCC_SHORT(COND_NE, tmp_idx);
                        break;

                /*
                 * BPF_LDX
                 */
                /* dst = *(u8 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_B:
                        EMIT(PPC_RAW_LBZ(dst_reg, src_reg, off));
                        if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;
                /* dst = *(u16 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_H:
                        EMIT(PPC_RAW_LHZ(dst_reg, src_reg, off));
                        if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;
                /* dst = *(u32 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_W:
                        EMIT(PPC_RAW_LWZ(dst_reg, src_reg, off));
                        if (insn_is_zext(&insn[i + 1]))
                                addrs[++i] = ctx->idx * 4;
                        break;
                /* dst = *(u64 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_DW:
                        PPC_BPF_LL(dst_reg, src_reg, off);
                        break;

                /*
                 * Doubleword load
                 * 16 byte instruction that uses two 'struct bpf_insn'
                 */
                case BPF_LD | BPF_IMM | BPF_DW: /* dst = (u64) imm */
                        imm64 = ((u64)(u32) insn[i].imm) |
                                    (((u64)(u32) insn[i+1].imm) << 32);
                        /* Adjust for two bpf instructions */
                        addrs[++i] = ctx->idx * 4;
                        PPC_LI64(dst_reg, imm64);
                        break;

                /*
                 * Return/Exit
                 */
                case BPF_JMP | BPF_EXIT:
                        /*
                         * If this isn't the very last instruction, branch to
                         * the epilogue. If we _are_ the last instruction,
                         * we'll just fall through to the epilogue.
                         */
                        if (i != flen - 1)
                                PPC_JMP(exit_addr);
                        /* else fall through to the epilogue */
                        break;

                /*
                 * Call kernel helper or bpf function
                 */
                case BPF_JMP | BPF_CALL:
                        ctx->seen |= SEEN_FUNC;

                        ret = bpf_jit_get_func_addr(fp, &insn[i], extra_pass,
                                                    &func_addr, &func_addr_fixed);
                        if (ret < 0)
                                return ret;

                        if (func_addr_fixed)
                                bpf_jit_emit_func_call_hlp(image, ctx, func_addr);
                        else
                                bpf_jit_emit_func_call_rel(image, ctx, func_addr);
                        /* move return value from r3 to BPF_REG_0 */
                        EMIT(PPC_RAW_MR(b2p[BPF_REG_0], 3));
                        break;

                /*
                 * Jumps and branches
                 */
                case BPF_JMP | BPF_JA:
                        PPC_JMP(addrs[i + 1 + off]);
                        break;

