From: tip-bot for Andy Lutomirski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: tglx@linutronix.de, mingo@kernel.org,
linux-kernel@vger.kernel.org, luto@amacapital.net, hpa@zytor.com
Subject: [tip:x86/vdso] x86/vdso: Make the PER_CPU segment start out accessed
Date: Tue, 28 Oct 2014 04:15:22 -0700 [thread overview]
Message-ID: <tip-9c0080ef93bce34db130db6dc3bd946348e6a203@git.kernel.org> (raw)
In-Reply-To: <ac63814ca4c637a08ec2fd0360d67ca67560a9ee.1411494540.git.luto@amacapital.net>
Commit-ID: 9c0080ef93bce34db130db6dc3bd946348e6a203
Gitweb: http://git.kernel.org/tip/9c0080ef93bce34db130db6dc3bd946348e6a203
Author: Andy Lutomirski <luto@amacapital.net>
AuthorDate: Tue, 23 Sep 2014 10:50:54 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 28 Oct 2014 11:22:11 +0100
x86/vdso: Make the PER_CPU segment start out accessed
The first userspace attempt to read or write the PER_CPU segment
will write the accessed bit to the GDT. This is visible to
userspace using the LAR instruction, and it also pointlessly
dirties a cache line.
Set the segment's accessed bit at boot to prevent userspace
access to segments from having side effects.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/ac63814ca4c637a08ec2fd0360d67ca67560a9ee.1411494540.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/vdso/vma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 261b134..0c799746 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -264,7 +264,7 @@ static void vsyscall_set_cpu(int cpu)
d = (struct desc_struct) {
.limit0 = cpu | ((node & 0xf) << 12),
.limit = node >> 4,
- .type = 4, /* RO data, expand down */
+ .type = 5, /* RO data, expand down, accessed */
.dpl = 3, /* Visible to user code */
.s = 1, /* Not a system segment */
.p = 1, /* Present */
next prev parent reply other threads:[~2014-10-28 11:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-23 17:50 [PATCH 0/8] x86: Disentangle the vdso and clean it up Andy Lutomirski
2014-09-23 17:50 ` [PATCH 1/8] x86_64,vsyscall: Move all of the gate_area code to vsyscall_64.c Andy Lutomirski
2014-10-28 11:14 ` [tip:x86/vdso] x86_64/vsyscall: " tip-bot for Andy Lutomirski
2014-09-23 17:50 ` [PATCH 2/8] x86_64: Move getcpu code from vsyscall_64.c to vdso/vma.c Andy Lutomirski
2014-10-28 11:14 ` [tip:x86/vdso] x86_64/vdso: " tip-bot for Andy Lutomirski
2014-09-23 17:50 ` [PATCH 3/8] x86,vdso: Change the PER_CPU segment to use struct desc_struct Andy Lutomirski
2014-10-28 11:15 ` [tip:x86/vdso] x86/vdso: " tip-bot for Andy Lutomirski
2014-09-23 17:50 ` [PATCH 4/8] x86,vdso: Make the PER_CPU segment start out accessed Andy Lutomirski
2014-10-28 11:15 ` tip-bot for Andy Lutomirski [this message]
2014-09-23 17:50 ` [PATCH 5/8] x86,vdso: Make the PER_CPU segment 32 bits Andy Lutomirski
2014-10-28 11:15 ` [tip:x86/vdso] x86/vdso: " tip-bot for Andy Lutomirski
2014-09-23 17:50 ` [PATCH 6/8] x86_64,vdso: Remove jiffies from the vvar page Andy Lutomirski
2014-10-28 11:15 ` [tip:x86/vdso] x86_64/vdso: " tip-bot for Andy Lutomirski
2014-09-23 17:50 ` [PATCH 7/8] x86_64,vdso: Clean up vgetcpu init and merge the vdso initcalls Andy Lutomirski
2014-10-28 11:16 ` [tip:x86/vdso] x86_64/vdso: " tip-bot for Andy Lutomirski
2014-09-23 17:50 ` [PATCH 8/8] x86,vdso: Replace vgetcpu_mode with static_cpu_has Andy Lutomirski
2014-10-20 17:44 ` [PATCH 0/8] x86: Disentangle the vdso and clean it up Andy Lutomirski
2014-10-20 21:41 ` H. Peter Anvin
2014-10-20 21:57 ` Andy Lutomirski
2014-10-20 22:03 ` H. Peter Anvin
2014-10-20 22:41 ` Andy Lutomirski
2014-10-21 4:38 ` Andy Lutomirski
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