Revert "[PATCH] x86-64: Fix up handling of non canonical user RIPs"

[linux-2.6.git] / arch / x86_64 / kernel / entry.S

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 22cb6ee074b91994df738b77e17aa8ca93cf7b58..7c10e9009d611173d13fddf90650a9dfe78ec7db 100644 (file)
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -178,12 +178,6 @@ rff_trace:
  * Interrupts are off on entry.
  * Only called from user space.
  *
  * Interrupts are off on entry.
  * Only called from user space.
  *

- * EM64T CPUs have somewhat weird error reporting for non canonical RIPs in SYSRET. 
- * We can't handle any exceptions there because the exception handler would
- * end up running on the user stack which is unsafe. To avoid problems 
- * any code that might end up with a user touched pt_regs should return
- * using int_ret_from_syscall.
- *

  * XXX if we had a free scratch register we could save the RSP into the stack frame
  *      and report it properly in ps. Unfortunately we haven't.
  */                                    
  * XXX if we had a free scratch register we could save the RSP into the stack frame
  *      and report it properly in ps. Unfortunately we haven't.
  */                                    


@@ -260,9 +254,7 @@ sysret_signal:
        xorl %esi,%esi # oldset -> arg2
        call ptregscall_common
 1:     movl $_TIF_NEED_RESCHED,%edi
        xorl %esi,%esi # oldset -> arg2
        call ptregscall_common
 1:     movl $_TIF_NEED_RESCHED,%edi

-       /* Stack frame might have been changed. The IRET path does
-          some additional checks to handle this */
-       jmp int_with_check
+       jmp sysret_check

        
 badsys:
        movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
        
 badsys:
        movq $-ENOSYS,RAX-ARGOFFSET(%rsp)


@@ -288,8 +280,7 @@ tracesys:
        call syscall_trace_leave
        RESTORE_TOP_OF_STACK %rbx
        RESTORE_REST
        call syscall_trace_leave
        RESTORE_TOP_OF_STACK %rbx
        RESTORE_REST

-       /* Stack frame might have been changed. Use the more careful IRET path */
-       jmp int_ret_from_sys_call
+       jmp ret_from_sys_call

        CFI_ENDPROC
                
 /* 
        CFI_ENDPROC
                
 /* 


@@ -417,9 +408,25 @@ ENTRY(stub_execve)
        CFI_ADJUST_CFA_OFFSET -8
        CFI_REGISTER rip, r11
        SAVE_REST
        CFI_ADJUST_CFA_OFFSET -8
        CFI_REGISTER rip, r11
        SAVE_REST

+       movq %r11, %r15
+       CFI_REGISTER rip, r15

        FIXUP_TOP_OF_STACK %r11
        call sys_execve
        FIXUP_TOP_OF_STACK %r11
        call sys_execve

+       GET_THREAD_INFO(%rcx)
+       bt $TIF_IA32,threadinfo_flags(%rcx)
+       CFI_REMEMBER_STATE
+       jc exec_32bit

        RESTORE_TOP_OF_STACK %r11
        RESTORE_TOP_OF_STACK %r11

+       movq %r15, %r11
+       CFI_REGISTER rip, r11
+       RESTORE_REST
+       pushq %r11
+       CFI_ADJUST_CFA_OFFSET 8
+       CFI_REL_OFFSET rip, 0
+       ret
+
+exec_32bit:
+       CFI_RESTORE_STATE

        movq %rax,RAX(%rsp)
        RESTORE_REST
        jmp int_ret_from_sys_call
        movq %rax,RAX(%rsp)
        RESTORE_REST
        jmp int_ret_from_sys_call