12:03 a.m.
The 04/20/2021 13:44, Firo Yang wrote:
Hi Kazu-san,
This new O option is very useful to specify the head node
offset for listing linked list whose head node embedded has a
different offset to other node, e.g. dentry.d_subdirs(the head node)
and dentry.d_child.
Signed-off-by: Firo Yang <firo.yang(a)suse.com>
---
defs.h | 1 +
help.c | 12 +++++++++++-
tools.c | 30 +++++++++++++++++++++++++++---
3 files changed, 39 insertions(+), 4 deletions(-)
diff --git a/defs.h b/defs.h
index 35b983a..764facf 100644
--- a/defs.h
+++ b/defs.h
@@ -2605,6 +2605,7 @@ struct list_data { /* generic structure used by
do_list() to walk */
#define LIST_PARSE_MEMBER (VERBOSE << 13)
#define LIST_READ_MEMBER (VERBOSE << 14)
#define LIST_BRENT_ALGO (VERBOSE << 15)
+#define LIST_HEAD_OFFSET_ENTERED (VERBOSE << 16)
struct tree_data {
ulong flags;
diff --git a/help.c b/help.c
index 531f50a..b561f3b 100644
--- a/help.c
+++ b/help.c
@@ -5716,7 +5716,7 @@ char *help__list[] = {
"list",
"linked list",
"[[-o] offset][-e end][-[s|S] struct[.member[,member] [-l offset]] -[x|d]]"
-"\n [-r|-B] [-h|-H] start",
+"\n [-r|-B] [-h [-O head_offset]|-H] start",
" ",
" This command dumps the contents of a linked list. The entries in a
linked",
" list are typically data structures that are tied together in one of two",
@@ -5800,6 +5800,16 @@ char *help__list[] = {
" -S struct Similar to -s, but instead of parsing gdb output, member
values",
" are read directly from memory, so the command works much
faster",
" for 1-, 2-, 4-, and 8-byte members.",
+" -O offset The -O option works only with -h option.",
+" It is used for specifying the offset of head node embedded in
a",
+" structure, like dentry.d_subdirs or
cgroup_subsys_state.children.",
+" The offset may be entered in either of two manners:",
+"",
+" 1. \"structure.member\" format.",
+" 2. a number of bytes.",
+"",
+" You can use it like the following:",
+" list -O <head node offset> -o <node offset> -h start -s
<...>",
" -l offset Only used in conjunction with -s, if the start address
argument",
" is a pointer to an embedded list head (or any other similar
list",
" linkage structure whose first member points to the next
linkage",
diff --git a/tools.c b/tools.c
index a26b101..792a567 100644
--- a/tools.c
+++ b/tools.c
@@ -3343,6 +3343,7 @@ void
cmd_list(void)
{
int c;
+ long head_member_offset; /* offset for head like denty.d_subdirs */
struct list_data list_data, *ld;
struct datatype_member struct_member, *sm;
struct syment *sp;
@@ -3353,7 +3354,7 @@ cmd_list(void)
BZERO(ld, sizeof(struct list_data));
struct_list_offset = 0;
- while ((c = getopt(argcnt, args, "BHhrs:S:e:o:xdl:")) != EOF) {
+ while ((c = getopt(argcnt, args, "BHhrs:S:e:o:O:xdl:")) != EOF) {
switch(c)
{
case 'B':
@@ -3394,6 +3395,24 @@ cmd_list(void)
optarg);
break;
+ case 'O':
+ if (ld->flags & LIST_HEAD_OFFSET_ENTERED)
+ error(FATAL,
+ "offset value %d (0x%lx) already entered\n",
+ head_member_offset, head_member_offset);
+ else if (IS_A_NUMBER(optarg))
+ head_member_offset = stol(optarg,
+ FAULT_ON_ERROR, NULL);
+ else if (arg_to_datatype(optarg,
+ sm, RETURN_ON_ERROR) > 1)
+ head_member_offset = sm->member_offset;
+ else
+ error(FATAL, "invalid -O argument: %s\n",
+ optarg);
+
+ ld->flags |= LIST_HEAD_OFFSET_ENTERED;
+ break;
+
case 'o':
if (ld->flags & LIST_OFFSET_ENTERED)
error(FATAL,
@@ -3599,8 +3618,13 @@ next_arg:
fprintf(fp, "(empty)\n");
return;
}
- } else
- ld->start += ld->list_head_offset;
+ } else {
+ if (ld->flags & LIST_HEAD_OFFSET_ENTERED)
+ readmem(ld->start + head_member_offset, KVADDR,
+ &ld->start, sizeof(void *), "LIST_HEAD contents",
FAULT_ON_ERROR);
+ else
+ ld->start += ld->list_head_offset;
+ }
}
ld->flags &= ~(LIST_OFFSET_ENTERED|LIST_START_ENTERED);
--
2.30.2
I am not sure whether this patch is considered helpful or not.
Could you please share some thoughts?
Thanks,
Firo
1258
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Firo Yang