From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: linux-kernel@vger.kernel.org, tglx@linutronix.de, bp@alien8.de,
luto@kernel.org
Cc: hpa@zytor.com, dave.hansen@intel.com, tony.luck@intel.com,
ak@linux.intel.com, ravi.v.shankar@intel.com,
chang.seok.bae@intel.com
Subject: [PATCH v9 03/17] x86/cpu: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE
Date: Fri, 4 Oct 2019 11:15:55 -0700 [thread overview]
Message-ID: <1570212969-21888-4-git-send-email-chang.seok.bae@intel.com> (raw)
In-Reply-To: <1570212969-21888-1-git-send-email-chang.seok.bae@intel.com>
From: Andy Lutomirski <luto@kernel.org>
This is temporary. It will allow the next few patches to be tested
incrementally.
Setting unsafe_fsgsbase is a root hole. Don't do it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
---
Changes from v8: none
Changes from v7: none
---
Documentation/admin-guide/kernel-parameters.txt | 3 +++
arch/x86/kernel/cpu/common.c | 24 ++++++++++++++++++++++++
2 files changed, 27 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index c7ac2f3..eb9a491 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2899,6 +2899,9 @@
no5lvl [X86-64] Disable 5-level paging mode. Forces
kernel to use 4-level paging instead.
+ unsafe_fsgsbase [X86] Allow FSGSBASE instructions. This will be
+ replaced with a nofsgsbase flag.
+
no_console_suspend
[HW] Never suspend the console
Disable suspending of consoles during suspend and
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 9ae7d1b..9f57fb0 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -438,6 +438,22 @@ static void __init setup_cr_pinning(void)
}
/*
+ * Temporary hack: FSGSBASE is unsafe until a few kernel code paths are
+ * updated. This allows us to get the kernel ready incrementally.
+ *
+ * Once all the pieces are in place, these will go away and be replaced with
+ * a nofsgsbase chicken flag.
+ */
+static bool unsafe_fsgsbase;
+
+static __init int setup_unsafe_fsgsbase(char *arg)
+{
+ unsafe_fsgsbase = true;
+ return 1;
+}
+__setup("unsafe_fsgsbase", setup_unsafe_fsgsbase);
+
+/*
* Protection Keys are not available in 32-bit mode.
*/
static bool pku_disabled;
@@ -1455,6 +1471,14 @@ static void identify_cpu(struct cpuinfo_x86 *c)
setup_smap(c);
setup_umip(c);
+ /* Enable FSGSBASE instructions if available. */
+ if (cpu_has(c, X86_FEATURE_FSGSBASE)) {
+ if (unsafe_fsgsbase)
+ cr4_set_bits(X86_CR4_FSGSBASE);
+ else
+ clear_cpu_cap(c, X86_FEATURE_FSGSBASE);
+ }
+
/*
* The vendor-specific functions might have changed features.
* Now we do "generic changes."
--
2.7.4
next prev parent reply other threads:[~2019-10-04 18:17 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 18:15 [PATCH v9 00/17] Enable FSGSBASE instructions Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 01/17] x86/ptrace: Prevent ptrace from clearing the FS/GS selector Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 02/17] selftests/x86/fsgsbase: Test GS selector on ptracer-induced GS base write Chang S. Bae
2019-10-04 18:15 ` Chang S. Bae [this message]
2019-10-04 18:15 ` [PATCH v9 04/17] x86/entry/64: Clean up paranoid exit Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 05/17] x86/entry/64: Switch CR3 before SWAPGS in paranoid entry Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 06/17] x86/entry/64: Introduce the FIND_PERCPU_BASE macro Chang S. Bae
2019-10-04 18:15 ` [PATCH v9 07/17] x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 08/17] x86/entry/64: Document GSBASE handling in the paranoid path Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 09/17] x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 10/17] x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 11/17] x86/fsgsbase/64: Use FSGSBASE in switch_to() if available Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 12/17] x86/fsgsbase/64: Use FSGSBASE instructions on thread copy and ptrace Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 13/17] x86/speculation/swapgs: Check FSGSBASE in enabling SWAPGS mitigation Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 14/17] selftests/x86/fsgsbase: Test ptracer-induced GS base write with FSGSBASE Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 15/17] x86/fsgsbase/64: Enable FSGSBASE on 64bit by default and add a chicken bit Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 16/17] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2019-10-04 18:16 ` [PATCH v9 17/17] Documentation/x86/64: Add documentation for GS/FS addressing mode Chang S. Bae
2019-10-04 22:54 ` Randy Dunlap
2019-11-15 18:29 ` [PATCH v9 00/17] Enable FSGSBASE instructions Thomas Gleixner
2019-11-15 19:12 ` Andi Kleen
2019-11-29 14:56 ` Metzger, Markus T
2019-11-29 16:51 ` Andy Lutomirski
2019-12-02 8:23 ` Metzger, Markus T
2019-12-04 20:20 ` Andy Lutomirski
2019-12-10 8:27 ` Metzger, Markus T
2020-02-24 18:02 ` Bae, Chang Seok
2020-04-13 20:03 ` Sasha Levin
2020-04-14 0:32 ` Andi Kleen
2020-04-17 13:30 ` Sasha Levin
2020-04-17 15:52 ` Andy Lutomirski
2020-04-20 14:13 ` Andi Kleen
2020-04-20 17:14 ` Thomas Gleixner
2020-04-21 16:06 ` Sasha Levin
2020-04-21 16:49 ` Andy Lutomirski
2020-04-21 20:02 ` Andi Kleen
2020-04-21 17:15 ` Bae, Chang Seok
2020-04-21 19:56 ` Andi Kleen
2020-04-21 20:21 ` Andy Lutomirski
2020-04-21 20:51 ` Sasha Levin
2020-04-22 23:00 ` Andy Lutomirski
2020-04-23 4:08 ` Sasha Levin
2020-04-25 22:39 ` Thomas Gleixner
2020-04-26 2:52 ` Sasha Levin
2020-04-26 10:04 ` Thomas Gleixner
2020-04-14 15:47 ` Bae, Chang Seok
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