[RFC/PATCH PV_OPS X86_64 14/17] paravirt_ops - vsyscall

[Steven Rostedt <rostedt@goodmis.org>]

plain text document attachment (xx-paravirt-vsyscall.patch)
vsyscall interface updates for paravirt ops.

Signed-off-by: Steven Rostedt srostedt@redhat.com
Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>


Index: clean-start/arch/x86_64/kernel/vsyscall.c
===================================================================
--- clean-start.orig/arch/x86_64/kernel/vsyscall.c
+++ clean-start/arch/x86_64/kernel/vsyscall.c
@@ -73,7 +73,7 @@ static __always_inline void do_vgettimeo
 		usec = __xtime.tv_nsec / 1000;
 
 		if (__vxtime.mode != VXTIME_HPET) {
-			t = get_cycles_sync();
+			t = vget_cycles_sync();
 			if (t < __vxtime.last_tsc)
 				t = __vxtime.last_tsc;
 			usec += ((t - __vxtime.last_tsc) *
@@ -147,8 +147,8 @@ 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 long j = 0;
+	unsigned int p;
+	unsigned long dummy, j = 0;
 
 	/* Fast cache - only recompute value once per jiffies and avoid
 	   relatively costly rdtscp/cpuid otherwise.
@@ -162,7 +162,8 @@ vgetcpu(unsigned *cpu, unsigned *node, s
 		p = tcache->blob[1];
 	} else if (__vgetcpu_mode == VGETCPU_RDTSCP) {
 		/* Load per CPU data from RDTSCP */
-		rdtscp(dummy, dummy, p);
+		/* rdtscp() cannot be called due to the paravirt indirection */
+		asm("rdtscp" : "=A" (dummy), "=c" (p));
 	} else {
 		/* Load per CPU data from GDT */
 		asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
@@ -256,7 +257,11 @@ static void __cpuinit vsyscall_set_cpu(i
 	node = cpu_to_node[cpu];
 #endif
 	if (cpu_has(&cpu_data[cpu], X86_FEATURE_RDTSCP))
-		write_rdtscp_aux((node << 12) | cpu);
+		/* This is write_rdtscp_aux. It cannot be called directly
+		 * due to the paravirt indirection */
+		asm("wrmsr"  :  /* no output */
+			     :  "d"(0),
+				"a" ((node << 12) | cpu), "c" (0xc0000103));
 
 	/* Store cpu number in limit so that it can be loaded quickly
 	   in user space in vgetcpu.
@@ -285,8 +290,12 @@ cpu_vsyscall_notifier(struct notifier_bl
 
 static void __init map_vsyscall(void)
 {
+#ifndef CONFIG_PARAVIRT
 	extern char __vsyscall_0;
 	unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
+#else
+	unsigned long physaddr_page0 = __pa_symbol(paravirt_ops.vsyscall_page);
+#endif
 
 	/* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */
 	__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
@@ -299,7 +308,14 @@ static int __init vsyscall_init(void)
 	BUG_ON((unsigned long) &vtime != VSYSCALL_ADDR(__NR_vtime));
 	BUG_ON((VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)));
 	BUG_ON((unsigned long) &vgetcpu != VSYSCALL_ADDR(__NR_vgetcpu));
-	map_vsyscall();
+#ifdef CONFIG_PARAVIRT
+	if (paravirt_ops.vsyscall_page)
+#endif
+		map_vsyscall();
+#ifdef CONFIG_PARAVIRT
+	else
+		__sysctl_vsyscall = 0;
+#endif
 #ifdef CONFIG_SYSCTL
 	register_sysctl_table(kernel_root_table2, 0);
 #endif

--