x86: fixup more paravirt fallout

[sfrench/cifs-2.6.git] / arch / x86 / kernel / entry_64.S

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index bea8474744ffb633ad2d367bc478ec8cae3fb962..6be39a387c5ae66780b0b5f946a71c336980fea8 100644 (file)
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -581,25 +581,41 @@ retint_restore_args:      /* return to kernel space */
         */
        TRACE_IRQS_IRETQ
 restore_args:
-       RESTORE_ARGS 0,8,0                                              
-iret_label:    
-#ifdef CONFIG_PARAVIRT
+       RESTORE_ARGS 0,8,0
+
+ENTRY(irq_return)
        INTERRUPT_RETURN
-#endif
+
+       .section __ex_table, "a"
+       .quad irq_return, bad_iret
+       .previous
+
+#ifdef CONFIG_PARAVIRT
 ENTRY(native_iret)
        iretq
 
        .section __ex_table,"a"
        .quad native_iret, bad_iret
        .previous
+#endif
+
        .section .fixup,"ax"
-       /* force a signal here? this matches i386 behaviour */
-       /* running with kernel gs */
 bad_iret:
-       movq $11,%rdi   /* SIGSEGV */
-       TRACE_IRQS_ON
-       ENABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI))
-       jmp do_exit
+       /*
+        * The iret traps when the %cs or %ss being restored is bogus.
+        * We've lost the original trap vector and error code.
+        * #GPF is the most likely one to get for an invalid selector.
+        * So pretend we completed the iret and took the #GPF in user mode.
+        *
+        * We are now running with the kernel GS after exception recovery.
+        * But error_entry expects us to have user GS to match the user %cs,
+        * so swap back.
+        */
+       pushq $0
+
+       SWAPGS
+       jmp general_protection
+
        .previous
 
        /* edi: workmask, edx: work */
@@ -796,7 +812,7 @@ paranoid_swapgs\trace:
        SWAPGS_UNSAFE_STACK
 paranoid_restore\trace:
        RESTORE_ALL 8
-       INTERRUPT_RETURN
+       jmp irq_return
 paranoid_userspace\trace:
        GET_THREAD_INFO(%rcx)
        movl threadinfo_flags(%rcx),%ebx
@@ -911,7 +927,7 @@ error_kernelspace:
           iret run with kernel gs again, so don't set the user space flag.
           B stepping K8s sometimes report an truncated RIP for IRET 
           exceptions returning to compat mode. Check for these here too. */
-       leaq iret_label(%rip),%rbp
+       leaq irq_return(%rip),%rbp
        cmpq %rbp,RIP(%rsp) 
        je   error_swapgs
        movl %ebp,%ebp  /* zero extend */