aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/include/asm/desc.h
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/include/asm/desc.h')
-rw-r--r--arch/x86/include/asm/desc.h58
1 files changed, 49 insertions, 9 deletions
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 12080d87da3b..cb8f9149f6c8 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -177,16 +177,8 @@ static inline void __set_tss_desc(unsigned cpu, unsigned int entry, void *addr)
struct desc_struct *d = get_cpu_gdt_table(cpu);
tss_desc tss;
- /*
- * sizeof(unsigned long) coming from an extra "long" at the end
- * of the iobitmap. See tss_struct definition in processor.h
- *
- * -1? seg base+limit should be pointing to the address of the
- * last valid byte
- */
set_tssldt_descriptor(&tss, (unsigned long)addr, DESC_TSS,
- IO_BITMAP_OFFSET + IO_BITMAP_BYTES +
- sizeof(unsigned long) - 1);
+ __KERNEL_TSS_LIMIT);
write_gdt_entry(d, entry, &tss, DESC_TSS);
}
@@ -213,6 +205,54 @@ static inline void native_load_tr_desc(void)
asm volatile("ltr %w0"::"q" (GDT_ENTRY_TSS*8));
}
+static inline void force_reload_TR(void)
+{
+ struct desc_struct *d = get_cpu_gdt_table(smp_processor_id());
+ tss_desc tss;
+
+ memcpy(&tss, &d[GDT_ENTRY_TSS], sizeof(tss_desc));
+
+ /*
+ * LTR requires an available TSS, and the TSS is currently
+ * busy. Make it be available so that LTR will work.
+ */
+ tss.type = DESC_TSS;
+ write_gdt_entry(d, GDT_ENTRY_TSS, &tss, DESC_TSS);
+
+ load_TR_desc();
+}
+
+DECLARE_PER_CPU(bool, need_tr_refresh);
+
+static inline void refresh_TR(void)
+{
+ DEBUG_LOCKS_WARN_ON(preemptible());
+
+ if (unlikely(this_cpu_read(need_tr_refresh))) {
+ force_reload_TR();
+ this_cpu_write(need_tr_refresh, false);
+ }
+}
+
+/*
+ * If you do something evil that corrupts the cached TSS limit (I'm looking
+ * at you, VMX exits), call this function.
+ *
+ * The optimization here is that the TSS limit only matters for Linux if the
+ * IO bitmap is in use. If the TSS limit gets forced to its minimum value,
+ * everything works except that IO bitmap will be ignored and all CPL 3 IO
+ * instructions will #GP, which is exactly what we want for normal tasks.
+ */
+static inline void invalidate_tss_limit(void)
+{
+ DEBUG_LOCKS_WARN_ON(preemptible());
+
+ if (unlikely(test_thread_flag(TIF_IO_BITMAP)))
+ force_reload_TR();
+ else
+ this_cpu_write(need_tr_refresh, true);
+}
+
static inline void native_load_gdt(const struct desc_ptr *dtr)
{
asm volatile("lgdt %0"::"m" (*dtr));

Privacy Policy