// SPDX-License-Identifier: GPL-2.0
/*
 * Common functionality for HPPA32 and HPPA64 BPF JIT compilers
 *
 * Copyright (c) 2023 Helge Deller <deller@gmx.de>
 *
 */

#include <linux/bpf.h>
#include <linux/filter.h>
#include "bpf_jit.h"

/* Number of iterations to try until offsets converge. */
#define NR_JIT_ITERATIONS       35

static int build_body(struct hppa_jit_context *ctx, bool extra_pass, int *offset)
{
        const struct bpf_prog *prog = ctx->prog;
        int i;

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

                ret = bpf_jit_emit_insn(insn, ctx, extra_pass);
                /* BPF_LD | BPF_IMM | BPF_DW: skip the next instruction. */
                if (ret > 0)
                        i++;
                if (offset)
                        offset[i] = ctx->ninsns;
                if (ret < 0)
                        return ret;
        }
        ctx->reg_seen_collect = false;
        return 0;
}

bool bpf_jit_needs_zext(void)
{
        return true;
}

struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
        unsigned int prog_size = 0, extable_size = 0;
        bool tmp_blinded = false, extra_pass = false;
        struct bpf_prog *tmp, *orig_prog = prog;
        int pass = 0, prev_ninsns = 0, prologue_len, i;
        struct hppa_jit_data *jit_data;
        struct hppa_jit_context *ctx;

        if (!prog->jit_requested)
                return orig_prog;

        tmp = bpf_jit_blind_constants(prog);
        if (IS_ERR(tmp))
                return orig_prog;
        if (tmp != prog) {
                tmp_blinded = true;
                prog = tmp;
        }

        jit_data = prog->aux->jit_data;
        if (!jit_data) {
                jit_data = kzalloc_obj(*jit_data);
                if (!jit_data) {
                        prog = orig_prog;
                        goto out;
                }
                prog->aux->jit_data = jit_data;
        }

        ctx = &jit_data->ctx;

        if (ctx->offset) {
                extra_pass = true;
                prog_size = sizeof(*ctx->insns) * ctx->ninsns;
                goto skip_init_ctx;
        }

        ctx->prog = prog;
        ctx->offset = kzalloc_objs(int, prog->len);
        if (!ctx->offset) {
                prog = orig_prog;
                goto out_offset;
        }
        for (i = 0; i < prog->len; i++) {
                prev_ninsns += 20;
                ctx->offset[i] = prev_ninsns;
        }

        for (i = 0; i < NR_JIT_ITERATIONS; i++) {
                pass++;
                ctx->ninsns = 0;
                if (build_body(ctx, extra_pass, ctx->offset)) {
                        prog = orig_prog;
                        goto out_offset;
                }
                ctx->body_len = ctx->ninsns;
                bpf_jit_build_prologue(ctx);
                ctx->prologue_len = ctx->ninsns - ctx->body_len;
                ctx->epilogue_offset = ctx->ninsns;
                bpf_jit_build_epilogue(ctx);

                if (ctx->ninsns == prev_ninsns) {
                        if (jit_data->header)
                                break;
                        /* obtain the actual image size */
                        extable_size = prog->aux->num_exentries *
                                sizeof(struct exception_table_entry);
                        prog_size = sizeof(*ctx->insns) * ctx->ninsns;

                        jit_data->header =
                                bpf_jit_binary_alloc(prog_size + extable_size,
                                                     &jit_data->image,
                                                     sizeof(long),
                                                     bpf_fill_ill_insns);
                        if (!jit_data->header) {
                                prog = orig_prog;
                                goto out_offset;
                        }

                        ctx->insns = (u32 *)jit_data->image;
                        /*
                         * Now, when the image is allocated, the image can
                         * potentially shrink more (auipc/jalr -> jal).
                         */
                }
                prev_ninsns = ctx->ninsns;
        }

        if (i == NR_JIT_ITERATIONS) {
                pr_err("bpf-jit: image did not converge in <%d passes!\n", i);
                if (jit_data->header)
                        bpf_jit_binary_free(jit_data->header);
                prog = orig_prog;
                goto out_offset;
        }

        if (extable_size)
                prog->aux->extable = (void *)ctx->insns + prog_size;

skip_init_ctx:
        pass++;
        ctx->ninsns = 0;

        bpf_jit_build_prologue(ctx);
        if (build_body(ctx, extra_pass, NULL)) {
                bpf_jit_binary_free(jit_data->header);
                prog = orig_prog;
                goto out_offset;
        }
        bpf_jit_build_epilogue(ctx);

        if (HPPA_JIT_DEBUG || bpf_jit_enable > 1) {
                if (HPPA_JIT_DUMP)
                        bpf_jit_dump(prog->len, prog_size, pass, ctx->insns);
                if (HPPA_JIT_REBOOT)
                        { extern int machine_restart(char *); machine_restart(""); }
        }

        prog->bpf_func = (void *)ctx->insns;
        prog->jited = 1;
        prog->jited_len = prog_size;

        bpf_flush_icache(jit_data->header, ctx->insns + ctx->ninsns);

        if (!prog->is_func || extra_pass) {
                if (bpf_jit_binary_lock_ro(jit_data->header)) {
                        bpf_jit_binary_free(jit_data->header);
                        prog->bpf_func = NULL;
                        prog->jited = 0;
                        prog->jited_len = 0;
                        goto out_offset;
                }
                prologue_len = ctx->epilogue_offset - ctx->body_len;
                for (i = 0; i < prog->len; i++)
                        ctx->offset[i] += prologue_len;
                bpf_prog_fill_jited_linfo(prog, ctx->offset);
out_offset:
                kfree(ctx->offset);
                kfree(jit_data);
                prog->aux->jit_data = NULL;
        }
out:
        if (HPPA_JIT_REBOOT)
                { extern int machine_restart(char *); machine_restart(""); }

        if (tmp_blinded)
                bpf_jit_prog_release_other(prog, prog == orig_prog ?
                                           tmp : orig_prog);
        return prog;
}

u64 hppa_div64(u64 div, u64 divisor)
{
        div = div64_u64(div, divisor);
        return div;
}

u64 hppa_div64_rem(u64 div, u64 divisor)
{
        u64 rem;
        div64_u64_rem(div, divisor, &rem);
        return rem;
}