Add a trivial sample to demonstrate that loading dwarf-4, dwarf-5,
with and without split-dwarf works.
Observe that before this patch there are valgrind leaks.
Obverse that there are even more valgrind leaks after this patch.
But it does make things load all 4 sample builds, and present the same
sample pahole output for all of them.
Abosolutely no idea what pointer_size variable is, or what it was in
dwarf_next_unit() or what it is in dwarf_cu_die(), or if that's what
cu__new() needs.
Separtely if one compiles linux kernel with dwarf-5 and split-dwarf,
and tries to run this build of pahole, even on like a trivial kernel
module it segfaults eventually when trying to
ftype__recode_dwarf_types, because eventually pos becomes NULL and
NULL dereference happens. So something about the created cus is not
quite right. Strongly suspecting that pointer_size actually matters
and possibly loaidng subdie needs to be properly accounted for.
NACKed-by: Dimitri John Ledkov <dimitri.ledkov@xxxxxxxxxxxxx>
---
dwarf_loader.c | 31 ++++++++++++-------------------
dwarves.c | 8 ++++++++
sample.c | 10 ++++++++++
sample.sh | 18 ++++++++++++++++++
4 files changed, 48 insertions(+), 19 deletions(-)
create mode 100644 sample.c
create mode 100755 sample.sh
diff --git a/dwarf_loader.c b/dwarf_loader.c
index ccf31943bb..84aebed7c5 100644
--- a/dwarf_loader.c
+++ b/dwarf_loader.c
@@ -2823,13 +2823,6 @@ static int die__process(Dwarf_Die *die, struct cu *cu, struct conf_load *conf)
const uint16_t tag = dwarf_tag(die);
if (tag == DW_TAG_skeleton_unit) {
- static bool warned;
-
- if (!warned) {
- fprintf(stderr, "WARNING: DW_TAG_skeleton_unit used, please look for a .dwo file and use it instead.\n"
- " A future version of pahole will support do this automagically.\n");
- warned = true;
- }
return 0; // so that other units can be processed
}
@@ -3068,20 +3061,22 @@ static int __cus__load_debug_types(struct conf_load *conf, Dwfl_Module *mod, Dwa
const char *filename, const unsigned char *build_id,
int build_id_len, struct cu **cup, struct dwarf_cu *dcup)
{
- Dwarf_Off off = 0, noff, type_off;
- size_t cuhl;
uint8_t pointer_size, offset_size;
- uint64_t signature;
+
+ Dwarf_CU *dgu_cu = NULL;
+ Dwarf_Die result;
+ Dwarf_Die cudie;
+ Dwarf_Die subdie;
*cup = NULL;
- while (dwarf_next_unit(dw, off, &noff, &cuhl, NULL, NULL, &pointer_size,
- &offset_size, &signature, &type_off)
- == 0) {
+ while (dwarf_get_units(dw,dgu_cu,&dgu_cu,NULL,NULL,&cudie,&subdie)==0) {
if (*cup == NULL) {
struct cu *cu;
+ dwarf_cu_die (dgu_cu, &result, NULL, NULL, &pointer_size, NULL, NULL, NULL);
+
cu = cu__new("", pointer_size, build_id,
build_id_len, filename, conf->use_obstack);
if (cu == NULL ||
@@ -3100,14 +3095,12 @@ static int __cus__load_debug_types(struct conf_load *conf, Dwfl_Module *mod, Dwa
*cup = cu;
}
- Dwarf_Die die_mem;
- Dwarf_Die *cu_die = dwarf_offdie_types(dw, off + cuhl,
- &die_mem);
-
- if (die__process(cu_die, *cup, conf) != 0)
+ if (die__process(&cudie, *cup, conf) != 0)
return DWARF_CB_ABORT;
+ if (dwarf_tag(&subdie) != DW_TAG_invalid)
+ if (die__process(&subdie, *cup, conf) != 0)
+ return DWARF_CB_ABORT;
- off = noff;
}
if (*cup != NULL && cu__recode_dwarf_types(*cup) != 0)
diff --git a/dwarves.c b/dwarves.c
index 9f97edaea2..2abab727fc 100644
--- a/dwarves.c
+++ b/dwarves.c
@@ -62,6 +62,10 @@ void *cu__malloc(struct cu *cu, size_t size)
void cu__free(struct cu *cu, void *ptr)
{
+ // FIXME it seems like loading split dwarf, causes multiple
+ // references to the same thing, and thus current clean up &
+ // free code aborts on double free's
+ return;
if (!cu->use_obstack)
free(ptr);
@@ -711,6 +715,10 @@ out_free:
void cu__delete(struct cu *cu)
{
+ // FIXME it seems like loading split dwarf, causes multiple
+ // references to the same thing, and thus current clean up &
+ // free code aborts on double free's
+ return;
if (cu == NULL)
return;
diff --git a/sample.c b/sample.c
new file mode 100644
index 0000000000..bff48d3139
--- /dev/null
+++ b/sample.c
@@ -0,0 +1,10 @@
+#include <stdio.h>
+struct Sample {
+ char sample_string[50];
+ int sample_integer;
+ float sample_float;
+};
+void main() {
+ struct Sample sample = {.sample_integer = 3};
+ printf("%i\n", sample.sample_integer);
+}
diff --git a/sample.sh b/sample.sh
new file mode 100755
index 0000000000..241d4adec8
--- /dev/null
+++ b/sample.sh
@@ -0,0 +1,18 @@
+#!/bin/sh
+set -x
+rc=0
+gcc -gdwarf-5 -gsplit-dwarf ./sample.c
+valgrind ./pahole ./a.out
+rc=$((rc + $?))
+gcc -gdwarf-4 -gsplit-dwarf ./sample.c
+valgrind ./pahole ./a.out
+rc=$((rc + $?))
+gcc -gdwarf-5 ./sample.c
+valgrind ./pahole ./a.out
+rc=$((rc + $?))
+gcc -gdwarf-4 ./sample.c
+valgrind ./pahole ./a.out
+rc=$((rc + $?))
+rm -f a.out
+exit $rc
+
--
2.34.1
