// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * probe-finder.c : C expression to kprobe event converter
 *
 * Written by Masami Hiramatsu <mhiramat@redhat.com>
 */

#include <inttypes.h>
#include <sys/utsname.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <dwarf-regs.h>

#include <linux/bitops.h>
#include <linux/zalloc.h>
#include "event.h"
#include "dso.h"
#include "debug.h"
#include "intlist.h"
#include "strbuf.h"
#include "strlist.h"
#include "symbol.h"
#include "probe-finder.h"
#include "probe-file.h"
#include "string2.h"

/* Kprobe tracer basic type is up to u64 */
#define MAX_BASIC_TYPE_BITS     64

/* Dwarf FL wrappers */
static char *debuginfo_path;    /* Currently dummy */

static const Dwfl_Callbacks offline_callbacks = {
        .find_debuginfo = dwfl_standard_find_debuginfo,
        .debuginfo_path = &debuginfo_path,

        .section_address = dwfl_offline_section_address,

        /* We use this table for core files too.  */
        .find_elf = dwfl_build_id_find_elf,
};

/* Get a Dwarf from offline image */
static int debuginfo__init_offline_dwarf(struct debuginfo *dbg,
                                         const char *path)
{
        int fd;

        fd = open(path, O_RDONLY);
        if (fd < 0)
                return fd;

        dbg->dwfl = dwfl_begin(&offline_callbacks);
        if (!dbg->dwfl)
                goto error;

        dwfl_report_begin(dbg->dwfl);
        dbg->mod = dwfl_report_offline(dbg->dwfl, "", "", fd);
        if (!dbg->mod)
                goto error;

        dbg->dbg = dwfl_module_getdwarf(dbg->mod, &dbg->bias);
        if (!dbg->dbg)
                goto error;

        dwfl_report_end(dbg->dwfl, NULL, NULL);

        return 0;
error:
        if (dbg->dwfl)
                dwfl_end(dbg->dwfl);
        else
                close(fd);
        memset(dbg, 0, sizeof(*dbg));

        return -ENOENT;
}

static struct debuginfo *__debuginfo__new(const char *path)
{
        struct debuginfo *dbg = zalloc(sizeof(*dbg));
        if (!dbg)
                return NULL;

        if (debuginfo__init_offline_dwarf(dbg, path) < 0)
                zfree(&dbg);
        if (dbg)
                pr_debug("Open Debuginfo file: %s\n", path);
        return dbg;
}

enum dso_binary_type distro_dwarf_types[] = {
        DSO_BINARY_TYPE__FEDORA_DEBUGINFO,
        DSO_BINARY_TYPE__UBUNTU_DEBUGINFO,
        DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
        DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
        DSO_BINARY_TYPE__MIXEDUP_UBUNTU_DEBUGINFO,
        DSO_BINARY_TYPE__NOT_FOUND,
};

struct debuginfo *debuginfo__new(const char *path)
{
        enum dso_binary_type *type;
        char buf[PATH_MAX], nil = '\0';
        struct dso *dso;
        struct debuginfo *dinfo = NULL;

        /* Try to open distro debuginfo files */
        dso = dso__new(path);
        if (!dso)
                goto out;

        for (type = distro_dwarf_types;
             !dinfo && *type != DSO_BINARY_TYPE__NOT_FOUND;
             type++) {
                if (dso__read_binary_type_filename(dso, *type, &nil,
                                                   buf, PATH_MAX) < 0)
                        continue;
                dinfo = __debuginfo__new(buf);
        }
        dso__put(dso);

out:
        /* if failed to open all distro debuginfo, open given binary */
        return dinfo ? : __debuginfo__new(path);
}

void debuginfo__delete(struct debuginfo *dbg)
{
        if (dbg) {
                if (dbg->dwfl)
                        dwfl_end(dbg->dwfl);
                free(dbg);
        }
}

/*
 * Probe finder related functions
 */

static struct probe_trace_arg_ref *alloc_trace_arg_ref(long offs)
{
        struct probe_trace_arg_ref *ref;
        ref = zalloc(sizeof(struct probe_trace_arg_ref));
        if (ref != NULL)
                ref->offset = offs;
        return ref;
}

/*
 * Convert a location into trace_arg.
 * If tvar == NULL, this just checks variable can be converted.
 * If fentry == true and vr_die is a parameter, do huristic search
 * for the location fuzzed by function entry mcount.
 */
static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
                                     Dwarf_Op *fb_ops, Dwarf_Die *sp_die,
                                     unsigned int machine,
                                     struct probe_trace_arg *tvar)
{
        Dwarf_Attribute attr;
        Dwarf_Addr tmp = 0;
        Dwarf_Op *op;
        size_t nops;
        unsigned int regn;
        Dwarf_Word offs = 0;
        bool ref = false;
        const char *regs;
        int ret, ret2 = 0;

        if (dwarf_attr(vr_die, DW_AT_external, &attr) != NULL)
                goto static_var;

        /* Constant value */
        if (dwarf_attr(vr_die, DW_AT_const_value, &attr) &&
            immediate_value_is_supported()) {
                Dwarf_Sword snum;

                dwarf_formsdata(&attr, &snum);
                ret = asprintf(&tvar->value, "\\%ld", (long)snum);

                return ret < 0 ? -ENOMEM : 0;
        }

        /* TODO: handle more than 1 exprs */
        if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL)
                return -EINVAL; /* Broken DIE ? */
        if (dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0) {
                ret = dwarf_entrypc(sp_die, &tmp);
                if (ret)
                        return -ENOENT;

                if (probe_conf.show_location_range &&
                        (dwarf_tag(vr_die) == DW_TAG_variable)) {
                        ret2 = -ERANGE;
                } else if (addr != tmp ||
                        dwarf_tag(vr_die) != DW_TAG_formal_parameter) {
                        return -ENOENT;
                }

                ret = dwarf_highpc(sp_die, &tmp);
                if (ret)
                        return -ENOENT;
                /*
                 * This is fuzzed by fentry mcount. We try to find the
                 * parameter location at the earliest address.
                 */
                for (addr += 1; addr <= tmp; addr++) {
                        if (dwarf_getlocation_addr(&attr, addr, &op,
                                                   &nops, 1) > 0)
                                goto found;
                }
                return -ENOENT;
        }
found:
        if (nops == 0)
                /* TODO: Support const_value */
                return -ENOENT;

        if (op->atom == DW_OP_addr) {
static_var:
                if (!tvar)
                        return ret2;
                /* Static variables on memory (not stack), make @varname */
                ret = strlen(dwarf_diename(vr_die));
                tvar->value = zalloc(ret + 2);
                if (tvar->value == NULL)
                        return -ENOMEM;
                snprintf(tvar->value, ret + 2, "@%s", dwarf_diename(vr_die));
                tvar->ref = alloc_trace_arg_ref((long)offs);
                if (tvar->ref == NULL)
                        return -ENOMEM;
                return ret2;
        }

        /* If this is based on frame buffer, set the offset */
        if (op->atom == DW_OP_fbreg) {
                if (fb_ops == NULL)
                        return -ENOTSUP;
                ref = true;
                offs = op->number;
                op = &fb_ops[0];
        }

        if (op->atom >= DW_OP_breg0 && op->atom <= DW_OP_breg31) {
                regn = op->atom - DW_OP_breg0;
                offs += op->number;
                ref = true;
        } else if (op->atom >= DW_OP_reg0 && op->atom <= DW_OP_reg31) {
                regn = op->atom - DW_OP_reg0;
        } else if (op->atom == DW_OP_bregx) {
                regn = op->number;
                offs += op->number2;
                ref = true;
        } else if (op->atom == DW_OP_regx) {
                regn = op->number;
        } else {
                pr_debug("DW_OP %x is not supported.\n", op->atom);
                return -ENOTSUP;
        }

        if (!tvar)
                return ret2;

        regs = get_dwarf_regstr(regn, machine);
        if (!regs) {
                /* This should be a bug in DWARF or this tool */
                pr_warning("Mapping for the register number %u "
                           "missing on this architecture.\n", regn);
                return -ENOTSUP;
        }

        tvar->value = strdup(regs);
        if (tvar->value == NULL)
                return -ENOMEM;

        if (ref) {
                tvar->ref = alloc_trace_arg_ref((long)offs);
                if (tvar->ref == NULL)
                        return -ENOMEM;
        }
        return ret2;
}

