Em Wed, Jul 01, 2020 at 08:25:34AM -0300, Arnaldo Carvalho de Melo escreveu:
> The latest changeset shows what this is about, see its example
> below, please help testing and suggesting whatever needs you have
> regarding pretty printing.
>
> Now to implement --skip.
Now to implement --seek, this time in bytes, so that we can, for
instance, pretty print perf.data records, looking at 'perf report -D'
and getting the offset of the start of a series of 'struct
perf_event_attr' or 'struct perf_event_header'.
- Arnaldo
commit 44af7c02b5d0a7f2b93fab9fda45907cd6fe0827
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Date: Wed Jul 1 08:36:28 2020 -0300
pahole: Implement --skip, just like dd
$ objcopy -O binary --only-section=__versions drivers/scsi/sg.ko versions
$ pahole -C modversion_info drivers/scsi/sg.ko
struct modversion_info {
long unsigned int crc; /* 0 8 */
char name[56]; /* 8 56 */
/* size: 64, cachelines: 1, members: 2 */
};
$ pahole --count 3 -C modversion_info drivers/scsi/sg.ko < versions
{
.crc = 0x8dabd84,
.name = "module_layout",
},
{
.crc = 0x45e4617b,
.name = "no_llseek",
},
{
.crc = 0xa23fae8c,
.name = "param_ops_int",
},
$ pahole --skip 1 --count 2 -C modversion_info drivers/scsi/sg.ko < versions
{
.crc = 0x45e4617b,
.name = "no_llseek",
},
{
.crc = 0xa23fae8c,
.name = "param_ops_int",
},
$
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
diff --git a/dwarves.h b/dwarves.h
index f224d05b28c3..24f9c7c37843 100644
--- a/dwarves.h
+++ b/dwarves.h
@@ -55,6 +55,7 @@ struct conf_load {
/** struct conf_fprintf - hints to the __fprintf routines
*
* @count - Just like 'dd', stop pretty printing input after 'count' records
+ * @skip - Just like 'dd', skip 'count' records when pretty printing input
* @flat_arrays - a->foo[10][2] becomes a->foo[20]
* @classes_as_structs - class f becomes struct f, CTF doesn't have a "class"
* @cachelinep - pointer to current cacheline, so that when expanding types we keep track of it,
@@ -71,6 +72,7 @@ struct conf_fprintf {
uint32_t base_offset;
uint32_t count;
uint32_t *cachelinep;
+ uint32_t skip;
uint8_t indent;
uint8_t expand_types:1;
uint8_t expand_pointers:1;
diff --git a/man-pages/pahole.1 b/man-pages/pahole.1
index 7e8207756432..db820cca323f 100644
--- a/man-pages/pahole.1
+++ b/man-pages/pahole.1
@@ -78,6 +78,10 @@ Set cacheline size to SIZE bytes.
.B \-\-count=COUNT
Pretty print the first COUNT records from input.
+.TP
+.B \-\-skip=COUNT
+Skip COUNT input records.
+
.TP
.B \-E, \-\-expand_types
Expand class members. Useful to find in what member of inner structs where an
@@ -502,6 +506,16 @@ $ pahole --count 3 -C modversion_info drivers/scsi/sg.ko < versions
.name = "param_ops_int",
},
$
+$ pahole --skip 1 --count 2 -C modversion_info drivers/scsi/sg.ko < versions
+{
+ .crc = 0x45e4617b,
+ .name = "no_llseek",
+},
+{
+ .crc = 0xa23fae8c,
+ .name = "param_ops_int",
+},
+$
.fi
.P
diff --git a/pahole.c b/pahole.c
index 1b84f5c2fa4a..7d8431c64423 100644
--- a/pahole.c
+++ b/pahole.c
@@ -803,6 +803,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
#define ARGP_just_unions 309
#define ARGP_just_structs 310
#define ARGP_count 311
+#define ARGP_skip 312
static const struct argp_option pahole__options[] = {
{
@@ -829,6 +830,12 @@ static const struct argp_option pahole__options[] = {
.arg = "COUNT",
.doc = "Print only COUNT input records"
},
+ {
+ .name = "skip",
+ .key = ARGP_skip,
+ .arg = "COUNT",
+ .doc = "Skip COUNT input records"
+ },
{
.name = "find_pointers_to",
.key = 'f',
@@ -1154,6 +1161,8 @@ static error_t pahole__options_parser(int key, char *arg,
just_structs = true; break;
case ARGP_count:
conf.count = atoi(arg); break;
+ case ARGP_skip:
+ conf.skip = atoi(arg); break;
default:
return ARGP_ERR_UNKNOWN;
}
@@ -1325,11 +1334,17 @@ static int tag__stdio_fprintf_value(struct tag *type, struct cu *cu, FILE *fp)
int _sizeof = tag__size(type, cu), printed = 0;
void *instance = malloc(_sizeof);
uint32_t count = 0;
+ uint32_t skip = conf.skip;
if (instance == NULL)
return -ENOMEM;
while (fread(instance, _sizeof, 1, stdin) == 1) {
+ if (skip) {
+ --skip;
+ continue;
+ }
+
printed += tag__fprintf_value(type, cu, instance, _sizeof, fp);
printed += fprintf(fp, ",\n");
