linux-kernel - [PATCH 4.4 091/107] x86/speculation: Rework speculative_store_bypass

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Date:   Mon, 23 Jul 2018 14:42:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...e.de>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        "Srivatsa S. Bhat" <srivatsa@...il.mit.edu>,
        "Matt Helsley (VMware)" <matt.helsley@...il.com>,
        Alexey Makhalov <amakhalov@...are.com>,
        Bo Gan <ganb@...are.com>
Subject: [PATCH 4.4 091/107] x86/speculation: Rework speculative_store_bypass_update()

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@...utronix.de>

commit 0270be3e34efb05a88bc4c422572ece038ef3608 upstream

The upcoming support for the virtual SPEC_CTRL MSR on AMD needs to reuse
speculative_store_bypass_update() to avoid code duplication. Add an
argument for supplying a thread info (TIF) value and create a wrapper
speculative_store_bypass_update_current() which is used at the existing
call site.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa@...il.mit.edu>
Reviewed-by: Matt Helsley (VMware) <matt.helsley@...il.com>
Reviewed-by: Alexey Makhalov <amakhalov@...are.com>
Reviewed-by: Bo Gan <ganb@...are.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---

 arch/x86/include/asm/spec-ctrl.h |    7 ++++++-
 arch/x86/kernel/cpu/bugs.c       |    2 +-
 arch/x86/kernel/process.c        |    4 ++--
 3 files changed, 9 insertions(+), 4 deletions(-)

--- a/arch/x86/include/asm/spec-ctrl.h
+++ b/arch/x86/include/asm/spec-ctrl.h
@@ -42,6 +42,11 @@ extern void speculative_store_bypass_ht_
 static inline void speculative_store_bypass_ht_init(void) { }
 #endif
 
-extern void speculative_store_bypass_update(void);
+extern void speculative_store_bypass_update(unsigned long tif);
+
+static inline void speculative_store_bypass_update_current(void)
+{
+	speculative_store_bypass_update(current_thread_info()->flags);
+}
 
 #endif
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -596,7 +596,7 @@ static int ssb_prctl_set(struct task_str
 	 * mitigation until it is next scheduled.
 	 */
 	if (task == current && update)
-		speculative_store_bypass_update();
+		speculative_store_bypass_update_current();
 
 	return 0;
 }
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -334,10 +334,10 @@ static __always_inline void __speculativ
 		intel_set_ssb_state(tifn);
 }
 
-void speculative_store_bypass_update(void)
+void speculative_store_bypass_update(unsigned long tif)
 {
 	preempt_disable();
-	__speculative_store_bypass_update(current_thread_info()->flags);
+	__speculative_store_bypass_update(tif);
 	preempt_enable();
 }