[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>

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 4b08452..3872fca 100644 (file)
--- 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

diff --git a/include/asm-i386/spinlock.h b/include/asm-i386/spinlock.h
index 3243293..b0b3043 100644 (file)
--- a/include/asm-i386/spinlock.h
+++ b/include/asm-i386/spinlock.h
@@ -7,6 +7,9 @@
 #include <asm/processor.h>
 #include <linux/compiler.h>
 
+#define CLI_STRING     "cli"
+#define STI_STRING     "sti"
+
 /*
  * Your basic SMP spinlocks, allowing only a single CPU anywhere
  *
@@ -55,12 +58,12 @@ static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long fla
                "2:\t"
                "testl $0x200, %1\n\t"
                "jz 4f\n\t"
-               "sti\n"
+               STI_STRING "\n"
                "3:\t"
                "rep;nop\n\t"
                "cmpb $0, %0\n\t"
                "jle 3b\n\t"
-               "cli\n\t"
+               CLI_STRING "\n\t"
                "jmp 1b\n"
                "4:\t"
                "rep;nop\n\t"