Re: [Crash-utility] [PATCH v3 1/1] tools: list: create O option for specifying head node offset

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(a)suse.com&gt;

--- 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