                case BPF_JMP | BPF_JGT | BPF_K:
                case BPF_JMP | BPF_JGT | BPF_X:
                case BPF_JMP | BPF_JSGT | BPF_K:
                case BPF_JMP | BPF_JSGT | BPF_X:
                case BPF_JMP32 | BPF_JGT | BPF_K:
                case BPF_JMP32 | BPF_JGT | BPF_X:
                case BPF_JMP32 | BPF_JSGT | BPF_K:
                case BPF_JMP32 | BPF_JSGT | BPF_X:
                        true_cond = COND_GT;
                        goto cond_branch;
                case BPF_JMP | BPF_JLT | BPF_K:
                case BPF_JMP | BPF_JLT | BPF_X:
                case BPF_JMP | BPF_JSLT | BPF_K:
                case BPF_JMP | BPF_JSLT | BPF_X:
                case BPF_JMP32 | BPF_JLT | BPF_K:
                case BPF_JMP32 | BPF_JLT | BPF_X:
                case BPF_JMP32 | BPF_JSLT | BPF_K:
                case BPF_JMP32 | BPF_JSLT | BPF_X:
                        true_cond = COND_LT;
                        goto cond_branch;
                case BPF_JMP | BPF_JGE | BPF_K:
                case BPF_JMP | BPF_JGE | BPF_X:
                case BPF_JMP | BPF_JSGE | BPF_K:
                case BPF_JMP | BPF_JSGE | BPF_X:
                case BPF_JMP32 | BPF_JGE | BPF_K:
                case BPF_JMP32 | BPF_JGE | BPF_X:
                case BPF_JMP32 | BPF_JSGE | BPF_K:
                case BPF_JMP32 | BPF_JSGE | BPF_X:
                        true_cond = COND_GE;
                        goto cond_branch;
                case BPF_JMP | BPF_JLE | BPF_K:
                case BPF_JMP | BPF_JLE | BPF_X:
                case BPF_JMP | BPF_JSLE | BPF_K:
                case BPF_JMP | BPF_JSLE | BPF_X:
                case BPF_JMP32 | BPF_JLE | BPF_K:
                case BPF_JMP32 | BPF_JLE | BPF_X:
                case BPF_JMP32 | BPF_JSLE | BPF_K:
                case BPF_JMP32 | BPF_JSLE | BPF_X:
                        true_cond = COND_LE;
                        goto cond_branch;
                case BPF_JMP | BPF_JEQ | BPF_K:
                case BPF_JMP | BPF_JEQ | BPF_X:
                case BPF_JMP32 | BPF_JEQ | BPF_K:
                case BPF_JMP32 | BPF_JEQ | BPF_X:
                        true_cond = COND_EQ;
                        goto cond_branch;
                case BPF_JMP | BPF_JNE | BPF_K:
                case BPF_JMP | BPF_JNE | BPF_X:
                case BPF_JMP32 | BPF_JNE | BPF_K:
                case BPF_JMP32 | BPF_JNE | BPF_X:
                        true_cond = COND_NE;
                        goto cond_branch;
                case BPF_JMP | BPF_JSET | BPF_K:
                case BPF_JMP | BPF_JSET | BPF_X:
                case BPF_JMP32 | BPF_JSET | BPF_K:
                case BPF_JMP32 | BPF_JSET | BPF_X:
                        true_cond = COND_NE;
                        /* Fall through */

cond_branch:
                        switch (code) {
                        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_JEQ | BPF_X:
                        case BPF_JMP | BPF_JNE | BPF_X:
                        case BPF_JMP32 | BPF_JGT | BPF_X:
                        case BPF_JMP32 | BPF_JLT | BPF_X:
                        case BPF_JMP32 | BPF_JGE | BPF_X:
                        case BPF_JMP32 | BPF_JLE | BPF_X:
                        case BPF_JMP32 | BPF_JEQ | BPF_X:
                        case BPF_JMP32 | BPF_JNE | BPF_X:
                                /* unsigned comparison */
                                if (BPF_CLASS(code) == BPF_JMP32)
                                        EMIT(PPC_RAW_CMPLW(dst_reg, src_reg));
                                else
                                        EMIT(PPC_RAW_CMPLD(dst_reg, src_reg));
                                break;
                        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_JMP32 | BPF_JSGT | BPF_X:
                        case BPF_JMP32 | BPF_JSLT | BPF_X:
                        case BPF_JMP32 | BPF_JSGE | BPF_X:
                        case BPF_JMP32 | BPF_JSLE | BPF_X:
                                /* signed comparison */
                                if (BPF_CLASS(code) == BPF_JMP32)
                                        EMIT(PPC_RAW_CMPW(dst_reg, src_reg));
                                else
                                        EMIT(PPC_RAW_CMPD(dst_reg, src_reg));
                                break;
                        case BPF_JMP | BPF_JSET | BPF_X:
                        case BPF_JMP32 | BPF_JSET | BPF_X:
                                if (BPF_CLASS(code) == BPF_JMP) {
                                        EMIT(PPC_RAW_AND_DOT(b2p[TMP_REG_1], dst_reg,
                                                    src_reg));
                                } else {
                                        int tmp_reg = b2p[TMP_REG_1];

                                        EMIT(PPC_RAW_AND(tmp_reg, dst_reg, src_reg));
                                        EMIT(PPC_RAW_RLWINM_DOT(tmp_reg, tmp_reg, 0, 0,
                                                       31));
                                }
                                break;
                        case BPF_JMP | BPF_JNE | BPF_K:
                        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_JMP32 | BPF_JNE | BPF_K:
                        case BPF_JMP32 | BPF_JEQ | BPF_K:
                        case BPF_JMP32 | BPF_JGT | BPF_K:
                        case BPF_JMP32 | BPF_JLT | BPF_K:
                        case BPF_JMP32 | BPF_JGE | BPF_K:
                        case BPF_JMP32 | BPF_JLE | BPF_K:
                        {
                                bool is_jmp32 = BPF_CLASS(code) == BPF_JMP32;

