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libdrgn: dwarf_info: handle split DWARF in dwarf_module_find_dwarf_scopes()

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dwarf_module_find_dwarf_scopes() and drgn_dwarf_die_iterator_next() just
need to go from skeleton units to split units. We need to use
dwarf_cu_info(), which was added in 0.171, which incidentally was when
elfutils gained split DWARF support anyways.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
This commit is contained in:
Omar Sandoval 2023-07-06 14:21:59 -07:00
parent 4fa1dfc063
commit a78d30e13e
1 changed files with 49 additions and 3 deletions
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52
libdrgn/dwarf_info.c
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@ -3200,10 +3200,17 @@ DEFINE_VECTOR(dwarf_die_vector, Dwarf_Die)
struct drgn_dwarf_die_iterator {
/** Stack of current DIE and its ancestors. */
struct dwarf_die_vector dies;
/**
* Dwarf handle that we're iterating over. For split DWARF, this is the
* main file.
*/
Dwarf *dwarf;
/** End of current CU (for bounds checking). */
/**
* End of current CU (for bounds checking). For split DWARF, this is in
* the split file.
*/
const char *cu_end;
/** Offset of next CU. */
/** Offset of next CU. For split DWARF, this is in the main file. */
Dwarf_Off next_cu_off;
/** Whether current CU is from .debug_types. */
bool debug_types;
@ -3347,11 +3354,35 @@ next_unit:;
r = !dwarf_offdie(it->dwarf, offset, TOP());
if (r)
return drgn_error_libdw();
Dwarf_Off cu_end_off = it->next_cu_off;
#if _ELFUTILS_PREREQ(0, 171)
// If the unit is a skeleton, replace it with the split unit.
Dwarf_Die subdie;
uint8_t unit_type;
if (dwarf_cu_info(TOP()->cu, NULL, &unit_type, NULL, &subdie,
NULL, NULL, NULL))
return drgn_error_libdw();
if (unit_type == DW_UT_skeleton && subdie.cu) {
offset = dwarf_dieoffset(&subdie);
if (dwarf_next_unit(dwarf_cu_getdwarf(subdie.cu),
offset - dwarf_cuoffset(&subdie),
&cu_end_off, NULL, NULL, NULL, NULL,
NULL, NULL, NULL))
return drgn_error_libdw();
*TOP() = subdie;
}
#endif
it->cu_end = ((const char *)TOP()->addr
- offset
+ it->next_cu_off);
+ cu_end_off);
return NULL;
} else if (r > 0) {
// Note that in split DWARF, there are no skeleton units for
// type units, and the main file doesn't have a .debug_types
// section. Instead, the split files contain a .debug_types.dwo
// section per type unit. elfutils as of 0.189 doesn't support
// multiple sections with the same name, so we don't support
// type units with split DWARF.
if (!it->debug_types) {
it->next_cu_off = 0;
it->debug_types = true;
@ -3404,6 +3435,21 @@ struct drgn_error *drgn_module_find_dwarf_scopes(struct drgn_module *module,
err = drgn_error_libdw();
goto err;
}
#if _ELFUTILS_PREREQ(0, 171)
// If the unit is a skeleton, replace it with the split unit.
Dwarf_Die subdie;
uint8_t unit_type;
if (dwarf_cu_info(cu_die->cu, NULL, &unit_type, NULL, &subdie,
NULL, NULL, NULL)) {
err = drgn_error_libdw();
goto err;
}
if (unit_type == DW_UT_skeleton && subdie.cu) {
dwarf = dwarf_cu_getdwarf(subdie.cu);
offset = dwarf_dieoffset(&subdie);
*cu_die = subdie;
}
#endif
if (dwarf_next_unit(dwarf, offset - dwarf_cuoffset(cu_die),
&it.next_cu_off, NULL, NULL, NULL, NULL,
NULL, NULL, NULL)) {