From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
Andi Kleen <ak@linux.intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>,
"Chang S . Bae" <chang.seok.bae@intel.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH v6 06/12] x86/fsgsbase/64: When copying a thread, use the FSGSBASE instructions if available
Date: Wed, 13 Feb 2019 13:36:18 -0800 [thread overview]
Message-ID: <20190213213624.14354-7-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20190213213624.14354-1-chang.seok.bae@intel.com>
Copy real FS/GSBASE values instead of approximation when FSGSBASE is
enabled.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
---
arch/x86/kernel/process_64.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index d3abe4748d8b..c4de0907d909 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -422,7 +422,8 @@ unsigned long x86_fsbase_read_task(struct task_struct *task)
if (task == current)
fsbase = x86_fsbase_read_cpu();
- else if (task->thread.fsindex == 0)
+ else if (static_cpu_has(X86_FEATURE_FSGSBASE) ||
+ (task->thread.fsindex == 0))
fsbase = task->thread.fsbase;
else
fsbase = x86_fsgsbase_read_task(task, task->thread.fsindex);
@@ -436,7 +437,8 @@ unsigned long x86_gsbase_read_task(struct task_struct *task)
if (task == current)
gsbase = x86_gsbase_read_cpu_inactive();
- else if (task->thread.gsindex == 0)
+ else if (static_cpu_has(X86_FEATURE_FSGSBASE) ||
+ (task->thread.gsindex == 0))
gsbase = task->thread.gsbase;
else
gsbase = x86_fsgsbase_read_task(task, task->thread.gsindex);
@@ -475,10 +477,11 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
p->thread.sp = (unsigned long) fork_frame;
p->thread.io_bitmap_ptr = NULL;
- savesegment(gs, p->thread.gsindex);
- p->thread.gsbase = p->thread.gsindex ? 0 : me->thread.gsbase;
- savesegment(fs, p->thread.fsindex);
- p->thread.fsbase = p->thread.fsindex ? 0 : me->thread.fsbase;
+ save_fsgs(me);
+ p->thread.fsindex = me->thread.fsindex;
+ p->thread.fsbase = me->thread.fsbase;
+ p->thread.gsindex = me->thread.gsindex;
+ p->thread.gsbase = me->thread.gsbase;
savesegment(es, p->thread.es);
savesegment(ds, p->thread.ds);
memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
--
2.19.1
next prev parent reply other threads:[~2019-02-13 21:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 21:36 [PATCH v6 00/12] x86: Enable FSGSBASE instructions Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 01/12] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 02/12] kbuild: Raise the minimum required binutils version to 2.21 Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 03/12] x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 04/12] x86/fsgsbase/64: Enable FSGSBASE instructions in the helper functions Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 05/12] x86/fsgsbase/64: Preserve FS/GS state in __switch_to() if FSGSBASE is on Chang S. Bae
2019-02-13 21:36 ` Chang S. Bae [this message]
2019-02-13 21:36 ` [PATCH v6 07/12] x86/fsgsbase/64: Introduce the FIND_PERCPU_BASE macro Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 08/12] x86/fsgsbase/64: Use the per-CPU base as GSBASE at the paranoid_entry Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 09/12] selftests/x86/fsgsbase: Test WRGSBASE Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 10/12] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 11/12] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2019-02-13 21:36 ` [PATCH v6 12/12] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
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