From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@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>,
Andrew Morton <akpm@linux-foundation.org>,
Randy Dunlap <rdunlap@infradead.org>
Subject: [RESEND PATCH v6 01/12] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE
Date: Fri, 15 Mar 2019 13:06:34 -0700 [thread overview]
Message-ID: <1552680405-5265-2-git-send-email-chang.seok.bae@intel.com> (raw)
In-Reply-To: <1552680405-5265-1-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: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
---
.../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 cf8f5877d85f..b6ed956a78ab 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2765,6 +2765,9 @@
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 cb28e98a0659..40a2f60e7251 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -365,6 +365,22 @@ static __always_inline void setup_umip(struct cpuinfo_x86 *c)
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)
+{
+ unsafe_fsgsbase = true;
+ return 1;
+}
+__setup("unsafe_fsgsbase", setup_unsafe_fsgsbase);
+
/*
* Protection Keys are not available in 32-bit mode.
*/
@@ -1352,6 +1368,14 @@ 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."
--
2.19.1
next prev parent reply other threads:[~2019-03-15 20:08 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-15 20:06 [RESEND PATCH v6 00/12] x86: Enable FSGSBASE instructions Chang S. Bae
2019-03-15 20:06 ` Chang S. Bae [this message]
2019-03-15 20:06 ` [RESEND PATCH v6 02/12] kbuild: Raise the minimum required binutils version to 2.21 Chang S. Bae
2019-03-15 20:06 ` [RESEND PATCH v6 03/12] x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions Chang S. Bae
2019-03-15 20:06 ` [RESEND PATCH v6 04/12] x86/fsgsbase/64: Enable FSGSBASE instructions in the helper functions Chang S. Bae
2019-03-25 11:38 ` Thomas Gleixner
2019-03-25 12:46 ` Thomas Gleixner
2019-03-25 13:05 ` Thomas Gleixner
2019-03-26 0:38 ` Andi Kleen
2019-03-26 15:01 ` New feature/ABI review process [was Re: [RESEND PATCH v6 04/12] x86/fsgsbase/64:..] Thomas Gleixner
2019-03-26 22:56 ` Andi Kleen
2019-03-27 21:15 ` Thomas Gleixner
2019-03-15 20:06 ` [RESEND PATCH v6 05/12] x86/fsgsbase/64: Preserve FS/GS state in __switch_to() if FSGSBASE is on Chang S. Bae
2019-03-15 20:06 ` [RESEND PATCH v6 06/12] x86/fsgsbase/64: When copying a thread, use the FSGSBASE instructions if available Chang S. Bae
2019-03-15 20:06 ` [RESEND PATCH v6 07/12] x86/fsgsbase/64: Introduce the FIND_PERCPU_BASE macro Chang S. Bae
2019-03-25 9:02 ` Thomas Gleixner
2019-05-01 13:52 ` Bae, Chang Seok
2019-03-15 20:06 ` [RESEND PATCH v6 08/12] x86/fsgsbase/64: Use the per-CPU base as GSBASE at the paranoid_entry Chang S. Bae
2019-03-25 9:44 ` Thomas Gleixner
2019-04-05 8:35 ` Thomas Gleixner
2019-04-05 13:50 ` Andy Lutomirski
2019-05-01 13:52 ` Bae, Chang Seok
2019-05-01 17:40 ` Andy Lutomirski
2019-05-01 18:01 ` Bae, Chang Seok
[not found] ` <7029A32B-958E-4C1E-8B5F-D49BA68E4755@intel.com>
2019-05-01 20:25 ` Andy Lutomirski
2019-05-01 21:04 ` Bae, Chang Seok
2019-05-02 0:29 ` Andy Lutomirski
2019-05-06 22:56 ` Bae, Chang Seok
2019-03-15 20:06 ` [RESEND PATCH v6 09/12] selftests/x86/fsgsbase: Test WRGSBASE Chang S. Bae
2019-03-15 20:06 ` [RESEND PATCH v6 10/12] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2019-03-15 20:06 ` [RESEND PATCH v6 11/12] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2019-03-15 20:06 ` [RESEND PATCH v6 12/12] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
2019-03-30 16:15 ` Randy Dunlap
2019-03-26 0:43 ` [RESEND PATCH v6 00/12] x86: Enable FSGSBASE instructions Andy Lutomirski
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