/*
 * 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
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; version 2
 * of the License.
 */
#include <linux/moduleloader.h>
#include <asm/cacheflush.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 void bpf_jit_fill_ill_insns(void *area, unsigned int size)
{
        memset32(area, BREAKPOINT_INSTRUCTION, size/4);
}

static inline void bpf_flush_icache(void *start, void *end)
{
        smp_wmb();
        flush_icache_range((unsigned long)start, (unsigned long)end);
}

static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
{
        return (ctx->seen & (1 << (31 - b2p[i])));
}

static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
{
        ctx->seen |= (1 << (31 - b2p[i]));
}

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, BPF_REG_FP);
}

/*
 * When not setting up our own stackframe, the redzone usage is:
 *
 *              [       prev sp         ] <-------------
 *              [         ...           ]               |
 * sp (r1) ---> [    stack pointer      ] --------------
 *              [   nv gpr save area    ] 8*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();
}

static void bpf_jit_emit_skb_loads(u32 *image, struct codegen_context *ctx)
{
        /*
         * Load skb->len and skb->data_len
         * r3 points to skb
         */
        PPC_LWZ(b2p[SKB_HLEN_REG], 3, offsetof(struct sk_buff, len));
        PPC_LWZ(b2p[TMP_REG_1], 3, offsetof(struct sk_buff, data_len));
        /* header_len = len - data_len */
        PPC_SUB(b2p[SKB_HLEN_REG], b2p[SKB_HLEN_REG], b2p[TMP_REG_1]);

        /* skb->data pointer */
        PPC_BPF_LL(b2p[SKB_DATA_REG], 3, offsetof(struct sk_buff, data));
}

static 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) {
                PPC_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 {
                PPC_NOP();
                PPC_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_INST_MFLR | __PPC_RT(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, i))
                        PPC_BPF_STL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));

        /*
         * Save additional non-volatile regs if we cache skb
         * Also, setup skb data
         */
        if (ctx->seen & SEEN_SKB) {
                PPC_BPF_STL(b2p[SKB_HLEN_REG], 1,
                                bpf_jit_stack_offsetof(ctx, b2p[SKB_HLEN_REG]));
                PPC_BPF_STL(b2p[SKB_DATA_REG], 1,
                                bpf_jit_stack_offsetof(ctx, b2p[SKB_DATA_REG]));
                bpf_jit_emit_skb_loads(image, ctx);
        }

        /* Setup frame pointer to point to the bpf stack area */
        if (bpf_is_seen_register(ctx, BPF_REG_FP))
                PPC_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, i))
                        PPC_BPF_LL(b2p[i], 1, bpf_jit_stack_offsetof(ctx, b2p[i]));

        /* Restore non-volatile registers used for skb cache */
        if (ctx->seen & SEEN_SKB) {
                PPC_BPF_LL(b2p[SKB_HLEN_REG], 1,
                                bpf_jit_stack_offsetof(ctx, b2p[SKB_HLEN_REG]));
                PPC_BPF_LL(b2p[SKB_DATA_REG], 1,
                                bpf_jit_stack_offsetof(ctx, b2p[SKB_DATA_REG]));
        }

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

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

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

        PPC_BLR();
}

static void bpf_jit_emit_func_call(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 LR */
        PPC_MTLR(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);
        PPC_MTLR(12);
#endif
        PPC_BLRL();
}

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;
         */
        PPC_LWZ(b2p[TMP_REG_1], b2p_bpf_array, offsetof(struct bpf_array, map.max_entries));
        PPC_RLWINM(b2p_index, b2p_index, 0, 0, 31);
        PPC_CMPLW(b2p_index, b2p[TMP_REG_1]);
        PPC_BCC(COND_GE, out);

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

        /*
         * tail_call_cnt++;
         */
        PPC_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]; */
        PPC_MULI(b2p[TMP_REG_1], b2p_index, 8);
        PPC_ADD(b2p[TMP_REG_1], b2p[TMP_REG_1], b2p_bpf_array);
        PPC_LD(b2p[TMP_REG_1], b2p[TMP_REG_1], offsetof(struct bpf_array, ptrs));

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

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

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

        PPC_BCTR();
        /* out: */
}

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

        /* 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;
                u64 imm64;
                u8 *func;
                u32 true_cond;

