[PATCH] x86-64: miscellaneous entry.S adjustments

This patch:
- makes ret_from_sys_call no longer global (all external users were
  previously switched to use int_ret_from_sys_call)
- adjusts placement of a CFI_{REMEMBER,RESTORE}_STATE pair to better
  fit logic flow
- eliminates an unnecessary pair of CFI_{REMEMBER,RESTORE}_STATE
- glues together function- and unwinder-wise the previously separate
  system_call and int_ret_from_sys_call function fragments
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>

arch/x86_64/kernel/entry.S

@@ -230,7 +230,6 @@ ENTRY(system_call)
 	CFI_REL_OFFSET rip,RIP-ARGOFFSET
 	GET_THREAD_INFO(%rcx)
 	testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),threadinfo_flags(%rcx)
-	CFI_REMEMBER_STATE
 	jnz tracesys
 	cmpq $__NR_syscall_max,%rax
 	ja badsys
@@ -241,7 +240,6 @@ ENTRY(system_call)
  * Syscall return path ending with SYSRET (fast path)
  * Has incomplete stack frame and undefined top of stack. 
  */		
-	.globl ret_from_sys_call
 ret_from_sys_call:
 	movl $_TIF_ALLWORK_MASK,%edi
 	/* edi:	flagmask */
@@ -251,8 +249,8 @@ sysret_check:
 	TRACE_IRQS_OFF
 	movl threadinfo_flags(%rcx),%edx
 	andl %edi,%edx
-	CFI_REMEMBER_STATE
 	jnz  sysret_careful 
+	CFI_REMEMBER_STATE
 	/*
 	 * sysretq will re-enable interrupts:
 	 */
@@ -265,10 +263,10 @@ sysret_check:
 	swapgs
 	sysretq
 
+	CFI_RESTORE_STATE
 	/* Handle reschedules */
 	/* edx:	work, edi: workmask */	
 sysret_careful:
-	CFI_RESTORE_STATE
 	bt $TIF_NEED_RESCHED,%edx
 	jnc sysret_signal
 	TRACE_IRQS_ON
@@ -306,7 +304,6 @@ badsys:
 
 	/* Do syscall tracing */
 tracesys:			 
-	CFI_RESTORE_STATE
 	SAVE_REST
 	movq $-ENOSYS,RAX(%rsp)
 	FIXUP_TOP_OF_STACK %rdi
@@ -322,32 +319,13 @@ tracesys:
 	call *sys_call_table(,%rax,8)
 1:	movq %rax,RAX-ARGOFFSET(%rsp)
 	/* Use IRET because user could have changed frame */
-	jmp int_ret_from_sys_call
-	CFI_ENDPROC
-END(system_call)
 		
 /* 
  * Syscall return path ending with IRET.
  * Has correct top of stack, but partial stack frame.
  */
-ENTRY(int_ret_from_sys_call)
-	CFI_STARTPROC	simple
-	CFI_SIGNAL_FRAME
-	CFI_DEF_CFA	rsp,SS+8-ARGOFFSET
-	/*CFI_REL_OFFSET	ss,SS-ARGOFFSET*/
-	CFI_REL_OFFSET	rsp,RSP-ARGOFFSET
-	/*CFI_REL_OFFSET	rflags,EFLAGS-ARGOFFSET*/
-	/*CFI_REL_OFFSET	cs,CS-ARGOFFSET*/
-	CFI_REL_OFFSET	rip,RIP-ARGOFFSET
-	CFI_REL_OFFSET	rdx,RDX-ARGOFFSET
-	CFI_REL_OFFSET	rcx,RCX-ARGOFFSET
-	CFI_REL_OFFSET	rax,RAX-ARGOFFSET
-	CFI_REL_OFFSET	rdi,RDI-ARGOFFSET
-	CFI_REL_OFFSET	rsi,RSI-ARGOFFSET
-	CFI_REL_OFFSET	r8,R8-ARGOFFSET
-	CFI_REL_OFFSET	r9,R9-ARGOFFSET
-	CFI_REL_OFFSET	r10,R10-ARGOFFSET
-	CFI_REL_OFFSET	r11,R11-ARGOFFSET
+	.globl int_ret_from_sys_call
+int_ret_from_sys_call:
 	cli
 	TRACE_IRQS_OFF
 	testl $3,CS-ARGOFFSET(%rsp)
@@ -394,8 +372,6 @@ int_very_careful:
 	popq %rdi
 	CFI_ADJUST_CFA_OFFSET -8
 	andl $~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edi
-	cli
-	TRACE_IRQS_OFF
 	jmp int_restore_rest
 	
 int_signal:
@@ -411,7 +387,7 @@ int_restore_rest:
 	TRACE_IRQS_OFF
 	jmp int_with_check
 	CFI_ENDPROC
-END(int_ret_from_sys_call)
+END(system_call)
 		
 /* 
  * Certain special system calls that need to save a complete full stack frame.