// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include <test_progs.h>

#ifdef HAVE_LLVM_SUPPORT

#include <llvm-c/Core.h>
#include <llvm-c/Disassembler.h>
#include <llvm-c/Target.h>
#include <llvm-c/TargetMachine.h>

/* The intent is to use get_jited_program_text() for small test
 * programs written in BPF assembly, thus assume that 32 local labels
 * would be sufficient.
 */
#define MAX_LOCAL_LABELS 32

/* Local labels are encoded as 'L42', this requires 4 bytes of storage:
 * 3 characters + zero byte
 */
#define LOCAL_LABEL_LEN 4

static bool llvm_initialized;

struct local_labels {
        bool print_phase;
        __u32 prog_len;
        __u32 cnt;
        __u32 pcs[MAX_LOCAL_LABELS];
        char names[MAX_LOCAL_LABELS][LOCAL_LABEL_LEN];
};

static const char *lookup_symbol(void *data, uint64_t ref_value, uint64_t *ref_type,
                                 uint64_t ref_pc, const char **ref_name)
{
        struct local_labels *labels = data;
        uint64_t type = *ref_type;
        int i;

        *ref_type = LLVMDisassembler_ReferenceType_InOut_None;
        *ref_name = NULL;
        if (type != LLVMDisassembler_ReferenceType_In_Branch)
                return NULL;
        /* Depending on labels->print_phase either discover local labels or
         * return a name assigned with local jump target:
         * - if print_phase is true and ref_value is in labels->pcs,
         *   return corresponding labels->name.
         * - if print_phase is false, save program-local jump targets
         *   in labels->pcs;
         */
        if (labels->print_phase) {
                for (i = 0; i < labels->cnt; ++i)
                        if (labels->pcs[i] == ref_value)
                                return labels->names[i];
        } else {
                if (labels->cnt < MAX_LOCAL_LABELS && ref_value < labels->prog_len)
                        labels->pcs[labels->cnt++] = ref_value;
        }
        return NULL;
}

static int disasm_insn(LLVMDisasmContextRef ctx, uint8_t *image, __u32 len, __u32 pc,
                       char *buf, __u32 buf_sz)
{
        int i, cnt;

        cnt = LLVMDisasmInstruction(ctx, image + pc, len - pc, pc,
                                    buf, buf_sz);
        if (cnt > 0)
                return cnt;
        PRINT_FAIL("Can't disasm instruction at offset %d:", pc);
        for (i = 0; i < 16 && pc + i < len; ++i)
                printf(" %02x", image[pc + i]);
        printf("\n");
        return -EINVAL;
}

static int cmp_u32(const void *_a, const void *_b)
{
        __u32 a = *(__u32 *)_a;
        __u32 b = *(__u32 *)_b;

        if (a < b)
                return -1;
        if (a > b)
                return 1;
        return 0;
}

static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len)
{
        char *label, *colon, *triple = NULL;
        LLVMDisasmContextRef ctx = NULL;
        struct local_labels labels = {};
        __u32 *label_pc, pc;
        int i, cnt, err = 0;
        char buf[64];

        triple = LLVMGetDefaultTargetTriple();
        ctx = LLVMCreateDisasm(triple, &labels, 0, NULL, lookup_symbol);
        if (!ASSERT_OK_PTR(ctx, "LLVMCreateDisasm")) {
                err = -EINVAL;
                goto out;
        }

        cnt = LLVMSetDisasmOptions(ctx, LLVMDisassembler_Option_PrintImmHex);
        if (!ASSERT_EQ(cnt, 1, "LLVMSetDisasmOptions")) {
                err = -EINVAL;
                goto out;
        }

        /* discover labels */
        labels.prog_len = len;
        pc = 0;
        while (pc < len) {
                cnt = disasm_insn(ctx, image, len, pc, buf, 1);
                if (cnt < 0) {
                        err = cnt;
                        goto out;
                }
                pc += cnt;
        }
        qsort(labels.pcs, labels.cnt, sizeof(*labels.pcs), cmp_u32);
        /* gcc is unable to infer upper bound for labels.cnt and
         * assumes it to be U32_MAX. U32_MAX takes 10 decimal digits.
         * snprintf below prints into labels.names[*], which has space
         * only for two digits and a letter.  To avoid truncation
         * warning use (i < MAX_LOCAL_LABELS), which informs gcc about
         * printed value upper bound.
         */
        for (i = 0; i < labels.cnt && i < MAX_LOCAL_LABELS; ++i)
                snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i);

