[PATCH] i386: move kernel_thread_helper into entry.S

And add proper CFI annotation to it which was previously
impossible. This prevents "stuck" messages by the dwarf2 unwinder
when reaching the top of a kernel stack.

Includes feedback from Jan Beulich

Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>

2 files changed, 13 insertions, 9 deletions

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index ba22ec8fab5..dede506e5bd 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -950,6 +950,19 @@ ENTRY(arch_unwind_init_running)
 ENDPROC(arch_unwind_init_running)
 #endif
 
+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
+        call do_exit
+        CFI_ENDPROC
+ENDPROC(kernel_thread_helper)
+
 .section .rodata,"a"
 #include "syscall_table.S"
 
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index b741c3e1a5e..220aeca59c3 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -321,15 +321,6 @@ void show_regs(struct pt_regs * regs)
  * the "args".
  */
 extern void kernel_thread_helper(void);
-__asm__(".section .text\n"
-        ".align 4\n"
-        "kernel_thread_helper:\n\t"
-        "movl %edx,%eax\n\t"
-        "pushl %edx\n\t"
-        "call *%ebx\n\t"
-        "pushl %eax\n\t"
-        "call do_exit\n"
-        ".previous");
 
 /*
  * Create a kernel thread