#define BYTES_TO_BITS(nb)       ((nb) * BITS_PER_LONG / sizeof(long))

static int convert_variable_type(Dwarf_Die *vr_die,
                                 struct probe_trace_arg *tvar,
                                 const char *cast, bool user_access)
{
        struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
        Dwarf_Die type;
        char buf[16];
        char sbuf[STRERR_BUFSIZE];
        int bsize, boffs, total;
        int ret;
        char prefix;

        /* TODO: check all types */
        if (cast && strcmp(cast, "string") != 0 && strcmp(cast, "ustring") &&
            strcmp(cast, "x") != 0 &&
            strcmp(cast, "s") != 0 && strcmp(cast, "u") != 0) {
                /* Non string type is OK */
                /* and respect signedness/hexadecimal cast */
                tvar->type = strdup(cast);
                return (tvar->type == NULL) ? -ENOMEM : 0;
        }

        bsize = dwarf_bitsize(vr_die);
        if (bsize > 0) {
                /* This is a bitfield */
                boffs = dwarf_bitoffset(vr_die);
                total = dwarf_bytesize(vr_die);
                if (boffs < 0 || total < 0)
                        return -ENOENT;
                ret = snprintf(buf, 16, "b%d@%d/%zd", bsize, boffs,
                                BYTES_TO_BITS(total));
                goto formatted;
        }

        if (die_get_real_type(vr_die, &type) == NULL) {
                pr_warning("Failed to get a type information of %s.\n",
                           dwarf_diename(vr_die));
                return -ENOENT;
        }

        pr_debug("%s type is %s.\n",
                 dwarf_diename(vr_die), dwarf_diename(&type));

        if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) {
                /* String type */
                ret = dwarf_tag(&type);
                if (ret != DW_TAG_pointer_type &&
                    ret != DW_TAG_array_type) {
                        pr_warning("Failed to cast into string: "
                                   "%s(%s) is not a pointer nor array.\n",
                                   dwarf_diename(vr_die), dwarf_diename(&type));
                        return -EINVAL;
                }
                if (die_get_real_type(&type, &type) == NULL) {
                        pr_warning("Failed to get a type"
                                   " information.\n");
                        return -ENOENT;
                }
                if (ret == DW_TAG_pointer_type) {
                        while (*ref_ptr)
                                ref_ptr = &(*ref_ptr)->next;
                        /* Add new reference with offset +0 */
                        *ref_ptr = zalloc(sizeof(struct probe_trace_arg_ref));
                        if (*ref_ptr == NULL) {
                                pr_warning("Out of memory error\n");
                                return -ENOMEM;
                        }
                        (*ref_ptr)->user_access = user_access;
                }
                if (!die_compare_name(&type, "char") &&
                    !die_compare_name(&type, "unsigned char")) {
                        pr_warning("Failed to cast into string: "
                                   "%s is not (unsigned) char *.\n",
                                   dwarf_diename(vr_die));
                        return -EINVAL;
                }
                tvar->type = strdup(cast);
                return (tvar->type == NULL) ? -ENOMEM : 0;
        }

        if (cast && (strcmp(cast, "u") == 0))
                prefix = 'u';
        else if (cast && (strcmp(cast, "s") == 0))
                prefix = 's';
        else if (cast && (strcmp(cast, "x") == 0) &&
                 probe_type_is_available(PROBE_TYPE_X))
                prefix = 'x';
        else
                prefix = die_is_signed_type(&type) ? 's' :
                         probe_type_is_available(PROBE_TYPE_X) ? 'x' : 'u';

        ret = dwarf_bytesize(&type);
        if (ret <= 0)
                /* No size ... try to use default type */
                return 0;
        ret = BYTES_TO_BITS(ret);

        /* Check the bitwidth */
        if (ret > MAX_BASIC_TYPE_BITS) {
                pr_info("%s exceeds max-bitwidth. Cut down to %d bits.\n",
                        dwarf_diename(&type), MAX_BASIC_TYPE_BITS);
                ret = MAX_BASIC_TYPE_BITS;
        }
        ret = snprintf(buf, 16, "%c%d", prefix, ret);

formatted:
        if (ret < 0 || ret >= 16) {
                if (ret >= 16)
                        ret = -E2BIG;
                pr_warning("Failed to convert variable type: %s\n",
                           str_error_r(-ret, sbuf, sizeof(sbuf)));
                return ret;
        }
        tvar->type = strdup(buf);
        if (tvar->type == NULL)
                return -ENOMEM;
        return 0;
}

static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
                                    struct perf_probe_arg_field *field,
                                    struct probe_trace_arg_ref **ref_ptr,
                                    Dwarf_Die *die_mem, bool user_access)
{
        struct probe_trace_arg_ref *ref = *ref_ptr;
        Dwarf_Die type;
        Dwarf_Word offs;
        int ret, tag;

        pr_debug("converting %s in %s\n", field->name, varname);
        if (die_get_real_type(vr_die, &type) == NULL) {
                pr_warning("Failed to get the type of %s.\n", varname);
                return -ENOENT;
        }
        pr_debug2("Var real type: %s (%x)\n", dwarf_diename(&type),
                  (unsigned)dwarf_dieoffset(&type));
        tag = dwarf_tag(&type);

        if (field->name[0] == '[' &&
            (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
                /* Save original type for next field or type */
                memcpy(die_mem, &type, sizeof(*die_mem));
                /* Get the type of this array */
                if (die_get_real_type(&type, &type) == NULL) {
                        pr_warning("Failed to get the type of %s.\n", varname);
                        return -ENOENT;
                }
                pr_debug2("Array real type: %s (%x)\n", dwarf_diename(&type),
                         (unsigned)dwarf_dieoffset(&type));
                if (tag == DW_TAG_pointer_type) {
                        ref = zalloc(sizeof(struct probe_trace_arg_ref));
                        if (ref == NULL)
                                return -ENOMEM;
                        if (*ref_ptr)
                                (*ref_ptr)->next = ref;
                        else
                                *ref_ptr = ref;
                }
                ref->offset += dwarf_bytesize(&type) * field->index;
                ref->user_access = user_access;
                goto next;
        } else if (tag == DW_TAG_pointer_type) {
                /* Check the pointer and dereference */
                if (!field->ref) {
                        pr_err("Semantic error: %s must be referred by '->'\n",
                               field->name);
                        return -EINVAL;
                }
                /* Get the type pointed by this pointer */
                if (die_get_real_type(&type, &type) == NULL) {
                        pr_warning("Failed to get the type of %s.\n", varname);
                        return -ENOENT;
                }
                /* Verify it is a data structure  */
                tag = dwarf_tag(&type);
                if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
                        pr_warning("%s is not a data structure nor a union.\n",
                                   varname);
                        return -EINVAL;
                }

                ref = zalloc(sizeof(struct probe_trace_arg_ref));
                if (ref == NULL)
                        return -ENOMEM;
                if (*ref_ptr)
                        (*ref_ptr)->next = ref;
                else
                        *ref_ptr = ref;
        } else {
                /* Verify it is a data structure  */
                if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
                        pr_warning("%s is not a data structure nor a union.\n",
                                   varname);
                        return -EINVAL;
                }
                if (field->name[0] == '[') {
                        pr_err("Semantic error: %s is not a pointer"
                               " nor array.\n", varname);
                        return -EINVAL;
                }
                /* While prcessing unnamed field, we don't care about this */
                if (field->ref && dwarf_diename(vr_die)) {
                        pr_err("Semantic error: %s must be referred by '.'\n",
                               field->name);
                        return -EINVAL;
                }
                if (!ref) {
                        pr_warning("Structure on a register is not "
                                   "supported yet.\n");
                        return -ENOTSUP;
                }
        }

        if (die_find_member(&type, field->name, die_mem) == NULL) {
                pr_warning("%s(type:%s) has no member %s.\n", varname,
                           dwarf_diename(&type), field->name);
                return -EINVAL;
        }

