From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Cornelia Huck <cohuck@redhat.com>,
David Hildenbrand <david@redhat.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jon Masters <jcm@redhat.com>, Marcus Meissner <meissner@suse.de>,
Jiri Kosina <jkosina@suse.cz>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
Pavel Machek <pavel@ucw.cz>,
David Woodhouse <dwmw2@infradead.org>
Subject: [PATCH 1/6] s390: scrub registers on kernel entry and KVM exit
Date: Wed, 7 Feb 2018 08:00:06 +0100 [thread overview]
Message-ID: <1517986811-27819-2-git-send-email-schwidefsky@de.ibm.com> (raw)
In-Reply-To: <1517986811-27819-1-git-send-email-schwidefsky@de.ibm.com>
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: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/kernel/entry.S | 47 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 6cd444d..5d87eda 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -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)
--
2.7.4
next prev parent reply other threads:[~2018-02-07 7:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-07 7:00 [PATCH 0/6] s390: improve speculative execution handling v3 Martin Schwidefsky
2018-02-07 7:00 ` Martin Schwidefsky [this message]
2018-02-07 7:00 ` [PATCH 2/6] s390: add optimized array_index_mask_nospec Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 3/6] s390/alternative: use a copy of the facility bit mask Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 4/6] s390: add options to change branch prediction behaviour for the kernel Martin Schwidefsky
2018-02-07 10:02 ` Pavel Machek
2018-02-07 11:49 ` Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 5/6] s390: run user space and KVM guests with modified branch prediction Martin Schwidefsky
2018-02-07 7:00 ` [PATCH 6/6] s390: introduce execute-trampolines for branches Martin Schwidefsky
2018-02-07 10:07 ` Pavel Machek
2018-02-07 11:51 ` Martin Schwidefsky
2018-02-07 12:07 ` David Woodhouse
2018-02-07 12:17 ` Martin Schwidefsky
2018-02-07 12:20 ` David Woodhouse
2018-02-07 17:55 ` Linus Torvalds
2018-02-07 23:44 ` Masahiro Yamada
2018-02-08 0:05 ` Linus Torvalds
2018-02-08 0:57 ` Kees Cook
2018-02-08 17:11 ` Masahiro Yamada
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