x86, 64-bit: Move kernel_thread to C
Prepare for merging with 32-bit.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1260380084-3707-2-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 63bca79..73d9b2c 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1166,63 +1166,20 @@
jmp 2b
.previous
-/*
- * Create a kernel thread.
- *
- * C extern interface:
- * extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
- *
- * asm input arguments:
- * rdi: fn, rsi: arg, rdx: flags
- */
-ENTRY(kernel_thread)
- CFI_STARTPROC
- FAKE_STACK_FRAME $child_rip
- SAVE_ALL
-
- # rdi: flags, rsi: usp, rdx: will be &pt_regs
- movq %rdx,%rdi
- orq kernel_thread_flags(%rip),%rdi
- movq $-1, %rsi
- movq %rsp, %rdx
-
- xorl %r8d,%r8d
- xorl %r9d,%r9d
-
- # clone now
- call do_fork
- movq %rax,RAX(%rsp)
- xorl %edi,%edi
-
- /*
- * It isn't worth to check for reschedule here,
- * so internally to the x86_64 port you can rely on kernel_thread()
- * not to reschedule the child before returning, this avoids the need
- * of hacks for example to fork off the per-CPU idle tasks.
- * [Hopefully no generic code relies on the reschedule -AK]
- */
- RESTORE_ALL
- UNFAKE_STACK_FRAME
- ret
- CFI_ENDPROC
-END(kernel_thread)
-
-ENTRY(child_rip)
+ENTRY(kernel_thread_helper)
pushq $0 # fake return address
CFI_STARTPROC
/*
* Here we are in the child and the registers are set as they were
* at kernel_thread() invocation in the parent.
*/
- movq %rdi, %rax
- movq %rsi, %rdi
- call *%rax
+ call *%rsi
# exit
mov %eax, %edi
call do_exit
ud2 # padding for call trace
CFI_ENDPROC
-END(child_rip)
+END(kernel_thread_helper)
/*
* execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