                /*
                 * 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, insn[i].dst_reg);
                if (src_reg >= BPF_PPC_NVR_MIN && src_reg < 32)
                        bpf_set_seen_register(ctx, insn[i].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 */
                        PPC_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 */
                        PPC_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)
                                        PPC_ADDI(dst_reg, dst_reg, IMM_L(imm));
                                else {
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        PPC_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)
                                PPC_MULW(dst_reg, dst_reg, src_reg);
                        else
                                PPC_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)
                                PPC_MULI(dst_reg, dst_reg, IMM_L(imm));
                        else {
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                if (BPF_CLASS(code) == BPF_ALU)
                                        PPC_MULW(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]);
                                else
                                        PPC_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) {
                                PPC_DIVWU(b2p[TMP_REG_1], dst_reg, src_reg);
                                PPC_MULW(b2p[TMP_REG_1], src_reg,
                                                b2p[TMP_REG_1]);
                                PPC_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]);
                        } else
                                PPC_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) {
                                PPC_DIVD(b2p[TMP_REG_1], dst_reg, src_reg);
                                PPC_MULD(b2p[TMP_REG_1], src_reg,
                                                b2p[TMP_REG_1]);
                                PPC_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]);
                        } else
                                PPC_DIVD(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) {
                                        PPC_DIVWU(b2p[TMP_REG_2], dst_reg,
                                                        b2p[TMP_REG_1]);
                                        PPC_MULW(b2p[TMP_REG_1],
                                                        b2p[TMP_REG_1],
                                                        b2p[TMP_REG_2]);
                                        PPC_SUB(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]);
                                } else
                                        PPC_DIVWU(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]);
                                break;
                        case BPF_ALU64:
                                if (BPF_OP(code) == BPF_MOD) {
                                        PPC_DIVD(b2p[TMP_REG_2], dst_reg,
                                                        b2p[TMP_REG_1]);
                                        PPC_MULD(b2p[TMP_REG_1],
                                                        b2p[TMP_REG_1],
                                                        b2p[TMP_REG_2]);
                                        PPC_SUB(dst_reg, dst_reg,
                                                        b2p[TMP_REG_1]);
                                } else
                                        PPC_DIVD(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 */
                        PPC_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 */
                        PPC_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))
                                PPC_ANDI(dst_reg, dst_reg, IMM_L(imm));
                        else {
                                /* Sign-extended */
                                PPC_LI32(b2p[TMP_REG_1], imm);
                                PPC_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 */
                        PPC_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);
                                PPC_OR(dst_reg, dst_reg, b2p[TMP_REG_1]);
                        } else {
                                if (IMM_L(imm))
                                        PPC_ORI(dst_reg, dst_reg, IMM_L(imm));
                                if (IMM_H(imm))
                                        PPC_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 */
                        PPC_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);
                                PPC_XOR(dst_reg, dst_reg, b2p[TMP_REG_1]);
                        } else {
                                if (IMM_L(imm))
                                        PPC_XORI(dst_reg, dst_reg, IMM_L(imm));
                                if (IMM_H(imm))
                                        PPC_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 */
                        PPC_SLW(dst_reg, dst_reg, src_reg);
                        break;
                case BPF_ALU64 | BPF_LSH | BPF_X: /* dst <<= src; */
                        PPC_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 */
                        PPC_SLWI(dst_reg, dst_reg, imm);
                        break;
                case BPF_ALU64 | BPF_LSH | BPF_K: /* dst <<== imm */
                        if (imm != 0)
                                PPC_SLDI(dst_reg, dst_reg, imm);
                        break;
                case BPF_ALU | BPF_RSH | BPF_X: /* (u32) dst >>= (u32) src */
                        PPC_SRW(dst_reg, dst_reg, src_reg);
                        break;
                case BPF_ALU64 | BPF_RSH | BPF_X: /* dst >>= src */
                        PPC_SRD(dst_reg, dst_reg, src_reg);
                        break;
                case BPF_ALU | BPF_RSH | BPF_K: /* (u32) dst >>= (u32) imm */
                        PPC_SRWI(dst_reg, dst_reg, imm);
                        break;
                case BPF_ALU64 | BPF_RSH | BPF_K: /* dst >>= imm */
                        if (imm != 0)
                                PPC_SRDI(dst_reg, dst_reg, imm);
                        break;
                case BPF_ALU64 | BPF_ARSH | BPF_X: /* (s64) dst >>= src */
                        PPC_SRAD(dst_reg, dst_reg, src_reg);
                        break;
                case BPF_ALU64 | BPF_ARSH | BPF_K: /* (s64) dst >>= imm */
                        if (imm != 0)
                                PPC_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 */
                        PPC_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;
                        break;

