[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>

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 7d401b00d8227dbd6182524259a402822a903db6..601d332c4b79edc11252d6a835bbe77e6a2812e9 100644 (file)
--- 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.