linux-kernel - [tip:sched/urgent] lockin/x86: Implement sync_core_before

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 5 Feb 2018 13:28:41 -0800
From:   tip-bot for Mathieu Desnoyers <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     paulmck@...ux.vnet.ibm.com, hpa@...or.com, tglx@...utronix.de,
        linux@...linux.org.uk, paulus@...ba.org, parri.andrea@...il.com,
        torvalds@...ux-foundation.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org, sehr@...gle.com, ahh@...gle.com,
        luto@...nel.org, avi@...lladb.com, mathieu.desnoyers@...icios.com,
        mingo@...nel.org, mpe@...erman.id.au, will.deacon@....com,
        davejwatson@...com, benh@...nel.crashing.org, arnd@...db.de,
        ghackmann@...gle.com, maged.michael@...il.com, boqun.feng@...il.com
Subject: [tip:sched/urgent] lockin/x86: Implement
 sync_core_before_usermode()

Commit-ID:  ac1ab12a3e6e878274e7107c8c6f326694a1c1f3
Gitweb:     https://git.kernel.org/tip/ac1ab12a3e6e878274e7107c8c6f326694a1c1f3
Author:     Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
AuthorDate: Mon, 29 Jan 2018 15:20:16 -0500
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 5 Feb 2018 21:34:57 +0100

lockin/x86: Implement sync_core_before_usermode()

Ensure that a core serializing instruction is issued before returning to
user-mode. x86 implements return to user-space through sysexit, sysrel,
and sysretq, which are not core serializing.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Acked-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Andrea Parri <parri.andrea@...il.com>
Cc: Andrew Hunter <ahh@...gle.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Avi Kivity <avi@...lladb.com>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Dave Watson <davejwatson@...com>
Cc: David Sehr <sehr@...gle.com>
Cc: Greg Hackmann <ghackmann@...gle.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Maged Michael <maged.michael@...il.com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Russell King <linux@...linux.org.uk>
Cc: Will Deacon <will.deacon@....com>
Cc: linux-api@...r.kernel.org
Cc: linux-arch@...r.kernel.org
Link: http://lkml.kernel.org/r/20180129202020.8515-8-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/Kconfig                 |  1 +
 arch/x86/include/asm/sync_core.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 423e4b6..31030ad 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -61,6 +61,7 @@ config X86
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_HAS_STRICT_MODULE_RWX
+	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_HAS_ZONE_DEVICE		if X86_64
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
diff --git a/arch/x86/include/asm/sync_core.h b/arch/x86/include/asm/sync_core.h
new file mode 100644
index 0000000..c67caaf
--- /dev/null
+++ b/arch/x86/include/asm/sync_core.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_SYNC_CORE_H
+#define _ASM_X86_SYNC_CORE_H
+
+#include <linux/preempt.h>
+#include <asm/processor.h>
+#include <asm/cpufeature.h>
+
+/*
+ * Ensure that a core serializing instruction is issued before returning
+ * to user-mode. x86 implements return to user-space through sysexit,
+ * sysrel, and sysretq, which are not core serializing.
+ */
+static inline void sync_core_before_usermode(void)
+{
+	/* With PTI, we unconditionally serialize before running user code. */
+	if (static_cpu_has(X86_FEATURE_PTI))
+		return;
+	/*
+	 * Return from interrupt and NMI is done through iret, which is core
+	 * serializing.
+	 */
+	if (in_irq() || in_nmi())
+		return;
+	sync_core();
+}
+
+#endif /* _ASM_X86_SYNC_CORE_H */