bpf_alu32_trunc:
                /* Truncate to 32-bits */
                if (BPF_CLASS(code) == BPF_ALU)
                        PPC_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 */
                                PPC_RLWINM(b2p[TMP_REG_1], dst_reg, 8, 16, 23);
                                /* Rotate 8 bits right & insert LSB to reg */
                                PPC_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 24, 31);
                                /* Move result back to dst_reg */
                                PPC_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)
                                 */
                                PPC_RLWINM(b2p[TMP_REG_1], dst_reg, 8, 0, 31);
                                /* Rotate 24 bits and insert byte 1 */
                                PPC_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 0, 7);
                                /* Rotate 24 bits and insert byte 3 */
                                PPC_RLWIMI(b2p[TMP_REG_1], dst_reg, 24, 16, 23);
                                PPC_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_STD(dst_reg, 1, bpf_jit_stack_local(ctx));
                                PPC_ADDI(b2p[TMP_REG_1], 1, bpf_jit_stack_local(ctx));
                                PPC_LDBRX(dst_reg, 0, b2p[TMP_REG_1]);
                                break;
                        }
                        break;

emit_clear:
                        switch (imm) {
                        case 16:
                                /* zero-extend 16 bits into 64 bits */
                                PPC_RLDICL(dst_reg, dst_reg, 0, 48);
                                break;
                        case 32:
                                /* zero-extend 32 bits into 64 bits */
                                PPC_RLDICL(dst_reg, dst_reg, 0, 32);
                                break;
                        case 64:
                                /* nop */
                                break;
                        }
                        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) {
                                PPC_LI(b2p[TMP_REG_1], imm);
                                src_reg = b2p[TMP_REG_1];
                        }
                        PPC_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) {
                                PPC_LI(b2p[TMP_REG_1], imm);
                                src_reg = b2p[TMP_REG_1];
                        }
                        PPC_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];
                        }
                        PPC_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_STD(src_reg, dst_reg, off);
                        break;

                /*
                 * BPF_STX XADD (atomic_add)
                 */
                /* *(u32 *)(dst + off) += src */
                case BPF_STX | BPF_XADD | BPF_W:
                        /* Get EA into TMP_REG_1 */
                        PPC_ADDI(b2p[TMP_REG_1], dst_reg, off);
                        /* error if EA is not word-aligned */
                        PPC_ANDI(b2p[TMP_REG_2], b2p[TMP_REG_1], 0x03);
                        PPC_BCC_SHORT(COND_EQ, (ctx->idx * 4) + 12);
                        PPC_LI(b2p[BPF_REG_0], 0);
                        PPC_JMP(exit_addr);
                        /* load value from memory into TMP_REG_2 */
                        PPC_BPF_LWARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0);
                        /* add value from src_reg into this */
                        PPC_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg);
                        /* store result back */
                        PPC_BPF_STWCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]);
                        /* we're done if this succeeded */
                        PPC_BCC_SHORT(COND_EQ, (ctx->idx * 4) + (7*4));
                        /* otherwise, let's try once more */
                        PPC_BPF_LWARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0);
                        PPC_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg);
                        PPC_BPF_STWCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]);
                        /* exit if the store was not successful */
                        PPC_LI(b2p[BPF_REG_0], 0);
                        PPC_BCC(COND_NE, exit_addr);
                        break;
                /* *(u64 *)(dst + off) += src */
                case BPF_STX | BPF_XADD | BPF_DW:
                        PPC_ADDI(b2p[TMP_REG_1], dst_reg, off);
                        /* error if EA is not doubleword-aligned */
                        PPC_ANDI(b2p[TMP_REG_2], b2p[TMP_REG_1], 0x07);
                        PPC_BCC_SHORT(COND_EQ, (ctx->idx * 4) + (3*4));
                        PPC_LI(b2p[BPF_REG_0], 0);
                        PPC_JMP(exit_addr);
                        PPC_BPF_LDARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0);
                        PPC_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg);
                        PPC_BPF_STDCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]);
                        PPC_BCC_SHORT(COND_EQ, (ctx->idx * 4) + (7*4));
                        PPC_BPF_LDARX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1], 0);
                        PPC_ADD(b2p[TMP_REG_2], b2p[TMP_REG_2], src_reg);
                        PPC_BPF_STDCX(b2p[TMP_REG_2], 0, b2p[TMP_REG_1]);
                        PPC_LI(b2p[BPF_REG_0], 0);
                        PPC_BCC(COND_NE, exit_addr);
                        break;

