perf probe: Fix probing symbols with optimization suffix

[mirror_ubuntu-zesty-kernel.git] / tools / perf / util / probe-finder.c

/*
 * probe-finder.c : C expression to kprobe event converter
 *
 * Written by Masami Hiramatsu <mhiramat@redhat.com>
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#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 <getopt.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <dwarf-regs.h>

#include <linux/bitops.h>
#include "event.h"
#include "debug.h"
#include "util.h"
#include "symbol.h"
#include "probe-finder.h"

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

/* Line number list operations */

/* Add a line to line number list */
static int line_list__add_line(struct list_head *head, int line)
{
        struct line_node *ln;
        struct list_head *p;

        /* Reverse search, because new line will be the last one */
        list_for_each_entry_reverse(ln, head, list) {
                if (ln->line < line) {
                        p = &ln->list;
                        goto found;
                } else if (ln->line == line)    /* Already exist */
                        return 1;
        }
        /* List is empty, or the smallest entry */
        p = head;
found:
        pr_debug("line list: add a line %u\n", line);
        ln = zalloc(sizeof(struct line_node));
        if (ln == NULL)
                return -ENOMEM;
        ln->line = line;
        INIT_LIST_HEAD(&ln->list);
        list_add(&ln->list, p);
        return 0;
}

/* Check if the line in line number list */
static int line_list__has_line(struct list_head *head, int line)
{
        struct line_node *ln;

        /* Reverse search, because new line will be the last one */
        list_for_each_entry(ln, head, list)
                if (ln->line == line)
                        return 1;

        return 0;
}

/* Init line number list */
static void line_list__init(struct list_head *head)
{
        INIT_LIST_HEAD(head);
}

/* Free line number list */
static void line_list__free(struct list_head *head)
{
        struct line_node *ln;
        while (!list_empty(head)) {
                ln = list_first_entry(head, struct line_node, list);
                list_del(&ln->list);
                free(ln);
        }
}

/* 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 *self,
                                         const char *path)
{
        int fd;

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

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

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

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

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

        return -ENOENT;
}

#if _ELFUTILS_PREREQ(0, 148)
/* This method is buggy if elfutils is older than 0.148 */
static int __linux_kernel_find_elf(Dwfl_Module *mod,
                                   void **userdata,
                                   const char *module_name,
                                   Dwarf_Addr base,
                                   char **file_name, Elf **elfp)
{
        int fd;
        const char *path = kernel_get_module_path(module_name);

        pr_debug2("Use file %s for %s\n", path, module_name);
        if (path) {
                fd = open(path, O_RDONLY);
                if (fd >= 0) {
                        *file_name = strdup(path);
                        return fd;
                }
        }
        /* If failed, try to call standard method */
        return dwfl_linux_kernel_find_elf(mod, userdata, module_name, base,
                                          file_name, elfp);
}

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

        .find_elf = __linux_kernel_find_elf,
        .section_address = dwfl_linux_kernel_module_section_address,
};

/* Get a Dwarf from live kernel image */
static int debuginfo__init_online_kernel_dwarf(struct debuginfo *self,
                                               Dwarf_Addr addr)
{
        self->dwfl = dwfl_begin(&kernel_callbacks);
        if (!self->dwfl)
                return -EINVAL;

        /* Load the kernel dwarves: Don't care the result here */
        dwfl_linux_kernel_report_kernel(self->dwfl);
        dwfl_linux_kernel_report_modules(self->dwfl);

        self->dbg = dwfl_addrdwarf(self->dwfl, addr, &self->bias);
        /* Here, check whether we could get a real dwarf */
        if (!self->dbg) {
                pr_debug("Failed to find kernel dwarf at %lx\n",
                         (unsigned long)addr);
                dwfl_end(self->dwfl);
                memset(self, 0, sizeof(*self));
                return -ENOENT;
        }

        return 0;
}
#else
/* With older elfutils, this just support kernel module... */
static int debuginfo__init_online_kernel_dwarf(struct debuginfo *self,
                                               Dwarf_Addr addr __maybe_unused)
{
        const char *path = kernel_get_module_path("kernel");

        if (!path) {
                pr_err("Failed to find vmlinux path\n");
                return -ENOENT;
        }

