From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, "H. Peter Anvin" <hpa@linux.intel.com>
Subject: [ 13/22] x86, fpu: correct the asm constraints for fxsave, unbreak mxcsr.daz
Date: Thu, 8 Aug 2013 18:41:29 -0700 [thread overview]
Message-ID: <20130809013952.106944525@linuxfoundation.org> (raw)
In-Reply-To: <20130809013949.226228694@linuxfoundation.org>
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: "H.J. Lu" <hjl.tools@gmail.com>
commit eaa5a990191d204ba0f9d35dbe5505ec2cdd1460 upstream.
GCC will optimize mxcsr_feature_mask_init in arch/x86/kernel/i387.c:
memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
asm volatile("fxsave %0" : : "m" (fx_scratch));
mask = fx_scratch.mxcsr_mask;
if (mask == 0)
mask = 0x0000ffbf;
to
memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
asm volatile("fxsave %0" : : "m" (fx_scratch));
mask = 0x0000ffbf;
since asm statement doesn’t say it will update fx_scratch. As the
result, the DAZ bit will be cleared. This patch fixes it. This bug
dates back to at least kernel 2.6.12.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kernel/i387.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -51,7 +51,7 @@ void __cpuinit mxcsr_feature_mask_init(v
clts();
if (cpu_has_fxsr) {
memset(&fx_scratch, 0, sizeof(struct i387_fxsave_struct));
- asm volatile("fxsave %0" : : "m" (fx_scratch));
+ asm volatile("fxsave %0" : "+m" (fx_scratch));
mask = fx_scratch.mxcsr_mask;
if (mask == 0)
mask = 0x0000ffbf;
next prev parent reply other threads:[~2013-08-09 1:41 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-09 1:41 [ 00/22] 3.0.90-stable review Greg Kroah-Hartman
2013-08-09 1:41 ` [ 01/22] serial/mxs-auart: fix race condition in interrupt handler Greg Kroah-Hartman
2013-08-09 1:41 ` [ 02/22] serial/mxs-auart: increase time to wait for transmitter to become idle Greg Kroah-Hartman
2013-08-09 1:41 ` [ 03/22] ath9k_htc: do some initial hardware configuration Greg Kroah-Hartman
2013-08-09 1:41 ` [ 04/22] nl80211: fix mgmt tx status and testmode reporting for netns Greg Kroah-Hartman
2013-08-09 1:41 ` [ 05/22] mac80211: fix duplicate retransmission detection Greg Kroah-Hartman
2013-08-09 1:41 ` [ 06/22] rt2x00: fix stop queue Greg Kroah-Hartman
2013-08-09 1:41 ` [ 07/22] mwifiex: Add missing endian conversion Greg Kroah-Hartman
2013-08-09 1:41 ` [ 08/22] ACPI / battery: Fix parsing _BIX return value Greg Kroah-Hartman
2013-08-09 1:41 ` [ 09/22] sched: Fix the broken sched_rr_get_interval() Greg Kroah-Hartman
2013-08-09 1:41 ` [ 10/22] fanotify: info leak in copy_event_to_user() Greg Kroah-Hartman
2013-08-09 1:41 ` [ 11/22] MAINTAINERS: fix up stable_kernel_rules.txt location Greg Kroah-Hartman
2013-08-09 1:41 ` [ 12/22] perf: Fix event group context move Greg Kroah-Hartman
2013-08-09 1:41 ` Greg Kroah-Hartman [this message]
2013-08-09 1:41 ` [ 14/22] perf: Use css_tryget() to avoid propping up css refcount Greg Kroah-Hartman
2013-08-09 1:41 ` [ 15/22] arcnet: cleanup sizeof parameter Greg Kroah-Hartman
2013-08-09 1:41 ` [ 16/22] sysctl net: Keep tcp_syn_retries inside the boundary Greg Kroah-Hartman
2013-08-09 1:41 ` [ 17/22] sctp: fully initialize sctp_outq in sctp_outq_init Greg Kroah-Hartman
2013-08-09 1:41 ` [ 18/22] ipv6: take rtnl_lock and mark mrt6 table as freed on namespace cleanup Greg Kroah-Hartman
2013-08-09 1:41 ` [ 19/22] usbnet: do not pretend to support SG/TSO Greg Kroah-Hartman
2013-08-09 1:41 ` [ 20/22] net_sched: Fix stack info leak in cbq_dump_wrr() Greg Kroah-Hartman
2013-08-09 1:41 ` [ 21/22] af_key: more info leaks in pfkey messages Greg Kroah-Hartman
2013-08-09 1:41 ` [ 22/22] net_sched: info leak in atm_tc_dump_class() Greg Kroah-Hartman
2013-08-09 3:42 ` [ 00/22] 3.0.90-stable review Guenter Roeck
2013-08-09 3:56 ` Greg Kroah-Hartman
2013-08-10 22:08 ` Shuah Khan
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