                /*
                 * BPF_LDX
                 */
                /* dst = *(u8 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_B:
                        PPC_LBZ(dst_reg, src_reg, off);
                        break;
                /* dst = *(u16 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_H:
                        PPC_LHZ(dst_reg, src_reg, off);
                        break;
                /* dst = *(u32 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_W:
                        PPC_LWZ(dst_reg, src_reg, off);
                        break;
                /* dst = *(u64 *)(ul) (src + off) */
                case BPF_LDX | BPF_MEM | BPF_DW:
                        PPC_LD(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
                 */
                case BPF_JMP | BPF_CALL:
                        ctx->seen |= SEEN_FUNC;
                        func = (u8 *) __bpf_call_base + imm;

                        /* Save skb pointer if we need to re-cache skb data */
                        if ((ctx->seen & SEEN_SKB) &&
                            bpf_helper_changes_pkt_data(func))
                                PPC_BPF_STL(3, 1, bpf_jit_stack_local(ctx));

                        bpf_jit_emit_func_call(image, ctx, (u64)func);

                        /* move return value from r3 to BPF_REG_0 */
                        PPC_MR(b2p[BPF_REG_0], 3);

                        /* refresh skb cache */
                        if ((ctx->seen & SEEN_SKB) &&
                            bpf_helper_changes_pkt_data(func)) {
                                /* reload skb pointer to r3 */
                                PPC_BPF_LL(3, 1, bpf_jit_stack_local(ctx));
                                bpf_jit_emit_skb_loads(image, ctx);
                        }
                        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:
                        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:
                        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:
                        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:
                        true_cond = COND_LE;
                        goto cond_branch;
                case BPF_JMP | BPF_JEQ | BPF_K:
                case BPF_JMP | 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:
                        true_cond = COND_NE;
                        goto cond_branch;
                case BPF_JMP | BPF_JSET | BPF_K:
                case BPF_JMP | 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:
                                /* unsigned comparison */
                                PPC_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:
                                /* signed comparison */
                                PPC_CMPD(dst_reg, src_reg);
                                break;
                        case BPF_JMP | BPF_JSET | BPF_X:
                                PPC_AND_DOT(b2p[TMP_REG_1], dst_reg, src_reg);
                                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:
                                /*
                                 * Need sign-extended load, so only positive
                                 * values can be used as imm in cmpldi
                                 */
                                if (imm >= 0 && imm < 32768)
                                        PPC_CMPLDI(dst_reg, imm);
                                else {
                                        /* sign-extending load */
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        /* ... but unsigned comparison */
                                        PPC_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:
                                /*
                                 * signed comparison, so any 16-bit value
                                 * can be used in cmpdi
                                 */
                                if (imm >= -32768 && imm < 32768)
                                        PPC_CMPDI(dst_reg, imm);
                                else {
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        PPC_CMPD(dst_reg, b2p[TMP_REG_1]);
                                }
                                break;
                        case BPF_JMP | BPF_JSET | BPF_K:
                                /* andi does not sign-extend the immediate */
                                if (imm >= 0 && imm < 32768)
                                        /* PPC_ANDI is _only/always_ dot-form */
                                        PPC_ANDI(b2p[TMP_REG_1], dst_reg, imm);
                                else {
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        PPC_AND_DOT(b2p[TMP_REG_1], dst_reg,
                                                    b2p[TMP_REG_1]);
                                }
                                break;
                        }
                        PPC_BCC(true_cond, addrs[i + 1 + off]);
                        break;

                /*
                 * Loads from packet header/data
                 * Assume 32-bit input value in imm and X (src_reg)
                 */

                /* Absolute loads */
                case BPF_LD | BPF_W | BPF_ABS:
                        func = (u8 *)CHOOSE_LOAD_FUNC(imm, sk_load_word);
                        goto common_load_abs;
                case BPF_LD | BPF_H | BPF_ABS:
                        func = (u8 *)CHOOSE_LOAD_FUNC(imm, sk_load_half);
                        goto common_load_abs;
                case BPF_LD | BPF_B | BPF_ABS:
                        func = (u8 *)CHOOSE_LOAD_FUNC(imm, sk_load_byte);
common_load_abs:
                        /*
                         * Load from [imm]
                         * Load into r4, which can just be passed onto
                         *  skb load helpers as the second parameter
                         */
                        PPC_LI32(4, imm);
                        goto common_load;

