[PATCH] [-next] net: marvell: prestera: Add explicit padding

From: Geert Uytterhoeven
Date: Tue Nov 02 2021 - 04:24:45 EST


On m68k:

In function ‘prestera_hw_build_tests’,
inlined from ‘prestera_hw_switch_init’ at drivers/net/ethernet/marvell/prestera/prestera_hw.c:788:2:
././include/linux/compiler_types.h:335:38: error: call to ‘__compiletime_assert_345’ declared with attribute error: BUILD_BUG_ON failed: sizeof(struct prestera_msg_switch_attr_req) != 16
...

The driver assumes structure members are naturally aligned, but does not
add explicit padding, thus breaking architectures where integral values
are not always naturally aligned (e.g. on m68k, __alignof(int) is 2, not
4).

Fixes: bb5dbf2cc64d5cfa ("net: marvell: prestera: add firmware v4.0 support")
Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
---
Compile-tested only.

BTW, I sincerely doubt the use of __packed on structs like:

union prestera_msg_switch_param {
u8 mac[ETH_ALEN];
__le32 ageing_timeout_ms;
} __packed;

This struct is only used as a member in another struct, where it is
be naturally aligned anyway.

Some of the other __packed attributes look fishy to me, too.
---
drivers/net/ethernet/marvell/prestera/prestera_hw.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/marvell/prestera/prestera_hw.c b/drivers/net/ethernet/marvell/prestera/prestera_hw.c
index 41ba17cb29657392..4f5f52dcdd9d2814 100644
--- a/drivers/net/ethernet/marvell/prestera/prestera_hw.c
+++ b/drivers/net/ethernet/marvell/prestera/prestera_hw.c
@@ -189,6 +189,7 @@ struct prestera_msg_switch_attr_req {
struct prestera_msg_cmd cmd;
__le32 attr;
union prestera_msg_switch_param param;
+ u8 pad[2];
};

struct prestera_msg_switch_init_resp {
@@ -313,6 +314,7 @@ struct prestera_msg_port_info_resp {
__le32 hw_id;
__le32 dev_id;
__le16 fp_id;
+ u8 pad[2];
};

struct prestera_msg_vlan_req {
@@ -345,11 +347,13 @@ struct prestera_msg_bridge_req {
__le32 port;
__le32 dev;
__le16 bridge;
+ u8 pad[2];
};

struct prestera_msg_bridge_resp {
struct prestera_msg_ret ret;
__le16 bridge;
+ u8 pad[2];
};

struct prestera_msg_acl_action {
@@ -408,16 +412,19 @@ struct prestera_msg_acl_ruleset_bind_req {
__le32 port;
__le32 dev;
__le16 ruleset_id;
+ u8 pad[2];
};

struct prestera_msg_acl_ruleset_req {
struct prestera_msg_cmd cmd;
__le16 id;
+ u8 pad[2];
};

struct prestera_msg_acl_ruleset_resp {
struct prestera_msg_ret ret;
__le16 id;
+ u8 pad[2];
};

struct prestera_msg_span_req {
@@ -425,11 +432,13 @@ struct prestera_msg_span_req {
__le32 port;
__le32 dev;
u8 id;
+ u8 pad[3];
};

struct prestera_msg_span_resp {
struct prestera_msg_ret ret;
u8 id;
+ u8 pad[3];
};

struct prestera_msg_stp_req {
@@ -443,6 +452,7 @@ struct prestera_msg_stp_req {
struct prestera_msg_rxtx_req {
struct prestera_msg_cmd cmd;
u8 use_sdma;
+ u8 pad[3];
};

struct prestera_msg_rxtx_resp {
@@ -455,12 +465,14 @@ struct prestera_msg_lag_req {
__le32 port;
__le32 dev;
__le16 lag_id;
+ u8 pad[2];
};

struct prestera_msg_cpu_code_counter_req {
struct prestera_msg_cmd cmd;
u8 counter_type;
u8 code;
+ u8 pad[2];
};

struct mvsw_msg_cpu_code_counter_ret {
--
2.25.1