        /* Get the offset of the field */
        if (tag == DW_TAG_union_type) {
                offs = 0;
        } else {
                ret = die_get_data_member_location(die_mem, &offs);
                if (ret < 0) {
                        pr_warning("Failed to get the offset of %s.\n",
                                   field->name);
                        return ret;
                }
        }
        ref->offset += (long)offs;
        ref->user_access = user_access;

        /* If this member is unnamed, we need to reuse this field */
        if (!dwarf_diename(die_mem))
                return convert_variable_fields(die_mem, varname, field,
                                                &ref, die_mem, user_access);

next:
        /* Converting next field */
        if (field->next)
                return convert_variable_fields(die_mem, field->name,
                                field->next, &ref, die_mem, user_access);
        else
                return 0;
}

static void print_var_not_found(const char *varname)
{
        pr_err("Failed to find the location of the '%s' variable at this address.\n"
               " Perhaps it has been optimized out.\n"
               " Use -V with the --range option to show '%s' location range.\n",
                varname, varname);
}

/* Show a variables in kprobe event format */
static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
{
        Dwarf_Die die_mem;
        int ret;

        pr_debug("Converting variable %s into trace event.\n",
                 dwarf_diename(vr_die));

        ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
                                        &pf->sp_die, pf->machine, pf->tvar);
        if (ret == -ENOENT && pf->skip_empty_arg)
                /* This can be found in other place. skip it */
                return 0;
        if (ret == -ENOENT || ret == -EINVAL) {
                print_var_not_found(pf->pvar->var);
        } else if (ret == -ENOTSUP)
                pr_err("Sorry, we don't support this variable location yet.\n");
        else if (ret == 0 && pf->pvar->field) {
                ret = convert_variable_fields(vr_die, pf->pvar->var,
                                              pf->pvar->field, &pf->tvar->ref,
                                              &die_mem, pf->pvar->user_access);
                vr_die = &die_mem;
        }
        if (ret == 0)
                ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type,
                                            pf->pvar->user_access);
        /* *expr will be cached in libdw. Don't free it. */
        return ret;
}

/* Find a variable in a scope DIE */
static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
{
        Dwarf_Die vr_die;
        char *buf, *ptr;
        int ret = 0;

        /* Copy raw parameters */
        if (!is_c_varname(pf->pvar->var))
                return copy_to_probe_trace_arg(pf->tvar, pf->pvar);

        if (pf->pvar->name)
                pf->tvar->name = strdup(pf->pvar->name);
        else {
                buf = synthesize_perf_probe_arg(pf->pvar);
                if (!buf)
                        return -ENOMEM;
                ptr = strchr(buf, ':'); /* Change type separator to _ */
                if (ptr)
                        *ptr = '_';
                pf->tvar->name = buf;
        }
        if (pf->tvar->name == NULL)
                return -ENOMEM;

        pr_debug("Searching '%s' variable in context.\n", pf->pvar->var);
        /* Search child die for local variables and parameters. */
        if (!die_find_variable_at(sc_die, pf->pvar->var, pf->addr, &vr_die)) {
                /* Search again in global variables */
                if (!die_find_variable_at(&pf->cu_die, pf->pvar->var,
                                                0, &vr_die)) {
                        if (pf->skip_empty_arg)
                                return 0;
                        pr_warning("Failed to find '%s' in this function.\n",
                                   pf->pvar->var);
                        ret = -ENOENT;
                }
        }
        if (ret >= 0)
                ret = convert_variable(&vr_die, pf);

        return ret;
}

/* Convert subprogram DIE to trace point */
static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
                                  Dwarf_Addr paddr, bool retprobe,
                                  const char *function,
                                  struct probe_trace_point *tp)
{
        Dwarf_Addr eaddr;
        GElf_Sym sym;
        const char *symbol;

        /* Verify the address is correct */
        if (!dwarf_haspc(sp_die, paddr)) {
                pr_warning("Specified offset is out of %s\n",
                           dwarf_diename(sp_die));
                return -EINVAL;
        }

        if (dwarf_entrypc(sp_die, &eaddr) == 0) {
                /* If the DIE has entrypc, use it. */
                symbol = dwarf_diename(sp_die);
        } else {
                /* Try to get actual symbol name and address from symtab */
                symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
                eaddr = sym.st_value;
        }
        if (!symbol) {
                pr_warning("Failed to find symbol at 0x%lx\n",
                           (unsigned long)paddr);
                return -ENOENT;
        }

        tp->offset = (unsigned long)(paddr - eaddr);
        tp->address = (unsigned long)paddr;
        tp->symbol = strdup(symbol);
        if (!tp->symbol)
                return -ENOMEM;

        /* Return probe must be on the head of a subprogram */
        if (retprobe) {
                if (eaddr != paddr) {
                        pr_warning("Failed to find \"%s%%return\",\n"
                                   " because %s is an inlined function and"
                                   " has no return point.\n", function,
                                   function);
                        return -EINVAL;
                }
                tp->retprobe = true;
        }

        return 0;
}

/* Call probe_finder callback with scope DIE */
static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
{
        Dwarf_Attribute fb_attr;
        Dwarf_Frame *frame = NULL;
        size_t nops;
        int ret;

        if (!sc_die) {
                pr_err("Caller must pass a scope DIE. Program error.\n");
                return -EINVAL;
        }

        /* If not a real subprogram, find a real one */
        if (!die_is_func_def(sc_die)) {
                if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
                        if (die_find_tailfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
                                pr_warning("Ignoring tail call from %s\n",
                                                dwarf_diename(&pf->sp_die));
                                return 0;
                        } else {
                                pr_warning("Failed to find probe point in any "
                                           "functions.\n");
                                return -ENOENT;
                        }
                }
        } else
                memcpy(&pf->sp_die, sc_die, sizeof(Dwarf_Die));

        /* Get the frame base attribute/ops from subprogram */
        dwarf_attr(&pf->sp_die, DW_AT_frame_base, &fb_attr);
        ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
        if (ret <= 0 || nops == 0) {
                pf->fb_ops = NULL;
#if _ELFUTILS_PREREQ(0, 142)
        } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
                   (pf->cfi_eh != NULL || pf->cfi_dbg != NULL)) {
                if ((dwarf_cfi_addrframe(pf->cfi_eh, pf->addr, &frame) != 0 &&
                     (dwarf_cfi_addrframe(pf->cfi_dbg, pf->addr, &frame) != 0)) ||
                    dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
                        pr_warning("Failed to get call frame on 0x%jx\n",
                                   (uintmax_t)pf->addr);
                        free(frame);
                        return -ENOENT;
                }
#endif
        }

        /* Call finder's callback handler */
        ret = pf->callback(sc_die, pf);