        /* now print with labels */
        labels.print_phase = true;
        pc = 0;
        while (pc < len) {
                cnt = disasm_insn(ctx, image, len, pc, buf, sizeof(buf));
                if (cnt < 0) {
                        err = cnt;
                        goto out;
                }
                label_pc = bsearch(&pc, labels.pcs, labels.cnt, sizeof(*labels.pcs), cmp_u32);
                label = "";
                colon = "";
                if (label_pc) {
                        label = labels.names[label_pc - labels.pcs];
                        colon = ":";
                }
                fprintf(text_out, "%x:\t", pc);
                for (i = 0; i < cnt; ++i)
                        fprintf(text_out, "%02x ", image[pc + i]);
                for (i = cnt * 3; i < 12 * 3; ++i)
                        fputc(' ', text_out);
                fprintf(text_out, "%s%s%s\n", label, colon, buf);
                pc += cnt;
        }

out:
        if (triple)
                LLVMDisposeMessage(triple);
        if (ctx)
                LLVMDisasmDispose(ctx);
        return err;
}

int get_jited_program_text(int fd, char *text, size_t text_sz)
{
        struct bpf_prog_info info = {};
        __u32 info_len = sizeof(info);
        __u32 jited_funcs, len, pc;
        __u32 *func_lens = NULL;
        FILE *text_out = NULL;
        uint8_t *image = NULL;
        int i, err = 0;

        if (!llvm_initialized) {
                LLVMInitializeAllTargetInfos();
                LLVMInitializeAllTargetMCs();
                LLVMInitializeAllDisassemblers();
                llvm_initialized = 1;
        }

        text_out = fmemopen(text, text_sz, "w");
        if (!ASSERT_OK_PTR(text_out, "open_memstream")) {
                err = -errno;
                goto out;
        }

        /* first call is to find out jited program len */
        err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
        if (!ASSERT_OK(err, "bpf_prog_get_info_by_fd #1"))
                goto out;

        len = info.jited_prog_len;
        image = malloc(len);
        if (!ASSERT_OK_PTR(image, "malloc(info.jited_prog_len)")) {
                err = -ENOMEM;
                goto out;
        }

        jited_funcs = info.nr_jited_func_lens;
        func_lens = malloc(jited_funcs * sizeof(__u32));
        if (!ASSERT_OK_PTR(func_lens, "malloc(info.nr_jited_func_lens)")) {
                err = -ENOMEM;
                goto out;
        }

        memset(&info, 0, sizeof(info));
        info.jited_prog_insns = (__u64)image;
        info.jited_prog_len = len;
        info.jited_func_lens = (__u64)func_lens;
        info.nr_jited_func_lens = jited_funcs;
        err = bpf_prog_get_info_by_fd(fd, &info, &info_len);
        if (!ASSERT_OK(err, "bpf_prog_get_info_by_fd #2"))
                goto out;

        for (pc = 0, i = 0; i < jited_funcs; ++i) {
                fprintf(text_out, "func #%d:\n", i);
                disasm_one_func(text_out, image + pc, func_lens[i]);
                fprintf(text_out, "\n");
                pc += func_lens[i];
        }

out:
        if (text_out)
                fclose(text_out);
        if (image)
                free(image);
        if (func_lens)
                free(func_lens);
        return err;
}

#else /* HAVE_LLVM_SUPPORT */

int get_jited_program_text(int fd, char *text, size_t text_sz)
{
        if (env.verbosity >= VERBOSE_VERY)
                printf("compiled w/o llvm development libraries, can't dis-assembly binary code");
        return -EOPNOTSUPP;
}

#endif /* HAVE_LLVM_SUPPORT */