linux-kernel - [PATCH 1/3] wifi: ath11k: mark some QMI driver event helpers as noinline

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241119-ath11k-noinline-v1-1-4ec0a8aa30b2@quicinc.com>
Date: Tue, 19 Nov 2024 07:47:38 -0800
From: Jeff Johnson <quic_jjohnson@...cinc.com>
To: Kalle Valo <kvalo@...nel.org>, Jeff Johnson <jjohnson@...nel.org>,
        "Nathan
 Chancellor" <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Bill Wendling <morbo@...gle.com>,
        Justin Stitt <justinstitt@...gle.com>,
        "Arnd Bergmann" <arnd@...nel.org>
CC: <linux-wireless@...r.kernel.org>, <ath11k@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <llvm@...ts.linux.dev>,
        Jeff Johnson
	<quic_jjohnson@...cinc.com>
Subject: [PATCH 1/3] wifi: ath11k: mark some QMI driver event helpers as
 noinline

When compiling the ath11k driver using clang with KASAN enabled, the
following warning is observed:

drivers/net/wireless/ath/ath11k/qmi.c:3199:13: warning: stack frame size (1560) exceeds limit (1024) in 'ath11k_qmi_driver_event_work' [-Wframe-larger-than]

This is similar to the issue found in ath12k/qmi.c that was discussed
in [1] and fixed with [2]. The issue is that clang inlining can
explode stack usage.

Just as in ath12k, ath11k_qmi_driver_event_work() itself is a pretty
lightweight function, but it dispatches to several other functions
which do the real work:

ath11k_qmi_driver_event_work()
	ath11k_qmi_event_server_arrive()
		ath11k_qmi_fw_ind_register_send()
		ath11k_qmi_host_cap_send() *
		ath11k_qmi_event_load_bdf()
	ath11k_qmi_event_mem_request()
		ath11k_qmi_respond_fw_mem_request()
	ath11k_qmi_event_load_bdf()
	ath11k_qmi_wlanfw_m3_info_send() *
		ath11k_qmi_m3_load()
	ath11k_qmi_process_coldboot_calibration()

Of these, the two marked with * have non-trivial stack usage. Mark
those functions as 'noinline_for_stack' to prevent them from being
inlined in ath12k_qmi_driver_event_work(), thereby eliminating the
excessive stack usage.

Note that this approach is a bit more "surgical" than the ath12k
approach as only the two functions with the largest stack usage are
modified.

Link: https://msgid.link/bc214795-1c51-4cb7-922f-67d6ef98bff2@quicinc.com # [1]
Link: https://patch.msgid.link/20241028-ath12k_qmi_driver_event_work-v1-1-0d532eb593fa@quicinc.com # [2]
Signed-off-by: Jeff Johnson <quic_jjohnson@...cinc.com>
---
 drivers/net/wireless/ath/ath11k/qmi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/qmi.c b/drivers/net/wireless/ath/ath11k/qmi.c
index 7a22483b35cd..5759fc521316 100644
--- a/drivers/net/wireless/ath/ath11k/qmi.c
+++ b/drivers/net/wireless/ath/ath11k/qmi.c
@@ -1704,7 +1704,9 @@ static const struct qmi_elem_info qmi_wlfw_fw_init_done_ind_msg_v01_ei[] = {
 	},
 };
 
-static int ath11k_qmi_host_cap_send(struct ath11k_base *ab)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath11k_qmi_host_cap_send(struct ath11k_base *ab)
 {
 	struct qmi_wlanfw_host_cap_req_msg_v01 req;
 	struct qmi_wlanfw_host_cap_resp_msg_v01 resp;
@@ -2570,7 +2572,9 @@ static void ath11k_qmi_m3_free(struct ath11k_base *ab)
 	m3_mem->size = 0;
 }
 
-static int ath11k_qmi_wlanfw_m3_info_send(struct ath11k_base *ab)
+/* clang stack usage explodes if this is inlined */
+static noinline_for_stack
+int ath11k_qmi_wlanfw_m3_info_send(struct ath11k_base *ab)
 {
 	struct m3_mem_region *m3_mem = &ab->qmi.m3_mem;
 	struct qmi_wlanfw_m3_info_req_msg_v01 req;

-- 
2.42.0