        /* Since *pf->fb_ops can be a part of frame. we should free it here. */
        free(frame);
        pf->fb_ops = NULL;

        return ret;
}

struct find_scope_param {
        const char *function;
        const char *file;
        int line;
        int diff;
        Dwarf_Die *die_mem;
        bool found;
};

static int find_best_scope_cb(Dwarf_Die *fn_die, void *data)
{
        struct find_scope_param *fsp = data;
        const char *file;
        int lno;

        /* Skip if declared file name does not match */
        if (fsp->file) {
                file = dwarf_decl_file(fn_die);
                if (!file || strcmp(fsp->file, file) != 0)
                        return 0;
        }
        /* If the function name is given, that's what user expects */
        if (fsp->function) {
                if (die_match_name(fn_die, fsp->function)) {
                        memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
                        fsp->found = true;
                        return 1;
                }
        } else {
                /* With the line number, find the nearest declared DIE */
                dwarf_decl_line(fn_die, &lno);
                if (lno < fsp->line && fsp->diff > fsp->line - lno) {
                        /* Keep a candidate and continue */
                        fsp->diff = fsp->line - lno;
                        memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
                        fsp->found = true;
                }
        }
        return 0;
}

/* Return innermost DIE */
static int find_inner_scope_cb(Dwarf_Die *fn_die, void *data)
{
        struct find_scope_param *fsp = data;

        memcpy(fsp->die_mem, fn_die, sizeof(Dwarf_Die));
        fsp->found = true;
        return 1;
}

/* Find an appropriate scope fits to given conditions */
static Dwarf_Die *find_best_scope(struct probe_finder *pf, Dwarf_Die *die_mem)
{
        struct find_scope_param fsp = {
                .function = pf->pev->point.function,
                .file = pf->fname,
                .line = pf->lno,
                .diff = INT_MAX,
                .die_mem = die_mem,
                .found = false,
        };
        int ret;

        ret = cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb,
                                   &fsp);
        if (!ret && !fsp.found)
                cu_walk_functions_at(&pf->cu_die, pf->addr,
                                     find_inner_scope_cb, &fsp);

        return fsp.found ? die_mem : NULL;
}

static int verify_representive_line(struct probe_finder *pf, const char *fname,
                                int lineno, Dwarf_Addr addr)
{
        const char *__fname, *__func = NULL;
        Dwarf_Die die_mem;
        int __lineno;

        /* Verify line number and address by reverse search */
        if (cu_find_lineinfo(&pf->cu_die, addr, &__fname, &__lineno) < 0)
                return 0;

        pr_debug2("Reversed line: %s:%d\n", __fname, __lineno);
        if (strcmp(fname, __fname) || lineno == __lineno)
                return 0;

        pr_warning("This line is sharing the address with other lines.\n");

        if (pf->pev->point.function) {
                /* Find best match function name and lines */
                pf->addr = addr;
                if (find_best_scope(pf, &die_mem)
                    && die_match_name(&die_mem, pf->pev->point.function)
                    && dwarf_decl_line(&die_mem, &lineno) == 0) {
                        __func = dwarf_diename(&die_mem);
                        __lineno -= lineno;
                }
        }
        pr_warning("Please try to probe at %s:%d instead.\n",
                   __func ? : __fname, __lineno);

        return -ENOENT;
}

static int probe_point_line_walker(const char *fname, int lineno,
                                   Dwarf_Addr addr, void *data)
{
        struct probe_finder *pf = data;
        Dwarf_Die *sc_die, die_mem;
        int ret;

        if (lineno != pf->lno || strtailcmp(fname, pf->fname) != 0)
                return 0;

        if (verify_representive_line(pf, fname, lineno, addr))
                return -ENOENT;

        pf->addr = addr;
        sc_die = find_best_scope(pf, &die_mem);
        if (!sc_die) {
                pr_warning("Failed to find scope of probe point.\n");
                return -ENOENT;
        }

        ret = call_probe_finder(sc_die, pf);

        /* Continue if no error, because the line will be in inline function */
        return ret < 0 ? ret : 0;
}

/* Find probe point from its line number */
static int find_probe_point_by_line(struct probe_finder *pf)
{
        return die_walk_lines(&pf->cu_die, probe_point_line_walker, pf);
}

/* Find lines which match lazy pattern */
static int find_lazy_match_lines(struct intlist *list,
                                 const char *fname, const char *pat)
{
        FILE *fp;
        char *line = NULL;
        size_t line_len;
        ssize_t len;
        int count = 0, linenum = 1;
        char sbuf[STRERR_BUFSIZE];

        fp = fopen(fname, "r");
        if (!fp) {
                pr_warning("Failed to open %s: %s\n", fname,
                           str_error_r(errno, sbuf, sizeof(sbuf)));
                return -errno;
        }

        while ((len = getline(&line, &line_len, fp)) > 0) {

                if (line[len - 1] == '\n')
                        line[len - 1] = '\0';

                if (strlazymatch(line, pat)) {
                        intlist__add(list, linenum);
                        count++;
                }
                linenum++;
        }

        if (ferror(fp))
                count = -errno;
        free(line);
        fclose(fp);

        if (count == 0)
                pr_debug("No matched lines found in %s.\n", fname);
        return count;
}

static int probe_point_lazy_walker(const char *fname, int lineno,
                                   Dwarf_Addr addr, void *data)
{
        struct probe_finder *pf = data;
        Dwarf_Die *sc_die, die_mem;
        int ret;

        if (!intlist__has_entry(pf->lcache, lineno) ||
            strtailcmp(fname, pf->fname) != 0)
                return 0;

        pr_debug("Probe line found: line:%d addr:0x%llx\n",
                 lineno, (unsigned long long)addr);
        pf->addr = addr;
        pf->lno = lineno;
        sc_die = find_best_scope(pf, &die_mem);
        if (!sc_die) {
                pr_warning("Failed to find scope of probe point.\n");
                return -ENOENT;
        }

        ret = call_probe_finder(sc_die, pf);

        /*
         * Continue if no error, because the lazy pattern will match
         * to other lines
         */
        return ret < 0 ? ret : 0;
}

/* Find probe points from lazy pattern  */
static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
{
        int ret = 0;
        char *fpath;

        if (intlist__empty(pf->lcache)) {
                const char *comp_dir;

                comp_dir = cu_get_comp_dir(&pf->cu_die);
                ret = get_real_path(pf->fname, comp_dir, &fpath);
                if (ret < 0) {
                        pr_warning("Failed to find source file path.\n");
                        return ret;
                }

                /* Matching lazy line pattern */
                ret = find_lazy_match_lines(pf->lcache, fpath,
                                            pf->pev->point.lazy_line);
                free(fpath);
                if (ret <= 0)
                        return ret;
        }

        return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
}

static void skip_prologue(Dwarf_Die *sp_die, struct probe_finder *pf)
{
        struct perf_probe_point *pp = &pf->pev->point;

        /* Not uprobe? */
        if (!pf->pev->uprobes)
                return;

        /* Compiled with optimization? */
        if (die_is_optimized_target(&pf->cu_die))
                return;

        /* Don't know entrypc? */
        if (!pf->addr)
                return;

        /* Only FUNC and FUNC@SRC are eligible. */
        if (!pp->function || pp->line || pp->retprobe || pp->lazy_line ||
            pp->offset || pp->abs_address)
                return;

