[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>

1 files changed, 6 insertions, 30 deletions

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 7d401b00d822..601d332c4b79 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/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.