From: tip-bot for Andy Lutomirski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
chang.seok.bae@intel.com, ravi.v.shankar@intel.com,
ak@linux.intel.com, tglx@linutronix.de, hpa@zytor.com,
luto@kernel.org
Subject: [tip:x86/cpu] x86/cpu: Enable FSGSBASE on 64bit by default and add a chicken bit
Date: Sat, 22 Jun 2019 03:14:01 -0700 [thread overview]
Message-ID: <tip-2032f1f96ee0da600633c6c627b9c0a2e0f8b8a6@git.kernel.org> (raw)
In-Reply-To: <1557309753-24073-17-git-send-email-chang.seok.bae@intel.com>
Commit-ID: 2032f1f96ee0da600633c6c627b9c0a2e0f8b8a6
Gitweb: https://git.kernel.org/tip/2032f1f96ee0da600633c6c627b9c0a2e0f8b8a6
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Wed, 8 May 2019 03:02:31 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 22 Jun 2019 11:38:56 +0200
x86/cpu: Enable FSGSBASE on 64bit by default and add a chicken bit
Now that FSGSBASE is fully supported, remove unsafe_fsgsbase, enable
FSGSBASE by default, and add nofsgsbase to disable it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lkml.kernel.org/r/1557309753-24073-17-git-send-email-chang.seok.bae@intel.com
---
Documentation/admin-guide/kernel-parameters.txt | 3 +--
arch/x86/kernel/cpu/common.c | 32 +++++++++++--------------
2 files changed, 15 insertions(+), 20 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b0fa5273b0fc..35bc3c3574c6 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2857,8 +2857,7 @@
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.
+ nofsgsbase [X86] Disables FSGSBASE instructions.
no_console_suspend
[HW] Never suspend the console
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 71defe2d1b7c..1305f16b6105 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -366,21 +366,21 @@ out:
cr4_clear_bits(X86_CR4_UMIP);
}
-/*
- * 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)
+static __init int x86_nofsgsbase_setup(char *arg)
{
- unsafe_fsgsbase = true;
+ /* Require an exact match without trailing characters. */
+ if (strlen(arg))
+ return 0;
+
+ /* Do not emit a message if the feature is not present. */
+ if (!boot_cpu_has(X86_FEATURE_FSGSBASE))
+ return 1;
+
+ setup_clear_cpu_cap(X86_FEATURE_FSGSBASE);
+ pr_info("FSGSBASE disabled via kernel command line\n");
return 1;
}
-__setup("unsafe_fsgsbase", setup_unsafe_fsgsbase);
+__setup("nofsgsbase", x86_nofsgsbase_setup);
/*
* Protection Keys are not available in 32-bit mode.
@@ -1387,12 +1387,8 @@ static void identify_cpu(struct cpuinfo_x86 *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);
- }
+ if (cpu_has(c, X86_FEATURE_FSGSBASE))
+ cr4_set_bits(X86_CR4_FSGSBASE);
/*
* The vendor-specific functions might have changed features.
next prev parent reply other threads:[~2019-06-22 10:16 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-08 10:02 [PATCH v7 00/18] x86: Enable FSGSBASE instructions Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 01/18] x86/fsgsbase/64: Fix ARCH_SET_FS/GS behaviors for a remote task Chang S. Bae
[not found] ` <74F4F506-2913-4013-9D81-A0C69FA8CDF1@intel.com>
[not found] ` <6420E1A5-B5AD-4028-AA91-AA4D5445AC83@intel.com>
2019-06-16 15:44 ` Bae, Chang Seok
2019-06-16 16:32 ` Thomas Gleixner
2019-06-22 10:04 ` [tip:x86/cpu] x86/ptrace: Prevent ptrace from clearing the FS/GS selector tip-bot for Chang S. Bae
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 02/18] selftests/x86/fsgsbase: Test ptracer-induced GSBASE write Chang S. Bae
2019-06-22 10:04 ` [tip:x86/cpu] " tip-bot for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 03/18] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2019-06-22 10:05 ` [tip:x86/cpu] x86/cpu: " tip-bot for Andy Lutomirski
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Andy Lutomirski
2019-05-08 10:02 ` [PATCH v7 04/18] kbuild: Raise the minimum required binutils version to 2.21 Chang S. Bae
2019-06-22 10:06 ` [tip:x86/cpu] " tip-bot for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 05/18] x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions Chang S. Bae
