x86_64/vdso: Move getcpu code from vsyscall_64.c to vdso/vma.c

This is pure cut-and-paste.  At this point, vsyscall_64.c
contains only code needed for vsyscall emulation, but some of
the comments and function names are still confused.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/a244daf7d3cbe71afc08ad09fdfe1866ca1f1978.1411494540.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 970463b566cf..a155dca5edb5 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -10,12 +10,14 @@
 #include <linux/init.h>
 #include <linux/random.h>
 #include <linux/elf.h>
+#include <linux/cpu.h>
 #include <asm/vsyscall.h>
 #include <asm/vgtod.h>
 #include <asm/proto.h>
 #include <asm/vdso.h>
 #include <asm/page.h>
 #include <asm/hpet.h>
+#include <asm/desc.h>
 
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
@@ -238,3 +240,62 @@ static __init int vdso_setup(char *s)
 }
 __setup("vdso=", vdso_setup);
 #endif
+
+#ifdef CONFIG_X86_64
+/*
+ * Assume __initcall executes before all user space. Hopefully kmod
+ * doesn't violate that. We'll find out if it does.
+ */
+static void vsyscall_set_cpu(int cpu)
+{
+	unsigned long d;
+	unsigned long node = 0;
+#ifdef CONFIG_NUMA
+	node = cpu_to_node(cpu);
+#endif
+	if (cpu_has(&cpu_data(cpu), X86_FEATURE_RDTSCP))
+		write_rdtscp_aux((node << 12) | cpu);
+
+	/*
+	 * Store cpu number in limit so that it can be loaded quickly
+	 * in user space in vgetcpu. (12 bits for the CPU and 8 bits for the node)
+	 */
+	d = 0x0f40000000000ULL;
+	d |= cpu;
+	d |= (node & 0xf) << 12;
+	d |= (node >> 4) << 48;
+
+	write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S);
+}
+
+static void cpu_vsyscall_init(void *arg)
+{
+	/* preemption should be already off */
+	vsyscall_set_cpu(raw_smp_processor_id());
+}
+
+static int
+cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg)
+{
+	long cpu = (long)arg;
+
+	if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN)
+		smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 1);
+
+	return NOTIFY_DONE;
+}
+
+static int __init vsyscall_init(void)
+{
+	cpu_notifier_register_begin();
+
+	on_each_cpu(cpu_vsyscall_init, NULL, 1);
+	/* notifier priority > KVM */
+	__hotcpu_notifier(cpu_vsyscall_notifier, 30);
+
+	cpu_notifier_register_done();
+
+	return 0;
+}
+__initcall(vsyscall_init);
+#endif