diff options
| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2016-12-28 11:33:48 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-07-05 14:37:20 +0200 |
| commit | 5416a88c2fef39a9d75ef59057625a2002959dff (patch) | |
| tree | acd1576197fae4de68e598b0fbc563566973e361 | |
| parent | 9a536d5872460def17d2279f81a4a4d09e36f620 (diff) | |
s390/ctl_reg: make __ctl_load a full memory barrier
[ Upstream commit e991c24d68b8c0ba297eeb7af80b1e398e98c33f ]
We have quite a lot of code that depends on the order of the
__ctl_load inline assemby and subsequent memory accesses, like
e.g. disabling lowcore protection and the writing to lowcore.
Since the __ctl_load macro does not have memory barrier semantics, nor
any other dependencies the compiler is, theoretically, free to shuffle
code around. Or in other words: storing to lowcore could happen before
lowcore protection is disabled.
In order to avoid this class of potential bugs simply add a full
memory barrier to the __ctl_load macro.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/s390/include/asm/ctl_reg.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/s390/include/asm/ctl_reg.h b/arch/s390/include/asm/ctl_reg.h index d7697ab802f6..8e136b88cdf4 100644 --- a/arch/s390/include/asm/ctl_reg.h +++ b/arch/s390/include/asm/ctl_reg.h @@ -15,7 +15,9 @@ BUILD_BUG_ON(sizeof(addrtype) != (high - low + 1) * sizeof(long));\ asm volatile( \ " lctlg %1,%2,%0\n" \ - : : "Q" (*(addrtype *)(&array)), "i" (low), "i" (high));\ + : \ + : "Q" (*(addrtype *)(&array)), "i" (low), "i" (high) \ + : "memory"); \ } #define __ctl_store(array, low, high) { \ |