From: tip-bot for Yu-cheng Yu <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: dave.hansen@linux.intel.com, tglx@linutronix.de,
haokexin@gmail.com, Joakim.Tjernlund@infinera.com,
peterz@infradead.org, mingo@kernel.org, ravi.v.shankar@intel.com,
linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
hpa@zytor.com, fenghua.yu@intel.com, luto@kernel.org, bp@suse.de,
yu-cheng.yu@intel.com
Subject: [tip:x86/urgent] x86/fpu/xstate: Fix xcomp_bv in XSAVES header
Date: Tue, 24 Jan 2017 00:46:17 -0800 [thread overview]
Message-ID: <tip-dffba9a31c7769be3231c420d4b364c92ba3f1ac@git.kernel.org> (raw)
In-Reply-To: <1485212084-4418-1-git-send-email-yu-cheng.yu@intel.com>
Commit-ID: dffba9a31c7769be3231c420d4b364c92ba3f1ac
Gitweb: http://git.kernel.org/tip/dffba9a31c7769be3231c420d4b364c92ba3f1ac
Author: Yu-cheng Yu <yu-cheng.yu@intel.com>
AuthorDate: Mon, 23 Jan 2017 14:54:44 -0800
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 24 Jan 2017 09:04:48 +0100
x86/fpu/xstate: Fix xcomp_bv in XSAVES header
The compacted-format XSAVES area is determined at boot time and
never changed after. The field xsave.header.xcomp_bv indicates
which components are in the fixed XSAVES format.
In fpstate_init() we did not set xcomp_bv to reflect the XSAVES
format since at the time there is no valid data.
However, after we do copy_init_fpstate_to_fpregs() in fpu__clear(),
as in commit:
b22cbe404a9c x86/fpu: Fix invalid FPU ptrace state after execve()
and when __fpu_restore_sig() does fpu__restore() for a COMPAT-mode
app, a #GP occurs. This can be easily triggered by doing valgrind on
a COMPAT-mode "Hello World," as reported by Joakim Tjernlund and
others:
https://bugzilla.kernel.org/show_bug.cgi?id=190061
Fix it by setting xcomp_bv correctly.
This patch also moves the xcomp_bv initialization to the proper
place, which was in copyin_to_xsaves() as of:
4c833368f0bf x86/fpu: Set the xcomp_bv when we fake up a XSAVES area
which fixed the bug too, but it's more efficient and cleaner to
initialize things once per boot, not for every signal handling
operation.
Reported-by: Kevin Hao <haokexin@gmail.com>
Reported-by: Joakim Tjernlund <Joakim.Tjernlund@infinera.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: haokexin@gmail.com
Link: http://lkml.kernel.org/r/1485212084-4418-1-git-send-email-yu-cheng.yu@intel.com
[ Combined it with 4c833368f0bf. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/fpu/core.c | 4 +++-
arch/x86/kernel/fpu/xstate.c | 1 -
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index e4e97a5..de72344 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -9,6 +9,7 @@
#include <asm/fpu/regset.h>
#include <asm/fpu/signal.h>
#include <asm/fpu/types.h>
+#include <asm/fpu/xstate.h>
#include <asm/traps.h>
#include <linux/hardirq.h>
@@ -183,7 +184,8 @@ void fpstate_init(union fpregs_state *state)
* it will #GP. Make sure it is replaced after the memset().
*/
if (static_cpu_has(X86_FEATURE_XSAVES))
- state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT;
+ state->xsave.header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT |
+ xfeatures_mask;
if (static_cpu_has(X86_FEATURE_FXSR))
fpstate_init_fxstate(&state->fxsave);
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index e287b90..1d77704 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1070,7 +1070,6 @@ int copyin_to_xsaves(const void *kbuf, const void __user *ubuf,
* Add back in the features that came in from userspace:
*/
xsave->header.xfeatures |= xfeatures;
- xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | xsave->header.xfeatures;
return 0;
}
next prev parent reply other threads:[~2017-01-24 8:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-23 22:54 [PATCH] x86/fpu/xstate: Fix xcomp_bv in XSAVES header Yu-cheng Yu
2017-01-24 8:09 ` Ingo Molnar
2017-02-02 20:18 ` Joakim Tjernlund
2017-01-24 8:46 ` tip-bot for Yu-cheng Yu [this message]
2017-02-14 21:26 ` [tip:x86/urgent] " Yu-cheng Yu
2017-02-14 22:53 ` Greg Kroah-Hartman
2017-02-16 17:51 ` Greg Kroah-Hartman
2017-02-16 17:51 ` Yu-cheng Yu
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