        /* Not interested in func parameter? */
        if (!perf_probe_with_var(pf->pev))
                return;

        pr_info("Target program is compiled without optimization. Skipping prologue.\n"
                "Probe on address 0x%" PRIx64 " to force probing at the function entry.\n\n",
                pf->addr);

        die_skip_prologue(sp_die, &pf->cu_die, &pf->addr);
}

static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
{
        struct probe_finder *pf = data;
        struct perf_probe_point *pp = &pf->pev->point;
        Dwarf_Addr addr;
        int ret;

        if (pp->lazy_line)
                ret = find_probe_point_lazy(in_die, pf);
        else {
                /* Get probe address */
                if (die_entrypc(in_die, &addr) != 0) {
                        pr_warning("Failed to get entry address of %s.\n",
                                   dwarf_diename(in_die));
                        return -ENOENT;
                }
                if (addr == 0) {
                        pr_debug("%s has no valid entry address. skipped.\n",
                                 dwarf_diename(in_die));
                        return -ENOENT;
                }
                pf->addr = addr;
                pf->addr += pp->offset;
                pr_debug("found inline addr: 0x%jx\n",
                         (uintmax_t)pf->addr);

                ret = call_probe_finder(in_die, pf);
        }

        return ret;
}

/* Callback parameter with return value for libdw */
struct dwarf_callback_param {
        void *data;
        int retval;
};

/* Search function from function name */
static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
{
        struct dwarf_callback_param *param = data;
        struct probe_finder *pf = param->data;
        struct perf_probe_point *pp = &pf->pev->point;

        /* Check tag and diename */
        if (!die_is_func_def(sp_die) ||
            !die_match_name(sp_die, pp->function))
                return DWARF_CB_OK;

        /* Check declared file */
        if (pp->file && strtailcmp(pp->file, dwarf_decl_file(sp_die)))
                return DWARF_CB_OK;

        pr_debug("Matched function: %s [%lx]\n", dwarf_diename(sp_die),
                 (unsigned long)dwarf_dieoffset(sp_die));
        pf->fname = dwarf_decl_file(sp_die);
        if (pp->line) { /* Function relative line */
                dwarf_decl_line(sp_die, &pf->lno);
                pf->lno += pp->line;
                param->retval = find_probe_point_by_line(pf);
        } else if (die_is_func_instance(sp_die)) {
                /* Instances always have the entry address */
                die_entrypc(sp_die, &pf->addr);
                /* But in some case the entry address is 0 */
                if (pf->addr == 0) {
                        pr_debug("%s has no entry PC. Skipped\n",
                                 dwarf_diename(sp_die));
                        param->retval = 0;
                /* Real function */
                } else if (pp->lazy_line)
                        param->retval = find_probe_point_lazy(sp_die, pf);
                else {
                        skip_prologue(sp_die, pf);
                        pf->addr += pp->offset;
                        /* TODO: Check the address in this function */
                        param->retval = call_probe_finder(sp_die, pf);
                }
        } else if (!probe_conf.no_inlines) {
                /* Inlined function: search instances */
                param->retval = die_walk_instances(sp_die,
                                        probe_point_inline_cb, (void *)pf);
                /* This could be a non-existed inline definition */
                if (param->retval == -ENOENT)
                        param->retval = 0;
        }

        /* We need to find other candidates */
        if (strisglob(pp->function) && param->retval >= 0) {
                param->retval = 0;      /* We have to clear the result */
                return DWARF_CB_OK;
        }

        return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
}

static int find_probe_point_by_func(struct probe_finder *pf)
{
        struct dwarf_callback_param _param = {.data = (void *)pf,
                                              .retval = 0};
        dwarf_getfuncs(&pf->cu_die, probe_point_search_cb, &_param, 0);
        return _param.retval;
}

struct pubname_callback_param {
        char *function;
        char *file;
        Dwarf_Die *cu_die;
        Dwarf_Die *sp_die;
        int found;
};

static int pubname_search_cb(Dwarf *dbg, Dwarf_Global *gl, void *data)
{
        struct pubname_callback_param *param = data;

        if (dwarf_offdie(dbg, gl->die_offset, param->sp_die)) {
                if (dwarf_tag(param->sp_die) != DW_TAG_subprogram)
                        return DWARF_CB_OK;

                if (die_match_name(param->sp_die, param->function)) {
                        if (!dwarf_offdie(dbg, gl->cu_offset, param->cu_die))
                                return DWARF_CB_OK;

                        if (param->file &&
                            strtailcmp(param->file, dwarf_decl_file(param->sp_die)))
                                return DWARF_CB_OK;

                        param->found = 1;
                        return DWARF_CB_ABORT;
                }
        }

        return DWARF_CB_OK;
}

static int debuginfo__find_probe_location(struct debuginfo *dbg,
                                  struct probe_finder *pf)
{
        struct perf_probe_point *pp = &pf->pev->point;
        Dwarf_Off off, noff;
        size_t cuhl;
        Dwarf_Die *diep;
        int ret = 0;

        off = 0;
        pf->lcache = intlist__new(NULL);
        if (!pf->lcache)
                return -ENOMEM;

        /* Fastpath: lookup by function name from .debug_pubnames section */
        if (pp->function && !strisglob(pp->function)) {
                struct pubname_callback_param pubname_param = {
                        .function = pp->function,
                        .file     = pp->file,
                        .cu_die   = &pf->cu_die,
                        .sp_die   = &pf->sp_die,
                        .found    = 0,
                };
                struct dwarf_callback_param probe_param = {
                        .data = pf,
                };

                dwarf_getpubnames(dbg->dbg, pubname_search_cb,
                                  &pubname_param, 0);
                if (pubname_param.found) {
                        ret = probe_point_search_cb(&pf->sp_die, &probe_param);
                        if (ret)
                                goto found;
                }
        }

        /* Loop on CUs (Compilation Unit) */
        while (!dwarf_nextcu(dbg->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
                /* Get the DIE(Debugging Information Entry) of this CU */
                diep = dwarf_offdie(dbg->dbg, off + cuhl, &pf->cu_die);
                if (!diep)
                        continue;

                /* Check if target file is included. */
                if (pp->file)
                        pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
                else
                        pf->fname = NULL;

                if (!pp->file || pf->fname) {
                        if (pp->function)
                                ret = find_probe_point_by_func(pf);
                        else if (pp->lazy_line)
                                ret = find_probe_point_lazy(&pf->cu_die, pf);
                        else {
                                pf->lno = pp->line;
                                ret = find_probe_point_by_line(pf);
                        }
                        if (ret < 0)
                                break;
                }
                off = noff;
        }

found:
        intlist__delete(pf->lcache);
        pf->lcache = NULL;

        return ret;
}

/* Find probe points from debuginfo */
static int debuginfo__find_probes(struct debuginfo *dbg,
                                  struct probe_finder *pf)
{
        int ret = 0;
        Elf *elf;
        GElf_Ehdr ehdr;

        if (pf->cfi_eh || pf->cfi_dbg)
                return debuginfo__find_probe_location(dbg, pf);

        /* Get the call frame information from this dwarf */
        elf = dwarf_getelf(dbg->dbg);
        if (elf == NULL)
                return -EINVAL;

        if (gelf_getehdr(elf, &ehdr) == NULL)
                return -EINVAL;

        pf->machine = ehdr.e_machine;

#if _ELFUTILS_PREREQ(0, 142)
        do {
                GElf_Shdr shdr;

                if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) &&
                    shdr.sh_type == SHT_PROGBITS)
                        pf->cfi_eh = dwarf_getcfi_elf(elf);

                pf->cfi_dbg = dwarf_getcfi(dbg->dbg);
        } while (0);
#endif

        ret = debuginfo__find_probe_location(dbg, pf);
        return ret;
}

struct local_vars_finder {
        struct probe_finder *pf;
        struct perf_probe_arg *args;
        bool vars;
        int max_args;
        int nargs;
        int ret;
};

