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perf annotate-data: Resolve type DIEs in the debug file they came from

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'perf report -s type' hangs burning CPU on the dwz compressed debug
info of libz.so.1 (zlib-ng): die_collect_vars() saves the
dwarf_dieoffset() of the type DIE, which is relative to the file it
lives in - the dwz alt file for the types shared by more than one CU -
and update_var_state() resolves that offset in the main debug file,
parsing whatever is at it, here a typedef whose DW_AT_type refers to
itself.

Record whether the type DIE came from the alt file and resolve the
offset with die_get_type_die() in that file, with no fallback.

Fixes: 06b2ce7538 ("perf annotate-data: Maintain variable type info")
Fixes: 55ee3d005d ("perf annotate-data: Add a cache for global variable types")
Reviewed-by: Ian Rogers <irogers@google.com>
Reviewed-by: Namhyung Kim <namhyung@kernel.org>
Assisted-by: LLM
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2026-09-24 16:27:56 -03:00
parent 3dfdd195c7
commit 14ca0a28de
1 changed files with 15 additions and 6 deletions
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21
tools/perf/util/annotate-data.c
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@ -739,6 +739,8 @@ struct global_var_entry {
u64 start;
u64 end;
u64 die_offset;
int die_tag;
bool from_alt; /* die_offset is relative to the alt (dwz) file */
};
static int global_var_cmp(const void *_key, const struct rb_node *node)
@ -776,7 +778,7 @@ static struct global_var_entry *global_var__find(struct data_loc_info *dloc, u64
}
static bool global_var__add(struct data_loc_info *dloc, u64 addr,
const char *name, Dwarf_Die *type_die)
const char *name, Dwarf_Die *type_die, bool from_alt)
{
struct dso *dso = map__dso(dloc->ms->map);
struct global_var_entry *gvar;
@ -798,6 +800,8 @@ static bool global_var__add(struct data_loc_info *dloc, u64 addr,
gvar->start = addr;
gvar->end = addr + size;
gvar->die_offset = dwarf_dieoffset(type_die);
gvar->die_tag = dwarf_tag(type_die);
gvar->from_alt = from_alt;
rb_add(&gvar->node, dso__global_vars(dso), global_var_less);
return true;
@ -872,12 +876,14 @@ static void global_var__collect(struct data_loc_info *dloc)
if (pos->reg != -1)
continue;
if (!dwarf_offdie(dwarf, pos->die_off, &type_die))
if (!die_get_type_die(dwarf, pos->die_off, pos->die_tag,
pos->from_alt, &type_die))
continue;
get_global_var_info(dloc, pos->addr, &var_name, &var_offset);
global_var__add(dloc, pos->addr, var_name, &type_die);
global_var__add(dloc, pos->addr, var_name, &type_die,
pos->from_alt);
}
delete_var_types(var_types);
@ -902,7 +908,8 @@ bool get_global_var_type(Dwarf_Die *cu_die, struct data_loc_info *dloc,
gvar = global_var__find(dloc, var_addr);
if (gvar) {
if (!dwarf_offdie(dloc->di->dbg, gvar->die_offset, type_die))
if (!die_get_type_die(dloc->di->dbg, gvar->die_offset,
gvar->die_tag, gvar->from_alt, type_die))
return false;
*var_offset = var_addr - gvar->start;
@ -932,7 +939,8 @@ bool get_global_var_type(Dwarf_Die *cu_die, struct data_loc_info *dloc,
ok:
/* The address should point to the start of the variable */
global_var__add(dloc, var_addr - *var_offset, var_name, type_die);
global_var__add(dloc, var_addr - *var_offset, var_name, type_die,
!die_same_file(cu_die, type_die));
return true;
}
@ -987,7 +995,8 @@ static void update_var_state(struct type_state *state, struct data_loc_info *dlo
continue;
}
/* Get the type DIE using the offset */
if (!dwarf_offdie(dloc->di->dbg, var->die_off, &mem_die))
if (!die_get_type_die(dloc->di->dbg, var->die_off,
var->die_tag, var->from_alt, &mem_die))
continue;
if (var->reg == DWARF_REG_FB || var->reg == fbreg || var->reg == state->stack_reg) {