makedumpfile -g with recent kernels
Atsushi Kumagai
kumagai-atsushi at mxc.nes.nec.co.jp
Thu Aug 2 02:04:29 EDT 2012
Hello HATAYAMA-san,
On Thu, 02 Aug 2012 14:47:14 +0900 (JST)
HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> wrote:
> From: Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp>
> Subject: Re: makedumpfile -g with recent kernels
> Date: Thu, 2 Aug 2012 14:12:51 +0900
>
> > Hello Stefan,
> >
> > On Mon, 09 Jul 2012 11:17:13 +0200
> > Stefan Bader <stefan.bader at canonical.com> wrote:
> >
> >> Hi,
> >>
> >> I am not sure whether this really is the preferred way as I heard the required
> >> info now is in vmcore and vmcoreinfo would not be needed anymore. But just to
> >> have it produce some output I noticed that it trips again over some member of
> >> struct page that moved into some anonymous structure/union combo.
> >> There was some code that was quite specific for the page.mapping case (which now
> >> seems to be outside again). I changed the code to be more generic. It did fix my
> >> _count problem and should also handle the mapping case (though I could not test).
> >> So maybe this would be worth adding to the upstream code.
> >>
> >> -Stefan
> >>
> >> Please include me in cc's as I am not subscribed to this ml.
> >
> > Thank you for your nice work!
> >
>
> Hello Kumagai-san,
>
> I want to see a whole part of Stefan's patch. Could you post it on the
> ml?
This is the Stefan's patch.
Thanks
Atsushi Kumagai
---
>From cde00fffeddddd1fcffd3085ded0947fdcd159ef Mon Sep 17 00:00:00 2001
From: Stefan Bader <stefan.bader at canonical.com>
Date: Thu, 5 Jul 2012 18:03:53 +0200
Subject: [PATCH] Generic search into anonymous members in search_member()
There was a special case to find page.mapping in case it would be
inside an anonymous union.struct. But recent kernel versions also
moved page._count into the depths of some unnamed elements.
Naturally not the same as page.mapping.
So this tries to approach the problem by implementing a generic
method of descending into anonymous sub-members. If this finds
a member and it is the member offset that is the target of the
search, that offset has to be adjusted on the way back out.
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
dwarf_info.c | 117 ++++++++++++++++++--------------------------------------
dwarf_info.h | 1 -
makedumpfile.c | 8 ----
makedumpfile.h | 6 ---
4 files changed, 38 insertions(+), 94 deletions(-)
diff --git a/dwarf_info.c b/dwarf_info.c
index 1429858..583df53 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 +446,40 @@ 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_union_type)
+ return TRUE;
+ if (dwarf_tag(die) == DW_TAG_structure_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;
+ long offset;
- 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));
-
- 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 +490,20 @@ 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))
@@ -535,7 +513,7 @@ 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;
@@ -545,29 +523,11 @@ search_member(Dwarf_Die *die)
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 +535,7 @@ 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 +544,14 @@ 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 +596,6 @@ 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) \
--
1.7.9.5
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