/* Collect available variables in this scope */
static int copy_variables_cb(Dwarf_Die *die_mem, void *data)
{
        struct local_vars_finder *vf = data;
        struct probe_finder *pf = vf->pf;
        int tag;

        tag = dwarf_tag(die_mem);
        if (tag == DW_TAG_formal_parameter ||
            (tag == DW_TAG_variable && vf->vars)) {
                if (convert_variable_location(die_mem, vf->pf->addr,
                                              vf->pf->fb_ops, &pf->sp_die,
                                              pf->machine, NULL) == 0) {
                        vf->args[vf->nargs].var = (char *)dwarf_diename(die_mem);
                        if (vf->args[vf->nargs].var == NULL) {
                                vf->ret = -ENOMEM;
                                return DIE_FIND_CB_END;
                        }
                        pr_debug(" %s", vf->args[vf->nargs].var);
                        vf->nargs++;
                }
        }

        if (dwarf_haspc(die_mem, vf->pf->addr))
                return DIE_FIND_CB_CONTINUE;
        else
                return DIE_FIND_CB_SIBLING;
}

static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf,
                             struct perf_probe_arg *args)
{
        Dwarf_Die die_mem;
        int i;
        int n = 0;
        struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false,
                                .max_args = MAX_PROBE_ARGS, .ret = 0};

        for (i = 0; i < pf->pev->nargs; i++) {
                /* var never be NULL */
                if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0)
                        vf.vars = true;
                else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) {
                        /* Copy normal argument */
                        args[n] = pf->pev->args[i];
                        n++;
                        continue;
                }
                pr_debug("Expanding %s into:", pf->pev->args[i].var);
                vf.nargs = n;
                /* Special local variables */
                die_find_child(sc_die, copy_variables_cb, (void *)&vf,
                               &die_mem);
                pr_debug(" (%d)\n", vf.nargs - n);
                if (vf.ret < 0)
                        return vf.ret;
                n = vf.nargs;
        }
        return n;
}

static bool trace_event_finder_overlap(struct trace_event_finder *tf)
{
        int i;

        for (i = 0; i < tf->ntevs; i++) {
                if (tf->pf.addr == tf->tevs[i].point.address)
                        return true;
        }
        return false;
}

/* Add a found probe point into trace event list */
static int add_probe_trace_event(Dwarf_Die *sc_die, struct probe_finder *pf)
{
        struct trace_event_finder *tf =
                        container_of(pf, struct trace_event_finder, pf);
        struct perf_probe_point *pp = &pf->pev->point;
        struct probe_trace_event *tev;
        struct perf_probe_arg *args = NULL;
        int ret, i;

        /*
         * For some reason (e.g. different column assigned to same address)
         * This callback can be called with the address which already passed.
         * Ignore it first.
         */
        if (trace_event_finder_overlap(tf))
                return 0;

        /* Check number of tevs */
        if (tf->ntevs == tf->max_tevs) {
                pr_warning("Too many( > %d) probe point found.\n",
                           tf->max_tevs);
                return -ERANGE;
        }
        tev = &tf->tevs[tf->ntevs++];

        /* Trace point should be converted from subprogram DIE */
        ret = convert_to_trace_point(&pf->sp_die, tf->mod, pf->addr,
                                     pp->retprobe, pp->function, &tev->point);
        if (ret < 0)
                goto end;

        tev->point.realname = strdup(dwarf_diename(sc_die));
        if (!tev->point.realname) {
                ret = -ENOMEM;
                goto end;
        }

        pr_debug("Probe point found: %s+%lu\n", tev->point.symbol,
                 tev->point.offset);

        /* Expand special probe argument if exist */
        args = zalloc(sizeof(struct perf_probe_arg) * MAX_PROBE_ARGS);
        if (args == NULL) {
                ret = -ENOMEM;
                goto end;
        }

        ret = expand_probe_args(sc_die, pf, args);
        if (ret < 0)
                goto end;

        tev->nargs = ret;
        tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
        if (tev->args == NULL) {
                ret = -ENOMEM;
                goto end;
        }

        /* Find each argument */
        for (i = 0; i < tev->nargs; i++) {
                pf->pvar = &args[i];
                pf->tvar = &tev->args[i];
                /* Variable should be found from scope DIE */
                ret = find_variable(sc_die, pf);
                if (ret != 0)
                        break;
        }

end:
        if (ret) {
                clear_probe_trace_event(tev);
                tf->ntevs--;
        }
        free(args);
        return ret;
}

static int fill_empty_trace_arg(struct perf_probe_event *pev,
                                struct probe_trace_event *tevs, int ntevs)
{
        char **valp;
        char *type;
        int i, j, ret;

        if (!ntevs)
                return -ENOENT;

        for (i = 0; i < pev->nargs; i++) {
                type = NULL;
                for (j = 0; j < ntevs; j++) {
                        if (tevs[j].args[i].value) {
                                type = tevs[j].args[i].type;
                                break;
                        }
                }
                if (j == ntevs) {
                        print_var_not_found(pev->args[i].var);
                        return -ENOENT;
                }
                for (j = 0; j < ntevs; j++) {
                        valp = &tevs[j].args[i].value;
                        if (*valp)
                                continue;

                        ret = asprintf(valp, "\\%lx", probe_conf.magic_num);
                        if (ret < 0)
                                return -ENOMEM;
                        /* Note that type can be NULL */
                        if (type) {
                                tevs[j].args[i].type = strdup(type);
                                if (!tevs[j].args[i].type)
                                        return -ENOMEM;
                        }
                }
        }
        return 0;
}

/* Find probe_trace_events specified by perf_probe_event from debuginfo */
int debuginfo__find_trace_events(struct debuginfo *dbg,
                                 struct perf_probe_event *pev,
                                 struct probe_trace_event **tevs)
{
        struct trace_event_finder tf = {
                        .pf = {.pev = pev, .callback = add_probe_trace_event},
                        .max_tevs = probe_conf.max_probes, .mod = dbg->mod};
        int ret, i;

        /* Allocate result tevs array */
        *tevs = zalloc(sizeof(struct probe_trace_event) * tf.max_tevs);
        if (*tevs == NULL)
                return -ENOMEM;

        tf.tevs = *tevs;
        tf.ntevs = 0;

        if (pev->nargs != 0 && immediate_value_is_supported())
                tf.pf.skip_empty_arg = true;

        ret = debuginfo__find_probes(dbg, &tf.pf);
        if (ret >= 0 && tf.pf.skip_empty_arg)
                ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);

        if (ret < 0 || tf.ntevs == 0) {
                for (i = 0; i < tf.ntevs; i++)
                        clear_probe_trace_event(&tf.tevs[i]);
                zfree(tevs);
                return ret;
        }

        return (ret < 0) ? ret : tf.ntevs;
}

/* Collect available variables in this scope */
static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
{
        struct available_var_finder *af = data;
        struct variable_list *vl;
        struct strbuf buf = STRBUF_INIT;
        int tag, ret;

        vl = &af->vls[af->nvls - 1];

        tag = dwarf_tag(die_mem);
        if (tag == DW_TAG_formal_parameter ||
            tag == DW_TAG_variable) {
                ret = convert_variable_location(die_mem, af->pf.addr,
                                                af->pf.fb_ops, &af->pf.sp_die,
                                                af->pf.machine, NULL);
                if (ret == 0 || ret == -ERANGE) {
                        int ret2;
                        bool externs = !af->child;

                        if (strbuf_init(&buf, 64) < 0)
                                goto error;

                        if (probe_conf.show_location_range) {
                                if (!externs)
                                        ret2 = strbuf_add(&buf,
                                                ret ? "[INV]\t" : "[VAL]\t", 6);
                                else
                                        ret2 = strbuf_add(&buf, "[EXT]\t", 6);
                                if (ret2)
                                        goto error;
                        }

                        ret2 = die_get_varname(die_mem, &buf);

