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Date: Wed, 17 Jan 2018 10:48:39 +0100
From: Martin Schwidefsky <schwidefsky@...ibm.com>
To: linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
kvm@...r.kernel.org
Cc: Heiko Carstens <heiko.carstens@...ibm.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jon Masters <jcm@...hat.com>,
Marcus Meissner <meissner@...e.de>,
Jiri Kosina <jkosina@...e.cz>
Subject: [PATCH 6/6] 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.
Suggested-by: Christian Borntraeger <borntraeger@...ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
---
arch/s390/kernel/entry.S | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 2a22c03..47227d3 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -322,6 +322,12 @@ 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
+ xgr %r1,%r1
+ 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
@@ -358,6 +364,7 @@ ENTRY(system_call)
UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER
BPENTER __TI_flags(%r12),_TIF_NOBP
stmg %r0,%r7,__PT_R0(%r11)
+ 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
@@ -640,6 +647,14 @@ ENTRY(pgm_check_handler)
4: lgr %r13,%r11
la %r11,STACK_FRAME_OVERHEAD(%r15)
stmg %r0,%r7,__PT_R0(%r11)
+ xgr %r0,%r0 # clear user space registers
+ 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
@@ -706,6 +721,15 @@ 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)
+ xgr %r0,%r0 # clear user space registers
+ 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
@@ -924,6 +948,15 @@ 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)
+ xgr %r0,%r0 # clear user space registers
+ 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
@@ -1133,6 +1166,14 @@ ENTRY(mcck_int_handler)
.Lmcck_skip:
lghi %r14,__LC_GPREGS_SAVE_AREA+64
stmg %r0,%r7,__PT_R0(%r11)
+ xgr %r0,%r0 # clear user space registers
+ 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)
--
2.7.4
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