[PATCH 3.16 040/131] x86/speculation: Rework speculative_store_bypass_update()

[Ben Hutchings]

3.16.59-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Reviewed-by: Borislav Petkov <bp@xxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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
@@ -635,7 +635,7 @@ 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
@@ -352,10 +352,10 @@ 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();
 }