x86, 32-bit: Use same regs as 64-bit for kernel_thread_helper

The arg should be in %eax, but that is clobbered by the return value
of clone.  The function pointer can be in any register.  Also, don't
push args onto the stack, since regparm(3) is the normal calling
convention now.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-4-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

2 files changed, 6 insertions, 10 deletions

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index cb12b9bfc9cc..44a8e0dc6737 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1047,12 +1047,8 @@ END(spurious_interrupt_bug)
 ENTRY(kernel_thread_helper)
         pushl $0                # fake return address for unwinder
         CFI_STARTPROC
-        movl %edx,%eax
-        push %edx
-        CFI_ADJUST_CFA_OFFSET 4
-        call *%ebx
-        push %eax
-        CFI_ADJUST_CFA_OFFSET 4
+        movl %edi,%eax
+        call *%esi
         call do_exit
         ud2                     # padding for call trace
         CFI_ENDPROC
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 506d5a7ba17c..bd874d2b6ab1 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -193,8 +193,8 @@ void show_regs(struct pt_regs *regs)
 }
 
 /*
- * This gets run with %bx containing the
- * function to call, and %dx containing
+ * This gets run with %si containing the
+ * function to call, and %di containing
  * the "args".
  */
 extern void kernel_thread_helper(void);
@@ -208,8 +208,8 @@ int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 
         memset(&regs, 0, sizeof(regs));
 
-        regs.bx = (unsigned long) fn;
-        regs.dx = (unsigned long) arg;
+        regs.si = (unsigned long) fn;
+        regs.di = (unsigned long) arg;
 
         regs.ds = __USER_DS;
         regs.es = __USER_DS;