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Date: Sat, 22 Jul 2006 23:34:48 +1000 From: Rusty Russell <rusty@...tcorp.com.au> To: Chuck Ebbert <76306.1226@...puserve.com> Cc: linux-kernel <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...l.org>, Andi Kleen <ak@....de> Subject: Re: [PATCH 5/6] Begin abstraction of sensitive instructions: asm files On Fri, 2006-07-21 at 23:23 -0400, Chuck Ebbert wrote: > In-Reply-To:<1153527274.13699.36.camel@...alhost.localdomain> > > On Sat, 22 Jul 2006 10:14:34 +1000, Rusty Russell wrote: > > +#define GET_CR0 movl %cr0, %eax > > Could you change GET_CR0 to MOV_CR0_EAX? GET_CR0 seems like it's > taking a reference or something. Hi Chuck, Agreed: certainly eax should be mentioned. GET_CR0_INTO_EAX? MOV is a bit close to describing how it's happening (which, on paravirt it might not be) so it might lead the reader to unwarranted assumptions. === 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@...tcorp.com.au> Index: working-2.6.18-rc2-hg-paravirt/arch/i386/kernel/entry.S =================================================================== --- working-2.6.18-rc2-hg-paravirt.orig/arch/i386/kernel/entry.S 2006-07-21 21:09:22.000000000 +1000 +++ working-2.6.18-rc2-hg-paravirt/arch/i386/kernel/entry.S 2006-07-22 04:32:25.000000000 +1000 @@ -76,8 +76,15 @@ 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 @@ -234,7 +241,7 @@ cmpl $SEGMENT_RPL_MASK, %eax jb resume_kernel # returning to kernel or vm86-space 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 @@ -245,7 +252,7 @@ #ifdef CONFIG_PREEMPT ENTRY(resume_kernel) - cli + DISABLE_INTERRUPTS cmpl $0,TI_preempt_count(%ebp) # non-zero preempt_count ? jnz restore_nocheck need_resched: @@ -273,7 +280,7 @@ * 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*/ @@ -318,7 +325,7 @@ 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 @@ -328,8 +335,7 @@ movl OLDESP(%esp), %ecx xorl %ebp,%ebp TRACE_IRQS_ON - sti - sysexit + ENABLE_INTERRUPTS_SYSEXIT CFI_ENDPROC @@ -354,7 +360,7 @@ 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 @@ -379,11 +385,11 @@ 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 @@ -407,7 +413,7 @@ * 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, @@ -417,7 +423,7 @@ 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 @@ -432,7 +438,7 @@ 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 @@ -488,7 +494,7 @@ 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 @@ -667,7 +673,7 @@ 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 @@ -797,7 +803,7 @@ 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 Index: working-2.6.18-rc2-hg-paravirt/include/asm-i386/spinlock.h =================================================================== --- working-2.6.18-rc2-hg-paravirt.orig/include/asm-i386/spinlock.h 2006-07-21 20:27:59.000000000 +1000 +++ working-2.6.18-rc2-hg-paravirt/include/asm-i386/spinlock.h 2006-07-22 04:32:51.000000000 +1000 @@ -17,6 +17,9 @@ * (the type definitions are in asm/spinlock_types.h) */ +#define CLI_STRING "cli" +#define STI_STRING "sti" + #define __raw_spin_is_locked(x) \ (*(volatile signed char *)(&(x)->slock) <= 0) @@ -43,12 +46,12 @@ "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" \ -- Help! 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