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Commit 7041d281 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390: scrub registers on kernel entry and KVM exit 



Clear all user space registers on entry to the kernel and all KVM guest
registers on KVM guest exit if the register does not contain either a
parameter or a result value.

Reviewed-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 364e3f90

arch/s390/kernel/entry.S

+47 −0
Original line number Diff line number Diff line
@@ -248,6 +248,12 @@ ENTRY(sie64a) 
sie_exit:

	lg	%r14,__SF_EMPTY+8(%r15)		# load guest register save area

	stmg	%r0,%r13,0(%r14)		# save guest gprs 0-13

	xgr	%r0,%r0				# clear guest registers to

	xgr	%r1,%r1				# prevent speculative use

	xgr	%r2,%r2

	xgr	%r3,%r3

	xgr	%r4,%r4

	xgr	%r5,%r5

	lmg	%r6,%r14,__SF_GPRS(%r15)	# restore kernel registers

	lg	%r2,__SF_EMPTY+16(%r15)		# return exit reason code

	br	%r14
@@ -282,6 +288,8 @@ ENTRY(system_call) 
.Lsysc_vtime:

	UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER

	stmg	%r0,%r7,__PT_R0(%r11)

	# clear user controlled register to prevent speculative use

	xgr	%r0,%r0

	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_SYNC

	mvc	__PT_PSW(16,%r11),__LC_SVC_OLD_PSW

	mvc	__PT_INT_CODE(4,%r11),__LC_SVC_ILC
@@ -561,6 +569,15 @@ ENTRY(pgm_check_handler) 
4:	lgr	%r13,%r11

	la	%r11,STACK_FRAME_OVERHEAD(%r15)

	stmg	%r0,%r7,__PT_R0(%r11)

	# clear user controlled registers to prevent speculative use

	xgr	%r0,%r0

	xgr	%r1,%r1

	xgr	%r2,%r2

	xgr	%r3,%r3

	xgr	%r4,%r4

	xgr	%r5,%r5

	xgr	%r6,%r6

	xgr	%r7,%r7

	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_SYNC

	stmg	%r8,%r9,__PT_PSW(%r11)

	mvc	__PT_INT_CODE(4,%r11),__LC_PGM_ILC
@@ -626,6 +643,16 @@ ENTRY(io_int_handler) 
	lmg	%r8,%r9,__LC_IO_OLD_PSW

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_ENTER_TIMER

	stmg	%r0,%r7,__PT_R0(%r11)

	# clear user controlled registers to prevent speculative use

	xgr	%r0,%r0

	xgr	%r1,%r1

	xgr	%r2,%r2

	xgr	%r3,%r3

	xgr	%r4,%r4

	xgr	%r5,%r5

	xgr	%r6,%r6

	xgr	%r7,%r7

	xgr	%r10,%r10

	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC

	stmg	%r8,%r9,__PT_PSW(%r11)

	mvc	__PT_INT_CODE(12,%r11),__LC_SUBCHANNEL_ID
@@ -839,6 +866,16 @@ ENTRY(ext_int_handler) 
	lmg	%r8,%r9,__LC_EXT_OLD_PSW

	SWITCH_ASYNC __LC_SAVE_AREA_ASYNC,__LC_ASYNC_ENTER_TIMER

	stmg	%r0,%r7,__PT_R0(%r11)

	# clear user controlled registers to prevent speculative use

	xgr	%r0,%r0

	xgr	%r1,%r1

	xgr	%r2,%r2

	xgr	%r3,%r3

	xgr	%r4,%r4

	xgr	%r5,%r5

	xgr	%r6,%r6

	xgr	%r7,%r7

	xgr	%r10,%r10

	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC

	stmg	%r8,%r9,__PT_PSW(%r11)

	lghi	%r1,__LC_EXT_PARAMS2
@@ -1046,6 +1083,16 @@ ENTRY(mcck_int_handler) 
.Lmcck_skip:

	lghi	%r14,__LC_GPREGS_SAVE_AREA+64

	stmg	%r0,%r7,__PT_R0(%r11)

	# clear user controlled registers to prevent speculative use

	xgr	%r0,%r0

	xgr	%r1,%r1

	xgr	%r2,%r2

	xgr	%r3,%r3

	xgr	%r4,%r4

	xgr	%r5,%r5

	xgr	%r6,%r6

	xgr	%r7,%r7

	xgr	%r10,%r10

	mvc	__PT_R8(64,%r11),0(%r14)

	stmg	%r8,%r9,__PT_PSW(%r11)

	xc	__PT_FLAGS(8,%r11),__PT_FLAGS(%r11)