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// SPDX-License-Identifier: GPL-2.0
#include "dso.h"
#include "libdw.h"
#include "srcline.h"
#include "symbol.h"
#include "dwarf-aux.h"
#include "callchain.h"
#include <fcntl.h>
#include <unistd.h>
#include <elfutils/libdwfl.h>
static const Dwfl_Callbacks offline_callbacks = {
.find_debuginfo = dwfl_standard_find_debuginfo,
.section_address = dwfl_offline_section_address,
.find_elf = dwfl_build_id_find_elf,
};
void dso__free_libdw(struct dso *dso)
{
Dwfl *dwfl = dso__libdw(dso);
if (dwfl) {
dwfl_end(dwfl);
dso__set_libdw(dso, NULL);
}
}
struct Dwfl *dso__libdw_dwfl(struct dso *dso)
{
Dwfl *dwfl = dso__libdw(dso);
const char *dso_name;
Dwfl_Module *mod;
int fd;
if (dwfl)
return dwfl;
dso_name = dso__long_name(dso);
/*
* Initialize Dwfl session.
* We need to open the DSO file to report it to libdw.
*/
fd = open(dso_name, O_RDONLY);
if (fd < 0)
return NULL;
dwfl = dwfl_begin(&offline_callbacks);
if (!dwfl) {
close(fd);
return NULL;
}
/*
* If the report is successful, the file descriptor fd is consumed
* and closed by the Dwfl. If not, it is not closed.
*/
mod = dwfl_report_offline(dwfl, dso_name, dso_name, fd);
if (!mod) {
dwfl_end(dwfl);
close(fd);
return NULL;
}
if (dwfl_report_end(dwfl, /*removed=*/NULL, /*arg=*/NULL) != 0) {
dwfl_end(dwfl);
return NULL;
}
dso__set_libdw(dso, dwfl);
return dwfl;
}
struct libdw_a2l_cb_args {
struct dso *dso;
struct symbol *sym;
struct inline_node *node;
char *leaf_srcline;
bool leaf_srcline_used;
int err;
};
static int libdw_a2l_cb(Dwarf_Die *die, void *_args)
{
struct libdw_a2l_cb_args *args = _args;
const char *call_fname = die_get_call_file(die);
int call_lineno = die_get_call_lineno(die);
char *call_srcline = srcline__unknown;
struct symbol *inline_sym;
if (dwarf_tag(die) == DW_TAG_subprogram && args->sym) {
/*
* cu_walk_functions_at() opens the walk with the
* containing DW_TAG_subprogram DIE (the non-inlined outer
* function). That's just the base symbol -- use it
* directly. Avoids a fragile name-vs-name compare in
* new_inline_sym() that misfires when GCC IPA passes
* (.isra/.constprop/.part/.cold) rename the ELF symbol
* while DWARF keeps the pre-clone linkage name, which
* left the outer frame spuriously tagged "(inlined)".
*/
inline_sym = args->sym;
} else {
/*
* Prefer DW_AT_linkage_name so C++ inline frames keep
* their namespace/class qualification. new_inline_sym()
* runs the name through dso__demangle_sym(), so the
* mangled linkage name is turned back into
* "Namespace::Class::method". Fall back to DW_AT_name
* (unqualified) when no linkage name is present, e.g.
* for C code or extern "C" functions.
*/
const char *funcname = die_get_linkage_name(die) ?: die_name(die);
inline_sym = new_inline_sym(args->dso, args->sym, funcname);
if (!inline_sym)
goto abort_enomem;
}
/* Assign caller information to the parent. */
if (call_fname)
call_srcline = srcline_from_fileline(call_fname, call_lineno >= 0 ? call_lineno : 0);
if (!list_empty(&args->node->val)) {
struct inline_list *parent;
if (callchain_param.order == ORDER_CALLEE)
parent = list_first_entry(&args->node->val, struct inline_list, list);
else
parent = list_last_entry(&args->node->val, struct inline_list, list);
if (args->leaf_srcline == parent->srcline)
args->leaf_srcline_used = false;
else if (parent->srcline != srcline__unknown)
free(parent->srcline);
parent->srcline = call_srcline;
call_srcline = NULL;
}
if (call_srcline && call_srcline != srcline__unknown)
free(call_srcline);
/* Add this symbol to the chain as the leaf. */
if (!args->leaf_srcline_used) {
if (inline_list__append_tail(inline_sym, args->leaf_srcline, args->node) != 0)
goto abort_delete_sym;
args->leaf_srcline_used = true;
} else {
char *srcline = strdup(args->leaf_srcline);
if (!srcline)
goto abort_delete_sym;
if (inline_list__append_tail(inline_sym, srcline, args->node) != 0) {
free(srcline);
goto abort_delete_sym;
}
}
return 0;
abort_delete_sym:
if (symbol__inlined(inline_sym))
symbol__delete(inline_sym);
abort_enomem:
args->err = -ENOMEM;
return DWARF_CB_ABORT;
}
int libdw__addr2line(u64 addr, char **file, unsigned int *line_nr,
struct dso *dso, bool unwind_inlines,
struct inline_node *node, struct symbol *sym)
{
Dwfl *dwfl = dso__libdw_dwfl(dso);
Dwfl_Module *mod;
Dwfl_Line *dwline;
Dwarf_Addr bias;
const char *src;
int lineno = 0;
if (!dwfl)
return 0;
mod = dwfl_addrmodule(dwfl, addr);
if (!mod)
return 0;
/*
* Get/ignore the dwarf information. Determine the bias, difference
* between the regular ELF addr2line addresses and those to use with
* libdw.
*/
if (!dwfl_module_getdwarf(mod, &bias))
return 0;
/* Find source line information for the address. */
dwline = dwfl_module_getsrc(mod, addr + bias);
if (!dwline)
return 0;
/* Get line information. */
src = dwfl_lineinfo(dwline, /*addr=*/NULL, &lineno, /*col=*/NULL, /*mtime=*/NULL,
/*length=*/NULL);
if (file)
*file = src ? strdup(src) : NULL;
if (line_nr)
*line_nr = lineno;
/* Optionally unwind inline function call chain. */
if (unwind_inlines && node) {
Dwarf_Addr unused_bias;
Dwarf_Die *cudie = dwfl_module_addrdie(mod, addr + bias, &unused_bias);
struct libdw_a2l_cb_args args = {
.dso = dso,
.sym = sym,
.node = node,
.leaf_srcline = srcline_from_fileline(src ?: "<unknown>", lineno),
};
if (!args.leaf_srcline) {
if (file && *file) {
free(*file);
*file = NULL;
}
return 0;
}
/* Walk from the parent down to the leaf. */
if (cudie)
cu_walk_functions_at(cudie, addr, libdw_a2l_cb, &args);
if (!args.leaf_srcline_used)
free(args.leaf_srcline);
if (args.err) {
if (file && *file) {
free(*file);
*file = NULL;
}
inline_node__clear_frames(node);
return 0;
}
}
return 1;
}
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