Commit 36f06199 authored by Linus Torvalds's avatar Linus Torvalds

Cache the MSR_IA32_SYSENTER_CS value in the per-CPU TSS (using

the otherwise unused cpl1 entry for SS), so that we can avoid
re-loading it on task switches if it doesn't change.
parent d1537fd1
......@@ -40,6 +40,7 @@ void enable_sep_cpu(void *info)
int cpu = get_cpu();
struct tss_struct *tss = init_tss + cpu;
tss->ss1 = __KERNEL_CS;
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
wrmsr(MSR_IA32_SYSENTER_ESP, tss->esp0, 0);
wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long) sysenter_entry, 0);
......
......@@ -291,7 +291,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
tss = init_tss + smp_processor_id();
tss->esp0 = tsk->thread.esp0 = (unsigned long) &info->VM86_TSS_ESP0;
disable_sysenter();
disable_sysenter(tss);
tsk->thread.screen_bitmap = info->screen_bitmap;
if (info->flags & VM86_SCREEN_BITMAP)
......
......@@ -347,7 +347,7 @@ struct tss_struct {
unsigned long esp0;
unsigned short ss0,__ss0h;
unsigned long esp1;
unsigned short ss1,__ss1h;
unsigned short ss1,__ss1h; /* ss1 is used to cache MSR_IA32_SYSENTER_CS */
unsigned long esp2;
unsigned short ss2,__ss2h;
unsigned long __cr3;
......@@ -413,15 +413,20 @@ static inline void load_esp0(struct tss_struct *tss, unsigned long esp0)
{
tss->esp0 = esp0;
if (cpu_has_sep) {
if (tss->ss1 != __KERNEL_CS) {
tss->ss1 = __KERNEL_CS;
wrmsr(MSR_IA32_SYSENTER_CS, __KERNEL_CS, 0);
}
wrmsr(MSR_IA32_SYSENTER_ESP, esp0, 0);
}
}
static inline void disable_sysenter(void)
static inline void disable_sysenter(struct tss_struct *tss)
{
if (cpu_has_sep)
if (cpu_has_sep) {
tss->ss1 = 0;
wrmsr(MSR_IA32_SYSENTER_CS, 0, 0);
}
}
#define start_thread(regs, new_eip, new_esp) do { \
......
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