        pr_debug2("Use file %s for debuginfo\n", path);
        return debuginfo__init_offline_dwarf(self, path);
}
#endif

struct debuginfo *debuginfo__new(const char *path)
{
        struct debuginfo *self = zalloc(sizeof(struct debuginfo));
        if (!self)
                return NULL;

        if (debuginfo__init_offline_dwarf(self, path) < 0) {
                free(self);
                self = NULL;
        }

        return self;
}

struct debuginfo *debuginfo__new_online_kernel(unsigned long addr)
{
        struct debuginfo *self = zalloc(sizeof(struct debuginfo));
        if (!self)
                return NULL;

        if (debuginfo__init_online_kernel_dwarf(self, (Dwarf_Addr)addr) < 0) {
                free(self);
                self = NULL;
        }

        return self;
}

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

/*
 * 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.
 */
static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr,
                                     Dwarf_Op *fb_ops,
                                     struct probe_trace_arg *tvar)
{
        Dwarf_Attribute attr;
        Dwarf_Op *op;
        size_t nops;
        unsigned int regn;
        Dwarf_Word offs = 0;
        bool ref = false;
        const char *regs;
        int ret;

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

        /* TODO: handle more than 1 exprs */
        if (dwarf_attr(vr_die, DW_AT_location, &attr) == NULL ||
            dwarf_getlocation_addr(&attr, addr, &op, &nops, 1) <= 0 ||
            nops == 0) {
                /* TODO: Support const_value */
                return -ENOENT;
        }

        if (op->atom == DW_OP_addr) {
static_var:
                if (!tvar)
                        return 0;
                /* 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 0;
        }

        /* 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 0;

        regs = get_arch_regstr(regn);
        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 -ERANGE;
        }

        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 0;
}

#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)
{
        struct probe_trace_arg_ref **ref_ptr = &tvar->ref;
        Dwarf_Die type;
        char buf[16];
        int bsize, boffs, total;
        int ret;

        /* TODO: check all types */
        if (cast && strcmp(cast, "string") != 0) {
                /* Non string type is OK */
                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") == 0) {      /* 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;
                        }
                }
                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;
        }

        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",
                       die_is_signed_type(&type) ? 's' : 'u', ret);

formatted:
        if (ret < 0 || ret >= 16) {
                if (ret >= 16)
                        ret = -E2BIG;
                pr_warning("Failed to convert variable type: %s\n",
                           strerror(-ret));
                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)
{
        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: (%x)\n", (unsigned)dwarf_dieoffset(&type));
        tag = dwarf_tag(&type);

        if (field->name[0] == '[' &&
            (tag == DW_TAG_array_type || tag == DW_TAG_pointer_type)) {
                if (field->next)
                        /* Save original type for next field */
                        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: (%x)\n",
                         (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;
                if (!field->next)
                        /* Save vr_die for converting types */
                        memcpy(die_mem, vr_die, sizeof(*die_mem));
                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 an 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 an union.\n",
                                   varname);
                        return -EINVAL;
                }
                if (field->name[0] == '[') {
                        pr_err("Semantic error: %s is not a pointor"
                               " nor array.\n", varname);
                        return -EINVAL;
                }
                if (field->ref) {
                        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(tyep:%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;

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

/* 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->tvar);
        if (ret == -ENOENT)
                pr_err("Failed to find the location of %s at this address.\n"
                       " Perhaps, it has been optimized out.\n", pf->pvar->var);
        else if (ret == -ENOTSUP)
                pr_err("Sorry, we don't support this variable location yet.\n");
        else if (pf->pvar->field) {
                ret = convert_variable_fields(vr_die, pf->pvar->var,
                                              pf->pvar->field, &pf->tvar->ref,
                                              &die_mem);
                vr_die = &die_mem;
        }
        if (ret == 0)
                ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type);
        /* *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[32], *ptr;
        int ret = 0;

