This -O option is very useful to specify the embedded head node's
offset which is different to the offset of other nodes embedded,
e.g. dentry.d_subdirs(the head node) and dentry.d_child.
Signed-off-by: Firo Yang <firo.yang@xxxxxxxx>
---
defs.h | 1 +
help.c | 32 +++++++++++++++++++++++++++++++-
tools.c | 36 +++++++++++++++++++++++++++++++++---
3 files changed, 65 insertions(+), 4 deletions(-)
diff --git a/defs.h b/defs.h
index 396d61a..d5fcd37 100644
--- a/defs.h
+++ b/defs.h
@@ -2613,6 +2613,7 @@ 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 e0c8408..1593f12 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 +5800,15 @@ 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 Only used in conjunction with -h; it specifies the offset of head",
+" node list_head embedded within a data structure which is different",
+" than the offset of list_head of other nodes embedded within a data",
+" structure.",
+" The offset may be entered in either of the following manners:",
+"",
+" 1. \"structure.member\" format.",
+" 2. a number of bytes.",
+"",
" -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",
@@ -6116,6 +6125,27 @@ char *help__list[] = {
" comm = \"sudo\"",
" ffff88005ac10180",
" comm = \"crash\"",
+"",
+" To display a liked list whose head node and other nodes are embedded within ",
+" either same or different data structures resulting in different offsets ",
+" for head node and other nodes, e.g. dentry.d_subdirs and dentry.d_child, this",
+" -O option can be used:",
+"",
+" %s> list -o dentry.d_child -s dentry.d_name.name -O dentry.d_subdirs -h ffff9c585b81a180",
+" ffff9c585b9cb140",
+" d_name.name = 0xffff9c585b9cb178 ccc.txt",
+" ffff9c585b9cb980",
+" d_name.name = 0xffff9c585b9cb9b8 bbb.txt",
+" ffff9c585b9cb740",
+" d_name.name = 0xffff9c585b9cb778 aaa.txt",
+"",
+" The dentry.d_subdirs example above is equal to the following sequence:",
+"",
+" %s> struct -o dentry.d_subdirs ffff9c585b81a180",
+" struct dentry {",
+" [ffff9c585b81a220] struct list_head d_subdirs;",
+" }",
+" %s> list -o dentry.d_child -s dentry.d_name.name -H ffff9c585b81a220",
NULL
};
diff --git a/tools.c b/tools.c
index a26b101..636adc6 100644
--- a/tools.c
+++ b/tools.c
@@ -3343,6 +3343,7 @@ void
cmd_list(void)
{
int c;
+ long head_member_offset = 0; /* 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 +3618,19 @@ next_arg:
fprintf(fp, "(empty)\n");
return;
}
- } else
- ld->start += ld->list_head_offset;
+ } else {
+ if (ld->flags & LIST_HEAD_OFFSET_ENTERED) {
+ if (!ld->end)
+ ld->end = ld->start + head_member_offset;
+ readmem(ld->start + head_member_offset, KVADDR,
+ &ld->start, sizeof(void *), "LIST_HEAD contents", FAULT_ON_ERROR);
+ if (ld->start == ld->end) {
+ fprintf(fp, "(empty)\n");
+ return;
+ }
+ } else
+ ld->start += ld->list_head_offset;
+ }
}
ld->flags &= ~(LIST_OFFSET_ENTERED|LIST_START_ENTERED);
--
2.31.1
--
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