Hello Stefan,
On Tue, 07 Aug 2012 09:50:49 +0200
Stefan Bader <stefan.bader at canonical.com> wrote:
> >
> > case DWARF_INFO_GET_MEMBER_OFFSET:
> > if ((!name) || strcmp(name, dwarf_info.member_name))
> > continue;
> > /*
> > * Get the member offset.
> > */
> > if (dwarf_tag(die) == DW_TAG_union_type)
> > offset = 0;
> > else if (!get_data_member_location(walker, &offset))
> > continue;
> > dwarf_info.member_offset = offset;
> > return TRUE;
> >
> > And about your code:
> >
> >> case DWARF_INFO_GET_MEMBER_OFFSET_1ST_UNION:
> >> if (!get_die_type(walker, &die_type))
> >> continue;
> >> if (dwarf_tag(&die_type) != DW_TAG_union_type)
> >> continue;
> >>
> >> /*
> >> * At this point it is clear that this is a union.
> >> * Though unions have no offset elements (the offset
> >> * is always 0. So get_data_member_location would fail.
> >> */
> >> dwarf_info.member_offset = 0;
> >> return TRUE;
> >
> > It's wrong that unions have no offset elements.
> > Correctly, members of union have no offset elements.
>
> That code was just based on the (incorrect) assumption that we talk about
> *_OFFSET_1ST_UNION and thinking those were the dies that had no offset tags.
> But the members having no offset makes much more sense. But then (without
> looking at dwarf output), if it is only the members of unions that need the
> change (and now I understand why it is checking die and not die_type), the first
> union should always have an offset and that call would only descent into
> structures while looking for the first union and never go past a union.
Did you point out the case like the example below ?
(names of unions are only for explanation.)
Example:
struct EXAMPLE { // top layer
int A;
union ONE { // the target of *_OFFSET_1ST_UNION
int B;
union TWO { // but, my code reaches here
int C;
};
};
};
Certainly, my change for *_OFFSET_1ST_UNION is wrong.
I changed is_anonymous_container() and attach the fixed patch to this mail.
I'll merge it into the next version unless you have any comment.
Thanks
Atsushi Kumagai
---
dwarf_info.c | 122 +++++++++++++++++++-------------------------------------
dwarf_info.h | 1 -
makedumpfile.c | 8 ----
makedumpfile.h | 6 ---
4 files changed, 42 insertions(+), 95 deletions(-)
diff --git a/dwarf_info.c b/dwarf_info.c
index 1429858..fb11e49 100644
--- a/dwarf_info.c
+++ b/dwarf_info.c
@@ -64,7 +64,6 @@ is_search_structure(int cmd)
if ((cmd == DWARF_INFO_GET_STRUCT_SIZE)
|| (cmd == DWARF_INFO_GET_MEMBER_OFFSET)
|| (cmd == DWARF_INFO_GET_MEMBER_TYPE)
- || (cmd == DWARF_INFO_GET_MEMBER_OFFSET_IN_UNION)
|| (cmd == DWARF_INFO_GET_MEMBER_OFFSET_1ST_UNION)
|| (cmd == DWARF_INFO_GET_MEMBER_ARRAY_LENGTH))
return TRUE;
@@ -447,75 +446,41 @@ get_dwarf_base_type(Dwarf_Die *die)
return TRUE;
}
-/*
- * Function for searching struct page.union.struct.mapping.
- */
static int
-__search_mapping(Dwarf_Die *die, long *offset)
+is_anonymous_container(Dwarf_Die *die)
{
- int tag;
- const char *name;
- Dwarf_Die child, *walker;
-
- if (dwarf_child(die, &child) != 0)
+ if (dwarf_diename(die))
return FALSE;
-
- walker = &child;
- do {
- tag = dwarf_tag(walker);
- name = dwarf_diename(walker);
-
- if (tag != DW_TAG_member)
- continue;
- if ((!name) || strcmp(name, dwarf_info.member_name))
- continue;
- if (!get_data_member_location(walker, offset))
- continue;
+ if (dwarf_tag(die) == DW_TAG_structure_type)
+ return TRUE;
+ if (dwarf_info.cmd != DWARF_INFO_GET_MEMBER_OFFSET_1ST_UNION
+ && dwarf_tag(die) == DW_TAG_union_type)
return TRUE;
-
- } while (!dwarf_siblingof(walker, walker));
-
return FALSE;
}
-/*
- * Function for searching struct page.union.struct.
- */
-static int
-search_mapping(Dwarf_Die *die, long *offset)
+static void
+adjust_member_offset(Dwarf_Die *die)
{
- Dwarf_Die child, *walker;
- Dwarf_Die die_struct;
-
- if (dwarf_child(die, &child) != 0)
- return FALSE;
-
- walker = &child;
-
- do {
- if (dwarf_tag(walker) != DW_TAG_member)
- continue;
- if (!get_die_type(walker, &die_struct))
- continue;
- if (dwarf_tag(&die_struct) != DW_TAG_structure_type)
- continue;
- if (__search_mapping(&die_struct, offset))
- return TRUE;
- } while (!dwarf_siblingof(walker, walker));
+ long offset;
- return FALSE;
+ if (dwarf_info.member_offset == NOT_FOUND_STRUCTURE)
+ return;
+ if (!get_data_member_location(die, &offset))
+ return;
+ dwarf_info.member_offset += offset;
}
-static void
+static int
search_member(Dwarf_Die *die)
{
int tag;
- long offset, offset_union;
+ long offset;
const char *name;
- Dwarf_Die child, *walker, die_union;
+ Dwarf_Die child, *walker, die_type;
if (dwarf_child(die, &child) != 0)
- return;
+ return FALSE;
walker = &child;
@@ -526,6 +491,20 @@ search_member(Dwarf_Die *die)
if (tag != DW_TAG_member)
continue;
+ /*
+ * Descend into anonymous members and search for member
+ * there.
