3 files changed, 21 insertions, 12 deletions

diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index 9603ccaba997..a4f67a6e6821 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -131,15 +131,13 @@ unsigned long profile_pc(struct pt_regs *regs)
         unsigned long pc = instruction_pointer(regs);
 
 #ifdef CONFIG_SMP
-        if (!user_mode_vm(regs) && in_lock_functions(pc)) {
+        if (!v8086_mode(regs) && SEGMENT_IS_KERNEL_CODE(regs->xcs) &&
+            in_lock_functions(pc)) {
 #ifdef CONFIG_FRAME_POINTER
                 return *(unsigned long *)(regs->ebp + 4);
 #else
-                unsigned long *sp;
-                if ((regs->xcs & 3) == 0)
-                        sp = (unsigned long *)&regs->esp;
-                else
-                        sp = (unsigned long *)regs->esp;
+                unsigned long *sp = (unsigned long *)&regs->esp;
+
                 /* Return address is either directly at stack pointer
                    or above a saved eflags. Eflags has bits 22-31 zero,
                    kernel addresses don't. */
diff --git a/include/asm-i386/ptrace.h b/include/asm-i386/ptrace.h
index 1646996c73da..6002597b9e12 100644
--- a/include/asm-i386/ptrace.h
+++ b/include/asm-i386/ptrace.h
@@ -49,6 +49,10 @@ static inline int user_mode_vm(struct pt_regs *regs)
 {
         return ((regs->xcs & SEGMENT_RPL_MASK) | (regs->eflags & VM_MASK)) >= USER_RPL;
 }
+static inline int v8086_mode(struct pt_regs *regs)
+{
+        return (regs->eflags & VM_MASK);
+}
 
 #define instruction_pointer(regs) ((regs)->eip)
 #define regs_return_value(regs) ((regs)->eax)
diff --git a/include/asm-i386/segment.h b/include/asm-i386/segment.h
index 3c796af33776..065f10bfa487 100644
--- a/include/asm-i386/segment.h
+++ b/include/asm-i386/segment.h
@@ -83,14 +83,8 @@
  * The GDT has 32 entries
  */
 #define GDT_ENTRIES 32
-
 #define GDT_SIZE (GDT_ENTRIES * 8)
 
-/* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */
-#define SEGMENT_IS_FLAT_CODE(x)  (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8)
-/* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
-#define SEGMENT_IS_PNP_CODE(x)   (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)
-
 /* Simple and small GDT entries for booting only */
 
 #define GDT_ENTRY_BOOT_CS               2
@@ -134,4 +128,17 @@
 #ifndef CONFIG_PARAVIRT
 #define get_kernel_rpl()  0
 #endif
+/*
+ * Matching rules for certain types of segments.
+ */
+
+/* Matches only __KERNEL_CS, ignoring PnP / USER / APM segments */
+#define SEGMENT_IS_KERNEL_CODE(x) (((x) & 0xfc) == GDT_ENTRY_KERNEL_CS * 8)
+
+/* Matches __KERNEL_CS and __USER_CS (they must be 2 entries apart) */
+#define SEGMENT_IS_FLAT_CODE(x)  (((x) & 0xec) == GDT_ENTRY_KERNEL_CS * 8)
+
+/* Matches PNP_CS32 and PNP_CS16 (they must be consecutive) */
+#define SEGMENT_IS_PNP_CODE(x)   (((x) & 0xf4) == GDT_ENTRY_PNPBIOS_BASE * 8)
+
 #endif