        if (!is_c_varname(pf->pvar->var)) {
                /* Copy raw parameters */
                pf->tvar->value = strdup(pf->pvar->var);
                if (pf->tvar->value == NULL)
                        return -ENOMEM;
                if (pf->pvar->type) {
                        pf->tvar->type = strdup(pf->pvar->type);
                        if (pf->tvar->type == NULL)
                                return -ENOMEM;
                }
                if (pf->pvar->name) {
                        pf->tvar->name = strdup(pf->pvar->name);
                        if (pf->tvar->name == NULL)
                                return -ENOMEM;
                } else
                        pf->tvar->name = NULL;
                return 0;
        }

        if (pf->pvar->name)
                pf->tvar->name = strdup(pf->pvar->name);
        else {
                ret = synthesize_perf_probe_arg(pf->pvar, buf, 32);
                if (ret < 0)
                        return ret;
                ptr = strchr(buf, ':'); /* Change type separator to _ */
                if (ptr)
                        *ptr = '_';
                pf->tvar->name = strdup(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))
                        ret = -ENOENT;
        }
        if (ret >= 0)
                ret = convert_variable(&vr_die, pf);

        if (ret < 0)
                pr_warning("Failed to find '%s' in this function.\n",
                           pf->pvar->var);
        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,
                                  struct probe_trace_point *tp)
{
        Dwarf_Addr eaddr, highaddr;
        GElf_Sym sym;
        const char *symbol;

        /* Verify the address is correct */
        if (dwarf_entrypc(sp_die, &eaddr) != 0) {
                pr_warning("Failed to get entry address of %s\n",
                           dwarf_diename(sp_die));
                return -ENOENT;
        }
        if (dwarf_highpc(sp_die, &highaddr) != 0) {
                pr_warning("Failed to get end address of %s\n",
                           dwarf_diename(sp_die));
                return -ENOENT;
        }
        if (paddr > highaddr) {
                pr_warning("Offset specified is greater than size of %s\n",
                           dwarf_diename(sp_die));
                return -EINVAL;
        }

        /* Get an appropriate symbol from symtab */
        symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
        if (!symbol) {
                pr_warning("Failed to find symbol at 0x%lx\n",
                           (unsigned long)paddr);
                return -ENOENT;
        }
        tp->offset = (unsigned long)(paddr - sym.st_value);
        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("Return probe must be on the head of"
                                   " a real function.\n");
                        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;
        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)) {
                        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 != NULL) {
                Dwarf_Frame *frame;
                if (dwarf_cfi_addrframe(pf->cfi, 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);
                        return -ENOENT;
                }
#endif
        }

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

        /* *pf->fb_ops will be cached in libdw. Don't free it. */
        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_compare_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;
}

/* 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,
        };

        cu_walk_functions_at(&pf->cu_die, pf->addr, find_best_scope_cb, &fsp);

        return fsp.found ? die_mem : NULL;
}

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;

        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 list_head *head,
                                 const char *fname, const char *pat)
{
        FILE *fp;
        char *line = NULL;
        size_t line_len;
        ssize_t len;
        int count = 0, linenum = 1;

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

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

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

                if (strlazymatch(line, pat)) {
                        line_list__add_line(head, 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 (!line_list__has_line(&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;

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

        return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
}

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 (dwarf_entrypc(in_die, &addr) != 0) {
                        pr_warning("Failed to get entry address of %s.\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_compare_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;

        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 (!dwarf_func_inline(sp_die)) {
                /* Real function */
                if (pp->lazy_line)
                        param->retval = find_probe_point_lazy(sp_die, pf);
                else {
                        if (dwarf_entrypc(sp_die, &pf->addr) != 0) {
                                pr_warning("Failed to get entry address of "
                                           "%s.\n", dwarf_diename(sp_die));
                                param->retval = -ENOENT;
                                return DWARF_CB_ABORT;
                        }
                        pf->addr += pp->offset;
                        /* TODO: Check the address in this function */
                        param->retval = call_probe_finder(sp_die, pf);
                }
        } else
                /* Inlined function: search instances */
                param->retval = die_walk_instances(sp_die,
                                        probe_point_inline_cb, (void *)pf);

        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_compare_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;
}

/* Find probe points from debuginfo */
static int debuginfo__find_probes(struct debuginfo *self,
                                  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;

#if _ELFUTILS_PREREQ(0, 142)
        /* Get the call frame information from this dwarf */
        pf->cfi = dwarf_getcfi(self->dbg);
#endif

        off = 0;
        line_list__init(&pf->lcache);

