x86: introduce native_read_tscp

Targetting paravirt, this patch introduces native_read_tscp, in
place of rdtscp() macro. When in a paravirt guest, this will
involve a function call, and thus, cannot be done in the vdso area.
These users then have to call the native version directly

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 4 insertions, 4 deletions

diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 018f7cf33790..c4c5e765cd2c 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -190,7 +190,7 @@ time_t __vsyscall(1) vtime(time_t *t)
 long __vsyscall(2)
 vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
 {
-        unsigned int dummy, p;
+        unsigned int p;
         unsigned long j = 0;
 
         /* Fast cache - only recompute value once per jiffies and avoid
@@ -205,7 +205,7 @@ vgetcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
                 p = tcache->blob[1];
         } else if (__vgetcpu_mode == VGETCPU_RDTSCP) {
                 /* Load per CPU data from RDTSCP */
-                rdtscp(dummy, dummy, p);
+                native_read_tscp(&p);
         } else {
                 /* Load per CPU data from GDT */
                 asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
diff --git a/arch/x86/vdso/vgetcpu.c b/arch/x86/vdso/vgetcpu.c
index 3b1ae1abfba9..c8097f17f8a9 100644
--- a/arch/x86/vdso/vgetcpu.c
+++ b/arch/x86/vdso/vgetcpu.c
@@ -15,11 +15,11 @@
 
 long __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
 {
-        unsigned int dummy, p;
+        unsigned int p;
 
         if (*vdso_vgetcpu_mode == VGETCPU_RDTSCP) {
                 /* Load per CPU data from RDTSCP */
-                rdtscp(dummy, dummy, p);
+                native_read_tscp(&p);
         } else {
                 /* Load per CPU data from GDT */
                 asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));