From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
To print structs that have as one of its members a struct with a
flexible array, i.e. the outer script has a flexible array in its
middle, which is dangerous.
One example should illustrate this nicely:
⬢[acme@toolbox pahole]$ pahole --with_embedded_flexible_array --sizes | wc -l
103
⬢[acme@toolbox pahole]$ pahole --with_embedded_flexible_array --sizes | tail
acpi_nhlt_format_config 44 0
xts_request_ctx 168 0
dbc_port 512 1
ethtool_link_usettings 96 0
pci_setup_rom 64 1
lirc_fh 112 1
lrw_request_ctx 96 0
xt_standard_target 40 0
xt_error_target 64 0
bpf_ctx_convert 7280 0
⬢[acme@toolbox pahole]$ pahole lirc_fh
struct lirc_fh {
struct list_head list; /* 0 16 */
struct rc_dev * rc; /* 16 8 */
int carrier_low; /* 24 4 */
/* XXX 4 bytes hole, try to pack */
struct {
union {
struct __kfifo kfifo; /* 32 24 */
unsigned int * type; /* 32 8 */
const unsigned int * const_type; /* 32 8 */
char * rectype; /* 32 8 */
unsigned int * ptr; /* 32 8 */
const unsigned int * ptr_const; /* 32 8 */
}; /* 32 24 */
unsigned int buf[]; /* 56 0 */
} rawir; /* 32 24 */
struct {
union {
struct __kfifo kfifo; /* 56 24 */
struct lirc_scancode * type; /* 56 8 */
const struct lirc_scancode * const_type; /* 56 8 */
char * rectype; /* 56 8 */
struct lirc_scancode * ptr; /* 56 8 */
const struct lirc_scancode * ptr_const; /* 56 8 */
}; /* 56 24 */
/* --- cacheline 1 boundary (64 bytes) was 16 bytes ago --- */
struct lirc_scancode buf[]; /* 80 0 */
} scancodes; /* 56 24 */
wait_queue_head_t wait_poll; /* 80 24 */
u8 send_mode; /* 104 1 */
u8 rec_mode; /* 105 1 */
/* size: 112, cachelines: 2, members: 8 */
/* sum members: 102, holes: 1, sum holes: 4 */
/* padding: 6 */
/* last cacheline: 48 bytes */
};
⬢[acme@toolbox pahole]$
Another case:
⬢[acme@toolbox pahole]$ pahole -E ethtool_link_usettings
struct ethtool_link_usettings {
struct ethtool_link_settings {
/* typedef __u32 */ unsigned int cmd; /* 0 4 */
/* typedef __u32 */ unsigned int speed; /* 4 4 */
/* typedef __u8 */ unsigned char duplex; /* 8 1 */
/* typedef __u8 */ unsigned char port; /* 9 1 */
/* typedef __u8 */ unsigned char phy_address; /* 10 1 */
/* typedef __u8 */ unsigned char autoneg; /* 11 1 */
/* typedef __u8 */ unsigned char mdio_support; /* 12 1 */
/* typedef __u8 */ unsigned char eth_tp_mdix; /* 13 1 */
/* typedef __u8 */ unsigned char eth_tp_mdix_ctrl; /* 14 1 */
/* typedef __s8 */ signed char link_mode_masks_nwords; /* 15 1 */
/* typedef __u8 */ unsigned char transceiver; /* 16 1 */
/* typedef __u8 */ unsigned char master_slave_cfg; /* 17 1 */
/* typedef __u8 */ unsigned char master_slave_state; /* 18 1 */
/* typedef __u8 */ unsigned char rate_matching; /* 19 1 */
/* typedef __u32 */ unsigned int reserved[7]; /* 20 28 */
/* typedef __u32 */ unsigned int link_mode_masks[]; /* 48 0 */
} base; /* 0 48 */
struct {
/* typedef __u32 */ unsigned int supported[4]; /* 48 16 */
/* --- cacheline 1 boundary (64 bytes) --- */
/* typedef __u32 */ unsigned int advertising[4]; /* 64 16 */
/* typedef __u32 */ unsigned int lp_advertising[4]; /* 80 16 */
} link_modes; /* 48 48 */
/* size: 96, cachelines: 2, members: 2 */
/* last cacheline: 32 bytes */
};
⬢[acme@toolbox pahole]$
Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
Cc: Willy Tarreau <w@xxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
man-pages/pahole.1 | 4 ++++
pahole.c | 13 +++++++++++++
2 files changed, 17 insertions(+)
diff --git a/man-pages/pahole.1 b/man-pages/pahole.1
index 7c1a69ad23690c75..19dfe676c9e30509 100644
--- a/man-pages/pahole.1
+++ b/man-pages/pahole.1
@@ -397,6 +397,10 @@ for instance when using the \fB\-\-reorganize\fR option.
.B \-P, \-\-with_flexible_array
Show only structs that have a flexible array.
+.TP
+.B \-P, \-\-with_embedded_flexible_array
+Show only structs that have an embedded flexible array, i.e. a contained struct that has flexible arrays, a flexible array "in the middle".
+
.TP
.B \-q, \-\-quiet
Be quieter.
diff --git a/pahole.c b/pahole.c
index 8bdfaf3e84c407d7..b9e97ef15e6c732e 100644
--- a/pahole.c
+++ b/pahole.c
@@ -66,6 +66,7 @@ static uint16_t nr_bit_holes;
static uint16_t hole_size_ge;
static uint8_t show_packable;
static bool show_with_flexible_array;
+static bool show_with_embedded_flexible_array;
static uint8_t global_verbose;
static uint8_t recursive;
static size_t cacheline_size;
@@ -825,6 +826,9 @@ static struct class *class__filter(struct class *class, struct cu *cu,
if (show_with_flexible_array && !class__has_flexible_array(class, cu))
return NULL;
+ if (show_with_embedded_flexible_array && !class__has_embedded_flexible_array(class, cu))
+ return NULL;
+
return class;
}
@@ -1226,6 +1230,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
#define ARGP_running_kernel_vmlinux 346
#define ARG_padding_ge 347
#define ARG_padding 348
+#define ARGP_with_embedded_flexible_array 349
/* --btf_features=feature1[,feature2,..] allows us to specify
* a list of requested BTF features or "default" to enable all default
@@ -1505,6 +1510,11 @@ static const struct argp_option pahole__options[] = {
.key = ARGP_with_flexible_array,
.doc = "show only structs with a flexible array",
},
+ {
+ .name = "with_embedded_flexible_array",
+ .key = ARGP_with_embedded_flexible_array,
+ .doc = "show only structs with an embedded flexible array (contaning a struct that has a flexible array)",
+ },
{
.name = "expand_types",
.key = 'E',
@@ -2006,6 +2016,9 @@ static error_t pahole__options_parser(int key, char *arg,
parse_btf_features("all", false); break;
case ARGP_with_flexible_array:
show_with_flexible_array = true; break;
+ case ARGP_with_embedded_flexible_array:
+ just_structs = true;
+ show_with_embedded_flexible_array = true; break;
case ARGP_prettify_input_filename:
prettify_input_filename = arg; break;
case ARGP_sort_output:
--
2.46.2
