1 files changed, 65 insertions, 0 deletions

diff --git a/arch/i386/kernel/sysenter.c b/arch/i386/kernel/sysenter.c
new file mode 100644
index 000000000000..960d8bd137d0
--- /dev/null
+++ b/arch/i386/kernel/sysenter.c
@@ -0,0 +1,65 @@
+/*
+ * linux/arch/i386/kernel/sysenter.c
+ *
+ * (C) Copyright 2002 Linus Torvalds
+ *
+ * This file contains the needed initializations to support sysenter.
+ */
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/thread_info.h>
+#include <linux/sched.h>
+#include <linux/gfp.h>
+#include <linux/string.h>
+#include <linux/elf.h>
+
+#include <asm/cpufeature.h>
+#include <asm/msr.h>
+#include <asm/pgtable.h>
+#include <asm/unistd.h>
+
+extern asmlinkage void sysenter_entry(void);
+
+void enable_sep_cpu(void *info)
+{
+        int cpu = get_cpu();
+        struct tss_struct *tss = &per_cpu(init_tss, cpu);
+
+        tss->ss1 = __KERNEL_CS;
+        tss->esp1 = sizeof(struct tss_struct) + (unsigned long) tss;
+        wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
+        wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp1, 0);
+        wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0);
+        put_cpu();      
+}
+
+/*
+ * These symbols are defined by vsyscall.o to mark the bounds
+ * of the ELF DSO images included therein.
+ */
+extern const char vsyscall_int80_start, vsyscall_int80_end;
+extern const char vsyscall_sysenter_start, vsyscall_sysenter_end;
+
+static int __init sysenter_setup(void)
+{
+        void *page = (void *)get_zeroed_page(GFP_ATOMIC);
+
+        __set_fixmap(FIX_VSYSCALL, __pa(page), PAGE_READONLY_EXEC);
+
+        if (!boot_cpu_has(X86_FEATURE_SEP)) {
+                memcpy(page,
+                       &vsyscall_int80_start,
+                       &vsyscall_int80_end - &vsyscall_int80_start);
+                return 0;
+        }
+
+        memcpy(page,
+               &vsyscall_sysenter_start,
+               &vsyscall_sysenter_end - &vsyscall_sysenter_start);
+
+        on_each_cpu(enable_sep_cpu, NULL, 1, 1);
+        return 0;
+}
+
+__initcall(sysenter_setup);