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From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: Andy Lutomirski <luto@kernel.org>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Markus T Metzger <markus.t.metzger@intel.com>,
	"Ravi V . Shankar" <ravi.v.shankar@intel.com>,
	"Chang S . Bae" <chang.seok.bae@intel.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH V2 11/15] x86/fsgsbase/64: When copying a thread, use FSGSBASE if enabled
Date: Thu, 31 May 2018 10:58:41 -0700	[thread overview]
Message-ID: <1527789525-8857-12-git-send-email-chang.seok.bae@intel.com> (raw)
In-Reply-To: <1527789525-8857-1-git-send-email-chang.seok.bae@intel.com>

When FSGSBASE enabled, copy real FS/GS base values instead
of approximation.

Factor out to save_fsgs() does not yield the exact same
behavior, because save_base_legacy() does not copy FS/GS base
when 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: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
---
 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 55af719..8f9f2f9 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -505,10 +505,16 @@ 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 = rd_inactive_gsbase();
+	} 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));
-- 
2.7.4

  parent reply	other threads:[~2018-05-31 18:00 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-31 17:58 [PATCH V2 00/15] x86: Enable FSGSBASE instructions Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 01/15] x86/fsgsbase/64: Introduce FS/GS base helper functions Chang S. Bae
2018-05-31 20:14   ` Andy Lutomirski
2018-05-31 21:03     ` Bae, Chang Seok
2018-05-31 17:58 ` [PATCH V2 02/15] x86/fsgsbase/64: Make ptrace read FS/GS base accurately Chang S. Bae
2018-05-31 20:14   ` Andy Lutomirski
2018-05-31 20:31     ` hpa
2018-05-31 20:38       ` Andy Lutomirski
2018-05-31 17:58 ` [PATCH V2 03/15] x86/fsgsbase/64: Use FS/GS base helpers in core dump Chang S. Bae
2018-05-31 20:15   ` Andy Lutomirski
2018-05-31 21:03     ` Bae, Chang Seok
2018-05-31 17:58 ` [PATCH V2 04/15] x86/fsgsbase/64: Factor out load FS/GS segments from __switch_to Chang S. Bae
2018-05-31 20:16   ` Andy Lutomirski
2018-05-31 17:58 ` [PATCH V2 05/15] x86/vdso: Move out the CPU number store Chang S. Bae
2018-05-31 20:25   ` Andy Lutomirski
2018-05-31 21:06     ` Bae, Chang Seok
2018-06-05  7:02   ` [lkp-robot] [x86/vdso] f52001961d: BUG:kernel_hang_in_early-boot_stage,last_printk:Probing_EDD(edd=off_to_disable)...ok kernel test robot
2018-05-31 17:58 ` [PATCH V2 06/15] taint: Add taint for insecure Chang S. Bae
2018-05-31 20:25   ` Andy Lutomirski
2018-05-31 20:50     ` hpa
2018-05-31 17:58 ` [PATCH V2 07/15] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 08/15] x86/fsgsbase/64: Add intrinsics/macros for FSGSBASE instructions Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 09/15] x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 10/15] x86/fsgsbase/64: Preserve FS/GS state in __switch_to if FSGSBASE is on Chang S. Bae
2018-05-31 17:58 ` Chang S. Bae [this message]
2018-05-31 17:58 ` [PATCH V2 12/15] x86/fsgsbase/64: Use per-CPU base as GS base on paranoid_entry Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 13/15] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 14/15] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 15/15] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
2018-05-31 20:37 ` [PATCH V2 00/15] x86: Enable FSGSBASE instructions Andy Lutomirski
2018-05-31 21:11   ` Bae, Chang Seok

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