+ */
+ if (!name) {
+ if (!get_die_type(walker, &die_type))
+ continue;
+ if (is_anonymous_container(&die_type))
+ if (search_member(&die_type)) {
+ adjust_member_offset(walker);
+ return TRUE;
+ }
+ }
+
switch (dwarf_info.cmd) {
case DWARF_INFO_GET_MEMBER_TYPE:
if ((!name) || strcmp(name, dwarf_info.member_name))
@@ -535,39 +514,23 @@ search_member(Dwarf_Die *die)
*/
if (!get_dwarf_base_type(walker))
continue;
- return;
+ return TRUE;
case DWARF_INFO_GET_MEMBER_OFFSET:
if ((!name) || strcmp(name, dwarf_info.member_name))
continue;
/*
* Get the member offset.
*/
- if (!get_data_member_location(walker, &offset))
+ if (dwarf_tag(die) == DW_TAG_union_type)
+ offset = 0;
+ else if (!get_data_member_location(walker, &offset))
continue;
dwarf_info.member_offset = offset;
- return;
- case DWARF_INFO_GET_MEMBER_OFFSET_IN_UNION:
- if (!get_die_type(walker, &die_union))
- continue;
- if (dwarf_tag(&die_union) != DW_TAG_union_type)
- continue;
- /*
- * Search page.mapping in union.
- */
- if (!search_mapping(&die_union, &offset_union))
- continue;
-
- /*
- * Get the member offset.
- */
- if (!get_data_member_location(walker, &offset))
- continue;
- dwarf_info.member_offset = offset + offset_union;
- return;
+ return TRUE;
case DWARF_INFO_GET_MEMBER_OFFSET_1ST_UNION:
- if (!get_die_type(walker, &die_union))
+ if (!get_die_type(walker, &die_type))
continue;
- if (dwarf_tag(&die_union) != DW_TAG_union_type)
+ if (dwarf_tag(&die_type) != DW_TAG_union_type)
continue;
/*
* Get the member offset.
@@ -575,7 +538,7 @@ search_member(Dwarf_Die *die)
if (!get_data_member_location(walker, &offset))
continue;
dwarf_info.member_offset = offset;
- return;
+ return TRUE;
case DWARF_INFO_GET_MEMBER_ARRAY_LENGTH:
if ((!name) || strcmp(name, dwarf_info.member_name))
continue;
@@ -584,14 +547,14 @@ search_member(Dwarf_Die *die)
*/
if (!get_data_array_length(walker))
continue;
- return;
+ return TRUE;
}
} while (!dwarf_siblingof(walker, walker));
/*
* Return even if not found.
*/
- return;
+ return FALSE;
}
static void
@@ -636,7 +599,6 @@ search_structure(Dwarf_Die *die, int *found)
break;
case DWARF_INFO_GET_MEMBER_TYPE:
case DWARF_INFO_GET_MEMBER_OFFSET:
- case DWARF_INFO_GET_MEMBER_OFFSET_IN_UNION:
case DWARF_INFO_GET_MEMBER_OFFSET_1ST_UNION:
case DWARF_INFO_GET_MEMBER_ARRAY_LENGTH:
search_member(die);
diff --git a/dwarf_info.h b/dwarf_info.h
index 1e07484..8d0084d 100644
--- a/dwarf_info.h
+++ b/dwarf_info.h
@@ -37,7 +37,6 @@
enum {
DWARF_INFO_GET_STRUCT_SIZE,
DWARF_INFO_GET_MEMBER_OFFSET,
- DWARF_INFO_GET_MEMBER_OFFSET_IN_UNION,
DWARF_INFO_GET_MEMBER_OFFSET_1ST_UNION,
DWARF_INFO_GET_MEMBER_ARRAY_LENGTH,
DWARF_INFO_GET_SYMBOL_ARRAY_LENGTH,
diff --git a/makedumpfile.c b/makedumpfile.c
index d024e95..d32ce55 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -874,17 +874,9 @@ get_structure_info(void)
SIZE_INIT(page, "page");
OFFSET_INIT(page.flags, "page", "flags");
OFFSET_INIT(page._count, "page", "_count");
-
OFFSET_INIT(page.mapping, "page", "mapping");
/*
- * On linux-2.6.16 or later, page.mapping is defined
- * in anonymous union.
- */
- if (OFFSET(page.mapping) == NOT_FOUND_STRUCTURE)
- OFFSET_IN_UNION_INIT(page.mapping, "page", "mapping");
-
- /*
* Some vmlinux(s) don't have debugging information about
* page.mapping. Then, makedumpfile assumes that there is
* "mapping" next to "private(unsigned long)" in the first
diff --git a/makedumpfile.h b/makedumpfile.h
index 6f5489d..4bf502f 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -239,12 +239,6 @@ do { \
== FAILED_DWARFINFO) \
return FALSE; \
} while (0)
-#define OFFSET_IN_UNION_INIT(X, Y, Z) \
-do { \
- if ((OFFSET(X) = get_member_offset(Y, Z, DWARF_INFO_GET_MEMBER_OFFSET_IN_UNION)) \
- == FAILED_DWARFINFO) \
- return FALSE; \
-} while (0)
#define SYMBOL_ARRAY_LENGTH_INIT(X, Y) \
do { \
if ((ARRAY_LENGTH(X) = get_array_length(Y, NULL, DWARF_INFO_GET_SYMBOL_ARRAY_LENGTH)) == FAILED_DWARFINFO) \
--
1.7.9.2
