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: Dave Hansen <dave.hansen@linux.intel.com>,
Markus T Metzger <markus.t.metzger@intel.com>,
Ravi Shankar <ravi.v.shankar@intel.com>,
"Chang S . Bae" <chang.seok.bae@intel.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH v4 07/13] x86/fsgsbase/64: When copying a thread, use the FSGSBASE instructions if available
Date: Wed, 16 Jan 2019 14:48:43 -0800 [thread overview]
Message-ID: <20190116224849.8617-8-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20190116224849.8617-1-chang.seok.bae@intel.com>
Copy real FS/GSBASE values instead of approximation when FSGSBASE is
enabled.
Factoring out to save_fsgs() does not result in the same behavior because
save_base_legacy() does not copy FS/GSBASE when the index is zero.
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>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
---
arch/x86/kernel/process_64.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index d8ade9530fdb..648e43b58c69 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -477,10 +477,16 @@ 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;
+ savesegment(gs, p->thread.gsindex);
+ if (static_cpu_has(X86_FEATURE_FSGSBASE)) {
+ p->thread.fsbase = rdfsbase();
+ p->thread.gsbase = __rdgsbase_inactive();
+ } else {
+ /* save_base_legacy() does not set base when index is zero. */
+ p->thread.fsbase = p->thread.fsindex ? 0 : me->thread.fsbase;
+ p->thread.gsbase = p->thread.gsindex ? 0 : 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:[~2019-01-16 22:50 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-16 22:48 [PATCH v4 00/13] x86: Enable FSGSBASE instructions Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 01/13] taint: Introduce a new taint flag (insecure) Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 02/13] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 03/13] kbuild: Raise the minimum required binutils version to 2.21 Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 04/13] x86/fsgsbase/64: Add intrinsics/macros for FSGSBASE instructions Chang S. Bae
2019-01-17 5:09 ` Andi Kleen
2019-01-17 18:04 ` Bae, Chang Seok
2019-01-16 22:48 ` [PATCH v4 05/13] x86/fsgsbase/64: Enable FSGSBASE instructions in the helper functions Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 06/13] x86/fsgsbase/64: Preserve FS/GS state in __switch_to() if FSGSBASE is on Chang S. Bae
2019-01-16 22:48 ` Chang S. Bae [this message]
2019-01-16 22:48 ` [PATCH v4 08/13] x86/fsgsbase/64: Introduce the FIND_PERCPU_BASE macro Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 09/13] x86/fsgsbase/64: Use the per-CPU base as GSBASE at the paranoid_entry Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 10/13] selftests/x86/fsgsbase: Test WRGSBASE Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 11/13] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 12/13] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2019-01-16 22:48 ` [PATCH v4 13/13] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
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