                /* Indirect loads */
                case BPF_LD | BPF_W | BPF_IND:
                        func = (u8 *)sk_load_word;
                        goto common_load_ind;
                case BPF_LD | BPF_H | BPF_IND:
                        func = (u8 *)sk_load_half;
                        goto common_load_ind;
                case BPF_LD | BPF_B | BPF_IND:
                        func = (u8 *)sk_load_byte;
common_load_ind:
                        /*
                         * Load from [src_reg + imm]
                         * Treat src_reg as a 32-bit value
                         */
                        PPC_EXTSW(4, src_reg);
                        if (imm) {
                                if (imm >= -32768 && imm < 32768)
                                        PPC_ADDI(4, 4, IMM_L(imm));
                                else {
                                        PPC_LI32(b2p[TMP_REG_1], imm);
                                        PPC_ADD(4, 4, b2p[TMP_REG_1]);
                                }
                        }

common_load:
                        ctx->seen |= SEEN_SKB;
                        ctx->seen |= SEEN_FUNC;
                        bpf_jit_emit_func_call(image, ctx, (u64)func);

                        /*
                         * Helper returns 'lt' condition on error, and an
                         * appropriate return value in BPF_REG_0
                         */
                        PPC_BCC(COND_LT, exit_addr);
                        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;
}

struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
{
        u32 proglen;
        u32 alloclen;
        u8 *image = NULL;
        u32 *code_base;
        u32 *addrs;
        struct codegen_context cgctx;
        int pass;
        int flen;
        struct bpf_binary_header *bpf_hdr;
        struct bpf_prog *org_fp = fp;
        struct bpf_prog *tmp_fp;
        bool bpf_blinded = false;

        if (!fp->jit_requested)
                return org_fp;

        tmp_fp = bpf_jit_blind_constants(org_fp);
        if (IS_ERR(tmp_fp))
                return org_fp;

        if (tmp_fp != org_fp) {
                bpf_blinded = true;
                fp = tmp_fp;
        }

        flen = fp->len;
        addrs = kzalloc((flen+1) * sizeof(*addrs), GFP_KERNEL);
        if (addrs == NULL) {
                fp = org_fp;
                goto out;
        }

        memset(&cgctx, 0, sizeof(struct codegen_context));

        /* Make sure that the stack is quadword aligned. */
        cgctx.stack_size = round_up(fp->aux->stack_depth, 16);

        /* Scouting faux-generate pass 0 */
        if (bpf_jit_build_body(fp, 0, &cgctx, addrs)) {
                /* We hit something illegal or unsupported. */
                fp = org_fp;
                goto out;
        }

        /*
         * Pretend to build prologue, given the features we've seen.  This will
         * update ctgtx.idx as it pretends to output instructions, then we can
         * calculate total size from idx.
         */
        bpf_jit_build_prologue(0, &cgctx);
        bpf_jit_build_epilogue(0, &cgctx);

        proglen = cgctx.idx * 4;
        alloclen = proglen + FUNCTION_DESCR_SIZE;

        bpf_hdr = bpf_jit_binary_alloc(alloclen, &image, 4,
                        bpf_jit_fill_ill_insns);
        if (!bpf_hdr) {
                fp = org_fp;
                goto out;
        }

        code_base = (u32 *)(image + FUNCTION_DESCR_SIZE);

        /* Code generation passes 1-2 */
        for (pass = 1; pass < 3; pass++) {
                /* Now build the prologue, body code & epilogue for real. */
                cgctx.idx = 0;
                bpf_jit_build_prologue(code_base, &cgctx);
                bpf_jit_build_body(fp, code_base, &cgctx, addrs);
                bpf_jit_build_epilogue(code_base, &cgctx);

                if (bpf_jit_enable > 1)
                        pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
                                proglen - (cgctx.idx * 4), cgctx.seen);
        }

        if (bpf_jit_enable > 1)
                /*
                 * Note that we output the base address of the code_base
                 * rather than image, since opcodes are in code_base.
                 */
                bpf_jit_dump(flen, proglen, pass, code_base);

#ifdef PPC64_ELF_ABI_v1
        /* Function descriptor nastiness: Address + TOC */
        ((u64 *)image)[0] = (u64)code_base;
        ((u64 *)image)[1] = local_paca->kernel_toc;
#endif

        fp->bpf_func = (void *)image;
        fp->jited = 1;
        fp->jited_len = alloclen;

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

out:
        kfree(addrs);

        if (bpf_blinded)
                bpf_jit_prog_release_other(fp, fp == org_fp ? tmp_fp : org_fp);

        return fp;
}

/* Overriding bpf_jit_free() as we don't set images read-only. */
void bpf_jit_free(struct bpf_prog *fp)
{
        unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
        struct bpf_binary_header *bpf_hdr = (void *)addr;

        if (fp->jited)
                bpf_jit_binary_free(bpf_hdr);

        bpf_prog_unlock_free(fp);
}