2019-06-22 10:06 ` [tip:x86/cpu] " tip-bot for Andi Kleen
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Andi Kleen
2019-05-08 10:02 ` [PATCH v7 06/18] x86/fsgsbase/64: Enable FSGSBASE instructions in the helper functions Chang S. Bae
2019-06-22 10:07 ` [tip:x86/cpu] x86/fsgsbase/64: Enable FSGSBASE instructions in " tip-bot for Chang S. Bae
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 07/18] x86/fsgsbase/64: Preserve FS/GS state in __switch_to() if FSGSBASE is on Chang S. Bae
2019-06-21 15:22 ` Thomas Gleixner
2019-06-22 10:08 ` [tip:x86/cpu] x86/process/64: Use FSBSBASE in switch_to() if available tip-bot for Andy Lutomirski
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Andy Lutomirski
2019-05-08 10:02 ` [PATCH v7 08/18] x86/fsgsbase/64: When copying a thread, use the FSGSBASE instructions Chang S. Bae
2019-06-22 10:09 ` [tip:x86/cpu] x86/process/64: Use FSGSBASE instructions on thread copy and ptrace tip-bot for Chang S. Bae
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 09/18] x86/entry/64: Add the READ_MSR_GSBASE macro Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 10/18] x86/entry/64: Switch CR3 before SWAPGS on the paranoid entry Chang S. Bae
2019-06-22 10:09 ` [tip:x86/cpu] x86/entry/64: Switch CR3 before SWAPGS in " tip-bot for Chang S. Bae
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 11/18] x86/fsgsbase/64: Introduce the FIND_PERCPU_BASE macro Chang S. Bae
2019-06-22 10:10 ` [tip:x86/cpu] x86/entry/64: " tip-bot for Chang S. Bae
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 12/18] x86/fsgsbase/64: GSBASE handling with FSGSBASE in the paranoid path Chang S. Bae
2019-06-22 10:11 ` [tip:x86/cpu] x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit tip-bot for Chang S. Bae
2019-06-29 7:21 ` [PATCH v7 12/18] x86/fsgsbase/64: GSBASE handling with FSGSBASE in the paranoid path Bae, Chang Seok
2019-06-29 7:37 ` Thomas Gleixner
2020-06-18 13:50 ` [tip: x86/fsgsbase] x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit tip-bot2 for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 13/18] x86/fsgsbase/64: Document GSBASE handling in the paranoid path Chang S. Bae
2019-06-22 10:11 ` [tip:x86/cpu] x86/entry/64: " tip-bot for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 14/18] selftests/x86/fsgsbase: Test WRGSBASE Chang S. Bae
2019-06-22 10:12 ` [tip:x86/cpu] selftests/x86/fsgsbase: Test RD/WRGSBASE tip-bot for Andy Lutomirski
2019-05-08 10:02 ` [PATCH v7 15/18] selftests/x86/fsgsbase: Test ptracer-induced GSBASE write with FSGSBASE Chang S. Bae
2019-06-22 10:13 ` [tip:x86/cpu] " tip-bot for Chang S. Bae
2019-05-08 10:02 ` [PATCH v7 16/18] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2019-06-22 10:14 ` tip-bot for Andy Lutomirski [this message]
2020-06-18 13:50 ` [tip: x86/fsgsbase] x86/cpu: Enable FSGSBASE on 64bit " tip-bot2 for Andy Lutomirski
2019-05-08 10:02 ` [PATCH v7 17/18] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2019-06-22 10:14 ` [tip:x86/cpu] " tip-bot for Andi Kleen
2020-06-18 13:50 ` [tip: x86/fsgsbase] " tip-bot2 for Andi Kleen
2019-05-08 10:02 ` [PATCH v7 18/18] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
2019-06-14 6:54 ` Thomas Gleixner
2019-06-14 20:07 ` Bae, Chang Seok
[not found] ` <89BE934A-A392-4CED-83E5-CA4FADDAE6DF@intel.com>
2019-06-16 8:39 ` Thomas Gleixner
2019-06-16 12:34 ` Thomas Gleixner
2019-06-16 15:34 ` Bae, Chang Seok
2019-06-16 16:05 ` Thomas Gleixner
2019-06-16 20:48 ` Bae, Chang Seok
2019-06-16 22:00 ` Thomas Gleixner
[not found] ` <8E2E84B6-BCCC-424D-A1A7-604828B389FB@intel.com>
2019-06-17 5:18 ` Thomas Gleixner
2019-06-16 15:54 ` Randy Dunlap
2019-06-16 16:07 ` Thomas Gleixner
2019-06-22 10:15 ` [tip:x86/cpu] Documentation/x86/64: Add documentation for GS/FS addressing mode tip-bot for Thomas Gleixner
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