x86, traps, i386: factor out lazy io-bitmap copy

x86_64 does not do the lazy io-bitmap dance. Putting it in
its own function makes i386's do_general_protection look
much more like x86_64's.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 43 insertions, 33 deletions

diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index ce1063c141fc..0206c915748c 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -95,6 +95,47 @@ die_if_kernel(const char *str, struct pt_regs *regs, long err)
                 die(str, regs, err);
 }
 
+/*
+ * Perform the lazy TSS's I/O bitmap copy. If the TSS has an
+ * invalid offset set (the LAZY one) and the faulting thread has
+ * a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS,
+ * we set the offset field correctly and return 1.
+ */
+static int lazy_iobitmap_copy(void)
+{
+        struct thread_struct *thread;
+        struct tss_struct *tss;
+        int cpu;
+
+        cpu = get_cpu();
+        tss = &per_cpu(init_tss, cpu);
+        thread = &current->thread;
+
+        if (tss->x86_tss.io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
+            thread->io_bitmap_ptr) {
+                memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
+                       thread->io_bitmap_max);
+                /*
+                 * If the previously set map was extending to higher ports
+                 * than the current one, pad extra space with 0xff (no access).
+                 */
+                if (thread->io_bitmap_max < tss->io_bitmap_max) {
+                        memset((char *) tss->io_bitmap +
+                                thread->io_bitmap_max, 0xff,
+                                tss->io_bitmap_max - thread->io_bitmap_max);
+                }
+                tss->io_bitmap_max = thread->io_bitmap_max;
+                tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
+                tss->io_bitmap_owner = thread;
+                put_cpu();
+
+                return 1;
+        }
+        put_cpu();
+
+        return 0;
+}
+
 static void __kprobes
 do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
         long error_code, siginfo_t *info)
@@ -187,44 +228,13 @@ void __kprobes
 do_general_protection(struct pt_regs *regs, long error_code)
 {
         struct task_struct *tsk;
-        struct thread_struct *thread;
-        struct tss_struct *tss;
-        int cpu;
 
         conditional_sti(regs);
 
-        cpu = get_cpu();
-        tss = &per_cpu(init_tss, cpu);
-        thread = &current->thread;
-
-        /*
-         * Perform the lazy TSS's I/O bitmap copy. If the TSS has an
-         * invalid offset set (the LAZY one) and the faulting thread has
-         * a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS
-         * and we set the offset field correctly. Then we let the CPU to
-         * restart the faulting instruction.
-         */
-        if (tss->x86_tss.io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
-            thread->io_bitmap_ptr) {
-                memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
-                       thread->io_bitmap_max);
-                /*
-                 * If the previously set map was extending to higher ports
-                 * than the current one, pad extra space with 0xff (no access).
-                 */
-                if (thread->io_bitmap_max < tss->io_bitmap_max) {
-                        memset((char *) tss->io_bitmap +
-                                thread->io_bitmap_max, 0xff,
-                                tss->io_bitmap_max - thread->io_bitmap_max);
-                }
-                tss->io_bitmap_max = thread->io_bitmap_max;
-                tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
-                tss->io_bitmap_owner = thread;
-                put_cpu();
-
+        if (lazy_iobitmap_copy()) {
+                /* restart the faulting instruction */
                 return;
         }
-        put_cpu();
 
         if (regs->flags & X86_VM_MASK)
                 goto gp_in_vm86;