[SRU][Trusty][PATCH] x86/asm/msr: Make wrmsrl_safe() a function

[Juerg Haefliger]

From: Andy Lutomirski <luto at kernel.org>

CVE-2017-5753
CVE-2017-5715

The wrmsrl_safe macro performs invalid shifts if the value
argument is 32 bits.  This makes it unnecessarily awkward to
write code that puts an unsigned long into an MSR.

Convert it to a real inline function.

For inspiration, see:

  7c74d5b7b7b6 ("x86/asm/entry/64: Fix MSR_IA32_SYSENTER_CS MSR value").

Signed-off-by: Andy Lutomirski <luto at kernel.org>
Cc: <linux-kernel at vger.kernel.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: H. Peter Anvin <hpa at zytor.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
[ Applied small improvements. ]
Signed-off-by: Ingo Molnar <mingo at kernel.org>
(cherry picked from commit cf991de2f614f454b3cb2a300c06ecdf69f3a70d)
Signed-off-by: Juerg Haefliger <juerg.haefliger at canonical.com>
---
 arch/x86/include/asm/msr.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index de36f22eb0b9..13bf576c401d 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -205,8 +205,13 @@ do {                                                            \
 
 #endif	/* !CONFIG_PARAVIRT */
 
-#define wrmsrl_safe(msr, val) wrmsr_safe((msr), (u32)(val),		\
-					     (u32)((val) >> 32))
+/*
+ * 64-bit version of wrmsr_safe():
+ */
+static inline int wrmsrl_safe(u32 msr, u64 val)
+{
+	return wrmsr_safe(msr, (u32)val,  (u32)(val >> 32));
+}
 
 #define write_tsc(low, high) wrmsr(MSR_IA32_TSC, (low), (high))
 
-- 
2.14.1