                        if (!ret2 && probe_conf.show_location_range &&
                                !externs) {
                                if (strbuf_addch(&buf, '\t') < 0)
                                        goto error;
                                ret2 = die_get_var_range(&af->pf.sp_die,
                                                        die_mem, &buf);
                        }

                        pr_debug("Add new var: %s\n", buf.buf);
                        if (ret2 == 0) {
                                strlist__add(vl->vars,
                                        strbuf_detach(&buf, NULL));
                        }
                        strbuf_release(&buf);
                }
        }

        if (af->child && dwarf_haspc(die_mem, af->pf.addr))
                return DIE_FIND_CB_CONTINUE;
        else
                return DIE_FIND_CB_SIBLING;
error:
        strbuf_release(&buf);
        pr_debug("Error in strbuf\n");
        return DIE_FIND_CB_END;
}

static bool available_var_finder_overlap(struct available_var_finder *af)
{
        int i;

        for (i = 0; i < af->nvls; i++) {
                if (af->pf.addr == af->vls[i].point.address)
                        return true;
        }
        return false;

}

/* Add a found vars into available variables list */
static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
{
        struct available_var_finder *af =
                        container_of(pf, struct available_var_finder, pf);
        struct perf_probe_point *pp = &pf->pev->point;
        struct variable_list *vl;
        Dwarf_Die die_mem;
        int ret;

        /*
         * For some reason (e.g. different column assigned to same address),
         * this callback can be called with the address which already passed.
         * Ignore it first.
         */
        if (available_var_finder_overlap(af))
                return 0;

        /* Check number of tevs */
        if (af->nvls == af->max_vls) {
                pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
                return -ERANGE;
        }
        vl = &af->vls[af->nvls++];

        /* Trace point should be converted from subprogram DIE */
        ret = convert_to_trace_point(&pf->sp_die, af->mod, pf->addr,
                                     pp->retprobe, pp->function, &vl->point);
        if (ret < 0)
                return ret;

        pr_debug("Probe point found: %s+%lu\n", vl->point.symbol,
                 vl->point.offset);

        /* Find local variables */
        vl->vars = strlist__new(NULL, NULL);
        if (vl->vars == NULL)
                return -ENOMEM;
        af->child = true;
        die_find_child(sc_die, collect_variables_cb, (void *)af, &die_mem);

        /* Find external variables */
        if (!probe_conf.show_ext_vars)
                goto out;
        /* Don't need to search child DIE for external vars. */
        af->child = false;
        die_find_child(&pf->cu_die, collect_variables_cb, (void *)af, &die_mem);

out:
        if (strlist__empty(vl->vars)) {
                strlist__delete(vl->vars);
                vl->vars = NULL;
        }

        return ret;
}

/*
 * Find available variables at given probe point
 * Return the number of found probe points. Return 0 if there is no
 * matched probe point. Return <0 if an error occurs.
 */
int debuginfo__find_available_vars_at(struct debuginfo *dbg,
                                      struct perf_probe_event *pev,
                                      struct variable_list **vls)
{
        struct available_var_finder af = {
                        .pf = {.pev = pev, .callback = add_available_vars},
                        .mod = dbg->mod,
                        .max_vls = probe_conf.max_probes};
        int ret;

        /* Allocate result vls array */
        *vls = zalloc(sizeof(struct variable_list) * af.max_vls);
        if (*vls == NULL)
                return -ENOMEM;

        af.vls = *vls;
        af.nvls = 0;

        ret = debuginfo__find_probes(dbg, &af.pf);
        if (ret < 0) {
                /* Free vlist for error */
                while (af.nvls--) {
                        zfree(&af.vls[af.nvls].point.symbol);
                        strlist__delete(af.vls[af.nvls].vars);
                }
                zfree(vls);
                return ret;
        }

        return (ret < 0) ? ret : af.nvls;
}

/* For the kernel module, we need a special code to get a DIE */
int debuginfo__get_text_offset(struct debuginfo *dbg, Dwarf_Addr *offs,
                                bool adjust_offset)
{
        int n, i;
        Elf32_Word shndx;
        Elf_Scn *scn;
        Elf *elf;
        GElf_Shdr mem, *shdr;
        const char *p;

        elf = dwfl_module_getelf(dbg->mod, &dbg->bias);
        if (!elf)
                return -EINVAL;

        /* Get the number of relocations */
        n = dwfl_module_relocations(dbg->mod);
        if (n < 0)
                return -ENOENT;
        /* Search the relocation related .text section */
        for (i = 0; i < n; i++) {
                p = dwfl_module_relocation_info(dbg->mod, i, &shndx);
                if (strcmp(p, ".text") == 0) {
                        /* OK, get the section header */
                        scn = elf_getscn(elf, shndx);
                        if (!scn)
                                return -ENOENT;
                        shdr = gelf_getshdr(scn, &mem);
                        if (!shdr)
                                return -ENOENT;
                        *offs = shdr->sh_addr;
                        if (adjust_offset)
                                *offs -= shdr->sh_offset;
                }
        }
        return 0;
}

/* Reverse search */
int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
                                struct perf_probe_point *ppt)
{
        Dwarf_Die cudie, spdie, indie;
        Dwarf_Addr _addr = 0, baseaddr = 0;
        const char *fname = NULL, *func = NULL, *basefunc = NULL, *tmp;
        int baseline = 0, lineno = 0, ret = 0;

        /* We always need to relocate the address for aranges */
        if (debuginfo__get_text_offset(dbg, &baseaddr, false) == 0)
                addr += baseaddr;
        /* Find cu die */
        if (!dwarf_addrdie(dbg->dbg, (Dwarf_Addr)addr, &cudie)) {
                pr_warning("Failed to find debug information for address %lx\n",
                           addr);
                ret = -EINVAL;
                goto end;
        }

        /* Find a corresponding line (filename and lineno) */
        cu_find_lineinfo(&cudie, addr, &fname, &lineno);
        /* Don't care whether it failed or not */

        /* Find a corresponding function (name, baseline and baseaddr) */
        if (die_find_realfunc(&cudie, (Dwarf_Addr)addr, &spdie)) {
                /* Get function entry information */
                func = basefunc = dwarf_diename(&spdie);
                if (!func ||
                    die_entrypc(&spdie, &baseaddr) != 0 ||
                    dwarf_decl_line(&spdie, &baseline) != 0) {
                        lineno = 0;
                        goto post;
                }

                fname = dwarf_decl_file(&spdie);
                if (addr == (unsigned long)baseaddr) {
                        /* Function entry - Relative line number is 0 */
                        lineno = baseline;
                        goto post;
                }

                /* Track down the inline functions step by step */
                while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
                                                &indie)) {
                        /* There is an inline function */
                        if (die_entrypc(&indie, &_addr) == 0 &&
                            _addr == addr) {
                                /*
                                 * addr is at an inline function entry.
                                 * In this case, lineno should be the call-site
                                 * line number. (overwrite lineinfo)
                                 */
                                lineno = die_get_call_lineno(&indie);
                                fname = die_get_call_file(&indie);
                                break;
                        } else {
                                /*
                                 * addr is in an inline function body.
                                 * Since lineno points one of the lines
                                 * of the inline function, baseline should
                                 * be the entry line of the inline function.
                                 */
                                tmp = dwarf_diename(&indie);
                                if (!tmp ||
                                    dwarf_decl_line(&indie, &baseline) != 0)
                                        break;
                                func = tmp;
                                spdie = indie;
                        }
                }
                /* Verify the lineno and baseline are in a same file */
                tmp = dwarf_decl_file(&spdie);
                if (!tmp || strcmp(tmp, fname) != 0)
                        lineno = 0;
        }

post:
        /* Make a relative line number or an offset */
        if (lineno)
                ppt->line = lineno - baseline;
        else if (basefunc) {
                ppt->offset = addr - (unsigned long)baseaddr;
                func = basefunc;
        }

