[PATCH 3.12 146/182] b43: Fix machine check error due to improper access of B43_MMIO_PSM_PHY_HDR

Jiri Slaby
2014-05-13T10:17:28Z

From: Rafał Miłecki <zajec5@gmail.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 12cd43c6ed6da7bf7c5afbd74da6959cda6d056b upstream.

Register B43_MMIO_PSM_PHY_HDR is 16 bit one, so accessing it with 32b
functions isn't safe. On my machine it causes delayed (!) CPU exception:

Disabling lock debugging due to kernel taint
mce: [Hardware Error]: CPU 0: Machine Check Exception: 4 Bank 4: b200000000070f0f
mce: [Hardware Error]: TSC 164083803dc
mce: [Hardware Error]: PROCESSOR 2:20fc2 TIME 1396650505 SOCKET 0 APIC 0 microcode 0
mce: [Hardware Error]: Run the above through 'mcelog --ascii'
mce: [Hardware Error]: Machine check: Processor context corrupt
Kernel panic - not syncing: Fatal machine check on current CPU
Kernel Offset: 0x0 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffff9fffffff)

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/net/wireless/b43/phy_n.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/b43/phy_n.c b/drivers/net/wireless/b43/phy_n.c
index 7c970d3ae358..80ecca3e1465 100644
--- a/drivers/net/wireless/b43/phy_n.c
+++ b/drivers/net/wireless/b43/phy_n.c
@@ -5175,22 +5175,22 @@ static void b43_nphy_channel_setup(struct b43_wldev *dev,
int ch = new_channel->hw_value;

u16 old_band_5ghz;
- u32 tmp32;
+ u16 tmp16;

old_band_5ghz =
b43_phy_read(dev, B43_NPHY_BANDCTL) & B43_NPHY_BANDCTL_5GHZ;
if (new_channel->band == IEEE80211_BAND_5GHZ && !old_band_5ghz) {
- tmp32 = b43_read32(dev, B43_MMIO_PSM_PHY_HDR);
- b43_write32(dev, B43_MMIO_PSM_PHY_HDR, tmp32 | 4);
+ tmp16 = b43_read16(dev, B43_MMIO_PSM_PHY_HDR);
+ b43_write16(dev, B43_MMIO_PSM_PHY_HDR, tmp16 | 4);
b43_phy_set(dev, B43_PHY_B_BBCFG, 0xC000);
- b43_write32(dev, B43_MMIO_PSM_PHY_HDR, tmp32);
+ b43_write16(dev, B43_MMIO_PSM_PHY_HDR, tmp16);
b43_phy_set(dev, B43_NPHY_BANDCTL, B43_NPHY_BANDCTL_5GHZ);
} else if (new_channel->band == IEEE80211_BAND_2GHZ && old_band_5ghz) {
b43_phy_mask(dev, B43_NPHY_BANDCTL, ~B43_NPHY_BANDCTL_5GHZ);
- tmp32 = b43_read32(dev, B43_MMIO_PSM_PHY_HDR);
- b43_write32(dev, B43_MMIO_PSM_PHY_HDR, tmp32 | 4);
+ tmp16 = b43_read16(dev, B43_MMIO_PSM_PHY_HDR);
+ b43_write16(dev, B43_MMIO_PSM_PHY_HDR, tmp16 | 4);
b43_phy_mask(dev, B43_PHY_B_BBCFG, 0x3FFF);
- b43_write32(dev, B43_MMIO_PSM_PHY_HDR, tmp32);
+ b43_write16(dev, B43_MMIO_PSM_PHY_HDR, tmp16);
}

b43_chantab_phy_upload(dev, e);
--
1.9.3