                                /*
                                 * Need sign-extended load, so only positive
                                 * values can be used as imm in cmpldi
                                 */
                                if (imm >= 0 && imm < 32768) {
                                        if (is_jmp32)
                                                EMIT(PPC_RAW_CMPLWI(dst_reg, imm));
                                        else
                                                EMIT(PPC_RAW_CMPLDI(dst_reg, imm));
                                } else {
                                        /* sign-extending load */
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        /* ... but unsigned comparison */
                                        if (is_jmp32)
                                                EMIT(PPC_RAW_CMPLW(dst_reg,
                                                          b2p[TMP_REG_1]));
                                        else
                                                EMIT(PPC_RAW_CMPLD(dst_reg,
                                                          b2p[TMP_REG_1]));
                                }
                                break;
                        }
                        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_JMP32 | BPF_JSGT | BPF_K:
                        case BPF_JMP32 | BPF_JSLT | BPF_K:
                        case BPF_JMP32 | BPF_JSGE | BPF_K:
                        case BPF_JMP32 | BPF_JSLE | BPF_K:
                        {
                                bool is_jmp32 = BPF_CLASS(code) == BPF_JMP32;

                                /*
                                 * signed comparison, so any 16-bit value
                                 * can be used in cmpdi
                                 */
                                if (imm >= -32768 && imm < 32768) {
                                        if (is_jmp32)
                                                EMIT(PPC_RAW_CMPWI(dst_reg, imm));
                                        else
                                                EMIT(PPC_RAW_CMPDI(dst_reg, imm));
                                } else {
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        if (is_jmp32)
                                                EMIT(PPC_RAW_CMPW(dst_reg,
                                                         b2p[TMP_REG_1]));
                                        else
                                                EMIT(PPC_RAW_CMPD(dst_reg,
                                                         b2p[TMP_REG_1]));
                                }
                                break;
                        }
                        case BPF_JMP | BPF_JSET | BPF_K:
                        case BPF_JMP32 | BPF_JSET | BPF_K:
                                /* andi does not sign-extend the immediate */
                                if (imm >= 0 && imm < 32768)
                                        /* PPC_ANDI is _only/always_ dot-form */
                                        EMIT(PPC_RAW_ANDI(b2p[TMP_REG_1], dst_reg, imm));
                                else {
                                        int tmp_reg = b2p[TMP_REG_1];

                                        PPC_LI32(tmp_reg, imm);
                                        if (BPF_CLASS(code) == BPF_JMP) {
                                                EMIT(PPC_RAW_AND_DOT(tmp_reg, dst_reg,
                                                            tmp_reg));
                                        } else {
                                                EMIT(PPC_RAW_AND(tmp_reg, dst_reg,
                                                        tmp_reg));
                                                EMIT(PPC_RAW_RLWINM_DOT(tmp_reg, tmp_reg,
                                                               0, 0, 31));
                                        }
                                }
                                break;
                        }
                        PPC_BCC(true_cond, addrs[i + 1 + off]);
                        break;

                /*
                 * Tail call
                 */
                case BPF_JMP | BPF_TAIL_CALL:
                        ctx->seen |= SEEN_TAILCALL;
                        bpf_jit_emit_tail_call(image, ctx, addrs[i + 1]);
                        break;

                default:
                        /*

                         * The filter contains something cruel & unusual.
                         * We don't handle it, but also there shouldn't be
                         * anything missing from our list.
                         */
                        pr_err_ratelimited("eBPF filter opcode %04x (@%d) unsupported\n",
                                        code, i);
                        return -ENOTSUPP;
                }
        }

        /* Set end-of-body-code address for exit. */
        addrs[i] = ctx->idx * 4;

        return 0;
}