        /* Fastpath: lookup by function name from .debug_pubnames section */
        if (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(self->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(self->dbg, off, &noff, &cuhl, NULL, NULL, NULL)) {
                /* Get the DIE(Debugging Information Entry) of this CU */
                diep = dwarf_offdie(self->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(NULL, pf);
                        else {
                                pf->lno = pp->line;
                                ret = find_probe_point_by_line(pf);
                        }
                        if (ret < 0)
                                break;
                }
                off = noff;
        }

found:
        line_list__free(&pf->lcache);

        return ret;
}

/* 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 probe_trace_event *tev;
        int ret, i;

        /* 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,
                                     pf->pev->point.retprobe, &tev->point);
        if (ret < 0)
                return ret;

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

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

        return 0;
}

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

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

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

        ret = debuginfo__find_probes(self, &tf.pf);
        if (ret < 0) {
                free(*tevs);
                *tevs = NULL;
                return ret;
        }

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

#define MAX_VAR_LEN 64

/* 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;
        char buf[MAX_VAR_LEN];
        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, NULL);
                if (ret == 0) {
                        ret = die_get_varname(die_mem, buf, MAX_VAR_LEN);
                        pr_debug2("Add new var: %s\n", buf);
                        if (ret > 0)
                                strlist__add(vl->vars, buf);
                }
        }

        if (af->child && dwarf_haspc(die_mem, af->pf.addr))
                return DIE_FIND_CB_CONTINUE;
        else
                return DIE_FIND_CB_SIBLING;
}

/* 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 variable_list *vl;
        Dwarf_Die die_mem;
        int ret;

        /* 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,
                                     pf->pev->point.retprobe, &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(true, 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 (!af->externs)
                goto out;
        /* Don't need to search child DIE for externs. */
        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 */
int debuginfo__find_available_vars_at(struct debuginfo *self,
                                      struct perf_probe_event *pev,
                                      struct variable_list **vls,
                                      int max_vls, bool externs)
{
        struct available_var_finder af = {
                        .pf = {.pev = pev, .callback = add_available_vars},
                        .mod = self->mod,
                        .max_vls = max_vls, .externs = externs};
        int ret;

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

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

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

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

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

        /* Adjust address with bias */
        addr += self->bias;

        /* Find cu die */
        if (!dwarf_addrdie(self->dbg, (Dwarf_Addr)addr - self->bias, &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 */
                tmp = dwarf_diename(&spdie);
                if (!tmp ||
                    dwarf_entrypc(&spdie, &baseaddr) != 0 ||
                    dwarf_decl_line(&spdie, &baseline) != 0)
                        goto post;
                func = tmp;

                if (addr == (unsigned long)baseaddr)
                        /* Function entry - Relative line number is 0 */
                        lineno = baseline;
                else if (die_find_inlinefunc(&spdie, (Dwarf_Addr)addr,
                                             &indie)) {
                        if (dwarf_entrypc(&indie, &_addr) == 0 &&
                            _addr == addr)
                                /*
                                 * addr is at an inline function entry.
                                 * In this case, lineno should be the call-site
                                 * line number.
                                 */
                                lineno = die_get_call_lineno(&indie);
                        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(&spdie, &baseline) == 0)
                                        func = tmp;
                        }
                }
        }

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

        /* 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) {
                        if (ppt->function) {
                                free(ppt->function);
                                ppt->function = NULL;
                        }
                        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 line_list__add_line(&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;

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

        if (line_range_add_line(fname, lineno, lf->lr) < 0)
                return -EINVAL;

        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 (!list_empty(&lf->lr->line_list))
                        ret = lf->found = 1;
                else
                        ret = 0;        /* Lines are not found */
        else {
                free(lf->lr->path);
                lf->lr->path = NULL;
        }
        return ret;
}

static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
{
        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
         */
        return 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_compare_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 (dwarf_func_inline(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 *self, 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(self->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(self->dbg, off, &noff, &cuhl,
                                 NULL, NULL, NULL) != 0)
                        break;

                /* Get the DIE(Debugging Information Entry) of this CU */
                diep = dwarf_offdie(self->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;
}