Commit 0da5db31 authored by Rusty Russell's avatar Rusty Russell Committed by Andi Kleen
Browse files

[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: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 7b0bda74

arch/i386/kernel/entry.S

+22 −16
Original line number Diff line number Diff line
@@ -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

include/asm-i386/spinlock.h

+5 −2
Original line number Diff line number Diff line
@@ -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"

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