netdev - [PATCHv2 net-next 2/4] cxgb4: For T4, don't read the Firmware Mailbox Control register

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Wed, 30 Sep 2015 20:33:29 +0530
From:	Hariprasad Shenai <hariprasad@...lsio.com>
To:	netdev@...r.kernel.org
Cc:	davem@...emloft.net, leedom@...lsio.com, nirranjan@...lsio.com,
	Hariprasad Shenai <hariprasad@...lsio.com>
Subject: [PATCHv2 net-next 2/4] cxgb4: For T4, don't read the Firmware Mailbox Control register

T4 doesn't have the Shadow copy of the register which we can read without
side effect. So don't read mbox control register for T4 adapter

Signed-off-by: Hariprasad Shenai <hariprasad@...lsio.com>
---
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
index 0a87a32..8001619 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
@@ -1134,12 +1134,20 @@ static int mbox_show(struct seq_file *seq, void *v)
 	unsigned int mbox = (uintptr_t)seq->private & 7;
 	struct adapter *adap = seq->private - mbox;
 	void __iomem *addr = adap->regs + PF_REG(mbox, CIM_PF_MAILBOX_DATA_A);
-	unsigned int ctrl_reg = (is_t4(adap->params.chip)
-				 ? CIM_PF_MAILBOX_CTRL_A
-				 : CIM_PF_MAILBOX_CTRL_SHADOW_COPY_A);
-	void __iomem *ctrl = adap->regs + PF_REG(mbox, ctrl_reg);
 
-	i = MBOWNER_G(readl(ctrl));
+	/* For T4 we don't have a shadow copy of the Mailbox Control register.
+	 * And since reading that real register causes a side effect of
+	 * granting ownership, we're best of simply not reading it at all.
+	 */
+	if (is_t4(adap->params.chip)) {
+		i = 4; /* index of "<unread>" */
+	} else {
+		unsigned int ctrl_reg = CIM_PF_MAILBOX_CTRL_SHADOW_COPY_A;
+		void __iomem *ctrl = adap->regs + PF_REG(mbox, ctrl_reg);
+
+		i = MBOWNER_G(readl(ctrl));
+	}
+
 	seq_printf(seq, "mailbox owned by %s\n\n", owner[i]);
 
 	for (i = 0; i < MBOX_LEN; i += 8)
-- 
2.3.4

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html