        /* Duplicate strings */
        if (func) {
                ppt->function = strdup(func);
                if (ppt->function == NULL) {
                        ret = -ENOMEM;
                        goto end;
                }
        }
        if (fname) {
                ppt->file = strdup(fname);
                if (ppt->file == NULL) {
                        zfree(&ppt->function);
                        ret = -ENOMEM;
                        goto end;
                }
        }
end:
        if (ret == 0 && (fname || func))
                ret = 1;        /* Found a point */
        return ret;
}

/* Add a line and store the src path */
static int line_range_add_line(const char *src, unsigned int lineno,
                               struct line_range *lr)
{
        /* Copy source path */
        if (!lr->path) {
                lr->path = strdup(src);
                if (lr->path == NULL)
                        return -ENOMEM;
        }
        return intlist__add(lr->line_list, lineno);
}

static int line_range_walk_cb(const char *fname, int lineno,
                              Dwarf_Addr addr __maybe_unused,
                              void *data)
{
        struct line_finder *lf = data;
        const char *__fname;
        int __lineno;
        int err;

        if ((strtailcmp(fname, lf->fname) != 0) ||
            (lf->lno_s > lineno || lf->lno_e < lineno))
                return 0;

        /* Make sure this line can be reversable */
        if (cu_find_lineinfo(&lf->cu_die, addr, &__fname, &__lineno) > 0
            && (lineno != __lineno || strcmp(fname, __fname)))
                return 0;

        err = line_range_add_line(fname, lineno, lf->lr);
        if (err < 0 && err != -EEXIST)
                return err;

        return 0;
}

/* Find line range from its line number */
static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
{
        int ret;

        ret = die_walk_lines(sp_die ?: &lf->cu_die, line_range_walk_cb, lf);

        /* Update status */
        if (ret >= 0)
                if (!intlist__empty(lf->lr->line_list))
                        ret = lf->found = 1;
                else
                        ret = 0;        /* Lines are not found */
        else {
                zfree(&lf->lr->path);
        }
        return ret;
}

static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
{
        int ret = find_line_range_by_line(in_die, data);

        /*
         * We have to check all instances of inlined function, because
         * some execution paths can be optimized out depends on the
         * function argument of instances. However, if an error occurs,
         * it should be handled by the caller.
         */
        return ret < 0 ? ret : 0;
}

/* Search function definition from function name */
static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
{
        struct dwarf_callback_param *param = data;
        struct line_finder *lf = param->data;
        struct line_range *lr = lf->lr;

        /* Check declared file */
        if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
                return DWARF_CB_OK;

        if (die_is_func_def(sp_die) &&
            die_match_name(sp_die, lr->function)) {
                lf->fname = dwarf_decl_file(sp_die);
                dwarf_decl_line(sp_die, &lr->offset);
                pr_debug("fname: %s, lineno:%d\n", lf->fname, lr->offset);
                lf->lno_s = lr->offset + lr->start;
                if (lf->lno_s < 0)      /* Overflow */
                        lf->lno_s = INT_MAX;
                lf->lno_e = lr->offset + lr->end;
                if (lf->lno_e < 0)      /* Overflow */
                        lf->lno_e = INT_MAX;
                pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
                lr->start = lf->lno_s;
                lr->end = lf->lno_e;
                if (!die_is_func_instance(sp_die))
                        param->retval = die_walk_instances(sp_die,
                                                line_range_inline_cb, lf);
                else
                        param->retval = find_line_range_by_line(sp_die, lf);
                return DWARF_CB_ABORT;
        }
        return DWARF_CB_OK;
}

static int find_line_range_by_func(struct line_finder *lf)
{
        struct dwarf_callback_param param = {.data = (void *)lf, .retval = 0};
        dwarf_getfuncs(&lf->cu_die, line_range_search_cb, &param, 0);
        return param.retval;
}

int debuginfo__find_line_range(struct debuginfo *dbg, struct line_range *lr)
{
        struct line_finder lf = {.lr = lr, .found = 0};
        int ret = 0;
        Dwarf_Off off = 0, noff;
        size_t cuhl;
        Dwarf_Die *diep;
        const char *comp_dir;

        /* Fastpath: lookup by function name from .debug_pubnames section */
        if (lr->function) {
                struct pubname_callback_param pubname_param = {
                        .function = lr->function, .file = lr->file,
                        .cu_die = &lf.cu_die, .sp_die = &lf.sp_die, .found = 0};
                struct dwarf_callback_param line_range_param = {
                        .data = (void *)&lf, .retval = 0};

                dwarf_getpubnames(dbg->dbg, pubname_search_cb,
                                  &pubname_param, 0);
                if (pubname_param.found) {
                        line_range_search_cb(&lf.sp_die, &line_range_param);
                        if (lf.found)
                                goto found;
                }
        }

        /* Loop on CUs (Compilation Unit) */
        while (!lf.found && ret >= 0) {
                if (dwarf_nextcu(dbg->dbg, off, &noff, &cuhl,
                                 NULL, NULL, NULL) != 0)
                        break;

                /* Get the DIE(Debugging Information Entry) of this CU */
                diep = dwarf_offdie(dbg->dbg, off + cuhl, &lf.cu_die);
                if (!diep)
                        continue;

                /* Check if target file is included. */
                if (lr->file)
                        lf.fname = cu_find_realpath(&lf.cu_die, lr->file);
                else
                        lf.fname = 0;

                if (!lr->file || lf.fname) {
                        if (lr->function)
                                ret = find_line_range_by_func(&lf);
                        else {
                                lf.lno_s = lr->start;
                                lf.lno_e = lr->end;
                                ret = find_line_range_by_line(NULL, &lf);
                        }
                }
                off = noff;
        }

found:
        /* Store comp_dir */
        if (lf.found) {
                comp_dir = cu_get_comp_dir(&lf.cu_die);
                if (comp_dir) {
                        lr->comp_dir = strdup(comp_dir);
                        if (!lr->comp_dir)
                                ret = -ENOMEM;
                }
        }

        pr_debug("path: %s\n", lr->path);
        return (ret < 0) ? ret : lf.found;
}

/*
 * Find a src file from a DWARF tag path. Prepend optional source path prefix
 * and chop off leading directories that do not exist. Result is passed back as
 * a newly allocated path on success.
 * Return 0 if file was found and readable, -errno otherwise.
 */
int get_real_path(const char *raw_path, const char *comp_dir,
                         char **new_path)
{
        const char *prefix = symbol_conf.source_prefix;

        if (!prefix) {
                if (raw_path[0] != '/' && comp_dir)
                        /* If not an absolute path, try to use comp_dir */
                        prefix = comp_dir;
                else {
                        if (access(raw_path, R_OK) == 0) {
                                *new_path = strdup(raw_path);
                                return *new_path ? 0 : -ENOMEM;
                        } else
                                return -errno;
                }
        }

        *new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));

        if (!*new_path)
                return -ENOMEM;

        for (;;) {
                sprintf(*new_path, "%s/%s", prefix, raw_path);

                if (access(*new_path, R_OK) == 0)
                        return 0;

                if (!symbol_conf.source_prefix) {
                        /* In case of searching comp_dir, don't retry */
                        zfree(new_path);
                        return -errno;
                }

                switch (errno) {
                case ENAMETOOLONG:
                case ENOENT:
                case EROFS:
                case EFAULT:
                        raw_path = strchr(++raw_path, '/');
                        if (!raw_path) {
                                zfree(new_path);
                                return -ENOENT;
                        }
                        continue;

                default:
                        zfree(new_path);
                        return -errno;
                }
        }
}