[PATCH] i386: Abstract sensitive instructions

Abstract sensitive instructions in assembler code, replacing them with macros
(which currently are #defined to the native versions).  We use long names:
assembler is case-insensitive, so if something goes wrong and macros do not
expand, it would assemble anyway.

Resulting object files are exactly the same as before.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 22 insertions, 16 deletions

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 4b0845249222..3872fca5c74a 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -76,8 +76,15 @@ DF_MASK		= 0x00000400
 NT_MASK         = 0x00004000
 VM_MASK         = 0x00020000
 
+/* These are replaces for paravirtualization */
+#define DISABLE_INTERRUPTS              cli
+#define ENABLE_INTERRUPTS               sti
+#define ENABLE_INTERRUPTS_SYSEXIT       sti; sysexit
+#define INTERRUPT_RETURN                iret
+#define GET_CR0_INTO_EAX                movl %cr0, %eax
+
 #ifdef CONFIG_PREEMPT
-#define preempt_stop            cli; TRACE_IRQS_OFF
+#define preempt_stop            DISABLE_INTERRUPTS; TRACE_IRQS_OFF
 #else
 #define preempt_stop
 #define resume_kernel           restore_nocheck
@@ -236,7 +243,7 @@ check_userspace:
         testl $(VM_MASK | 3), %eax
         jz resume_kernel
 ENTRY(resume_userspace)
-        cli                             # make sure we don't miss an interrupt
+        DISABLE_INTERRUPTS              # make sure we don't miss an interrupt
                                         # setting need_resched or sigpending
                                         # between sampling and the iret
         movl TI_flags(%ebp), %ecx
@@ -247,7 +254,7 @@ ENTRY(resume_userspace)
 
 #ifdef CONFIG_PREEMPT
 ENTRY(resume_kernel)
-        cli
+        DISABLE_INTERRUPTS
         cmpl $0,TI_preempt_count(%ebp)  # non-zero preempt_count ?
         jnz restore_nocheck
 need_resched:
@@ -275,7 +282,7 @@ sysenter_past_esp:
          * No need to follow this irqs on/off section: the syscall
          * disabled irqs and here we enable it straight after entry:
          */
-        sti
+        ENABLE_INTERRUPTS
         pushl $(__USER_DS)
         CFI_ADJUST_CFA_OFFSET 4
         /*CFI_REL_OFFSET ss, 0*/
@@ -320,7 +327,7 @@ sysenter_past_esp:
         jae syscall_badsys
         call *sys_call_table(,%eax,4)
         movl %eax,EAX(%esp)
-        cli
+        DISABLE_INTERRUPTS
         TRACE_IRQS_OFF
         movl TI_flags(%ebp), %ecx
         testw $_TIF_ALLWORK_MASK, %cx
@@ -330,8 +337,7 @@ sysenter_past_esp:
         movl OLDESP(%esp), %ecx
         xorl %ebp,%ebp
         TRACE_IRQS_ON
-        sti
-        sysexit
+        ENABLE_INTERRUPTS_SYSEXIT
         CFI_ENDPROC
 
 
@@ -356,7 +362,7 @@ syscall_call:
         call *sys_call_table(,%eax,4)
         movl %eax,EAX(%esp)             # store the return value
 syscall_exit:
-        cli                             # make sure we don't miss an interrupt
+        DISABLE_INTERRUPTS              # make sure we don't miss an interrupt
                                         # setting need_resched or sigpending
                                         # between sampling and the iret
         TRACE_IRQS_OFF
@@ -381,11 +387,11 @@ restore_nocheck_notrace:
         RESTORE_REGS
         addl $4, %esp
         CFI_ADJUST_CFA_OFFSET -4
-1:      iret
+1:      INTERRUPT_RETURN
 .section .fixup,"ax"
 iret_exc:
         TRACE_IRQS_ON
-        sti
+        ENABLE_INTERRUPTS
         pushl $0                        # no error code
         pushl $do_iret_error
         jmp error_code
@@ -409,7 +415,7 @@ ldt_ss:
          * dosemu and wine happy. */
         subl $8, %esp           # reserve space for switch16 pointer
         CFI_ADJUST_CFA_OFFSET 8
-        cli
+        DISABLE_INTERRUPTS
         TRACE_IRQS_OFF
         movl %esp, %eax
         /* Set up the 16bit stack frame with switch32 pointer on top,
@@ -419,7 +425,7 @@ ldt_ss:
         TRACE_IRQS_IRET
         RESTORE_REGS
         lss 20+4(%esp), %esp    # switch to 16bit stack
-1:      iret
+1:      INTERRUPT_RETURN
 .section __ex_table,"a"
         .align 4
         .long 1b,iret_exc
@@ -434,7 +440,7 @@ work_pending:
         jz work_notifysig
 work_resched:
         call schedule
-        cli                             # make sure we don't miss an interrupt
+        DISABLE_INTERRUPTS              # make sure we don't miss an interrupt
                                         # setting need_resched or sigpending
                                         # between sampling and the iret
         TRACE_IRQS_OFF
@@ -490,7 +496,7 @@ syscall_exit_work:
         testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP), %cl
         jz work_pending
         TRACE_IRQS_ON
-        sti                             # could let do_syscall_trace() call
+        ENABLE_INTERRUPTS               # could let do_syscall_trace() call
                                         # schedule() instead
         movl %esp, %eax
         movl $1, %edx
@@ -668,7 +674,7 @@ ENTRY(device_not_available)
         pushl $-1                       # mark this as an int
         CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
-        movl %cr0, %eax
+        GET_CR0_INTO_EAX
         testl $0x4, %eax                # EM (math emulation bit)
         jne device_not_available_emulate
         preempt_stop
@@ -811,7 +817,7 @@ nmi_16bit_stack:
         call do_nmi
         RESTORE_REGS
         lss 12+4(%esp), %esp            # back to 16bit stack
-1:      iret
+1:      INTERRUPT_RETURN
         CFI_ENDPROC
 .section __ex_table,"a"
         .align 4